Adsorption characteristics of a cationic porphyrin on nanoclay at various pHZachary Rice
- The document analyzes the adsorption behavior of a cationic porphyrin molecule (TMAP) onto montmorillonite clay at various pH levels using buffers.
- Spectroscopic analysis showed TMAP adsorbed to the clay in a monolayer at low and high pH, while slightly acidic/neutral pH caused it to possibly rearrange or form aggregates on the surface.
- Absorption spectra of TMAP on clay exhibited red shifts compared to free TMAP in solution, indicating flattening and electron delocalization of the porphyrin rings when adsorbed.
This document discusses fluorinated amino acids, their properties, and potential applications. It begins by providing background on amino acids and fluorine chemistry. It then discusses several potential applications of fluorinated amino acids, including as probes to study protein structure and dynamics, as enzyme inhibitors, and for protein engineering to develop novel or improved properties. Specific examples discussed include using fluorinated amino acids to study protein complexes using NMR, incorporating them into peptides to provide immunological and kinetic data, and designing hyperstable protein folds using fluorinated building blocks. In summary, the document reviews promising applications of fluorinated amino acids in life sciences by exploiting their unique properties.
Understanding the adsorption mechanisms in nanostructured polymer films has become crucial for their use in technological applications, since film properties vary considerably with the experimental conditions utilized for film fabrication. In this paper, we employ small-angle X-ray
scattering (SAXS) to investigate solutions of polyanilines and correlate the chain conformations with morphological features of the nanostructured films obtained with atomic force microscopy (AFM). It is shown that aggregates formed already in solution affect the film morphology; in
particular, at early stages of adsorption film morphology appears entirely governed by the chain conformation in solution and adsorption of aggregates. We also use SAXS data for modeling poly(o-ethoxyaniline) (POEA) particle shape through an ab initio procedure based on simulated
annealing using the dummy atom model (DAM), which is then compared to the morphological features of POEA films fabricated with distinct pHs and doping acids. Interestingly, when the derivative POEA is doped with p-toluene sulfonic acid (TSA), the resulting films exhibit a fibrillar morphology—seen with atomic force microscopy and transmission electron microscopy—that is consistent with the cylindrical shape inferred from the SAXS data. This is in contrast with the globular morphology observed for POEA films doped with other acids.
The document discusses testing the reactivity between various Good's buffers and vernadite (δ-Mn(IV)O2). X-ray diffraction analysis found structural modifications to vernadite when reacted with EPPS, MOPSO, HEPES, and MOPS buffers, indicating partial reduction of Mn(IV) to Mn(III). The inertness of BES may be due to its molecular geometry lacking nitrogen-containing rings found in the other buffers. Diffraction patterns of vernadite reacted with varying concentrations of MOPS and EPPS showed stacking order was not directly proportional to buffer concentration.
The document discusses strategies for drug design such as varying substituents on lead compounds to optimize binding interactions and selectivity. Key strategies include varying alkyl and aryl substituents, extending functional groups, and modifying ring systems through expansions, contractions, or isosteric replacements. Other approaches involve simplifying molecule structures while retaining essential pharmacophores or rigidifying flexible structures to limit undesirable conformations. The goal is to systematically modify lead compounds to improve desired target interactions and properties like potency, selectivity, and toxicity profile.
Longifolene is common naturally occurring, oily liquid hydrocarbon found in the high boiling fraction of certain pine resins.
Juvabione is a terpene- derived-keto-ester that has been isolated from plant sources.
Morphine is a major component of opium,it is isolated from poppy straw of the opium poppy.
This document summarizes the synthesis and characterization of the oxomolybdenum mono-ene-1,2-dithiolate complex (Tp*)MoO(bdtCl2) (3). X-ray crystallography showed compound 3 crystallizes in the monoclinic space group P21/c, with a distorted octahedral coordination geometry around the Mo atom. IR, EPR, and electronic absorption spectroscopy indicate the chlorine substituents do not significantly perturb the electronic structure of the Mo(V) center, but solution redox potentials and gas-phase ionization energies are sensitive to remote substituent effects. The coordination environment of 3 is similar to the related complex (Tp*)MoO(
Nitrate Reductases: Structure, Functions, and Effect of Stress FactorsIPN
Nitrogen is essential for life and its biogeochemical cycle involves many processes. There are four main types of nitrate reductases - eukaryotic assimilatory, bacterial cytoplasmic assimilatory, membrane-bound respiratory, and periplasmic dissimilatory. They contain molybdenum and molybdenum cofactor in their active sites and catalyze the reduction of nitrate to nitrite. Bacterial nitrate reductases are further classified based on their electron donors as either ferredoxin-dependent or NADH-dependent. Genes encoding the enzymes for nitrate assimilation are often organized in operons along with those for nitrate and nitrite transporters.
Adsorption characteristics of a cationic porphyrin on nanoclay at various pHZachary Rice
- The document analyzes the adsorption behavior of a cationic porphyrin molecule (TMAP) onto montmorillonite clay at various pH levels using buffers.
- Spectroscopic analysis showed TMAP adsorbed to the clay in a monolayer at low and high pH, while slightly acidic/neutral pH caused it to possibly rearrange or form aggregates on the surface.
- Absorption spectra of TMAP on clay exhibited red shifts compared to free TMAP in solution, indicating flattening and electron delocalization of the porphyrin rings when adsorbed.
This document discusses fluorinated amino acids, their properties, and potential applications. It begins by providing background on amino acids and fluorine chemistry. It then discusses several potential applications of fluorinated amino acids, including as probes to study protein structure and dynamics, as enzyme inhibitors, and for protein engineering to develop novel or improved properties. Specific examples discussed include using fluorinated amino acids to study protein complexes using NMR, incorporating them into peptides to provide immunological and kinetic data, and designing hyperstable protein folds using fluorinated building blocks. In summary, the document reviews promising applications of fluorinated amino acids in life sciences by exploiting their unique properties.
Understanding the adsorption mechanisms in nanostructured polymer films has become crucial for their use in technological applications, since film properties vary considerably with the experimental conditions utilized for film fabrication. In this paper, we employ small-angle X-ray
scattering (SAXS) to investigate solutions of polyanilines and correlate the chain conformations with morphological features of the nanostructured films obtained with atomic force microscopy (AFM). It is shown that aggregates formed already in solution affect the film morphology; in
particular, at early stages of adsorption film morphology appears entirely governed by the chain conformation in solution and adsorption of aggregates. We also use SAXS data for modeling poly(o-ethoxyaniline) (POEA) particle shape through an ab initio procedure based on simulated
annealing using the dummy atom model (DAM), which is then compared to the morphological features of POEA films fabricated with distinct pHs and doping acids. Interestingly, when the derivative POEA is doped with p-toluene sulfonic acid (TSA), the resulting films exhibit a fibrillar morphology—seen with atomic force microscopy and transmission electron microscopy—that is consistent with the cylindrical shape inferred from the SAXS data. This is in contrast with the globular morphology observed for POEA films doped with other acids.
The document discusses testing the reactivity between various Good's buffers and vernadite (δ-Mn(IV)O2). X-ray diffraction analysis found structural modifications to vernadite when reacted with EPPS, MOPSO, HEPES, and MOPS buffers, indicating partial reduction of Mn(IV) to Mn(III). The inertness of BES may be due to its molecular geometry lacking nitrogen-containing rings found in the other buffers. Diffraction patterns of vernadite reacted with varying concentrations of MOPS and EPPS showed stacking order was not directly proportional to buffer concentration.
The document discusses strategies for drug design such as varying substituents on lead compounds to optimize binding interactions and selectivity. Key strategies include varying alkyl and aryl substituents, extending functional groups, and modifying ring systems through expansions, contractions, or isosteric replacements. Other approaches involve simplifying molecule structures while retaining essential pharmacophores or rigidifying flexible structures to limit undesirable conformations. The goal is to systematically modify lead compounds to improve desired target interactions and properties like potency, selectivity, and toxicity profile.
Longifolene is common naturally occurring, oily liquid hydrocarbon found in the high boiling fraction of certain pine resins.
Juvabione is a terpene- derived-keto-ester that has been isolated from plant sources.
Morphine is a major component of opium,it is isolated from poppy straw of the opium poppy.
This document summarizes the synthesis and characterization of the oxomolybdenum mono-ene-1,2-dithiolate complex (Tp*)MoO(bdtCl2) (3). X-ray crystallography showed compound 3 crystallizes in the monoclinic space group P21/c, with a distorted octahedral coordination geometry around the Mo atom. IR, EPR, and electronic absorption spectroscopy indicate the chlorine substituents do not significantly perturb the electronic structure of the Mo(V) center, but solution redox potentials and gas-phase ionization energies are sensitive to remote substituent effects. The coordination environment of 3 is similar to the related complex (Tp*)MoO(
Nitrate Reductases: Structure, Functions, and Effect of Stress FactorsIPN
Nitrogen is essential for life and its biogeochemical cycle involves many processes. There are four main types of nitrate reductases - eukaryotic assimilatory, bacterial cytoplasmic assimilatory, membrane-bound respiratory, and periplasmic dissimilatory. They contain molybdenum and molybdenum cofactor in their active sites and catalyze the reduction of nitrate to nitrite. Bacterial nitrate reductases are further classified based on their electron donors as either ferredoxin-dependent or NADH-dependent. Genes encoding the enzymes for nitrate assimilation are often organized in operons along with those for nitrate and nitrite transporters.
Austin Journal of Bioorganic & Organic Chemistry is a peer reviewed, open acc...Austin Publishing Group
Austin Journal of Bioorganic & Organic Chemistry is a peer reviewed, open access journal publishes manuscripts in the following areas but not limited to structures, synthesis, kinetics, organic synthesis, physical organic chemistry, supramolecular chemistry and chemical biology.
Austin Journal of Bioorganic & Organic Chemistry accepts original research articles, review articles, commentaries, Letters, perspectives, and rapid communication on all the aspects of Bioorganic & Organic Chemistry.
Meulepas, 2010, Trace Methane Oxidation And The Methane Dependency Of Sulfate...roelmeulepas
This research article investigates trace methane oxidation and the methane dependency of sulfate reduction in three types of anaerobic granular sludge. The researchers found that all sludge samples anaerobically oxidized 13C-labeled methane to 13C-labeled carbon dioxide, while also producing endogenous methane. Labeled methane oxidation rates followed methane production rates. The presence of sulfate inhibited both labeled methane oxidation and methanogenesis. Labeled methane oxidation was linked to methanogenesis, referred to as trace methane oxidation. The ratio of labeled methane oxidation to methanogenesis increased with higher methane partial pressures. Higher methane partial pressures also increased sulfate reduction and inhibited methanogenesis, giving sulfate reducers a competitive advantage over methanogens for common substrates.
This document summarizes research into how excess D,L-asparagine causes preferential crystallization of other coexisting racemic D,L-amino acids to have an enantiomeric excess during recrystallization. Experiments showed that when mixtures containing 12 different racemic D,L-amino acids were recrystallized with excess D,L-asparagine, the amino acids adopted the same chirality as asparagine. Similar results were found for other individual amino acids recrystallized with D,L-asparagine. This suggests D,L-asparagine can induce optical resolution and spontaneous symmetry breaking in mixtures of racemic amino acids during crystallization, potentially
1) The document describes the total synthesis of the natural product 10-hydroxyasimicin, which contains a bis-THF motif in its central core.
2) A key step was the development of a template approach to link two alkenol building blocks and induce stereocontrol during ring-closing metathesis to generate the bis-THF framework.
3) The synthesis involved coupling the building blocks, ring-closing metathesis, asymmetric dihydroxylation, macrocycle opening and elaboration to install side chains, and final coupling and deprotection to yield the target natural product.
A Comparison of Spectrophotometric and Oxidoreduction Potential Method for La...CrimsonpublishersMedical
Polyphenol oxidases (PPOs) oxidize phenolic compounds forming quinones, which undergo non-enzymatic reactions resulting in colored
compounds. We studied ferulic acid and catechol oxidation by Myceliophthora thermophila laccases using oxidoreduction potential (ORP or Eh) as a novel
method to determine PPO activity compared to the traditional spectrophotometric method. Eh varied time-dependently on ferulic acid and catechol
concentrations. Eh increased to a maximum value (Ehmax), then decreased irreversibly proportional with substrate concentration. The ΔEh curves of
ferulic acid and catechol oxidation at different concentrations by laccase exhibited two steps substrate oxidation: enzymatic and non-enzymatic; linear
segments with increasing and decreasing slopes (rate of ΔEh change). The Km values determined spectrophotometrically and ORP were 0.55, 0.75 and
0.39, 0.32mM for catechol and ferulic acid, respectively. The kinetic parameters (Km, Vmax) of enzymatic reaction were not significantly different between
the spectrophotometry and ORP methods. The ORP method is simple, low-cost and fast enabling the differentiation between the enzymatic and nonenzymatic phenol oxidation reactions
This document describes the chemoselective synthesis of isomeric pairs of (E),(Z)-mono-sulfones and bis-sulfones. The synthesis begins with compound (A) which is treated with thiophenol to yield a mixture of (E) and (Z) isomers of mono-sulfones. These isomers are separated. The mono-sulfones undergo further reactions including bromination and oxidation to yield (E) and (Z) isomers of bis-sulfones. UV irradiation is used to convert some E-isomers to the corresponding Z-isomers. The structures of the products are confirmed using spectral data and reactions are carried out to systematically synthesize both E and Z isomer pairs
1. Eleven new secondary metabolites were isolated from the endophytic fungal strain Phomopsis sp. XZ-26 from Camptotheca acuminate, including nine lovastatin analogues (oblongolides N-V and 5-11), one linear furanopolyketide, one monoterpene, and four known compounds.
2. The structures of the new compounds were elucidated using spectroscopic data including NMR, HR-MS, and X-ray crystallography. The new compounds included hydroxylated derivatives of known oblongolides and linear furanopolyketides.
3. The antimicrobial activities of some of the isolated compounds were evaluated but
This document summarizes research on the reduction of manganese porphyrins by flavoenzymes and mitochondrial particles, and how this relates to the catalytic reduction of peroxynitrite. It finds that flavoenzymes like xanthine oxidase and glucose oxidase, as well as mitochondrial Complex I and II, catalyze the reduction of manganese porphyrins using substrates like NADH and succinate. Reduced manganese porphyrins can then rapidly react with peroxynitrite via a two-electron process, producing nitrite and manganese porphyrin radicals. This redox cycle can protect peroxynitrite-sensitive targets in submitochondrial particles.
The study of intermolecular interactions at interfaces is essential for a number of applications, in addition
to the understanding of mechanisms involved in sensing and biosensing with liquid samples. There are,
however, only a few methods to probe such interfacial phenomena, one of which is the atomic force
spectroscopy (AFS) where the force between an atomic force microscope tip and the sample surface is
measured. In this study, we used AFS to estimate adhesion forces for a nanostructured film of poly(oethoxyaniline)
(POEA) doped with various acids, in measurements performed in air. The adhesion force
was lower for POEA doped with inorganic acids, such as HCl and H2SO4, than with organic acids, because
the counterions were screened by the ethoxy groups. Significantly, the morphology of POEA both in the
film and in solution depends on the doping acid. Using small-angle X-ray scattering (SAXS) we observed
that POEA dissolved in amixture of dimethyl acetamide exhibits a more extended coil-like conformation,
with smaller radius of gyration, than for POEA in water, as in the latter POEA solubility is lower. In AFS
measurements in a liquid cell, the force curves for a POEA layer displayed an attractive region for pH 5
due to van der Waals interactions, with no contribution from a double-layer since POEA was dedoped. In
contrast, for pH 3, POEA was doped and the repulsive double-layer force dominated. With AFS one is
therefore able to correlate molecular-level interactions with doping and morphology of semiconducting
polymers.
Methanotrophs are unique bacteria that use methane as their sole carbon and energy source. They play several important roles in the environment. First, they oxidize methane produced by archaea, reducing the amount of this potent greenhouse gas that enters the atmosphere. Second, they can degrade various organic pollutants using monooxygenase enzymes. Finally, they can remediate heavy metals by transforming more toxic forms into less toxic forms or facilitating precipitation. Methanotrophs thus aid in carbon and pollutant cycling while also helping to mitigate climate change.
This article discusses how methanol (MeOH) affects ascorbate (AsA) levels and related gene expression in Oncidium orchids. The study found that a low concentration of MeOH (50 mM) triggered hydrogen peroxide (H2O2) production and increased expression of AsA biosynthesis genes. However, a high MeOH concentration was toxic and depleted AsA levels. The increased gene expression from low MeOH levels was blocked by inhibitors of alcohol oxidase and NADPH oxidase, suggesting H2O2 is a signaling molecule regulating AsA gene expression in response to MeOH. The results help explain the mechanism by which MeOH stimulates AsA production in Oncidium at the molecular level.
This document is an assignment cover sheet for a student named Muhammad Zeeshan Ahmed for an assignment on organic solvents. It includes his student ID number, the assignment name, and due date. At the bottom is a declaration stating that the work is his own and has not been plagiarized. The accompanying document discusses various organic solvents like benzene, toluene, methanol, ethanol, and their properties, structures, and common uses.
This article discusses the solvent-conjugated polymer interactions of MEH-PPV and PF in various solvent solutions and thin films. Absorption and emission spectra were measured for polymer solutions, and thin films were prepared by dip or spin coating. The results show that MEH-PPV and PF exhibit different behaviors in solutions and films based on solvent quality and chain conformation. Specifically, dispersive forces were found to influence the effective conjugation of MEH-PPV chains, while energy transfer processes differed for the a and b chains of PF based on solvent. The memory effect, where chain conformations are maintained from solution to film, also varied between the two polymers and based on solvent used.
This document summarizes a study on the long-term effects of fertilization and soil warming on the decomposition of recalcitrant litter.
[1] The study examines how nitrogen addition and increased soil temperatures impact the later stages of litter decomposition, as most experiments only look at initial decomposition. [2] Results found that nitrogen addition had a neutralizing effect on the stimulation of decomposition from warming, as nitrogen addition and warming had interactive effects. [3] Further analyses are still needed to better understand the interaction between litter quality, warming, and nitrogen on decomposition over longer time periods.
Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce oxygen and energy in the form of glucose. It occurs in chloroplasts in plant leaves. Chloroplasts contain chlorophyll which captures light energy and drives the photosynthetic process. Photosynthesis splits water molecules to produce oxygen gas and electrons that are used to reduce carbon dioxide into sugars. It is a redox process consisting of two stages - the light-dependent reactions where ATP and NADPH are produced, and the Calvin cycle where sugars are assembled from carbon dioxide.
This proposal outlines a project to synthesize water soluble ruthenium precursors for use in coordination-driven self-assembly of metallacycles and cages. The student proposes modifying the arene ligand of common ruthenium molecular clips with an ethylene glycol group to impart improved water solubility. This water soluble clip will first be assembled into an oxalate-bridged complex and characterized. Alternative bridging ligands will then be explored, with a focus on aromatic ligands that show enhanced biological activity. The goal is to establish the water solubility of the resulting supramolecular coordination complexes and evaluate their potential for biological applications like drug delivery.
Extraction, identification and antioxidant activities of carotenoids from Ipo...Pragati Shah
These presentation slides are about extraction, identification and antioxidant activities of carotenoids from Ipomoea aquatica Forsk. It is commonly known as Morning water glory or water spinach which is rich source of nutrients,, wide array of carotenoids are extracted and identified by GC- MS techniques by researcher arond the Globe. Antioxidant activity of natural products can be evaluated by different assay; some them are discussed in these slides.
This document discusses phenylboronate chromatography (PBC), which uses phenylboronic acid ligands to selectively separate glycoproteins. PBC has advantages over other separation methods like lower cost and stability. The document examines the various interactions that can occur between proteins and phenylboronic acid ligands, including cis-diol bonding, electrostatic interactions, Lewis acid-base interactions, and hydrophobic interactions. It describes experiments using a library of glycosylated and non-glycosylated proteins to characterize the dominant interactions between different classes of proteins and the ligands over a pH range, and determine solution conditions that can minimize non-specific interactions.
This document describes the large scale photochemical synthesis of M@TiO2 nanocomposites (M = Ag, Pd, Au, Pt) and investigates their optical properties, catalytic activity for CO oxidation, and antibacterial effects. Well-dispersed M@TiO2 nanocomposites with particle diameters of 200-400 nm were synthesized using a clean photochemical method without additives. The sizes of the noble metal nanoparticles formed on the TiO2 support were approximately 1 nm for Pt, 5 nm for Au and Pd, and 2-20 nm for Ag. The nanocomposites exhibited excellent catalytic activity for CO oxidation at low temperatures. Tests also showed the nanocomposites had antibacterial effects against E
1. Paracetamol is generally safe at recommended doses but can cause acute liver failure and require transplantation at higher overdose doses due to its intrinsic toxicity.
2. At therapeutic doses, paracetamol is mainly metabolized through non-toxic pathways like sulfation and glucuronidation. However, at overdose levels it is oxidized by cytochrome P450 2E1 to form the toxic metabolite NAPQI.
3. NAPQI is normally detoxified by conjugating with glutathione, but an overdose depletes glutathione reserves allowing NAPQI to accumulate and cause
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Austin Journal of Bioorganic & Organic Chemistry is a peer reviewed, open acc...Austin Publishing Group
Austin Journal of Bioorganic & Organic Chemistry is a peer reviewed, open access journal publishes manuscripts in the following areas but not limited to structures, synthesis, kinetics, organic synthesis, physical organic chemistry, supramolecular chemistry and chemical biology.
Austin Journal of Bioorganic & Organic Chemistry accepts original research articles, review articles, commentaries, Letters, perspectives, and rapid communication on all the aspects of Bioorganic & Organic Chemistry.
Meulepas, 2010, Trace Methane Oxidation And The Methane Dependency Of Sulfate...roelmeulepas
This research article investigates trace methane oxidation and the methane dependency of sulfate reduction in three types of anaerobic granular sludge. The researchers found that all sludge samples anaerobically oxidized 13C-labeled methane to 13C-labeled carbon dioxide, while also producing endogenous methane. Labeled methane oxidation rates followed methane production rates. The presence of sulfate inhibited both labeled methane oxidation and methanogenesis. Labeled methane oxidation was linked to methanogenesis, referred to as trace methane oxidation. The ratio of labeled methane oxidation to methanogenesis increased with higher methane partial pressures. Higher methane partial pressures also increased sulfate reduction and inhibited methanogenesis, giving sulfate reducers a competitive advantage over methanogens for common substrates.
This document summarizes research into how excess D,L-asparagine causes preferential crystallization of other coexisting racemic D,L-amino acids to have an enantiomeric excess during recrystallization. Experiments showed that when mixtures containing 12 different racemic D,L-amino acids were recrystallized with excess D,L-asparagine, the amino acids adopted the same chirality as asparagine. Similar results were found for other individual amino acids recrystallized with D,L-asparagine. This suggests D,L-asparagine can induce optical resolution and spontaneous symmetry breaking in mixtures of racemic amino acids during crystallization, potentially
1) The document describes the total synthesis of the natural product 10-hydroxyasimicin, which contains a bis-THF motif in its central core.
2) A key step was the development of a template approach to link two alkenol building blocks and induce stereocontrol during ring-closing metathesis to generate the bis-THF framework.
3) The synthesis involved coupling the building blocks, ring-closing metathesis, asymmetric dihydroxylation, macrocycle opening and elaboration to install side chains, and final coupling and deprotection to yield the target natural product.
A Comparison of Spectrophotometric and Oxidoreduction Potential Method for La...CrimsonpublishersMedical
Polyphenol oxidases (PPOs) oxidize phenolic compounds forming quinones, which undergo non-enzymatic reactions resulting in colored
compounds. We studied ferulic acid and catechol oxidation by Myceliophthora thermophila laccases using oxidoreduction potential (ORP or Eh) as a novel
method to determine PPO activity compared to the traditional spectrophotometric method. Eh varied time-dependently on ferulic acid and catechol
concentrations. Eh increased to a maximum value (Ehmax), then decreased irreversibly proportional with substrate concentration. The ΔEh curves of
ferulic acid and catechol oxidation at different concentrations by laccase exhibited two steps substrate oxidation: enzymatic and non-enzymatic; linear
segments with increasing and decreasing slopes (rate of ΔEh change). The Km values determined spectrophotometrically and ORP were 0.55, 0.75 and
0.39, 0.32mM for catechol and ferulic acid, respectively. The kinetic parameters (Km, Vmax) of enzymatic reaction were not significantly different between
the spectrophotometry and ORP methods. The ORP method is simple, low-cost and fast enabling the differentiation between the enzymatic and nonenzymatic phenol oxidation reactions
This document describes the chemoselective synthesis of isomeric pairs of (E),(Z)-mono-sulfones and bis-sulfones. The synthesis begins with compound (A) which is treated with thiophenol to yield a mixture of (E) and (Z) isomers of mono-sulfones. These isomers are separated. The mono-sulfones undergo further reactions including bromination and oxidation to yield (E) and (Z) isomers of bis-sulfones. UV irradiation is used to convert some E-isomers to the corresponding Z-isomers. The structures of the products are confirmed using spectral data and reactions are carried out to systematically synthesize both E and Z isomer pairs
1. Eleven new secondary metabolites were isolated from the endophytic fungal strain Phomopsis sp. XZ-26 from Camptotheca acuminate, including nine lovastatin analogues (oblongolides N-V and 5-11), one linear furanopolyketide, one monoterpene, and four known compounds.
2. The structures of the new compounds were elucidated using spectroscopic data including NMR, HR-MS, and X-ray crystallography. The new compounds included hydroxylated derivatives of known oblongolides and linear furanopolyketides.
3. The antimicrobial activities of some of the isolated compounds were evaluated but
This document summarizes research on the reduction of manganese porphyrins by flavoenzymes and mitochondrial particles, and how this relates to the catalytic reduction of peroxynitrite. It finds that flavoenzymes like xanthine oxidase and glucose oxidase, as well as mitochondrial Complex I and II, catalyze the reduction of manganese porphyrins using substrates like NADH and succinate. Reduced manganese porphyrins can then rapidly react with peroxynitrite via a two-electron process, producing nitrite and manganese porphyrin radicals. This redox cycle can protect peroxynitrite-sensitive targets in submitochondrial particles.
The study of intermolecular interactions at interfaces is essential for a number of applications, in addition
to the understanding of mechanisms involved in sensing and biosensing with liquid samples. There are,
however, only a few methods to probe such interfacial phenomena, one of which is the atomic force
spectroscopy (AFS) where the force between an atomic force microscope tip and the sample surface is
measured. In this study, we used AFS to estimate adhesion forces for a nanostructured film of poly(oethoxyaniline)
(POEA) doped with various acids, in measurements performed in air. The adhesion force
was lower for POEA doped with inorganic acids, such as HCl and H2SO4, than with organic acids, because
the counterions were screened by the ethoxy groups. Significantly, the morphology of POEA both in the
film and in solution depends on the doping acid. Using small-angle X-ray scattering (SAXS) we observed
that POEA dissolved in amixture of dimethyl acetamide exhibits a more extended coil-like conformation,
with smaller radius of gyration, than for POEA in water, as in the latter POEA solubility is lower. In AFS
measurements in a liquid cell, the force curves for a POEA layer displayed an attractive region for pH 5
due to van der Waals interactions, with no contribution from a double-layer since POEA was dedoped. In
contrast, for pH 3, POEA was doped and the repulsive double-layer force dominated. With AFS one is
therefore able to correlate molecular-level interactions with doping and morphology of semiconducting
polymers.
Methanotrophs are unique bacteria that use methane as their sole carbon and energy source. They play several important roles in the environment. First, they oxidize methane produced by archaea, reducing the amount of this potent greenhouse gas that enters the atmosphere. Second, they can degrade various organic pollutants using monooxygenase enzymes. Finally, they can remediate heavy metals by transforming more toxic forms into less toxic forms or facilitating precipitation. Methanotrophs thus aid in carbon and pollutant cycling while also helping to mitigate climate change.
This article discusses how methanol (MeOH) affects ascorbate (AsA) levels and related gene expression in Oncidium orchids. The study found that a low concentration of MeOH (50 mM) triggered hydrogen peroxide (H2O2) production and increased expression of AsA biosynthesis genes. However, a high MeOH concentration was toxic and depleted AsA levels. The increased gene expression from low MeOH levels was blocked by inhibitors of alcohol oxidase and NADPH oxidase, suggesting H2O2 is a signaling molecule regulating AsA gene expression in response to MeOH. The results help explain the mechanism by which MeOH stimulates AsA production in Oncidium at the molecular level.
This document is an assignment cover sheet for a student named Muhammad Zeeshan Ahmed for an assignment on organic solvents. It includes his student ID number, the assignment name, and due date. At the bottom is a declaration stating that the work is his own and has not been plagiarized. The accompanying document discusses various organic solvents like benzene, toluene, methanol, ethanol, and their properties, structures, and common uses.
This article discusses the solvent-conjugated polymer interactions of MEH-PPV and PF in various solvent solutions and thin films. Absorption and emission spectra were measured for polymer solutions, and thin films were prepared by dip or spin coating. The results show that MEH-PPV and PF exhibit different behaviors in solutions and films based on solvent quality and chain conformation. Specifically, dispersive forces were found to influence the effective conjugation of MEH-PPV chains, while energy transfer processes differed for the a and b chains of PF based on solvent. The memory effect, where chain conformations are maintained from solution to film, also varied between the two polymers and based on solvent used.
This document summarizes a study on the long-term effects of fertilization and soil warming on the decomposition of recalcitrant litter.
[1] The study examines how nitrogen addition and increased soil temperatures impact the later stages of litter decomposition, as most experiments only look at initial decomposition. [2] Results found that nitrogen addition had a neutralizing effect on the stimulation of decomposition from warming, as nitrogen addition and warming had interactive effects. [3] Further analyses are still needed to better understand the interaction between litter quality, warming, and nitrogen on decomposition over longer time periods.
Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce oxygen and energy in the form of glucose. It occurs in chloroplasts in plant leaves. Chloroplasts contain chlorophyll which captures light energy and drives the photosynthetic process. Photosynthesis splits water molecules to produce oxygen gas and electrons that are used to reduce carbon dioxide into sugars. It is a redox process consisting of two stages - the light-dependent reactions where ATP and NADPH are produced, and the Calvin cycle where sugars are assembled from carbon dioxide.
This proposal outlines a project to synthesize water soluble ruthenium precursors for use in coordination-driven self-assembly of metallacycles and cages. The student proposes modifying the arene ligand of common ruthenium molecular clips with an ethylene glycol group to impart improved water solubility. This water soluble clip will first be assembled into an oxalate-bridged complex and characterized. Alternative bridging ligands will then be explored, with a focus on aromatic ligands that show enhanced biological activity. The goal is to establish the water solubility of the resulting supramolecular coordination complexes and evaluate their potential for biological applications like drug delivery.
Extraction, identification and antioxidant activities of carotenoids from Ipo...Pragati Shah
These presentation slides are about extraction, identification and antioxidant activities of carotenoids from Ipomoea aquatica Forsk. It is commonly known as Morning water glory or water spinach which is rich source of nutrients,, wide array of carotenoids are extracted and identified by GC- MS techniques by researcher arond the Globe. Antioxidant activity of natural products can be evaluated by different assay; some them are discussed in these slides.
This document discusses phenylboronate chromatography (PBC), which uses phenylboronic acid ligands to selectively separate glycoproteins. PBC has advantages over other separation methods like lower cost and stability. The document examines the various interactions that can occur between proteins and phenylboronic acid ligands, including cis-diol bonding, electrostatic interactions, Lewis acid-base interactions, and hydrophobic interactions. It describes experiments using a library of glycosylated and non-glycosylated proteins to characterize the dominant interactions between different classes of proteins and the ligands over a pH range, and determine solution conditions that can minimize non-specific interactions.
This document describes the large scale photochemical synthesis of M@TiO2 nanocomposites (M = Ag, Pd, Au, Pt) and investigates their optical properties, catalytic activity for CO oxidation, and antibacterial effects. Well-dispersed M@TiO2 nanocomposites with particle diameters of 200-400 nm were synthesized using a clean photochemical method without additives. The sizes of the noble metal nanoparticles formed on the TiO2 support were approximately 1 nm for Pt, 5 nm for Au and Pd, and 2-20 nm for Ag. The nanocomposites exhibited excellent catalytic activity for CO oxidation at low temperatures. Tests also showed the nanocomposites had antibacterial effects against E
1. Paracetamol is generally safe at recommended doses but can cause acute liver failure and require transplantation at higher overdose doses due to its intrinsic toxicity.
2. At therapeutic doses, paracetamol is mainly metabolized through non-toxic pathways like sulfation and glucuronidation. However, at overdose levels it is oxidized by cytochrome P450 2E1 to form the toxic metabolite NAPQI.
3. NAPQI is normally detoxified by conjugating with glutathione, but an overdose depletes glutathione reserves allowing NAPQI to accumulate and cause
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
This document summarizes an experimental study on the use of unmodified lignocellulosic fibrous layer of palm tree trunk (ULFPT) as a low-cost biosorbent for removing copper (Cu2+) and zinc (Zn2+) from aqueous solutions. Batch experiments were conducted to investigate the effects of pH, initial metal ion concentration, and contact time on biosorption. Equilibrium isotherm data were fitted to Langmuir, Freundlich, Redlich-Peterson, and Temkin models to understand adsorption mechanisms. The Redlich-Peterson model provided the best fit for Cu2+ and Zn2+ biosorption. The Langmuir model also fitted the experimental data well.
This document summarizes an experimental study on the use of unmodified lignocellulosic fibrous layer of palm tree trunk (ULFPT) as a low-cost biosorbent for removing copper (Cu2+) and zinc (Zn2+) from aqueous solutions. Batch experiments were conducted to investigate the effects of pH, initial metal ion concentration, and contact time on biosorption. Equilibrium data were modeled using Langmuir, Freundlich, Redlich-Peterson, and Temkin isotherm models. The Redlich-Peterson model provided the best fit for Cu2+ and Zn2+ biosorption. The Langmuir model also provided a good fit. Maximum Cu2+ removal (
This document summarizes the development of a mild and efficient method for synthesizing symmetrical and unsymmetrical azo compounds from aromatic anilines using copper bromide (CuBr) and N-methylmorpholine N-oxide (NMO) as an oxidizing system. Optimization experiments showed that CuBr with 1 equivalent of NMO in an acetonitrile/water solvent mixture gave the best yields. A variety of substituted anilines underwent homocoupling to produce symmetrical azo compounds in good to excellent yields. Unsymmetrical azo compounds were also synthesized via cross-coupling of different anilines in moderate to good yields. The reaction was shown to proceed via single electron transfer from Cu(I) to NMO
1) Ion pair chromatography is a type of column chromatography that uses ion pairing agents to neutralize charged analytes and allow their separation on a reversed-phase column.
2) By adding counter ions with the opposite charge to the mobile phase, ion pairs form between the counter ions and analytes, neutralizing their charge and increasing their hydrophobicity.
3) The use of ion-pairing reagents as mobile phase additives allows the separation of ionic and highly polar substances that cannot otherwise be separated by reversed-phase chromatography.
The document summarizes the determination of acid dissociation constants (pKa) for several organic compounds using UV-Vis spectrophotometry. It discusses acid-base theory, factors that affect pKa, and the biological importance of pKa values. The method involves taking UV-Vis absorbance scans of compound solutions across a range of pH values. An isosbestic point is identified and used to select an absorption wavelength for analyzing the pH-absorbance curve in GraphPad Prism software. This yields the pKa value from the Boltzmann sigmoidal fit. Determining pKa is important for understanding a compound's properties, metabolism, and suitability as a dye or probe.
Partial Molar Volumes of Tetra alkyl ammonium salts in 10%(W/W) 2-(Ethoxy) et...Premier Publishers
In this article densities and apparent molar volumes of Tetra alkyl ammonium bromide salts ( ) in 10% (W/W) 2-(Ethoxy) ethanol-water mixture is studied at 30o, 35o and 40oC. Partial molar volumes are divided into ionic components using different methods such as Conway et al. and Jolicoeur et al. The results are compared with the values of partial molar volumes of ions reported in literature for pure water. Decrease in hydrophobic hydration is noticed. This may be due to the addition of co-solvent 2-(Ethoxy) ethanol (confirming the conclusions drawn from our viscosity studies that in 2-(Ethoxy) ethanol-water mixture, the structuredness of water is reduced by the breaking of hydrogen bonds). The values are divided into and . Making use of the Padova’s equation values of salts are calculated. These are also divided into ionic contributions. Dimensions of ions have been calculated to understand solvation behavior. It is shown that the classification of salts into structure makers and structure breakers on the basis of the sign of is not valid for the present water rich mixed solvent system.
Kinetics of Ruthenium(III) Catalyzed and Uncatalyzed Oxidation of Monoethanol...Ratnakaram Venkata Nadh
Kinetics of uncatalyzed and ruthenium(III) catalyzed oxidation of monoethanolamine by N-bromosuccinimide
(NBS) has been studied in an aqueous acetic acid medium in the presence of sodium acetate
and perchloric acid, respectively. In the uncatalyzed oxidation the kinetic orders are: the first order in NBS,
a fractional order in the substrate. The rate of the reaction increased with an increase in the sodium acetate
concentration and decreased with an increase in the perchloric acid concentration. This indicates that free
amine molecules are the reactive species. Addition of halide ions results in a decrease in the kinetic rate,
which is noteworthy. Both in absence and presence of a catalyst, a decrease in the dielectric constant of the
medium decreases the kinetic rate pointing out that these are dipole—dipole reactions. A relatively higher
oxidation state of ruthenium i.e., Ru(V) was found to be the active species in Ru(III) catalyzed reactions. A
suitable mechanism consistent with the observations has been proposed and a rate law has been derived to
explain the kinetic orders.
1. Amino acids are the building blocks of proteins and contain an amino group, a carboxyl group, a central carbon, and a variable R group.
2. The 20 common amino acids that make up proteins each have different R groups that determine their properties like polarity, acidity, and solubility.
3. Amino acids are classified based on the properties of their R groups into nonpolar, polar uncharged, and polar charged categories. The R group also influences how an amino acid interacts with other molecules in proteins.
SIMONA CAVALU_Raman and surface-enhanced Raman spectroscopy of tempyo spin la...Simona Cavalu
Tempyo labelled ovalbumin at different pH values was prepared and investigated using Raman and SERS spectroscopy.
Raman spectra of tempyo labelled ovalbumin in the pH range from 6.7 to 11 were compared to those of the corresponding free
ovalbumin. In the basic pH range from 6.7 to 11 the molecular conformation was found to be unaffected by the tempyo
presence. Adsorption versatility to the colloidal Ag particles of pure- and tempyo labelled ovalbumin was also found to be
unchanged in this basic pH range. As the SERS binding site of protein the a-helix conformation is favourable.
This lab report summarizes a Diels-Alder reaction experiment where a diene and dienophile were reacted to produce a cycloaddition product. The product was analyzed using melting point determination, IR spectroscopy, and NMR spectroscopy. A low yield of 17.34% was obtained, which could be due to impurities as indicated by the wide melting point range of the product. The IR spectrum confirmed the presence of structural units expected in the product. While NMR analysis was unsuccessful, the evidence suggests the desired Diels-Alder reaction occurred between the diene and dienophile.
This document discusses a study on the inhibitive properties and quantum chemical analysis of 1,4-benzothiazine derivatives for corrosion inhibition of mild steel in acidic medium. Two derivatives, compounds P3 and P4, were synthesized and their structures were confirmed through various analytical techniques. Electrochemical tests including polarization, electrochemical impedance spectroscopy, and weight loss measurements were used to evaluate the corrosion inhibition efficiency of P3 and P4 in 1 M HCl solution. Quantum chemical calculations based on density functional theory were also performed to correlate inhibition efficiency with molecular properties. The results showed that P3 and P4 acted as efficient corrosion inhibitors for mild steel in acidic solution, with inhibition efficiency increasing with increasing concentration. Adsorption
The document examines the effects of acid on the chlorophyll production and biomass of common duckweed (Lemna minor L.). Two experiments were conducted exposing duckweed to pH levels of 4.1, 5.4, and 6.5 (control) over 10-12 days. The first experiment showed no significant differences in biomass between pH treatments. The second experiment found significantly lower biomass at pH 4.1 compared to pH 5.4 and 6.5. Neither experiment found significant differences in chlorophyll content between pH treatments. The results partially supported the hypothesis, showing acid inhibited biomass but not through impacts on chlorophyll. Longer exposure periods or lower pH levels may be needed to impact chlorophyll.
The document summarizes research on the biodegradation kinetics of three nitrogen-substituted naphthalenes (1-aminonaphthalene, 2-aminonaphthalene, and 1-amino-2-methylnaphthalene) under aerobic conditions in flooded soil. The researchers found that mineralization of the compounds proceeded in two phases - an initial fast phase followed by a slower second phase. Sorption of the compounds onto the soil followed hyperbolic isotherms described by the Langmuir model. Initial mineralization rates obeyed Michaelis-Menten kinetics and were directly proportional to aqueous concentrations, reaching a maximum at 100 μg/g soil slurry. The second phase mineralization rates were
Ion-Pair chromatography is an alternative to ion exchange chromatography.
ion pair reagent.
Mechanism of ion pair chromatography.
Factors influencing retention.
experimental conditions.
2. Beilstein Journal of Organic Chemistry 2010, 6, No. 31.
Figure 1: Examples of some currently available Good buffers (and their reported pKa values) for the low end of the physiological pH range.
Introduction
Some of the most widely used biological buffers are the com- between the amine and sulfonic acid moieties [2,3]. We
pounds based on tertiary and secondary aminoalkanesulfonic reasoned that by synthesizing compounds with a single carbon
acids (and their salts) initially reported by Norman Good, and linkage (α-aminosulfonic acids) – we should be able to decrease
which are now available from commercial sources (Figure 1) the pKa of the resulting compounds.
[1,2]. While these compounds provide good coverage of the
physiological pH range and above, they have not been as widely The aminoalkylsulfonic acids are similar to amino acids, in that
useful in biochemical studies at acidic pH levels. Other classes they can exist in multiple states of ionization, including a
of buffers that are usable in acidic pH ranges can be problem- zwitterionic form (1a) at the isoelectric point (Figure 3). Since
atic in biochemical studies because of toxicity or metabolic the ionization of the sulfonic acid functional group is essen-
interferences (i.e. citrate, borate, phosphate). This is particu- tially complete in aqueous solution, for purposes of creating
larly the case in studies of acidiophilic bacteria or biochemical buffers we are primarily interested in the pKa of the ammonium
systems that operate most efficiently in an acidic pH range. The ion proton dissociation (1a to 1c). The pKa of this dissociation
impetus for this study was to investigate compounds with the is observed to be influenced by the proximity of the sulfonic
potential for use as biological buffers in acidic pH ranges. acid group in the Good’s buffer class of compounds. In
previous work on the series of unsubstituted aminosulfonates
Our focus was to synthesize a series of compounds that are with 0–3 carbons between the amino and sulfonate groups, the
analogous to currently available Good buffers – but with a pKa for sulfamic acid, aminomethanesulfonic acid, and taurine
single carbon atom between the amino and sulfonate functional (2-aminoethanesulfonic acid) in water are reported to be 1.01,
groups (Figure 2). Our approach to the problem was based on 5.75, and 9.06, respectively [4]. The rapid decrease in pKa in
noting that the pKa values of currently available Good buffers the series is likely due to inductive electron-withdrawing effect
decrease systematically as the number of carbon atoms decrease of the sulfonic acid group acting through fewer bonds as the
Figure 2: Aminomethanesulfonic acids in this study and their proposed acronyms.
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3. Beilstein Journal of Organic Chemistry 2010, 6, No. 31.
carbon chain length is decreased. While an inductive effect is
the most likely explanation for the observed ammonium ion
acidity, the possibility of a through space intramolecular inter-
action (i.e. hydrogen-bonding or similar stabilization) of the
proton with the sulfonate moiety cannot be discounted as a
contributing factor.
Scheme 1: Routes reported previously for the synthesis of Good
buffers.
reports of the lack of reactivity of chloro- and bromomethane-
sulfonic acids (and related derivatives) in nucleophilic substitu-
tion reactions, especially those with weaker nucleophiles such
as amines [6-8]. We therefore abandoned this route in favor of a
different approach previously reported in the literature for the
Figure 3: Possible ionization states of 1.
specific synthesis of aminomethanesulfonates.
Results and Discussion In this approach amines are reacted with the product of add-
Synthetic methodology ition of sodium hydrogensulfite to formaldehyde [9,10]. The
Currently available Good buffers have been reportedly synthe- sodium hydrogensulfite/formaldehyde addition product 7
sized by one of two routes (Scheme 1). The first route is by (sodium hydroxymethanesulfonate) is readily available from
nucleophilic substitution of haloalkylsulfonic acids (or their de- commercial sources and reacts in good yield with morpholine in
rivatives) with the selected primary or secondary amine, as aqueous solution over several days at room temperature, or in
described by Good [1,2]. The second route is by ring-opening of hours with moderate heating, to form the desired product 1 in a
cyclic sulfonate esters (sultones) with an appropriate primary or zwitterionic or salt form (depending on the workup conditions).
secondary amine. However, this method is limited by the avail-
able sultone ring size to the production of 3 carbon aminoalkyl- We extended this methodology to produce other compounds
sulfonates and larger [5]. that are the α-aminosulfonic acid analogs of other commonly
used Good buffers including N-(2-hydroxyethyl)piperazine-N′-
The second approach above is not amenable to the synthesis of methanesulfonic acid [HEPMS] (2), piperazine-N,N′-bis(meth-
aminomethanesulfonates, so our initial efforts were to anesulfonic acid) [PBMS] (3), and cyclohexylaminomethane-
synthesize the initial target compound N-morpholinomethane- sulfonic acid [CAMS] (4). Our initial attempts to synthesize
sulfonic acid (MMS) (1) by the reaction of morpholine with N-[tris(hydroxymethyl)methyl]-aminomethanesulfonic acid
chloromethanesulfonic acid (Scheme 2). In spite of numerous [TAMS] (5) have resulted in a product that is a mixture of the
attempts, this route produced no product, however. A desired compound with what appears to be the O-alkylated de-
subsequent literature search indicated that there were some prior rivative. We have also attempted to synthesize N,N-bis(2-
Scheme 2: Synthetic routes investigated.
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4. Beilstein Journal of Organic Chemistry 2010, 6, No. 31.
hydroxyethyl)aminomethanesulfonic acid [BAMS] (6), but have Table 2: OD600 of cultures with varying concentrations of amino-
been unable to characterize the product as it forms an intract- methanesulfonate.
able aqueous gel (hydrogel) that was completely resistant to all
attempts to dehydrate it. Buffer Initial OD600 Final OD600
Conc. used 10 mM 20 mM 50 mM
Characterization as buffers
1 0.015 1.16 1.22 1.18
We then performed titrations to determine the pKa values of
2 0.015 1.16 1.08 0.66
proton dissociation from the ammonium ion (1a and 3 0.015 1.23 1.21 1.08
equivalent). The pKa values determined for these compounds, Control 0.015 1.24 1.28 1.33
along with those of the analogous aminoethanesulfonate and
aminopropanesulfonate buffer pKa values for comparison is
presented in Table 1.
The results of this testing indicate that the three new buffer
Table 1: pKa comparison of aminoalkylsulfonates. Acronyms refer to
compounds (1, 2 and 3) supported culture growth at all concen-
compounds in the Good’s buffer series that are commercially available. trations tested. However, there is some indication of possible
Some of the less common ones are CHES [2-(cyclohexylamino)-
toxicity or other culture growth inhibition occurring at the
ethanesulfonic acid], EPPS [4-(2-hydroxyethyl)-1-piperazinepropane-
sulfonic acid], PIPPS [piperazine-N,N′-bis(3-propanesulfonic acid], and higher concentrations of HEPMS 2 and PBMS 3 due to the
CAPS [3-(cyclohexylamino)-1-propanesulfonic acid]. Experimental significantly lower optical densities resulting when the concen-
values reported at or above precision of measurement (see Supporting
Information for statistics). trations of these buffers were increased.
pKa Ethyl analog pKaa Propyl analog pKaa During testing it became apparent that these compounds are
1 3.9 MES 6.2 MOPS 7.2
unstable at pH values that are below the pKa value. They can
2 7.9 HEPES 7.5 EPPS 8.0 stably maintain buffered pH at room temperatures for days
3 4.9b PIPES 6.8b PIPPS 8.0b when above their pKa values, but at pH levels below the pKa
4 7c CHES 9.3 CAPS 10.4 they rapidly lose the ability to maintain a buffering effect (pH
aValues from references [1,5,7]. drifts to higher values). The compounds also become unstable at
b2nd (ammonium) dissociation constant value.
cEstimate only (precipitates at pH ≈ pK ).
elevated temperatures. When autoclaved, buffered solutions
a
change pH and lose buffering capability. Therefore, while they
may be suitable for niche use in some applications as lower pH
biological buffers at room temperature, they are severely
As can be seen in Table 1, two of the new compounds (MMS 1 limited by the stability of the aminomethanesulfonate structure
and PBMS 3) have pKa values that are significantly lower than at low pH or elevated temperature.
their two and three carbon Good buffer counterparts (counting
number of carbons between amine and sulfonic acid) and are Crystallographic structures
well into the acidic pH range. All of the compounds except 2 All of the buffers exhibit a marked trend of pKa decrease in
show evidence of a systematic decrease in pKa as the number of Table 1, with the exception of the 2-hydroxypiperazine series
carbons between the amine and sulfonic acid functional groups (2, HEPES, and EPPS). A possible explanation of why this
decreases. In addition, PBMS 3 does not demonstrate the series is not as impacted by the shortening of the carbon chain
limited aqueous solubility that its two carbon analog PIPES between the sulfonic acid and amino group is if the zwitterion is
does at low pH. CAMS 4 is the only one of the new com- formed by protonation at the piperazine nitrogen that is bonded
pounds that shows limited solubility in aqueous solution (when to the hydroxyethyl functional group. This nitrogen’s basicity
pH ≤ pKa). would be expected to be only slightly impacted by structural
modifications of the alkylsulfonic acid group at the other
In order to assess the potential utility of these compounds as nitrogen. This hypothesis is supported by the crystal structure of
biological buffers, we conducted an initial experiment with HEPMS 2 as a zwitterion shown in Figure 4. The crystal struc-
different concentrations of the new compounds with E. coli ture of 2 is consistent with the one previously reported for
strain HB101 at pH 7.2 and 37 °C for 18 h. Culture growth was HEPES [11]. Both have piperazine rings in the chair conform-
estimated by optical density measurement at 600 nm, and the ation, with extended conformation for the side chains. Both
results are summarized in Table 2 (in which each value is the have extensive intermolecular hydrogen bonding forming
result of 3 separate trials, with an overall standard error for all centrosymmetric dimers, although HEPMS 2 forms ribbons
final measurements of 0.025). (Figure 5), while HEPES forms corrugated sheets.
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5. Beilstein Journal of Organic Chemistry 2010, 6, No. 31.
appropriate amine (0.200 mol) was then dissolved separately in
100 mL of deionized water and added to the stirred solution
drop-wise via an addition funnel. The mixture was then stirred
at 60 °C for 48 h. The volume of the reaction solution was
reduced in vacuo by one-third, and then stored at 4 °C overnight
to crystallize/precipitate the product. The precipitate was then
collected by vacuum filtration and washed once with cold
ethanol. Recrystallization solvents were limited to water and/or
hot low M.W. alcohols (i.e. methanol, ethanol), as the materials
Figure 4: Crystal structure of HEPMS 2 with displacement ellipsoids at are insoluble in other solvents.
the 30% probability level.
N-Morpholinomethanesulfonic acid [MMS (or MoMS)] (1).
The crystal structure of 2 shows protonation occurring at the This was prepared as the half sodium salt by the general
hydroxyethylamino nitrogen (N2), which is consistent with the procedure from 0.200 mol of morpholine (17.4 mL), yielding
protonation found in the crystal structure of zwitterionic 31.6 g (0.164 mol) of 1 (82% isolated yield) as a yellowish-
HEPES. Protonation at this site is likely favorable due to the white semi-crystalline material. The product was recrystallized
regular hydrogen bonding formed in the solid phase (Figure 5). from 50% ethanol-water solution. The pKa of a 0.3 M solution
However, it is also likely that this nitrogen is protonated first in at 20 °C was determined to be 3.8. mp 143–149 °C dec; IR
aqueous solution phase, as this nitrogen would be expected to (KBr) 3409(s), 3138(br), 1196, 1216(s), 1250, 1108, 1059, 1014
be more basic than the aminomethanesulfonate nitrogen (N1). cm−1; 1H NMR (500 MHz, D2O/TSP): δ 2.92 (4H, t, J = 4.8),
3.76 (4H, t, J = 4.8), 3.8 (2H, s); 13C NMR (125 MHz, D2O/
In the other compounds, the only amine available for protona- TSP): δ 54.7 (t), 69.2 (t), 75.8 (s). Anal. Calcd for
tion is the amine attached to an alkylsulfonic acid group. There- C 5 H 11 NO 4 S·0.5Na: C, 31.24%; H, 5.51%; N, 7.29%; Na,
fore, in these compounds (1, 3, 4) we see a pronounced reduc- 5.98%; O, 33.30%; S, 16.68%. Found: C, 31.05%; H, 6.13%; N,
tion in the basicity of the amine as the carbon chain between the 7.63%; S, 16.66%. Structure assignment supported by single
amine and sulfonic acid group has been reduced. As the basi- crystal X-ray structure of the sodium salt form (in Supporting
city of the amine is reduced, the pKa of its ammonium form is Information File 2).
reduced – making it available for buffering in a lower pH range.
N-(2-hydroxyethyl)piperazine-N′-methanesulfonic acid
Experimental [HEPMS] (2). This was prepared as the sodium salt mono-
Acid dissociation constants hydrate by the general procedure from 0.200 mol of 1-(2-
Acid dissociation constants for the ammonium ions were deter- hydroxyethyl)piperazine (24.5 mL), yielding 49.2 g (0.186 mol)
mined by aqueous solution titrimetry (min. 5 repetitions from of 2 (93% isolated yield) as a white semi-crystalline solid. The
low to high, then high to low pH) using standardized NaOH and product was recrystallized from ethanol. The pKa of a 0.25M
HCl solutions. solution at 20 °C was determined to be 7.4. mp 178–185 °C
dec; IR (KBr) 3408(s), 3240(br), 1223(s), 1163, 1057 cm−1;
General synthetic procedure 1H NMR (250 MHz, D O): δ 2.58–2.66 (6H, m), 2.96 (4H, t,
2
The compounds were prepared by dissolving 0.200 mol (26.8 g) J = 5.2), 3.76 (2H, t, J = 6.3), 3.81 (2H, s). 13 C NMR
of sodium hydrogensulfite-formaldehyde addition product in (62.9 MHz, MeOD): δ 52.5, 54.0, 59.2, 60.7, 74.2. Anal. Calcd
250 mL deionized water in a 500 mL RBF with stirring. One for C7H17N2NaO5S·H2O: C, 31.81%; H, 6.48%; N, 10.60%;
equivalent (one-half equivalent in the case of piperazine) of the Na, 8.70%; O, 30.27%; S, 12.13%. Found: C, 30.72%;
Figure 5: Hydrogen bonded molecular ribbon in solid phase 2 along [101].
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6. Beilstein Journal of Organic Chemistry 2010, 6, No. 31.
H, 6.48%; N, 10.22%; S, 10.82%. Structure assignment
supported by single crystal X-ray structure of the zwitterion Supporting Information File 2
form (in Supporting Information File 3). CIF file for MMS 1
[http://www.beilstein-journals.org/bjoc/content/
Piperazine-N,N′-bis(methanesulfonic acid) [PBMS] (3). This supplementary/1860-5397-6-31-S2.cif]
was prepared as the disodium salt dihydrate by modification of
the general procedure [using 0.400 mol (53.6 g) of formalde- Supporting Information File 3
hyde-sodium hydrogensulfite addition product] from 0.200 mol CIF file for HEPMS 2
of piperazine (17.2 g), yielding 46.5 g (0.131 mol) of 3 (66% [http://www.beilstein-journals.org/bjoc/content/
isolated yield) as a white semi-crystalline solid. The product supplementary/1860-5397-6-31-S3.cif]
was recrystallized from 50% ethanol-water solution. The pKa of
a 0.3 M solution at 20 °C was determined to be 4.8. mp
226–245 °C dec; IR (KBr) 3400(s), 3144(br), 1244, 1223(s), Acknowledgements
1190, 1059 cm−1; 1H NMR (500 MHz, D2O/TSP): δ 2.94 (8H, We acknowledge the support of the National Institutes of
s), 3.80 (4H, s). 13C NMR (125 MHz, D2O/TSP): δ 54.1, 75.6. Health (NIH) via grant No. P 20 RR-16480 from the INBRe
Anal. Calcd for C 6 H 16 N 2 Na 2 O 8 S 2 ·2H 2 O: C, 20.34%; H, program of the National Center for Research Resources
4.55%; N, 7.91%; Na, 12.98%; O, 36.13%; S, 18.10%. Found: (NCRR), which has provided infrastructure that has been used
C, 20.28%; H, 4.32%; N, 8.33%; S, 16.59%. for this project. UCSD (via ACS-PRF funded workshop “Crys-
tallography for Organic Chemists”) and New Mexico High-
Cyclohexylaminomethanesulfonic acid [CAMS] (4). This was lands University (with support of DMR/NSF grant No.
prepared as the sodium salt by the general procedure from 0.200 0430863) provided X-ray crystallographic instrumentation and
mol of freshly distilled cyclohexylamine (22.9 mL), yielding services for this project. University of New Mexico and Texas
36.2 g (0.168 mol) of 4 (84% isolated yield) as white semi-crys- Tech University provided access to NMR instrumentation and
talline powder. The product was recrystallized from 50% services for this project. All of this assistance is greatly appreci-
ethanol-water solution. The pKa of 0.3 M solution at 20 °C was ated.
determined to be 7.8. mp 182–195 °C dec; IR (KBr) 3450(br),
3034(s), 1602, 1458, 1249, 1158, 1053 cm −1 ; 1 H NMR References
(500 MHz, D2O/TSP): δ 1.14–1.22 (1H, m), 1.28–1.40 (4H, m), 1. Good, N. E.; Winget, G. D.; Winter, W.; Connolly, T. N.; Izawa, S.;
1.63–1.69 (1H, m), 1.77–1.83 (2H, m), 1.97–2.02 (2H, m), Singh, R. M. M. Biochemistry 1966, 5, 467–477.
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3.12–3.19 (1H, m), 4.40 (2H, s). 13C NMR (125 MHz, D2O/
2. Good, N. E.; Izawa, S. Methods Enzymol. 1972, 24, 53–68.
TSP): δ 26.7, 27.0, 33.2, 53.2, 77.0. Anal. Calcd for doi:10.1016/0076-6879(72)24054-X
C7H14NNaO3S: C, 39.06%; H, 6.56%; N, 6.51%; Na, 10.68%; 3. Ferguson, W. J.; Braunschweiger, K. I.; Braunschweiger, W. R.;
O, 22.30%; S, 14.90. Found: C, 39.56%; H, 7.05%; N, 7.29%; Smith, J. R.; McCormick, J. J.; Wasmann, C. C.; Jarvis, N. P.;
S, 15.95%. Bell, D. H.; Good, N. E. Anal. Biochem. 1980, 104, 300–310.
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Publishers: New York, 1965.
statistics from the titrations. Details of additional
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7. Beilstein Journal of Organic Chemistry 2010, 6, No. 31.
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