Deuteration presentation
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This document summarizes the synthesis and characterization of two new Ru(II),Rh(III),Ru(II) trimetallic complexes containing selectively deuterated ligands. NMR spectroscopy of the deuterated complexes allows for better structural assignment compared to the undeuterated variants. The deuterated complexes show identical ground state properties but increased excited state lifetime and emission quantum yield, indicating decreased nonradiative decay. Previous studies found deuterated bimetallic complexes to be more efficient for photocatalytic hydrogen production. Studying the deuterated trimetallics aims to further understand and improve their mechanism for photocatalytic water reduction.
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5 (TL=
Terminal Ligand; BL= Bridging Ligand; TL= bpy or d8-bpy; BL= dpp or d10-dpp; bpy= 2-2’-
bipyridine; dpp= 2-3-bis(2-pyridyl)pyrazine) using 1H NMR spectroscopy, electrochemistry,
electronic absorption and excited state luminescence spectroscopy provide structural and
functional classification. NMR spectra of undeuterated trimetallic complexes do not
provide conclusive structural assignments due to numerous equivalent aromatic protons
and structural isomers. Deuteration of bpy TL and dpp BL allows qualitative assignment of
1H NMR spectra. Greater structural understanding provides a possible path to better
understand the mechanism of photocatalytic water reduction of these Ru(II), Rh(III), Ru(II)
trimetallic compounds. Electrochemistry, emission and absorption spectroscopy show
identical ground state electronic properties between the two selectively deuterated
compounds and the fully protiated variant. Complexes containing BL d10-dpp showed an
increased excited state lifetime (τ) and greater quantum yield of emission (Фem) from the
Ru(dπ)→d10-dpp(π*) 3MLCT (metal-to-ligand charge transfer) excited state due to a
decrease in nonradiative decay rate constant (knr). Previously synthesized deuterated Ru(II),
Rh(III) bimetallic complexes that display similar 3MLCT excited state properties are more
efficient H2 photocatalysts than those with undeuterated ligands. Studying selectively
deuterated ligands in Ru(II), Rh(III), Ru(II) trimetallic complexes permit opportunities to
further understand and improve photocatalytic water reduction.
[{(bpy)2Ru(d10-dpp)}2RhCl2]
Supramolecular Architechture
Ru(II) acts as an LA (Light Absorber) connected to two TL’s, bpy,
and one BL, in this case d10-dpp, which connects Ru(II) to the RM
(reactive metal) center, Rh(III). Polyazine BL’s permits electron
coupling and the transfer of electrons through the complex.
3MLCT permitted by the BL create charge imbalances; therefore
providing the complex properties necessary for the
photocatalytic reduction of water.
Synthesis
Synthesizing the supramolecular architechture of the trimetallic
is completed through a building block mechanism beginning
with the creation of a monometallic. Monometallic synthesis
begins by reacting metal halides with TL’s in DMF. From there
the monometallic is attached to the BL, preparing it to react with
the metal halide that is used as the RM center.
Electrochemistry
Electrochemical analysis of the
trimetallic complexes shows
reversible oxidation at the Ru(II) LA’s.
Data gathered from cyclic
voltammograms are consistent with
previous work indicating that Ru(II)
contains the highest occupied
molecular orbital (HOMO). Reversible
reduction is observed in both the
ligands as well as the metal center
Rh(III), with observed voltages
showing the existence of the lowest
unoccupied molecular orbital (LUMO)
on the RM center. Cyclic voltammetry
provides us with a clear electronic
pathway throughout the
supramolecular architechture.
Oxidation first occurs at Ru(II)
transferring an electron to the dpp BL.
Energetic similarity between the BL
and RM depicts obvious electronic
motion from the BL to the RM. Rh(III)
most favorably accepts the electron
creating a charge imbalance across
the complex.
RuII/III
RhIII/II/I dpp0/-
dpp0/-
bpy0/-
[{bpy}2Ru(d10-dpp)]2RhCl2
Emission spectra for the complexes produced peaks at 750
nm. Intensity of emission is slightly higher for the d10-dpp
complex.
Top to bottom: [{(d8-bpy)2Ru(dpp)}2RhCl2] ; [{(bpy)2Ru(dpp)}2RhCl2];
[{(bpy)2Ru(d10-dpp)}2RhCl2]
Deuteration of complexes eliminates the 1H NMR signal of
the deuterated ligands; however, the amount of structural
isomers prevent complete assignment. NMR signals for
deuterated compounds may provide insight into the H2O
reduction mechanism of the trimetallic.
Future Work
Test the deuterated compounds efficiency at H2 production.
Use structural characterization to gain insight into the
mechanism of the trimetallic photocatalytic reduction of water.
Objective
To gain insight into the mechanism of photocatalytic water reduction to more
efficiently produce H2 gas.
[M-2PF6]2+
Counts/sec
Mass Spec. Top: [{(bpy)2Ru(d10-dpp)}2RhCl2]
Bottom: [{(d8-bpy)2Ru(dpp)}2RhCl2]
References
1. Balzani, V.; Credi, A.; Venturi, M.; Photochemical Conversion of Solar Energy.
ChemSUSChem 2008
2. White, T.; Mallalieu, H.; Wang, J.; Brewer, K.; Mechanistic Insight into the Elctronic
Influences Imposed by Substituent Variation in Polyazine-Bridged
Ruthenium(II)/Rhodium(III) Supramolecules. Chemistry A European Journal 2014](https://image.slidesharecdn.com/2ed2c8af-20e5-4458-82d1-c82ea0da0e54-150711155150-lva1-app6892/85/Deuteration-presentation-1-320.jpg)
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Study of substituent effect on properties of platinum(II) porphyrin had been performed using the DFT method. The aim of the study is to investigate the effect of a substituent group on the electronic and optical properties of the platinum(II) porphyrin. Geometry optimization was conducted using DFT/B3LYP/LANL2DZ to obtain the molecular structure, electronic structure and energy profile. Band gap energy (Eg), the density of states (DOS), and UV-visible spectra are the semiconductor parameters to study. Computational results show that platinum(II) porphyrin and substituted platinum(II) porphyrin have properties of semiconductor based on Eg value, DOS, and UV-visible spectra. The results show that Mulliken partial charges of electron withdrawing substituents are higher than the electron donating substituents (CH3, OH, and NH2). Eg values of the complexes with respect to the substituents follow this order: NH2 < OH < NO2 < COOH < I < CH3 < Br < F < H, for DOSHOMO values, the order is CH3 < NO2 < I < OH < F < NH2 < COOH < Br < H and the maximum wavelength (λmax) for UV-visible adsorption spectra follows this order: NH2 > OH > COOH > NO2 > I > Br > CH3 > F > H. Molecules with smaller Eg and DOSHOMO values and higher λmax are considered as the most appropriate semiconductor materials. Our results show that Pt(II)P-NH2 has the smallest Eg and the highest λmax among other substituted platinum(II) porphyrin molecules. Therefore, Pt(II)P-NH2 are the most suitable semiconductor material based on the aforementioned criteria.Crystal field theory
This document provides an overview of crystal field theory and how it can be used to explain the bonding and spectroscopic properties of transition metal complexes. It discusses how ligands arranged in octahedral, tetrahedral and square planar geometries cause the d-orbitals of the transition metal to split into different energy levels. Factors that influence the size of the crystal field splitting parameter Δo, such as oxidation state, metal identity and ligand type, are also covered.
Ligand substitution reactions
This document discusses ligand substitution reactions in coordination compounds. It begins by defining ligand substitution and classifying the mechanisms as dissociative, associative, or interchange. For octahedral complexes, dissociative mechanisms are seen at high concentrations of the entering ligand and associative at low concentrations. Evidence for dissociative mechanisms includes little effect of the entering ligand on rate. Ligand substitution can also occur in octahedral complexes without breaking the metal-ligand bond. The document also discusses substitution in square planar complexes, factors affecting rate, and the trans effect, providing theories to explain it such as electrostatic polarization and pi bonding. Applications of the trans effect in synthesis are also mentioned.
c5ce00043b
The document summarizes the synthesis and characterization of coordination polymers formed from linking Pd(acacCN)2 building blocks with AgI salts. Pd(acacCN)2 forms a square planar building unit that can be crosslinked by AgI ions coordinating to the peripheral nitrile groups, forming 1D chain polymers with alternating Pd and Ag (compounds 2-6). Compounds 2 and 3 are isomorphic 1D polymers that undergo a reversible phase transition. Compound 7 unexpectedly forms a close-packed 3D structure from layers of Ag(NO3) connected by Pd(acacCN)2 linkers.
Computational Study on the Effect of Axial Ligation Upon the Electronic Struc...
This document describes a computational study examining the effect of different axial ligands on the electronic structure of copper(II) porphyrinate complexes. Density functional theory was used to model complexes with nitrite, imidazole, phenol, and water ligands. The results show that axial ligands influence the copper spin density and delocalization in the complex. Ligands like nitrite and phenolate induce more spin delocalization compared to neutral ligands like water and phenol. The strength of axial bonding also varies, with ionic ligands forming stronger bonds than neutral ones involved in hydrogen bonding. This variation in electronic structure induced by different axial ligands could explain changes seen in experimental electron paramagnetic resonance spectra of related complexes.
Molecular orbital theory (conjugated molecules)
Bonding and Antibonding interactions; Idea about σ, σ*, π, π *, n – MOs; HOMO, LUMO and SOMO; Energy levels of π MOs of different conjugated acyclic and cyclic systems; Hückel’s rules for aromaticity; Frost diagram
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Elementary steps in catalysis using transition metal compounds
Elementary steps in catalysis using transition metal compounds
REDOX REACTION : inner & outer sphere Complimentary & non-complimentary reaction
REDOX REACTION : inner & outer sphere Complimentary & non-complimentary reaction
Study of Substituent Effect on Properties of Platinum(II) Porphyrin Semicondu...
Study of Substituent Effect on Properties of Platinum(II) Porphyrin Semicondu...
Computational Study on the Effect of Axial Ligation Upon the Electronic Struc...
Computational Study on the Effect of Axial Ligation Upon the Electronic Struc...
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This document provides an overview of nuclear magnetic resonance spectroscopy using carbon-13 (13C NMR). It discusses key aspects of 13C NMR including the properties of 13C nuclei, chemical shifts, hydrogen decoupling, DEPT experiments, 2D NMR techniques like COSY and HECTOR, and applications of 13C NMR such as structure elucidation and in vivo analysis. Examples are provided to illustrate concepts like hydrogen decoupling, DEPT spectra, and 2D NMR correlations. In summary, the document serves as an introduction to 13C NMR spectroscopy, covering fundamental principles, experimental techniques, and applications of the method.
Synthesis, Physicochemical Characterization and Structure Determination of So...
Some novel nickel(II) complexes with the ligand (z)-4-((2-hydroxy-3-
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1) 13C NMR spectroscopy provides valuable structural information when 1H NMR is insufficient or ambiguous. It directly detects carbon atoms and gives signals based on their chemical environment rather than hydrogen bonding.
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C-13 NMR Spectroscopy ppt(10 Minute explanation)
Nuclear magnetic resonance spectroscopy techniques such as 13C NMR and 2D NMR experiments like COSY and HECTOR can be used to analyze organic compounds. [13C NMR provides information about the number and types of carbon atoms in a molecule based on their chemical shifts. Two-dimensional NMR experiments reveal coupling between nuclei like 1H-13C and 1H-1H couplings to help determine molecular structure.] DEPT NMR experiments distinguish between methylene, methine and methyl carbons. 13C NMR finds applications in fields like metabolic analysis, drug purity determination and polymer characterization.
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M.Sc. 2D NMR.pptx
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3. Based on analytical data and characterization, the complexes were determined to have a 1:2 metal to ligand ratio and the ligand was found to act as a bidentate ligand coordinating through nitrogen atoms in the ring.
High pressure structural properties of rare earth antimonide
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Synthesis, Physicochemical Characterization and Structure Determination of So...
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Deuteration presentation
- 1. Incorporating Selectively Deuterated Ligands into Ru(II),Rh(III),Ru(II) Trimetallic Compounds to Gain Mechanistic Insight Abstract Synthesis and characterization of two new complexes [{(TL)2Ru(BL)}2RhCl2](PF6)5 (TL= Terminal Ligand; BL= Bridging Ligand; TL= bpy or d8-bpy; BL= dpp or d10-dpp; bpy= 2-2’- bipyridine; dpp= 2-3-bis(2-pyridyl)pyrazine) using 1H NMR spectroscopy, electrochemistry, electronic absorption and excited state luminescence spectroscopy provide structural and functional classification. NMR spectra of undeuterated trimetallic complexes do not provide conclusive structural assignments due to numerous equivalent aromatic protons and structural isomers. Deuteration of bpy TL and dpp BL allows qualitative assignment of 1H NMR spectra. Greater structural understanding provides a possible path to better understand the mechanism of photocatalytic water reduction of these Ru(II), Rh(III), Ru(II) trimetallic compounds. Electrochemistry, emission and absorption spectroscopy show identical ground state electronic properties between the two selectively deuterated compounds and the fully protiated variant. Complexes containing BL d10-dpp showed an increased excited state lifetime (τ) and greater quantum yield of emission (Фem) from the Ru(dπ)→d10-dpp(π*) 3MLCT (metal-to-ligand charge transfer) excited state due to a decrease in nonradiative decay rate constant (knr). Previously synthesized deuterated Ru(II), Rh(III) bimetallic complexes that display similar 3MLCT excited state properties are more efficient H2 photocatalysts than those with undeuterated ligands. Studying selectively deuterated ligands in Ru(II), Rh(III), Ru(II) trimetallic complexes permit opportunities to further understand and improve photocatalytic water reduction. [{(bpy)2Ru(d10-dpp)}2RhCl2] Supramolecular Architechture Ru(II) acts as an LA (Light Absorber) connected to two TL’s, bpy, and one BL, in this case d10-dpp, which connects Ru(II) to the RM (reactive metal) center, Rh(III). Polyazine BL’s permits electron coupling and the transfer of electrons through the complex. 3MLCT permitted by the BL create charge imbalances; therefore providing the complex properties necessary for the photocatalytic reduction of water. Synthesis Synthesizing the supramolecular architechture of the trimetallic is completed through a building block mechanism beginning with the creation of a monometallic. Monometallic synthesis begins by reacting metal halides with TL’s in DMF. From there the monometallic is attached to the BL, preparing it to react with the metal halide that is used as the RM center. Electrochemistry Electrochemical analysis of the trimetallic complexes shows reversible oxidation at the Ru(II) LA’s. Data gathered from cyclic voltammograms are consistent with previous work indicating that Ru(II) contains the highest occupied molecular orbital (HOMO). Reversible reduction is observed in both the ligands as well as the metal center Rh(III), with observed voltages showing the existence of the lowest unoccupied molecular orbital (LUMO) on the RM center. Cyclic voltammetry provides us with a clear electronic pathway throughout the supramolecular architechture. Oxidation first occurs at Ru(II) transferring an electron to the dpp BL. Energetic similarity between the BL and RM depicts obvious electronic motion from the BL to the RM. Rh(III) most favorably accepts the electron creating a charge imbalance across the complex. RuII/III RhIII/II/I dpp0/- dpp0/- bpy0/- [{bpy}2Ru(d10-dpp)]2RhCl2 Emission spectra for the complexes produced peaks at 750 nm. Intensity of emission is slightly higher for the d10-dpp complex. Top to bottom: [{(d8-bpy)2Ru(dpp)}2RhCl2] ; [{(bpy)2Ru(dpp)}2RhCl2]; [{(bpy)2Ru(d10-dpp)}2RhCl2] Deuteration of complexes eliminates the 1H NMR signal of the deuterated ligands; however, the amount of structural isomers prevent complete assignment. NMR signals for deuterated compounds may provide insight into the H2O reduction mechanism of the trimetallic. Future Work Test the deuterated compounds efficiency at H2 production. Use structural characterization to gain insight into the mechanism of the trimetallic photocatalytic reduction of water. Objective To gain insight into the mechanism of photocatalytic water reduction to more efficiently produce H2 gas. [M-2PF6]2+ Counts/sec Mass Spec. Top: [{(bpy)2Ru(d10-dpp)}2RhCl2] Bottom: [{(d8-bpy)2Ru(dpp)}2RhCl2] References 1. Balzani, V.; Credi, A.; Venturi, M.; Photochemical Conversion of Solar Energy. ChemSUSChem 2008 2. White, T.; Mallalieu, H.; Wang, J.; Brewer, K.; Mechanistic Insight into the Elctronic Influences Imposed by Substituent Variation in Polyazine-Bridged Ruthenium(II)/Rhodium(III) Supramolecules. Chemistry A European Journal 2014