this presentation discusses the crystal field theory and its role in explaining the formation of coordination complexes by transition elements, their magnetic and colour properties; and its limitations!
A brief introduction to lanthanide elements is given.
Order .ppts like this at <https://www.fiverr.com/anikmal/teamup-with-you-to-prepare-the-best-presentation>
Along with their physical and chemical properties are also shown. Helpful for quick understanding on lanthanide series.
A brief introduction to lanthanide elements is given.
Order .ppts like this at <https://www.fiverr.com/anikmal/teamup-with-you-to-prepare-the-best-presentation>
Along with their physical and chemical properties are also shown. Helpful for quick understanding on lanthanide series.
Introductory PPT on Metal Carbonyls having its' classification,structure and applications.This is a basic level PPT specially prepared for UG/PG Chemistry students.
Classification Of Mechanisms, Ligand Substitution In Octahedral Complexes Without Breaking Metal-ligand Bond, Substitution Reaction In Square Planar Complexes, Factors Which Affect The Rate Of Substitution, Trans Effect (Labilizing Effect), Theories and applications Of Trans Effect
Hi guys !!!!!
This is a presentation on the crystal field theory.Here you can find the complete information regarding the CFT .
If you have any doubts regarding the crystal field theory feel free to ask in the comments section.
THANK YOU!!!!
Introductory PPT on Metal Carbonyls having its' classification,structure and applications.This is a basic level PPT specially prepared for UG/PG Chemistry students.
Classification Of Mechanisms, Ligand Substitution In Octahedral Complexes Without Breaking Metal-ligand Bond, Substitution Reaction In Square Planar Complexes, Factors Which Affect The Rate Of Substitution, Trans Effect (Labilizing Effect), Theories and applications Of Trans Effect
Hi guys !!!!!
This is a presentation on the crystal field theory.Here you can find the complete information regarding the CFT .
If you have any doubts regarding the crystal field theory feel free to ask in the comments section.
THANK YOU!!!!
Quantum Physics is already a very interesting subject, and so even though the presentation has all the required information to get yourself a hold on the subject, I would highly recommend everyone to do some extensive research. Well actually, there is no need for anyone to point out on the research part, you will automatically find yourselves filling the search history with some deep quantum-ish.
POLARIZATION - BIREFRINGENCE AND HUYGEN'S THEORY OF DOUBLE REFRACTION Anuroop Ashok
SIMPLE AND ACCESSIBLE SLIDES ON POLARIZATION. IT INCLUDES SLIDES ON DOUBLE REFRACTION , CALCITE CRYSTALS, HUYGEN'S THEORY , NEGATIVE AND POSITIVE CRYSTALS,...
1_ Introduction to Optical Mineralogy, Light & Theories-converted.pdfAdnanKhan153072
introduction to optical minerology and description about optical properties of mineral and importance and uses of optical minerology and how to identify a mineral through its optical properties.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
6. WHY CFT???
Werner’s Theory
Valence Bond Theory
COULD NOT
EXPLAIN THE
COLOUR
PROPERTIES
7. Introduction To CFT
• Proposed by Bethe and van Vleck.
• Orgel used the concept of crystal field theory to define nature of
bonding between ligands and metals.
• It defines the bonding in ionic crystals due to which
this theory is known as crystal field theory.
8. • Crystal field theory (CFT) explains many important properties of
transition-metal complexes, including their
ocolours,
omagnetism,
ostructures,
ostability, and
oreactivity
9.
10. • d-orbitals are degenerate
• BUT, when ligands get
attached and are uniformly
distributed; their energy gets
higher
• IF, the ligands are oriented at
the axes i.e. x, y and z, the
degeneracy gets removed and
the d-orbitals split into two
groups [ 𝐞 𝒈 & 𝐭2𝑔]
11. • the 𝐞 𝐠 group consists of
𝐝 𝑧
2 & d𝜘2 𝑦2 , these have
electrons ON the x, y
and z axis
• while, the t2g has dxy,
dyz dzx having electrons
in BETWEEN the xy, yz
and zx axes
• the energies of these two
groups 𝐞 𝐠 & t2g depend
on their orientations in
space
12.
13. APPEARANCE OF COLOURS
• The striking colours that these metal complexes show are because
of the d-d transition of electrons in the d-orbitals
• Involves the jumping of electrons from lower energy orbitals and
their subsequent jumping back
• Jumping occurs when electrons get excited
• In case of colour properties, excitation is caused by photons of
visible light
• A photon of light can excite and can cause jumping, if its energy is
equal to the crystal field splitting energy (Δo) (CFSE)
• CFSE is the difference in energy between the two sets of d-orbitals
• Energy is absorbed and then released, respectively
14.
15. COLORS & HOW WE
PERCEIVE IT
800
430
650 580
560
490
Artist color wheel
showing the colors which
are complementary to one
another and the wavelength
range of each color.
400
16. BLACK & WHITE
If a sample absorbs all wavelength
of visible light, none reaches our
eyes from that sample.
Consequently, it appears black.
When a sample absorbs light, what we see is the sum
of the remaining colors that strikes our eyes.
If the sample absorbs no
visible light, it is white
or colorless.
18. Gemstone owe their color from trace
transition-metal ions
Corundum mineral, Al2O3: Colorless
Cr → Al : Ruby
Mn → Al : Amethyst
Fe → Al : Topaz
TRANSITITON METAL GEMS
19. Ti & Co Al: Sapphire
Beryl mineral, Be3 Al 2Si6O18: Colorless
Cr → Al : Emerald
Fe → Al : Aquamarine
20. LIMITATIONS OF CFT
1. This theory does not consider the splitting of the orbital other than d
orbital.
2. The order of ligand in the Spectro-chemical series can not be
explained solely on electrostatic ground.
CFT focuses on the interaction of the five degenerate d-orbitals with ligands arranged in a regular array around a transition-metal ion.
Mostly octahedral complexes (because they are the most common and the easiest to visualize. Other common structures, such as square planar complexes, can be treated as a distortion of the octahedral model.)
The octahedral geometry is easily found because since the ligands interact with one other electrostatically, the lowest-energy arrangement of six identical negative charges is an octahedron, which minimizes repulsive interactions between the ligands and prevents the distortion of the octahedron.
The occurrence of distortion depends on the strength and size of the approaching ligands.
Gauss’s Law (when charge is uniformly distributed over a sphere then the overall charge is zero or unaffected)