Related Concept Videos
01:11Channel Rhodopsins
Most organisms use photoreceptors to sense and respond to light. Examples of photoreceptors include bacteriorhodopsins and bacteriophytochromes in some bacteria, phytochromes in plants, and rhodopsins in the photoreceptor cells of the vertebral retina. The light-sensitive property of these receptors is because of the bound chromophores, such as bilin in the phytochromes and retinal in the rhodopsins.
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
02:52Stereoisomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
00:58¹H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons
Replacing each alpha-hydrogen in chloroethane by bromine (or a different functional group) yields a pair of enantiomers. Such protons are called prochiral or enantiotopic and are related by a mirror plane. Enantiotopic protons are chemically equivalent in an achiral environment. Because most proton NMR spectra are recorded using achiral solvents, enantiotopic hydrogens yield a single signal.
In chiral compounds such as 2-butanol, replacing the methylene hydrogens at C3 produces a pair of...
In chiral compounds such as 2-butanol, replacing the methylene hydrogens at C3 produces a pair of...
01:15The Antenna Complex
Plants and other photosynthetic organisms comprise pigments capable of absorption of direct sunlight. These pigments are present in the reaction center - the main site of photochemical reactions as well as in the antenna complex. Under average light conditions, the rate at which reaction center pigments absorb light is far below the electron transport chain's capacity. As a result, the reaction center alone cannot provide enough energy to drive photosynthesis. The photosynthetic efficiency can...
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Related Experiment Video
Updated: Jun 15, 2026
14:11
Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Non-planar push-pull chromophores.
Shin-ichiro Kato1, François Diederich
1Laboratorium für Organische Chemie, ETH Zürich, Hönggerberg, HCI, CH-8093 Zürich, Switzerland.
Chemical Communications (Cambridge, England)
|March 12, 2010
Summary
Researchers developed non-planar push-pull chromophores using click chemistry. These dendritic electron sinks exhibit strong near-infrared absorption and high optical nonlinearities, suitable for advanced optoelectronic devices.
Area of Science:
- Organic Chemistry
- Materials Science
- Optoelectronics
Background:
- Push-pull chromophores are crucial for optoelectronic devices.
- Existing planar chromophores face limitations in solubility and film formation.
Purpose of the Study:
- To develop novel non-planar push-pull chromophores with enhanced properties.
- To explore their potential as advanced functional materials for optoelectronics.
Main Methods:
- Utilizing [2 + 2] cycloaddition followed by cycloreversion reactions.
- Employing electron-deficient olefins like TCNE, TCNQ, and F(4)-TCNQ with donor-substituted alkynes.
- Synthesizing an [AB]-type oligomer via a one-pot, multi-component cascade reaction.
Main Results:
- Achieved high-yielding synthesis of non-planar chromophores with dendritic structures.
- Observed intense intramolecular charge-transfer bands extending into the near-infrared region.
- Demonstrated high third-order optical nonlinearities and potent electron-accepting capabilities.
Conclusions:
- Non-planar chromophores exhibit superior solubility, thermal stability, and sublimability compared to planar analogues.
- These materials enable the formation of high-quality thin films for optoelectronic applications.
- The developed chromophores represent promising candidates for next-generation optoelectronic devices.