Related Experiment Video
Updated: Jun 29, 2025
05:51
Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
6.2K
Optically induced charge-transfer in donor-acceptor-substituted p- and m- C2B10H12 carboranes
Lin Wu1, Marco Holzapfel2, Alexander Schmiedel2
1Frontiers Science Center for Flexible Electronics (FSCFE), Shaanxi Institute of Flexible Electronics (SIFE) & Shaanxi Institute of Biomedical Materials and Engineering (SIBME), Northwestern Polytechnical University (NPU), 127 West Youyi Road, Xi'an, 710072, China.
Nature Communications
|April 8, 2024
Summary
Icosahedral carboranes act as aromatic bridges, facilitating intramolecular charge transfer in optical functional chromophores. Their conjugation extent depends on substituent torsional angles, confirmed by experimental and computational studies.
Area of Science:
- Organic Chemistry
- Materials Science
- Photochemistry
Background:
- Icosahedral carboranes (C2B10H12) are known for their aromaticity, but their role in conjugation with substituents is debated.
- Carboranes serve as potential building blocks in advanced materials and molecular devices.
Purpose of the Study:
- To investigate the conjugation extent of meta- and para-carboranes as bridges in optical functional chromophores.
- To compare carborane bridges with traditional phenylene bridges in donor-acceptor systems.
Main Methods:
- Femtosecond transient absorption spectroscopy
- Time-resolved fluorescence spectroscopy
- Broadband fluorescence upconversion
- Quantum chemical calculations
Main Results:
- Experimental data confirm strong intramolecular charge transfer (ICT) between donor and acceptor groups through the carborane bridge.
- Absorption and emission processes are significantly influenced by the carborane cluster's electronic properties.
- Quantum chemical calculations reveal that ICT efficiency is dependent on the torsional angles of donor and acceptor groups.
Conclusions:
- Icosahedral carboranes effectively mediate charge transfer, supporting their role in conjugated systems.
- The electronic communication through carborane bridges is tunable via substituent orientation.
- Carboranes offer a promising alternative to phenylenes for designing novel optical functional materials.
Related Concept Videos
02:10Carbocations
11.2K
Carbocations are one of the reaction intermediates formed during several nucleophilic substitutions or elimination reactions. A carbocation is an electron-deficient species with the central carbon atom having six electrons and three bonded atoms. The central carbon in a carbocation is sp2 hybridized with trigonal planar geometry. It has an empty p orbital perpendicular to the plane of the structure that can accept electrons. Thus, carbocations act as strong electrophiles and may react with any...
11.2K
01:18π Molecular Orbitals of the Allyl Cation and Anion
4.2K
An allyl group is a three-carbon conjugated system where the sp³-hybridized allylic carbon is bonded to a CH=CH2 group via a single bond. Allyl anions can be obtained by treating propene with a strong base that can deprotonate methyl groups. Allyl cations are formed as intermediates during substitution reactions involving allylic halides. In both cases, the hybridization of the allylic carbon changes from sp3 to sp2, giving rise to a carbon chain with three sp2-hybridized carbons, each with...
4.2K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
1.8K
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
1.8K
02:36Regioselectivity and Stereochemistry of Hydroboration
8.1K
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
8.1K
01:07Radicals: Electronic Structure and Geometry
4.0K
This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
4.0K
01:11ortho–para-Directing Activators: –CH3, –OH, –NH2, –OCH3
6.0K
All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...
6.0K