Definition of twisted intramolecular charge transfer

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Photonics Dictionary

twisted intramolecular charge transfer: Twisted intramolecular charge transfer (TICT) is a phenomenon observed in certain organic molecules containing electron-donor and electron-acceptor groups that are linked together within the same molecule. In TICT systems, the molecule undergoes a non-planar molecular distortion, leading to a change in the distribution of electronic charge (charge transfer) within the molecule.

The TICT process typically occurs when the molecule is excited to an electronically excited state by absorbing light (photoexcitation). In the ground state, the electron-donor and electron-acceptor groups are typically in close proximity, facilitating efficient charge transfer. However, upon photoexcitation, the molecule undergoes a conformational change or twisting motion, causing the electron-donor and electron-acceptor groups to move away from each other, disrupting the initial charge transfer pathway.

As a result of this conformational change, the excited electron becomes delocalized over both the donor and acceptor groups, leading to a redistribution of electronic charge within the molecule. This redistribution of charge alters the electronic and optical properties of the molecule, resulting in characteristic changes in its photophysical behavior, such as shifts in absorption and emission spectra, changes in fluorescence lifetimes, and alterations in emission colors.

TICT is commonly observed in certain classes of organic molecules, such as charge-transfer fluorophores, where it can have significant implications for their optical properties and applications. Understanding and controlling TICT processes are essential for the design of efficient fluorescent probes, sensors, and optoelectronic devices, as well as for elucidating the fundamental photophysical mechanisms governing the behavior of organic materials.

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