TICT twisted intramolecular charge

Intramolecular charge transfer in conjugated donor-acceptor molecules may be accompanied by internal rotation leading to TICT (twisted intramolecular charge transfer) states. A dual fluorescence may be observed as in PCT-5 (Letard et al., 1994) (which resembles the well-known DMABN (see section 3.4.4) containing a dimethylamino group instead of the monoaza-15-crown-5) the short-wavelength... 

Compounds 268a and 269a showed large Stokes shifts in polar solvents. Such large Stokes shifts have been observed in many TICT (twisted intramolecular charge transfer) molecules. Fluorescence decay time measurement indicated that there were two kinds of excited states, fast and slower decaying components, and the latter was the emission from the more polar state. 

In another investigation, picosecond absorption studies were conducted on TPE singlet excited state in supercritical fluids. Studies were also carried out on ethyl-(Af,Af-dimethylamino)benzoate TICT (twisted intramolecular charge transfer) state for comparison with the TPE studies in supercritical fluids [62]. The decay rates of excited singlet of TPE were found to be correlatable with the solvent-induced changes. The results of this study indicated that the singlet excited state of TPE is twisted and is associated with a polar or zwitterionic character. 

Gormin D, Kasha M (1988) Triple fluorescence in aminosalicylates. Modulation of normal, proton-transfer, and twisted intramolecular charge-transfer (TICT) fluorescence by physical and chemical perturbations. Chem Phys Lett 153 574-576... 

Rettig W, Lapouyade R (1994) Fluorescence probes based on twisted intramolecular charge transfer (TICT) states and other adiabatic photoreactions. Topics in fluorescence spectroscopy 4 109-149... 

Grabowski ZG, Dobkowski J (1983) Twisted intramolecular charge transfer (TICT) excited states energy and molecular structure. Pure Appl Chem 55(2) 245-252... 

Bulgarevich DS, Kajimoto O, Hara K (1995) High-pressure studies of the viscosity effects on the formation of the twisted intramolecular charge-transfer (TICT) state in 4,4 -diaminodi-phenyl sulfone (DAPS). J Phys Chem 99(36) 13356—13361... 

Jiang Y (1994) pH Dependence of the twisted intramolecular charge transfer(TICT) of p-N, N-dimethylaminobenzoic acid in aqueous solution. J Photochem Photobiol A Chem 78 (3) 205-208... 

Molecular rotors are fluorophores characteristic for having a fluorescent quantum yield that strongly depends on the viscosity of the solvent [50], This property relies on the ability to resume a twisted conformation in the excited state (twisted intramolecular charge transfer or TICT state) that has a lower energy than the planar conformation. The de-excitation from the twisted conformation happens via a non-radiative pathway. Since the formation of the TICT state is favored in viscous solvents or at low temperature, the probability of fluorescence emission is reduced under those conditions [51]. Molecular rotors have been used as viscosity and flow sensors for biological applications [52], Modifications on their structure have introduced new reactivity that might increase the diversity of their use in the future [53] (see Fig. 6.7). 

Rettig W. (1982) Application of Simplified Microstructural Solvent Interaction Model to the Solvatochromism of Twisted Intramolecular Charge Transfer (TICT) States, /. Mol. Struct. 8, 303-327. 

Rettig W. and Lapouyade R. (1994) Fluorescent Probes Based on Twisted Intramolecular Charge Transfer (TICT) States and Other Adiabatic Reactions, in Lakowicz J. R. (Ed.), Topics in Fluorescence Spectroscopy, Vol. 4, Probe Design and Chemical Sensing, Plenum Press, New York, pp. 109-149. 

Fluorescence Probes Based on Twisted Intramolecular Charge Transfer (TICT) States and Other Adiabatic Photoreactions... 

W. Rettig and G. Wermuth, The kinetics of formation of twisted intramolecular charge transfer (TICT) states in p-substituted dialkylanilines Consequences of conical intersections along the reaction coordinate, /. Photochem. 28, 351 (1985). 

Z. R. Grabowski, K. Rotkiewicz, A. Siemiarczuk, D. J. Cowley, and W. Baumann, Twisted intramolecular charge transfer states (TICT). A new class of excited states with a full charge separation, Now. J. Chim. (NewJ. Chem.) 3, 443 (1979). 

W. Rettig and W. Baumann, Luminescent and nonluminescent twisted intramolecular charge transfer (TICT) states Dipole moments and applications, in Photochemistry and Photophysics, Vol. 6 (J. F. Rabek, ed.), pp. 79-134, CRC Press, Boca Raton, Florida (1992). 

K. A. Al-Hassan and T. Azumi, The role of free volume in the twisted intramolecular charge transfer (TICT) emission of dimethylaminobenzonitrile and related compounds in rigid polymer matrices. Chem. Phys. Lett. 146, 121 (1988). 

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