Photoinduced charge transfer as revealed by ground and excited state dipole moments

1993 ◽  
Vol 65 (8) ◽  
pp. 1729-1732 ◽  
Author(s):  
W. Baumann ◽  
Z. Nagy
2021 ◽  
Author(s):  
Federico Coppola ◽  
Paola Cimino ◽  
Umberto Raucci ◽  
Maria Gabriella Chiariello ◽  
Alessio Petrone ◽  
...  

We present electronic structure methods to unveil non-radiative pathways of photoinduced charge transfer (CT) reactions that play a main role in photophysics and light harvesting technologies. A prototypical π-stacked molecular...


1992 ◽  
Vol 70 (7) ◽  
pp. 1932-1938 ◽  
Author(s):  
Hemant K. Sinha ◽  
S. Muralidharan ◽  
Keith Yates

Electric field induced change in the absorption spectrum (electrochromism) has been employed to obtain the ground and excited state dipole moments of planar and sterically hindered (twisted) p-N,N-(dimethylamino)benzonitriles in dioxane solution. These studies support the twisted intramolecular charge transfer (TICT) hypothesis and provide additional insight to the TICT concept. The charge transfer nature of the excited state has been found to directly depend on the torsional angle of the N,N-dimethylamino group with respect to the benzonitrile moiety. It is suggested that solvent coupling is essential to initiate twisting by affecting the intramolecular degrees of freedom and the existence of the highly dipolar excited state is a result of such twisting of the donor–acceptor bond. Theoretical calculations have been performed to explain the observed changes in dipole moment values.


1990 ◽  
Vol 68 (9) ◽  
pp. 1507-1513 ◽  
Author(s):  
Hemant K. Sinha ◽  
Paul C. P. Thomson ◽  
Keith Yates

Electric field induced changes in the optical absorption spectra (electrochromism) have been used to obtain the excited state dipole moments and polarizabilities of styrene, 2-vinylnaphthalene, 2-naphthylacetylene, and 9-vinylanthracene. Excited state dipole moments of the order of 4–6 debye have been obtained for all these molecules except for 9-vinylanthracene, for which the excited state dipole moment is zero within experimental error. These results support earlier proposals of the involvement of charge transfer excited states in the fast and efficient acid-catalysed photohydration reactions of this type of substrate. 9-Vinylanthracene, on the other hand, under similar conditions reacts differently to give a dimer as the major photoproduct, and its reaction is not subject to acid catalysis. These results shed light on the importance of charge transfer excited states on the efficiency of photohydration reactions. Keywords: electrochromism, excited state, dipole moments, polarizabilities.


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