Excited state dipole moments of electron donor‐acceptor systems

1973 ◽  
Vol 59 (3) ◽  
pp. 1555-1556 ◽  
Author(s):  
C. N. R. Rao ◽  
P. C. Dwivedi
1977 ◽  
Vol 33 (4) ◽  
pp. 933-942 ◽  
Author(s):  
Edgar J.J. Groenen ◽  
Peter N.Th. Van Velzen

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.


1982 ◽  
Vol 37 (12) ◽  
pp. 1427-1448
Author(s):  
Wolfgang Liptay ◽  
Torsten Rehm ◽  
Detlev Wehning ◽  
Lothar Schanne ◽  
Wolfram Baumann ◽  
...  

AbstractThe formation of electron-donor-acceptor complexes of hexamethylbenzene (HMB) with tetracyanoethylene (TCNE) was investigated by measurements of the optical absorptions, the densities, the permittivities and the electro-optical absorptions of solutions in CCl4. The careful evaluation of data based on some previously reported models, has shown that the assumption of the formation of the 1: 1 and the 2 : 1 complex agrees with all experimental data, but that the assumption of the formation of only the 1: 1 complex is contradictory to experimental facts even if the activity effects on the equilibrium constant and of the solvent dependences of observed molar quantities are taken into account. The evaluation leads to the molar optical absorption coefficients and the molar volumes of both complexes and to their electric dipole moments in the electronic ground state and the considered excited state. According to these results the complexes are of the sandwich type HMB-TCNE and HMB-TCNE-HMB. In spite of the fact that the 2: 1 complex owns a center of symmetry, at least approximately, there is a rather large electric dipole moment in its excited state. Furthermore, values for the equilibrium constants and for the standard reaction enthalpies of both complex formation reactions are estimated from experimental data.


1991 ◽  
Vol 180 (6) ◽  
pp. 556-562 ◽  
Author(s):  
A.M. Brouwer ◽  
R.D. Mout ◽  
P.H.Maassen van den Brink ◽  
H.J. van Ramesdonk ◽  
J.W. Verhoeven ◽  
...  

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