Conformational equilibria in EE-1,3-di-(3′-thienylethenyl)benzene: One-way adiabatic interconversion of rotamers in S1 and their excited state properties

Adiabatic Pathways in the Conformational and Geometrical Photoisomerizations of the 1,2-Distyrylbenzene Isomers

“…Examples of interconversion of excited rotamers with or without inversion of their stability in the S 1 state as compared to S 0 were previously reported for 2-vinylanthracene and its β-alkyl derivatives, − 2-anthrylethenes and 1,3-di-(3′-thienylethenyl)benzene (one-way process), while interconversions followed by re-equilibration among rotamers (equilibrium case) were reported for the trans isomers of 1-(2′-propenyl),2-(2′-anthryl)ethene and N -methoxy-1-(2-anthryl)ethanimine …”

“…The photophysical and photochemical behavior of all-trans (EE) geometrical isomers of 1, n -DSB bearing the two styryl substituents in the para ( n = 4, linear conjugation) − and meta ( n = 3, crossed conjugation) − positions has been particularly investigated in the last decades. Both series of compounds show a very small trans → cis photoisomerization yield, while the radiative relaxation is predominant.…”

“…Both series of compounds show a very small trans → cis photoisomerization yield, while the radiative relaxation is predominant. In these compounds, conformational equilibria are present in the ground state (S 0 ), and their role on the deactivation channels of the excited states has been investigated. − ,− …”

“…The photobehavior of 1,n-distyrylbenzenes [1,n-DSB, with n ) 2, 3, or 4] has received wide attention because delocalization of the π electrons in their electronically excited states can induce new and specific properties, which can find potential applications in the field of material science, particularly in optoelectronics. 1,2 The photophysical and photochemical behavior of all-trans (EE) geometrical isomers of 1,n-DSB bearing the two styryl substituents in the para (n ) 4, linear conjugation) [3][4][5][6] and meta (n ) 3, crossed conjugation) [7][8][9][10] positions has been particularly investigated in the last decades. Both series of compounds show a very small trans f cis photoisomerization yield, while the radiative relaxation is predominant.…”

“…In these compounds, conformational equilibria are present in the ground state (S 0 ), and their role on the deactivation channels of the excited states has been investigated. [3][4][5][6][7][8][10][11][12][13][14] On the contrary, the nonconjugated ortho positional isomer (n ) 2, 1,2-DSB) has been relatively less investigated from the photophysical point of view. 9,11,12,15,16 The results have shown that the lack of conjugation markedly affects the properties of this molecule in the excited states.…”