On the UV spectrum of cross-conjugated 2,3-diphenyl-1,3-butadiene

• Published in: Chemical physics letters 2012-03, Vol.528, p.29-33
• Main Authors: van Walree, Cornelis A., van Lenthe, Joop H., van der Wiel, Bas C.
• Format: Article
• Language: English
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/j.cplett.2012.01.032

[Display omitted] ► UV spectrum of cross-conjugated compound 2,3-diphenylbutadiene studied with ZINDO calculations. ► Limited difference with the UV spectrum of styrene. ► Dependence of the electronic spectrum on the molecular conformation. ► Coulomb and electron exchange terms are important in the UV spectrum. ► UV spectrum is hardly indicative of conjugation. The UV spectrum of the cross-conjugated compound 2,3-diphenyl-1,3-butadiene, which can occur in both an s-gauche and s-trans conformation, is reported. The spectrum is interpreted with the use of ZINDO/S calculations and compared to the spectrum of styrene. In both conformations the difference in electronic transition energy with styrene is negligible, despite a shift in HOMO and LUMO energy. This is the consequence of the decrease of Coulomb and exchange energies by which extension of the π-system is accompanied. As such, the UV spectrum of 2,3-diphenylbutadiene, as compared to that of styrene, does not reflect extension of the π-system.