Structures and conformational dynamics of trans- and cis-crotonaldehydes in excited electronic states: A quantum-chemical study

Publication date: Available online 28 November 2018Source: Computational and Theoretical ChemistryAuthor(s): O.S. Bokaeva, V.A. Bataev, I.A. GodunovAbstractFor trans- and cis-crotonaldehydes CH3–CH=CH–CHO in the triplet and singlet lowest excited electronic states of n,π* and π,π* types, the geometries of conformers, conformer energy differences, and conformational dynamics have been addressed using ab initio multi-reference techniques (CASSCF and CASPT2). The conformers of investigated molecules under study have been shown to possess a symmetry plane in 1,3(n,π*) states and to be significantly non-planar in 1,3(π,π*) states. Couplings of asymmetric internal rotations around C–C and C=C bonds with others large amplitude molecular motions such as methyl torsion, non-planar distortions of CCHO, C–CH=C, and C=CH(CH3) fragments are discussed. The type of coupling between large-amplitude motions has been shown to be connected with the localization of electronic excitation.Graphical abstract

Source: Computational and Theoretical Chemistry - November 29, 2018 Category: Chemistry Source Type: research