Affiliation:
1. Departamento de Fisica, Facultad de Ciencias Exactas y Naturales and IFIBA CONICET, Universidad de Buenos Aires, Ciudad Universitaria Pab. I, (1428) Buenos Aires Argentina
2. Department of Physics University of Northeast, IMIT – CONICET Av. Libertad 5500 Corrientes W3404AAS Argentina
3. Dipartimento di Chimica e Biologia “A. Zambelli” Università degli Studi di Salerno via Giovanni Paolo II 132 Fisciano 84084 Italy
Abstract
AbstractThe diagonal components and the trace of two tensors which account for chiroptical response of the leucoindigo molecule that is, static anapole magnetizability, and dynamic electric dipole‐magnetic dipole polarisability depending on the frequency of impinging light, are a function of the dihedral angle of torsion about the central CC bond, assumed to lie in the direction of the coordinate system. They vanish for symmetry reasons at and , corresponding respectively to and point group symmetries, that is, cis and trans conformers characterized by the presence of molecular symmetry planes. Nonetheless, diagonal components and average value of static anapole polarizability and optical rotation tensors vanish at , where leucondigo is unquestionably chiral from the geometrical viewpoint. Vanishing values of the average chiroptical properties have been observed also in the proximity of other angles. Attempts have been made to explain the occurrence of accidental zeros of chiroptical properties in terms of transition frequencies and scalar products appearing in the numerator of their quantum mechanical definitions. Within the electric dipole approximation, the presence of anomalous vanishing values of tensor components of anapole magnetizability and electric‐magnetic dipole polarizability is ascribed to physical achirality, arising from the lack of either toroidal or spiral electron flow along the , and directions.
Subject
Computational Mathematics,General Chemistry