Structural and vibrational analysis of azodendrimers by molecular orbital methods

The structural optimization and normal-mode analysis are performed for the aryl ether azodendrimers on the basis of the semi-empirical molecular orbit al methods. Through the geometrical characterization for the stable structu res, the fractal dimension and the degree of azo core wrapping are found to provide key parameters related to the unique photoinduced isomerization. W e also find that the normal-mode frequency distribution is virtually invari able irrespective of the molecular structure and generation of azodendrimer s. The importance of normal-mode distribution gap in the range of 700-900 c m(-1) is suggested regarding the efficient vibrational energy transfer to t he azo core region. (C) 2000 Elsevier Science B.V. All rights reserved.