Experimental and theoretical studies of the low-lying electronic states of the simplest benzylic amide [2]catenane

The lowest electronically excited states of the simplest benzylic amide [2]catenane (1) have been studied by a combination of experimental and theoretical techniques. Experimentally, steady-state and transient absorption spectra, emission spectra, and the optoacoustic response in solution have been recorded for the catenane and a model compound (N, N'-dibenzylisophthalic diamide (2)), as well as the electron energy loss spectrum of the catenane deposited on the Au(111) surface. The theoretical picture builds on the results of semiempirical quantum chemical calculations and shows that partial delocalisation of the electronic states over the many chromophores of the catenanes can occur. (C) 1998 Elsevier Science B.V. All rights reserved.