Generation-Dependent Energy Dissipation in Rigid Dendrimers Studied by Femtosecond to Nanosecond Time-Resolved Fluorescence Spectroscopy

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2002-03, Vol.106 (10), p.2083-2090
• Main Authors: Lor, M, De, R, Jordens, S, De Belder, G, Schweitzer, G, Cotlet, M, Hofkens, J, Weil, T, Herrmann, A, Müllen, K, Van Der Auweraer, M, De Schryver, F. C
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp012310p

Intramolecular kinetic processes in a series of second-generation polyphenyl dendrimers with multiple peryleneimide chromophores attached to the para position of the outer phenyl ring were investigated by steady-state and femtosecond to nanosecond time-resolved fluorescence spectroscopy. The results obtained were compared to the ones of the corresponding first-generation dendrimer series. The energy-hopping rate constant, k hopp, observed from anisotropy decay times was found to be 5 times smaller than that of the first-generation series and scales well with the difference in average distance between the chromophores. In addition to the processes observed in first-generation dendrimers in the ultrafast time domain by fluorescence up-conversion, a second annihilation process is found in the second-generation multichromophoric dendrimer. The observation of two singlet−singlet annihilation processes in this compound can be explained by the presence of a mixture of constitutional isomers leading to a broader distribution of distances between neighboring chromophores compared to first-generation multichromophoric dendrimers.