Photophysical investigation on molecular aggregation of 1-benzyl-2-hydro[60]fullerene in Langmuir–Blodgett multilayers

The aggregation behavior of a substituted fullerene compound, 1-benzyl-2-hydro[60]fullerene (C60-Bh), in Z-type Langmuir–Blodgett (LB) multilayers has been studied by UV–VIS absorption, steady-state and time-resolved fluorescence spectroscopics. The LB multilayers of pure C60-Bh showed J-aggregate formation, characterized by a large red-shift of two absorption peaks (ΔE∼2098 cm−1 from 260→275 nm and ΔE∼1076 cm−1 from 328→340 nm). The main fluorescence emission bands were found at 710, 646, 603 and 595 nm for pure C60-Bh, mixed C60-Bh/arachidic acid (AA) (1:1), mixed C60-Bh/nitrogencrown (NC) (1:3) multilayers and monomeric C60-Bh in solution, respectively. The aggregates were dissociated by mixing with AA or NC. The fluorescence decay profiles of C60-Bh, C60-Bh/AA and C60-Bh/NC in LB films could be fitted by a bi-exponential decay model.