Preferred Formation of Coplanar Inclined Fluorescent J-Dimers in Rhodamine 101 Doped Silica Gels

Rhodamine 101 (R101) doped silica gels were prepared through the sol−gel process with dye concentrations ranging from 4.0 × 10 - 6 to 6.4 × 10 - 4 M. Excitation and emission fluorescence spectra and lifetime measurements were recorded for R101 doped silica gels in the whole range of concentrations. The photophysical behavior of the gel-glasses doped with high concentrations of R101 resembles that of fluorescent J-dimers in a coplanar inclined configuration. The formation of fluorescent J-dimers in a coplanar inclined rather than in an oblique configuration is discussed in terms of the molecular structure of R101.