Observation of Intramolecular Interaction in Fluorescent Star-Shaped Polymers: Evidence for Energy Hopping between Branch Chains

Abstract

Time-resolved fluorescence anisotropy measurements were performed on three-branched star-shaped polymers, based on precisely synthesized poly­(9,9-di-n-octyl-fluorene vinylene)­s containing C6F5 end groups. The star-shaped polymers showed identical fluorescence spectra, fluorescence lifetimes, and quantum yields to those of the reference single-chain oligomer. However, a rapid fluorescence anisotropy decay was observed in two kinds of star-shaped polymers, while such decay was not seen in the corresponding single-chain oligomer. On the basis of the analysis using an incoherent hopping model, the observed rapid anisotropy decay is attributable to energy hopping processes between branches within a single polymer species, and its rate was deduced to be ca.100 ps depending upon the core part.

Significance of the connecting position between Zn(ii) porphyrin and Re(i) bipyridine tricarbonyl complex units in dyads for room-temperature phosphorescence and photocatalytic CO2reduction: unexpected enhancement by triethanolamine in catalytic activity

“…Time-resolved emission signals for fluorescence lifetimes were obtained by a pico-second fluorescence measurement system consisting of Chromex 250IS imaging spectrograph and a charge-coupled device (CCD) streak scope Hamamatsu model C4334, with excitation by a light pulser Hamamatsu model PLP-1-040 (406 nm, full width at half-maximum (fwhm) = 70 ps). 47 Hi-resolution MALDI-TOF mass spectra were collected on JEOL JMS S-3000 with dithranol or trans -2-[3-(4- tert -butylphenyl)-2-methyl-2-propenylidene]-malononitrile (DCTB) as a matrix. FTIR spectra were recorded in KBr or acetonitrile using a JASCO FT/IR-4600.…”