Dynamics of Excitation Energy Transfer from Biphenylylene Excimers in Pore Walls of Periodic Mesoporous Organosilica to Coumarin 1 in the Mesochannels

To understand the energy transfer dynamics of biphenylylene (Bp)-bridged periodic mesoporous organosilica (PMO) powder doped with coumarin 1, picosecond time-resolved fluorescence spectroscopic studies were carried out. The time-resolved fluorescence spectra after excitation of the Bp moieties in the pore walls revealed rapid formation of Bp excimers, followed by transfer of their excitation energy to coumarin 1 placed in the mesochannels. The fluorescence decay curves were analyzed by Monte Carlo simulation on the basis of the Bp excimer distribution and the position of coumarin 1 in the mesochannels of Bp-PMO. The analytical results suggest that Forster-type energy transfer occurs from the three types of Bp excimers to coumarin 1 located in the vicinity of the pore surface, more precisely at the hydrophilic silica layers on the pore walls, while some of the Bp excimers are not affected by any acceptors.