Fluorescence enhancement of organic chromophore in solid state via organic–inorganic hybrid matrix: Steady state and kinetic studies

Abstract

Xerogels of silica-based organic–inorganic hybrid materials consisting of covalently bound fluorophores, terthiophene and terphenylene derivatives, were fabricated and analyzed. The synthesized chromophore-containing alkoxysilane derivatives were no emission in solid state, but showed strong fluorescence in organic–inorganic hybrid materials as well as in solution. Moreover, the fluorescence quantum yield of chromophore could be further improved in organic–inorganic hybrid materials with the optimized component than that of chromophore dissolved in solution. On the other hand, the fluorescence intensity of hybrid materials decreased with increasing the concentration of chromophore in organic–inorganic hybrid materials. Obviously, the relative distance between chromophores was shortened to perturb radiative relaxation. Temperature-dependent fluorescence spectra revealed that the fluorescence of chromophore in organic–inorganic hybrid materials was temperature-independent. This result indicated the inter-chromophore interactions and intra-molecular motion have been forbidden. The kinetic measurements confirmed that the chromophore spread in organic–inorganic hybrid materials was fixed with rigid conformation. The florescence decay lifetime of chromophore also kept similar at different temperature with organic–inorganic hybrid materials skeleton. This hybrid matrix provided a platform that enhanced fluorescence of chromophore in solid state at ambient temperature. Emission enhancement of organic chromophores, terthiophene and terphenylene, was performed through the utilization of covalently bound silica-based organic–inorganic hybrid material (OIHM). The chromophore was no emission in solid state, but showed strong fluorescence in OIHM as well as in solution. Moreover, the fluorescence quantum yield of chromophore could be better in OIHM with optimized component than that in solution. Temperature-dependent fluorescence spectra revealed that the fluorescence of chromophore in OIHM was temperature-independent. The kinetic measurements confirmed that the chromophore spread in OIHM was fixed with rigid conformation. This OIHM system offered a useful platform to maintain the emission behavior of organic chromophores in quasi-solid state.