A novel path to luminescent hybrid molecular materials: modifying the hydroxyl group of 6-hydroxynicotinic acid by grafting to a silica network

In this paper, a novel path was put forward to modify the hydroxyl group of 6-hydroxynicotinic acid by 3-(triethoxysilyl)-propyl isocyanate and prepare the corresponding organic -inorganic molecular-based hybrid material with the two components connected by covalent bonds. The bridging unit is a derivative of 6-hydroxynicotinic acid that is utilized to coordinate to Tb3+ via hydrolysis and polycondensation processes with functional triethoxysilyl groups. Ultraviolet absorption, phosphorescence spectra and luminescence spectra were applied to characterize the photophysical properties of the hybrid material obtained and the spectroscopic data show that the triplet energy of modified 6-hydroxynicotinic acid efficiently initiates the antenna effect and matches the emissive energy level of the metal ions. As a result, the intramolecular energy transfer process is completed within these molecular-based hybrids. Copyright (c) 2005 John Wiley & Sons, Ltd.