jp071303j偶氮苯侧链接枝聚合物的荧光发射和结构控制.pdfVIP

6364 J. Phys. Chem. B 2007, 111, Structure Control for Fine Tuning Fluorescence Emission from Side-Chain Azobenzene Polymers P. Smitha and S. K. Asha* Polymer Research Group, Chemical Sciences and Technology Di ision, National Institute for Interdisciplinary Science and Technology, (Formerly: Regional Research Laboratory), Thiruananthapuram - 695019, Kerala, India Recei ed: February 15, 2007; In Final Form: April 10, 2007 New fluorescent azobenzene dyes and side-chain polymers have been synthesized and characterized and their photophysical properties studied. A series of azobenzene dyes having different fluorophores such as phenol (S1), phenylphenol (S2) and naphthol (S3) incorporated in them were synthesized. S2 had unusually high fluorescence with a quantum yield of f 0.2 recorded in dichloromethane (DCM), whereas S1 and S3 were found to be weakly fluorescent. The azobenzene dyes were converted into methacrylate monomers having short ethyleneoxy spacers and then free radically polymerized. Phenylphenol-based azobenzene polymer (P2) continued to show fluorescence, whereas fluorescence was completely quenched in the case of phenol (P1)- and naphthol (P3)-based polymers. Phenylphenol, though twisted in the ground state is known to have a more planar geometry in the excited statea factor that enables it to retain its fluorescence behavior even when it is incorporated as part of an azobenzene unit. In contrast, naphthol, which is a better fluorophore compared to phenylphenol, loses much of its emissive behavior upon coupling to the azobenzene unit. The extent of