三苯胺-噁二唑超支化共轭聚合物的多光子泵浦绿色荧光

Multiphoton Pumped Green Fluorescence in a Hyperbranched Triphenylamine-oxadiazole Conjugated Polymer

采用钯催化Heck反应制备了一种新型三苯胺-噁二唑超支化荧光聚合物PI.用飞秒Ti:sapphire激光研究了PI的三光子和双光子上转换荧光光谱,激发波长位于近红外区(800～1350 nm).在1280 nm和80 fs激光激发下,PI的三光子上转换荧光发射波长分别为525 nm(THF),534 nm(CH2Cl2)和578 nm(DMF).在800 nm和150 fs激光激发下,PI的双光子上转换荧光发射波长分别为527 nm(THF),532 nm(CH2Cl2)和573nm(DMF).采用非线性透过率法测定荧光聚合物PI的三光子和双光子吸收系数.系统研究了PI的线性吸收和透过、单光子荧光、荧光寿命、前线轨道能级及热稳定性.实验结果表明,三苯胺-噁二唑超支化共轭聚合物的多光子吸收和上转换荧光发射性能比树型分子或线型聚合物更为优异.

A novel hyperbranched triphenylamine-oxadiazole fluorescence polymer（PI） was synthesized by Pd-catalyzed Heck reaction.Three-photon and two-photon upconversion fluorescence spectra of polymer PI were measured using a femtosecond Ti： sapphire that was pumped by a femtosecond laser at the near-infrared region of 800—1350 nm.Its three-photon and two-photon absorption coefficient were determined by mearuring the nonlinear transmissivity at a known input intensity level.The three-photon excited fluorescence was observed with the central wavelength at 525 nm in THF,at 534 nm in CH2Cl2 and at 578 nm in DMF,respectively.The maximum peak of two-photon excited fluorescence was at 527 nm in THF,at 532 nm in CH2Cl2 and at 573 nm in DMF,respectively.Increased solvent polarity were found to induced a marked red-shift of the emission band of multiphoton pumped fluorescence in polymer PI.The hyperbranched triphenylamine-oxadiazole conjugated alternate copolymer displayed large multi-photon absorption and strong upconversion fluorescence properties.