Evaluation of electron or charge transfer processes between chromenylium-based fluorophores and protonated–deprotonated aniline

Jin-Wei Xiao^a,Wei-Jin Zhu^a,Ru Sun*^a（孙如）,Yu-Jie Xu^bandJian-Feng Ge*^a（葛健锋）

^aCollege of Chemistry, Chemical Engineering and Material Science, State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Soochow University, 199 Ren’Ai Road, Suzhou 215123, China

^bSchool of Radiation Medicine and Protection, Medicine College of Soochow University, Suzhou 215123, China

RSC Adv.,2016,6, 98985-98993

Three functional dyes based on a chromenylium skeleton were prepared. The chromenylium-based fluorophores were regarded as acceptor parts and the aniline served as donor parts; their pH-dependent fluorescent responses were used to evaluate the photoinduced electron transfer (PET) or intramolecular charge transfer (ICT) processes between the chromenylium-based fluorophores and aniline. Two chromenylium–indole hybrid functional dyes (1a–b) respectively showed a fluorescence enhancement and decrease with increasing acidity, while chromenylium–coumarin hybrid dye (1c) gave an OFF–ON response towards a gradually decreasing pH. The three dyes gave emissions at 675–850 nm when they were excited at 650 nm, and the calculated pK_avalues of1a–care 4.13, 3.15 and 2.48, respectively. The optical responses were also illustrated by (TD)DFT calculation; the OFF–ON emission of dye1cwas mainly controlled by the PET process, and both PET and ICT processes were found between the aniline parts and the chromenylium–indole parts in dyes1a–b.

链接：http://pubs.rsc.org/-/content/articlelanding/2016/ra/c6ra19831g#!divAbstract