ABSTRACT
In this contribution, a dye (THBT) with 2,5-dimethylthiophene substituted to 2-(2-hydroxyphenyl)benzothiazole was synthesized and characterized by NMR and mass spectroscopic techniques. Its emission behavior in various solvents was investigated and obvious negative solvatochromism was observed. The emission maximum of THBT varied from deep blue (425 nm) in DMSO to orange (550 nm) in chloroform. It is also highly emissive in polycarbonate film and solid powder with the emission peaks 546 and 554 nm, respectively. The ESIPT effect, together with the relaxation of free rotation of thiophene in the excited states, shifted the solid emission 34 nm toward longer wavelength furtherly, with respect the 520 nm (green) emission of HBT. Quantum calculation of frontier molecular orbitals uncovers the underlying mechanism of negative solvatochromism.
Acknowledgments
This work was supported by the National Natural Science Foundation of China (21272060), PCSIRT (grant no. IRT1061), and the Program for Innovative Research Team in University of Henan Province (15IRTSTHN003). This study was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (Grant No. 2015021972).