Luminescent non-traditional π-gels fabricated from pyrimidine derivatives bearing carbazole for the detection of acid vapors

Abstract

A series of new pyrimidine derivatives modified with carbazole (CM, CMH, CMCl and CMBr) and tert-butyl carbazole (TCM, TCMH, TCMCl and TCMBr) were synthesized. It was found that CM, CMCl, CMBr, TCM, TCMCl and TCMBr without traditional gelation groups could self-assemble into organogels with intense emission. It was found that V-shaped π-conjugated skeleton and π-π interactions were essential for the organogelation. It was interesting that the organogels could be destroyed by adding TFA (trifluoroacetic acid), accompanied with the quenching of the emission on account of the protonation of pyrimidine unit. In particular, the xerogel-based film of TCM emitting strong bluish green light could be used as fluorescent sensor to detect TFA vapor with the decay time and detection limit of 0.6 s and 95 ppb, respectively. Such high performance of the xerogel-based film in fluorescent responsive ability was originated from the high surface-to-volume ratios of nanomaterials and the large space in 3D networks, which were favorable for the adsorption and diffusion of the analytes. We provided new strategy for the design of non-traditional π-gelators and the fabrication of fluorescent sensory materials with high performance to detect gaseous analytes.