Solid-supported synergistic twain probes with aggregation-induced emission: A sensing platform for fingerprinting volatile amines

Abstract Two solid emitters DMA and HBA were synthetized, showing aggregation-induced emission (AIE) phenomenon. Incorporation of electron donor-acceptor (D-A) pairs endows the solid emitters with both charge transfer (CT) state emission and distinct solvatochromic effect. The compounds undergo a rapid interaction with amines followed by the resulting weakened electron withdrawing ability to yield florescent products with either hypochromatic shift or decrease in the emission intensity. DFT calculations on HOMO and LUMO electronic cloud distribution and energy levels have demonstrated that the transition from CT state to locally excited (LE) state is mainly responsible for the spectral changes. The AIE compounds were thus developed into solid-supported amine sensor and show nice linear relationship. The detection limits of DMA- and HBA-based sensing film to ammonia gas are 2.61 Pa and 2.63 Pa, respectively. Time-dependent emission spectra upon treating with a variety of amines exhibited differential responses, in which two factors were defined accordingly, including maximum emission wavelength and quenching efficiency. Two-dimensional coordinate system was then built on the basis of the two factors, creating a fingerprint data base for the involved amines. The fingerprint map shows a clear differentiation of the tested amines, making DMA and HBA synergistic twain probes for identification of diverse amines.