Synthesis and Properties of a Multi-functional Luminescent Material with Carbazolyl and Tetraphenylethylene Moiety

A new multi-functional aggregation-induced emission compound (TPECz) was synthesized by introducing carbazole groups to the tetraphenylethylene backbone through long alkyl chains. Its properties were investigated by UV-Visible absorption spectra (UV-Vis), photoluminescence spectroscopy (PL), thermogravimetric analyses (TG) and differential scanning calorimetry (DSC). It was found that the molecule emitted weakly in pure THF solution, but emittted strong fluorescence in their aggregated state, indicating that the TPECz was characterized as AIE-active. Meanwhile, the results demonstrated that the TPECz emitted strong blue fluorescence, and possessed good thermal stability with the fluorescence emission wavelength (lambda(em) = 465 nm), decomposition temperature with 5% weight loss (T-d) at 381 degrees C and glass transition temperature (T-g) at 58.7 degrees C, respectively. It showed that TPECz can visually detect Fe3+ in H2O-THF mixed solvent (V/V = 98/2) by quenching emission. The detection limit of Fe3+ in the mixed solvent can be down to 0.2 mmol/L for Fe3+ ion concentration. Moreover, the detection was of high sensitivity as the addition of other metal ions, including Mg2+, Al3+, Pb2+, Cr3+, Fe3+, Co2+, Ni2+ and Cu2+, did not induce obvious change on the solution fluorescence intensity. It indicated that TPECz was expected to work as an effective luminescent indicator for qualitative and quantitative detection of Fe3+ ions. Thanks to the electroactive moieties of the four peripheral carbazole units of TPECz, TPECz can be applied as a precursor to prepare the luminescent network film by electrochemical polymerization using a three-electrode cell with a Ti counter electrode, a Ag/Ag+ reference electrode, and a ITO glass working electrode. The resultant cross-linked film was characterized using scanning electron microscopy (SEM) and atomic force microscope (AFM). Moreover, it exhibits deep blue fluorescence with lambda(em) at 470 nm, so it is a potential material for fabrication of OLED devices. Therefore, TPECz can be used as a multi-functional luminophor.