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An effective and clean aerobic oxidative method for the synthesis of 2,6-disubstituted benzobisoxazole using the free radical catalysis was obtained. 2, 6-Di(pyridin-4-yl)-benzo[1,2-d:4,5-d']bisoxazole was synthesized and characterized by 1H and 13C NMR spectroscopy, elemental analysis, UV–vis and emission spectroscopy, as well as by single-crystal X-ray crystallography. In the crystal structure, a self-assembled two-dimensional (2-D) layer supramolecular frameworks is formed with the help of intermolecular hydrogen bonds and π···π stacking interactions. On the basis of experimental results, a plausible reaction mechanism of 2,2′-disubstituted benzoxdiazoles with 4-methoxy-TEMPO as the catalyst is proposed. To obtain more insights into the structure and bonding, DFT calculations were performed. The obtained calculation results were compared with the X-ray diffraction data. The electronic transitions and spectral features of 5a and 5b were discussed by TD-DFT calculations. In addition, the noncovalent interactions among compounds have been also analyzed using Hirshfeld surface analysis.

By adopting a similar strategy, we have nowsynthesized a new type of linear compound which consists ofthiomethyl-terminated OPV (TOPV) with methoxyl sidegroups. This new OPV compound is highly prone to formsingle crystals. X-ray analysis indicates that it exhibits a rigidplanar structure with extended p-conjugated length, whichleads to strong solid-state fluorescence induced by absorptionof one or two photons. Furthermore, a sharp stimulatedemission band is observed to emerge at high excitationintensity in the emission spectrum of TOPV single crystals.The strong two-photon excited fluorescence and stimulatedemission are extremely attractive for numerous applicationssuch as light-emitting diodes (LEDs), nonlinear optics,photoconductors, photovoltaics, and upconversion lasing(UCL).

A new multisignaling molecular probe DFDB was designed for the selective detection of Zn(2+). DFDB can be synthesized by a simple one-step reaction in high yield. Theoretical calculation suggests a novel sandwich structure of the DFDB·Zn(2+) complex.