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Published on: April 14, 2020
Ultraviolet Nonlinear Optical Single Crystals of A Three-Dimensional Chiral Covalent Framework Containing Te-O-B-O
Miaomiao Xue1, Lei Zhang1, Xin Meng2
1Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong SAR, P. R. China.
Abstract:
Extending covalent organic frameworks (COFs) into crystalline carbon-free covalent backbones is an important strategy to endow these materials with more exotic functions. Integrating metal-free inorganic and organic components into one covalent framework is an effective way to address the issue of poor thermal/solvent stability in the field of nonlinear optics (NLO). However, constructing such structures is very challenging. Here, we linked 3-connected nods (BO3) and 2-connected organic building blocks (Te(Ph)2) together to produce colorless single crystals (size up to 400 μm) of a three-dimensional (3D) chiral covalent framework (CityU-22). The single-crystal X-ray diffraction (SCXRD) analysis reveals that CityU-22 has a non-carbon Te-O-B-O bond-based network with the srs topology. The chiral CityU-22 displays good stability under the treatment of different common solvents or heat (the decomposition temperature above 300 °C). Due to its non-π-conjugated backbone (-Te-O-B-O-), CityU-22 shows an ultraviolet NLO behavior with a second-harmonic generation (SHG) response similar to KH2PO4 (KDP).
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