Homochiral Cu(I) Coordination Polymers Based on a Double-Stranded Helical Building Block from Achiral Ligands: Symmetry-Breaking Crystallization, Photophysical and Photocatalytic Properties

Abstract

A pair of homochiral coordination polymers, [Cu(DPT)]_<i>n</i> (<b>1M</b> and <b>1P</b>, HDPT = 3,5-di-4-pyridinyl-2H-tetrazole), were assembled from achiral precursors. Crystal structure analysis showed that they are chiral three-dimensional (3D) coordination polymers based on a new double-stranded helical building block that is composed of two different 1D helices. Interestingly, rare symmetry-breaking crystallization was observed, in which the possibility of obtaining enantio-enriched bulk product with excessive <i>M</i> enantiomers (<b>1-A</b>) was obviously higher than that for <i>P</i> enantiomers (<b>1-B</b>) as demonstrated in multiple, repeated experiments with single-crystal diffraction and vibrational circular dichroism (VCD) spectra. Moreover, compound [Cu(DPT)]_<i>n</i> shows good chemical stability in water, with pH values ranging from 3 to 13, as well as in many common organic solvents. Photophysical properties, including thermochromic properties and two-photon excited luminescence, were studied, and the potential for applications in temperature sensing was exhibited. In addition, the photocatalytic degradation of methylene blue in water indicated that compound [Cu(DPT)]_<i>n</i> can be used as a photocatalyst.