Solvothermal Stepwise Formation of Cu/I/S-Based Semiconductors from a Three-Dimensional Net to One-Dimensional Chains

Solvothermal reactions of CuI with 4,4′-dipyridyl disulfide (dpds) and oxalic acid in toluene and acetonitrile at three different time periods gave rise to three Cu/I/S-based coordination polymers, [Cu6(μ-4-SpyH)4I6]n (1), {[Cu2(μ-I)(μ-4-SpyH)3]I}n (2), and [Cu5(μ-4-SpyH)7(μ-I)I4]n (3). The preparation of 1−3 was involved in the in situ formation of the zwitterionic pyridium-4-thiolate (4-SpyH) molecule from the S−S cleavage of the dpds ligand. These compounds were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), X-ray powder diffraction (XRPD), and single crystal X-ray diffraction. Compound 1 contains an adamantine-type [Cu6S4] core that links the neighboring ones via double iodide bridges to form a three-dimensional (3D) diamond-like net. Compound 2 has a one-dimensional (1D) cationic {[Cu2(μ-I)(μ-4-SpyH)3]n}n+ polymeric chain with disordered iodides embedded between chains. Compound 3 contains the [Cu5(μ-I)I4(μ-4-SpyH)7] species that is interconnected with its neighboring ones through two μ-4-SpyH ligands to form a 1D neutral chain. The formation of 1−3 provided an interesting example that different coordination polymers could be produced from the same components under solvothermal conditions at different time periods. In addition, optical absorption and electric conductivity experiments revealed that 1−3 exhibited good semiconducting performances.