1,4-Bis(arylthio)but-2-enes as Assembling Ligands for (Cu₂X₂)_<i>n</i> (X = I, Br; <i>n</i> = 1, 2) Coordination Polymers: Aryl Substitution, Olefin Configuration, and Halide Effects on the Dimensionality, Cluster Size, and Luminescence Properties

Abstract

CuI reacts with E-PhS(CH2CH═CHCH2)SPh, L1, to afford the coordination polymer (CP) [Cu2I2{μ-E-PhS(CH2CH═CHCH2)SPh}2]n (1a). The unprecedented square-grid network of 1 is built upon alternating two-dimensional (2D) layers with an ABAB sequence and contains rhomboid Cu2(μ2-I)2 clusters as secondary building units (SBUs). Notably, layer A, interconnected by bridging L1 ligands, contains exclusively dinuclear units with short Cu···Cu separations [2.6485(7) Å; 115 K]. In contrast, layer B exhibits Cu···Cu distances of 2.8133(8) Å. The same network is observed when CuBr reacts with L1. In the 2D network of [Cu2Br2{μ-E-PhS(CH2CH═CHCH2)SPh}2]n (1b), isotype to 1a, one square-grid-type layer contains Cu2(μ2-Br)2 SBUs with short Cu···Cu contacts [2.7422(6) Å at 115K], whereas the next layer incorporates exclusively Cu2(μ2-Br)2 SBUs with a significantly longer Cu···Cu separation [2.9008(10) Å]. The evolution of the crystallographic parameters of 1a and 1b was monitored between 115 and 275 K. Conversely, the isomeric Z-PhS(CH2CH═CHCH2)SPh ligand L2 reacts with CuI to form the 2D CP [Cu4(μ3-I)4(μ-Z-PhS(CH2CH═CHCH2)SPh}2]n (2a) with closed-cubane SBUs. A dinuclear zero-dimensional complex [Cu2Br2{μ-Z-PhS(CH2CH═CHCH2)SPh}2] (2b) is formed when CuBr is reacted with L2. Upon reaction of E-TolS(CH2CH═CHCH2)STol, L3, with CuI, the 2D CP [{Cu(μ3-I)}2(μ-L3)]n containing parallel-arranged infinite inorganic staircase ribbons, is generated. When CuX reacts with Z-TolS(CH2CH═CHCH2)STol, L4, the isostructural 2D CPs [Cu2X2{μ-Z-TolS(CH2CH═CHCH2)STol}2] (4a X = I; 4b X = Br) are formed. In contrast to the CPs 1a,b, the layers based on rhombic grids of 4a,b incorporate Cu2(μ2-X)2 SBUs featuring uniformly identical Cu···Cu distances within each layer. The TGA traces showed that all these materials are stable up to ∼200 °C. Moreover, the photophysical properties have been studied, including absorption, emission, excitation spectra, and emission lifetimes at 298 and 77 K. The spectra were interpreted using density functional theory (DFT) and time-dependent DFT calculations.