Chain Length Effect on the Structural and Emission Properties of the CuI/Bis((4-methoxyphenyl)thio)alkane Coordination Polymers.

A systematic chain length variation of the ligand para -MeOC 6 H 4 S(CH 2 ) m SC 6 H 4 OMe (1 ≤ m ≤ 8) was performed to study its effect on the structures and photophysical properties of the coordination polymers (CP) when reacted with CuI. Indeed, direct correlations are noted between these features and m . When m is an odd number, the secondary building unit is systematically the common closed-cubane Cu 4 I 4 cluster, rendering the material strongly luminescent ( i.e. , emission quantum yield, Φ e > 20%), and the CP is one-dimensional (1D). However, when m is 2, 4, and 6, the SBUs exhibit rare polymeric motifs of (Cu 2 I 2 ) n : staircase ribbon, fused poly(rhombic pseudo-dodecahedron), and accordion ribbon, respectively, and the emission intensities are either very weak (Φ e < 0.001%) or of medium intensity (Φ e ∼ 10% when m = 6). When m = 8 ( i.e . the most flexible chain), the SBU is a closed-cubane Cu 4 I 4 and the emission intensity is medium (Φ e ∼ 10%). A special case was observed for m = 3, where a co-crystallization of the molecular cluster Cu 4 I 4 (NCCH 3 ) 4 is observed in the lattice, which turns out to be quite important for the stability of the network.