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

A systematic chain length variation of the ligand para-MeOC6H4S-(CH2)(m)SC6H4OMe (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 Cu4I4 cluster, rendering the material strongly luminescent (i.e., emission quantum yield, Phi(e) > 20%), and the CP is one-dimensional (1D). However, when m is 2, 4, and 6, the SBUs exhibit rare polymeric motifs of (Cu2I2)(n): staircase ribbon, fused poly(rhombic pseudo-dodecahedron), and accordion ribbon, respectively, and the emission intensities are either very weak (Phi(e) < 0.001%) or of medium intensity (Phi(e) similar to 10% when m = 6). When m = 8 (i.e. the most flexible chain), the SBU is a closed-cubane Cu4I4 and the emission intensity is medium (Phi(e) similar to 10%). A special case was observed for m = 3, where a co-crystallization of the molecular cluster Cu4I4(NCCH3)(4) is observed in the lattice, which turns out to be quite important for the stability of the network.

Automated summary

The influence of ligand chain length on the structures and photophysical properties of coordination polymers was investigated. The results showed a direct correlation between chain length and the secondary building units.