Ligand-Induced Formation of Copper(I) Iodide Clusters: Exocyclic Coordination Polymers with Bis-dithiamacrocycle Isomers

A comparative
study on the formation of guest clusters induced by different shapes
(or sizes) of exocyclic binding sites embedded in the bis-macrocyclic
host isomers is reported. CuI reacts with two regioisomers of a bis-dithiamacrocycle, o-bis-L (W-shaped binding site)
and m-bis-L (U-shaped binding
site), to yield one-dimensional coordination polymers {[(μ4-Cu4I4)­(o-bis-L)]·2CH3CN}n (1a) and [(μ4-Cu2I2)­(m-bis-L)]n (2). In 1a, the o-bis-L ligand isomer
is linked by a spacious cubane [Cu4I4] cluster,
while the m-bis-L ligand
in 2 is linked by a smaller rhomboid [Cu2I2] cluster because of the different exocyclic binding sites.
The results observed illustrate the possibility for the metal clusters
including [CunIn] (n = 2 or 4) to adopt a controlled formation
through the binding site alternation or design. Because of the adaptive
cluster formations, the products show different photophysical properties.
Additionally, sliding of the one-dimensional chains in 1a was observed upon loss of the lattice solvent molecules in ambient
condition.