Structural Diversity of Coordination Polymers Based on a Heterotopic Ligand: Cu(II)-Carboxylate vs Cu(I)-Thiolate.

Two copper(II)-carboxylate disulfide coordination polymers [Cu2((O2CPhS)2)2(H2O)2] n (1, 2) and one copper(I)-thiolate coordination polymer [Cu( p-SPhCO2H)] n (3) have been synthesized using either the 4-mercaptobenzoic acid (HSPhCO2H) or the 4,4'-dithiodibenzoic acid ((SPhCO2H)2) as ligand. These three compounds were characterized by X-ray diffraction, IR, and thermogravimetric analyses. Compounds 1 and 2 are polymorphs with the presence, for both, of dinuclear paddle-wheel copper(II)-carboxylates. In 1, the adjacent dimeric Cu2 units are linked by two (O2CPhS)2 ligands generating a cyclic loop chain, and in 2, each pair of Cu (II) atoms is linked by four ligands to create 2D networks, that are 2-fold interpenetrated. Compound 3 presents a lamellar structure, with an exceptional thermal and chemical stability, and exhibits intrinsic multiple emission between 485 and 660 nm. The different intensities of these bands generate a cyclic luminescence thermochromism from yellow to green to yellow.