Rigidity effect of the dithioether spacer on the size of the luminescent cluster (Cu₂I₂)_n(n = 2, 3) in their coordination polymers

Abstract

Treatment of CuI with the flexible PhS(CH(2))(4)SPh dithioether ligand in MeCN solution affords the strongly luminescent metal-organic 2D coordination polymer [Cu(4)I(4){mu-PhS(CH(2))(4)SPh}(2)](n) (). The interpenetrated 2D network of is built upon by Cu(4)(mu(3)-I)(4) cubane-like clusters as secondary building units (SBUs), which are interconnected via bridging 1,4-bis(phenylthio)butane ligands. In contrast, the auto-assembly reaction of the unsaturated semi-flexible PhSCH(2)C[triple bond, length as m-dash]CCH(2)SPh ligand with CuI results in formation of the 3D metallopolymer [(Cu(6)I(6)){mu-PhSCH(2)C[triple bond, length as m-dash]CCH(2)SPh}(3)](n) (). The SBUs of luminescent consist of discrete Cu(6)(mu(3)-I)(6) hexagon prisms, which are coordinated with bridging 1,4-bis(phenythio)butyne ligands via Cu-S bonds. Contrary to the other rare literature-known examples of metallopolymers incorporating Cu(6)X(6) SBUs as connecting nodes, the CuCu interactions of [2.8484(6) A] are markedly shorter, being close to the sum of the Van der Waals radii of two Cu atoms ( approximately 2.8 A). The photophysics of these compounds, which exhibit reversible luminescence thermochromism, has been investigated in detail. The solid-state luminescence spectra of and feature at room temperature intense emissions around 560 and 555 nm, respectively. The luminescence properties of the unusual Cu(6)(mu(3)-I)(6) hexagon prism motif are rationalized by means of DFT and TDDFT computations.