Construction of cluster-based supramolecular wire and rectangle

Reactions of [Et4N][Tp*WS3(CuCl)(3)] (1) (Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate) with 2 equiv. of AgOTf (OTf- = trifluoromethanesulfonate) and 1 equiv. of several bidentate pyridine ligands including 2,5-bis(pyridine-4-yl)thiazolo[5,4-d]thiazole (L1), 2,7-di(pyridin-4-yl)-9H-fluorene (L2), 2,7-di(pyridin-4-yl)-9H-carbazole (L3), and 2,7-di(pyridin-4-yl)-9H-fluoren-9-one (L4) afforded four W/Cu/S cluster-based supramolecular compounds [(Tp*WS3Cu2Cl)(2)(L1)] (2), {[(Tp*WS3Cu3)(2)(mu-Cl)(2)(mu(4)-Cl)](2)(L2)(2)}(OTf)(2) (3), {[(Tp*WS3Cu3)(2)(mu-Cl)(2)(mu(4)-Cl)](2)(L3)(2)}(OTf)(2) (4) and {[(Tp*WS3Cu3)(2)(mu-Cl)(2)(mu 4-Cl)](2)(L4)(2)}(OTf)(2) (5). Compounds 2-5 were characterized by elemental analysis, IR, UV-vis, H-1 NMR, and single-crystal X-ray diffraction analysis. The neutral cluster 2 behaves as a supramolecular wire constructed by L1 bridging two butterfly-shaped [Tp*WS3Cu2Cl] cores. The cluster cations of 3-5 contain two [(Tp*WS3Cu3)(2)(mu-Cl)(2)(mu(4)-Cl)](+) cores linked by two L2, L3, or L4 ligands, which finally formed a cationic supramolecular rectangle. The third-order nonlinear-optical (NLO) properties of 3-5 in DMF were also investigated by Z-scan techniques and their NLO responses were enhanced compared to those of their precursor 1.