Construction of cluster-based supramolecular wire and rectangle.

Reactions of [Et 4 N][Tp*WS 3 (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)-9 H -fluorene (L2), 2,7-di(pyridin-4-yl)-9 H -carbazole (L3), and 2,7-di(pyridin-4-yl)-9 H -fluoren-9-one (L4) afforded four W/Cu/S cluster-based supramolecular compounds [(Tp*WS 3 Cu 2 Cl) 2 (L1)] (2), {[(Tp*WS 3 Cu 3 ) 2 (μ-Cl) 2 (μ 4 -Cl)] 2 (L2) 2 }(OTf) 2 (3), {[(Tp*WS 3 Cu 3 ) 2 (μ-Cl) 2 (μ 4 -Cl)] 2 (L3) 2 }(OTf) 2 (4) and {[(Tp*WS 3 Cu 3 ) 2 (μ-Cl) 2 (μ4-Cl)] 2 (L4) 2 }(OTf) 2 (5). Compounds 2-5 were characterized by elemental analysis, IR, UV-vis, 1 H 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*WS 3 Cu 2 Cl] cores. The cluster cations of 3-5 contain two [(Tp*WS 3 Cu 3 ) 2 (μ-Cl) 2 (μ 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.