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 . A set of W/Cu/S cluster-supported supramolecular wire and rectangle compounds were assembled and exhibited enhanced third-order nonlinear optical responses.