Tetracopper(I) phosphonitocavitand: synthesis, halide anion inclusion and optical nonlinearity

Treatment of tetraphosphonitoresorcinarene [(CH3)2CHCH2CHC6H2O2PPh]4 (1) with an excess [CuCl] powder in the presence of pyridine (py) yielded a tetracopper(I) phosphonitocavitand [pyH][1·Cu4(μ-Cl)4(μ4-Cl)] (2). The Included μ4-Cl in 2 was easily substituted by heavy halide anion to give [pyH][1·Cu4(μ-Cl)4(μ4-X)] (X=Br, 3; I, 4). The complexes 2, 3, and 4 have been characterized by X-ray structure determinations. The similar structure contains four coplanar cupper atoms bridged by four μ-Cl and one central trapped μ4-X atoms in the inside of the closing bowl-shaped cavitand. The third-order nonlinear optical properties of 2 as a typical metal-cavitand complex were investigated in this paper.