Synthesis, crystal structure and third-order non-linear optical properties of two-dimensional supramolecular polymer [Co2(μ2-4,4′- bipy)2(μ2-be)2(be)2]n

Two-dimensional (2D) metal-organic supramolecular polymer [Co2(μ2-4,4′-bipy)2(μ2-be)2(be)2]n 1 (4,4′-bipy = 4,4′-bipyridine, be = benzoate) has been synthesized by low-temperature solid-state reaction and characterized by single-crystal X-ray diffraction, elemental analyses, TGA, IR spectra and UV–visible spectra. The 2D structure is built from the linkage of secondary building units of binuclear [Co2(μ2-4,4′-bipy)2(μ2-be)2(be)2] clusters by a mixed connector of 4,4′-bipyridine and benzoate. The third-order non-linear optical (NLO) properties of the 1 were also investigated and they exhibit the reverse saturable absorption and self-defocusing performance with modulus of the hyperpolarizability (γ) 8.30 × 10−30 esu for 1 in a 2.70 × 10−4 mol dm−3 DMF solution.