Synthesis, crystal structure and fluorescence properties of a 3D framework based on hexanuclear lanthanum 5-nitroisophthalate entities

The reaction of lanthanum(III) nitrate and 5-nitroisophthalic acid in isopropanol/ H2O under hydrothermal conditions leads to a 3D lanthanum-containing coordination polymer with the general chemical formula {[La ₆(Nip) ₉(H2O) ₄].(H2O) ₄}8 (1, Nip = 5-nitroisophthalate). The single-crystal X-ray analyses show that this compound crystallizes in the orthorhombic system, space group Ima2 with a = 9.7769(12), b = 28.239(3), c = 21.149(2) Å, V = 5839.1(11) Å ³, Z = 2, M _r = 2859.61, D _c = 1.626 g/cm ³, F(000) = 2752. 14040 reflections are collected, of which 5275 are unique (R _int = 0.0241). Final GOOF = 1.083, R = 0.0406 and wR = 0.1182, R indices based on 5183 reflections with I > 2o-(I) (refinement on F ²), 443 parameters, 1 restraint. Lp and absorption corrections were applied, μ = 2.242 mm ^-1. Absolute structure parameter x = 0.08(3). The crystal structure can be described as the butterfly-liked hexanuclear lanthanum entities {La ₆O ₆(CO ₂) ₈} covalently linked to each other by nitroisophthalate ligands into an intricate three-dimensional structure. The fluorescence spectroscopy of compound 1 has been investigated.