Preparation, Structure and Properties of [Tb(HIA)2(IA)(H2O)2(HgCl2)]n(nHgCl4)·3nH2O (IA = Isonicotinate Anion)

Abstract

A novel 4f-5d compound [Tb(HIA)2(IA)(H2O)2(HgCl2)]n(nHgCl4)·3nH2O (1, IA = isonicotinate anion) has been prepared and structurally determined by X-ray diffraction. Complex 1 crystallizes in the P21/c space group of the monoclinic system with a = 9.6875(3), b = 19.8318(7), c = 17.0899(5) A, β = 101.609(3)o, V = 3216.16(18) A3, C18H24Cl6Hg2N3O11Tb, Mr = 1231.20, Z = 4, Dc = 2.543 g/cm3, μ(MoKα) = 12.251 mm–1 and F(000) = 2272. The crystal structure of complex 1 is characterized by a two-dimensional (2-D) layer-like structure. The photoluminescence measurements with solid-state samples reveal that it exhibits a yellowish green emission with the emission bands locating at 490, 546, 586 and 620 nm, respectively. The photoluminescence emission bands are resulted from the characteristic emission of the 4f electrons intrashell transition of the 5D4 → 7FJ (J = 6, 5, 4, 3) of the Tb3+ ion. The energy transfer mechanism is explained by using the energy level diagram of the Tb3+ ion and isonicotinic acid ligand. Complex 1 exhibits CIE chromaticity coordinates being of 0.3823 and 0.5141. A solid-state diffuse reflectance measurement shows that the complex possesses a wide optical band gap of 2.67 eV. A novel 4f-5d compound featuring a 2-D layer-like structure has been reported for the crystal structure and properties.