Syntheses and characterisation of two lanthanide compounds with upconversion luminescence

Compounds [Gd(HIA) 3 (H 2 O) 2 ] 2 n ·(3HgBr 4 )·4H 2 O (1; HIA = isonicotinic acid) and [Pr(H 2 O) 5 (2,5-PA)] n nCl (2; 2,5-PA = 2,5-Pyridinedicarboxylic acid) were reported. Compound 1 is monoclinic C2/c with a = 24.3657(9), b = 20.8859(8), c = 15.8559(6) Å, β = 128.156(3)°, V = 6345.0(4) Å 3 , Z = 4, M r = 2757.98, D c = 2.887 g/cm 3 , S = 1.062, μ(MoKα) = 16.921 mm −1 , F(000) = 5008, R = 0.0729 and wR = 0.1928. Compound 2 is orthorhombic Pbca with a = 13.4474(6), b = 8.3953(3), c = 23.8453(10) Å, V = 2692.01(19) Å 3 , Z = 8, M r = 431.54, D c = 2.130 g/cm 3 , S = 1.007, μ(MoKα) = 3.857 mm −1 , F(000) = 1680, R = 0.0267 and wR = 0.0600. Compound 1 is one-dimensional, while compound 2 is two-dimensional. The Gd III is eight-coordination and displays a distorted square antiprismatic geometry. The Pr III is nine-coordination and shows a mono-capped square antiprismatic geometry. Both compounds show upconversion photoluminescence and they are resulted from 6 P 7/2 → 8 S 7/2 of Gd 3+ and 3 P 0 → 3 H 4 transition of Pr 3+ . Compound 2 possesses CIE (Commission Internationale de I’Éclairage) chromaticity coordinates (0.0774, 0.2475) and CCT (correlated colour temperature) 349196 K. Their bandgaps are 3.16 and 2.95 eV.