Crystal structure of poly[aqua-(μ4-pyridine-2,5-dicarboxylato- κ5N,O:O’:O’’:O’’’)-(μ2-picolinato-κ2O:O’)-terbium(III)], C13H9N2O7Tb

Abstract

C 13 H 9 N 2 O 7 Tb, monoclinic, P2 1 /c (no. 14), a =9.2251 (7) Source of materialAll chemicals were of reagent grade quality obtained from commercial sources and were used without further purification. The title compound was prepared under ionothermal conditions using the ionic liquid 1-ethyl-3-methylimidazolium ([Emim]Br) as solvent. The title compound was prepared from am ixture of terbium(III) nitrate hexahydrate (0.45 g, 1m mol), pyridine-2,5-dicarboxylic acid (0.24 g, 1.5 mmol), nicotinic acid (0.25 g, 2 mmol) and [Emim]Br (1.0 g, 5.23 mmol). The mixture was stirred for half an hour, and then transferred into aTeflon-lined stainless steel autoclave (50 ml)and heated at 438 Kfor 7d.After the mixture had been cooled slowly to room temperature, colourless rodshaped crystals were obtained. The product was filtered off, washed with deionized water and dried in avacuum desiccator at ambient temperature (yield 36 %, based on terbium(III) nitrate hexahydrate). It is worth noting that, the title compound can also be obtained using ionic liquid 1-methyl-3-butylimidazolium bromide ([Bmim]Br) as solvent. In order to confirm the chemical composition of the title compound, C, H, and Nelements analysis were performedo naP erkinElmer 2400II elemental analyzer. Anal.c alcd.( %) for C 13 H 9 N 2 O 7 Tb: C, 33.64; H, 1.95; N, 6.04. Found (%): C, 33.91; H, 1.69; N, 5.88. The results support the formula of the title compound. Experimental detailsThe Hatomsbonded to Cwere positioned geometrically and refined using ariding model, with C-H =0.93 Åand with U iso (H) = 1.2 times U eq (C). The Hatoms bonded to O1W were located from Fourierd ifferencem apsa nd refinedw ithd istancer estraintso f O1W-H1WA=0.83 Åand O1W-H1WB=0.83 Å. DiscussionThere has been growing interest in the design and synthesis of lanthanide-based coordination polymers motivated by their fascinating structure and the exploitable applications in luminescent materials, molecular adsorption, bimetallic catalysis and so on [1-6].T he polycarboxylic ligands have been proved to be extremelyversatile organicligands due to thefactthattheycan exhibit flexible coordination modes, including chelating, bidentate bridging or chelating bridging modes [7,8]. As an extension of research toward rational design and preparation of lanthanide coordination polymer, we recently have isolated anovel three-dimensional terbium (III) coordinated polymer containing two types of ligands (pyridine-2,5-dicarboxylate and picolinate) [Tb(C 7 H 3 NO 4 )(C 6 H 4 NO 2 )(H 2 O)] n under ionothermal conditions using the ionicliquid1-ethyl-3-methylimidazolium([Emim]Br) as solvent.Asillustrated in theFigure,the asymmetricunit of title compound contains one Tb(III) cation, one pyridine-2,5-dicarboxylate anion, one picolinate anion and one coordinated water molecule. Within the structure, Tb(III) cation is coordinated by seven oxygen atomsand one Natom,exhibiting adistorted bicapped trigonal prismatic geometry, among which, six oxygen atomsare derived from carboxylate groups and one oxygen at...