Two unique hydroxyl bridged lanthanide polymers incorporating mixed carboxylate ligands: Syntheses, structures, luminescence and magnetic property

• Published in: Inorganica Chimica Acta 2017-04, Vol.459, p.87-94
• Main Authors: Feng, Xun, Li, Rongfang, Guo, Nan, Sun, Yiling, Ng, Seik Weng, Liu, Xinfang, Wang, Liya
• Format: Article
• Language: English
• Subjects: Antiferromagnetic interaction; Benzene; Benzoic acid; Charge transfer; Chemical synthesis; Coordination polymers; Fluorescence; Gadolinium; Hydroxyl-oxygen bridging; Imidazole; Infrared radiation; Lanthanide–organic coordination polymer; Ligands; Luminescence; Magnetic permeability; Magnetic properties; Magnetism; Molecular chains; Polymers; Tetranuclear unit; X-ray diffraction
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2017.01.028

Two new lanthanide–organic coordination polymers incorporating both substituted imdazole dicarboxylate and benzene monocarboxylate auxiliary ligands have been obtained successfully. The polymer 2 shows characteristic f-f transition luminescence, and can be considered as a fluorescent molecular sensor for zinc cation recognition in environment. Variable-temperature magnetic susceptibility measurement reveals that the multi-bridging fashion of carboxylic group in 1 gives rise to possible antiferromagntic interactions between adjacent Gd(III) ions within the carboxylato bridged binuclear unit. [Display omitted] •Two new lanthanide–organic coordination polymers have been obtained successfully.•They both incorporate hydroxyl bridged tetranuclear clusters.•The polymer 2 shows characteristic f-f transition luminescence of Tb(III) ion.•Polymer 2 can be considered as a fluorescent molecular sensor for zinc cation.•The existence possible antiferromagntic interactions between adjacent Gd(III) ions. Two lanthanide–organic coordination polymers incorporating both substituted imdazole dicarboxylate and benzene monocarboxylate auxiliary ligand, namely, {[Gd2(μ3-OH)(pimda)(imba) (H2pimda) H2O]·2H2O}n (1) and {[Tb2((μ3-OH)(pimda)(imba) (H2pimda) H2O]·2H2O}n (2) (H3pimda=2-propyl-1H-imidazole-4,5-dicarboxylic acid and H2imba=4-(1H-imidazole-1-ly) benzoic acid) have been obtained under the hydrothermal conditions, and have been structurally characterized by elemental analysis, IR spectrum and single X-ray diffraction. The polymers are isostructural, both crystallizing in the triclinic system, with space group of p-1. They display one dimensional (1-D) double-stranded ribbon chains based on hydroxyl-bridged [Ln4pimda2] tetranuclear unit as second building block, which are interlinked forming 2-D corrugated layer. The extensive hydrogen bondings further extend these 2-D lamellar networks into 3-D supramolecular architecture. The emission spectrum of polymer 1 exhibits ligand-to-ligand charge-transfer (LLCT) transition luminescence; polymer 2 shows characteristic f-f transition luminescence, which can be considered as a fluorescent molecular sensor for zinc(II) ions in environment. Variable-temperature magnetic susceptibility measurement reveals that multi-bridging fashion of carboxylic group in 1 results in depopulation of the stark levels for a single Gd(III) ion and/or possible antiferromagntic interactions between adjacent Gd(III) cations within the carboxylato bridged binu