Synthesis and characterizations of a bis(triazole)-based 3D crystalline copper(II) MOF with high adsorption capacity for congo red dye

abstract Article history:Received 26 December 2014Received in revised form 20 January 2015Accepted 28 January 2015Available online 29 January 2015Keywords:AdsorptionBis(triazole)Coordination polymerCopper(II)Fluorescence property Hydrothermal synthesis has afforded a 3D copper(II) metal–organic framework (MOF) based on a new rigidbis(triazole)-based ligand, namely, {[Cu 3 (btb) 3 (nbta) 2 ]·(H 2 O) 2 } n (btb = 4,4′-bis(1,2,4-triazolyl-1-yl)-biphenyl,H 3 nbta = 5-nitro-1,2,3-benzenetricarboxylic acid), which has been characterized by IR, elemental analysis,thermalgravimetricandsingle-crystalX-raydiffraction.Thestructuralanalysesrevealthattitlecomplexdisplaysa rarely 3D trinodal (3,4,4)-connected network with 3,4,4T20 topology. Further, fluorescence and excellentadsorption properties for congo red dye of the compound have been investigated.© 2015 Elsevier B.V. All rights reserved. In recent years, great interest has been focused on the rapidlyexpanding field of construction of novel functional metal–organicframeworks (MOFs) owing to their controllable shape, size, composi-tion, and structural diversity but also their promising properties,suchas adsorption, luminescence, separation, magnetism, and catalysis[1,2]. The key to building a desired MOF is usually the selection ofsuitable organic ligands, and in some cases, a subtle alteration of or-ganicmotifsmayleadtoanovelarchitecture[3–5].Amongthem,thebis(1,2,4-triazole) ligands have attracted considerable interest incrystal engineering and supramolecular chemistry because of theirexcellent coordinating ability and variable conformations[6–8].However, when searching the Cambridge Structural Database (version5.35, May 2014) [9] for MOFs constructed from rigid rod-like 4,4′-bis(1,2,4-triazolyl-1-yl)-biphenyl (btb) ligand, no structures werefound. Bis(triazole) ligands bearing rigid spacers should exhibit thespecialabilitytocoordinatetovariousmetalcentersintwotypicalcoor-dination fashions (cis-configuration and trans-configuration) throughbondrotationof theterminal triazolyl rings.Furthermore,asanimpor-tant family of multidentate O-donor ligands, organic polycarboxylateanions seem to be excellent secondary building units with charge, ver-satile coordination modes as well as the remarkable stability for theconstruction of MOFs [10]. Herein, we selected btb and 5-nitro-1,2,3-benzenetricarboxylic acid (H