| Studies of coordination polymers are of considerable interest due to theirfascinating network topologies and potential applications in gas adsorption andseparation, ion exchange, catalysis, molecular magnetism, photoluminescence, etc. Inprinciple, selection and synthesis of the organic bridging ligands play a crucial role inthe design and construction of desirable frameworks, because changes in flexibility,length, and symmetry of organic ligands can result in materials bearing diversearchitectures and functions. Thus, the prospect of tuning the properties of MOFsthrough a systematic change of organic ligands provides an impetus for furtherresearch on metal-organic supramolecular architectures. Among various organicligands, polycarboxylic compounds bearing multiple bridging moieties, a variety ofconnection modes with metal centers, have been extensively used as multifunctionalmaterials, due to their extension ability both in covalent bonding and supramolecularinteractions (H-bonding and aromatic stacking). Such coordination polymers haveprofound applications in materials, molecular recognition, self-assembly and so on.In this paper, hydrothermal reaction of5-nitro-1,2,3-benzenetricarboxylic acidor2,3’,5,5’-biphenyl tetracarboxylic acid and a series of N-donor auxiliary ligandswith transition metal ions, yielding twelve new coordination polymers. Their crystalstructures and solid state properties have been characterized. Main contents andresults are as follows:1. Assembly of5-nitro-1,2,3-benzenetricarboxylic acid with CuIIin thepresence of1,3-bis(1,2,4-triazol-1-yl)propane leads to a new metal–organicframework with a dia topology,{[Cu(Hnbta)(1,3-btp)]·2H2O}n(1). Its crystalstructure was determined by X-ray single crystal diffraction, and further characterizedby elemental analysis, infrared spectrum and powder X-ray diffraction. Complex1isshown to be an efficient and recyclable heterogeneous catalyst for enamination ofβ-ketoesters with excellent product yields. Further, it is noted that all reactionsdisplay excellent chemoselectivity. The nucleophilic reactant amine only reacts withthe ketone part of the β-ketoesters. And reaction with the ester part was not observedin all cases to give the corresponding amide. To our knowledge, this is the first report on selective enamination of β-ketoesters performed using CuIIwith unsaturatedcoordination spheres as active sites.2. Five coordination polymers,{[Cd2(Hbptc)2(H2O)2]·(1,3-H2bip)}n(2),{Cd2(bptc)(1,4-bib)(H2O)2}n(3),{[Cd2(bptc)(biyb)(H2O)2]·3H2O}n(4),{Cd(H2bptc)(bimb)(H2O)}n(5),{Cd2(bptc)(tib)(H2O)}n(6), were synthesized underhydrothermal reactions with2,3’,5,5’-biphenyl tetracarboxylic acid and differentN-donor ligands and CdIIion. Their crystal structures were determined bysingle-crystal X-ray diffraction and further characterized by elemental analyses andIR spectra. These complexes show a3D supramolecular framework, two3D networks,a2-fold interpenetrated (4,4) net and a3D self-penetrating network. Furthermore, thefluorescent properties of2-6have also been investigated.3. Six complexes, namely {[Ni(H2O)6][Ni4(bptc)2(μ3-OH)2(H2O)2]}n(7),{[Mn2(bptc)(bpy)2]·2H2O}n(8),{[Mn2(bptc)2(phen)4]·6H2O}n(9),{[Mn3(bptc)2(bipy)4(H2O)2]·6H2O}n(10),[Mn2(bptc)(biyb)2]n(11),[Mn1.5(bptc)(biip)(H2O)]n(12), were synthesized using2,3’,5,5’-biphenyltetracarboxylic acid with N-donor auxiliary ligands, and nickel acetate or manganeseacetate. Their crystal structures were determined by single-crystal X-ray diffractionand further characterized by elemental analyses, IR spectra and PXRD. Thesecomplexes show various3D networks and3D supramolecular framework. Here incomplex7, the anionic tetranuclear component acts as the host, with the mononuclearcationic component as the guest. Furthermore, the magnetic properties of7-11havealso been investigated. The results show that H4bptc can act as a versatile buildingblock for the construction of various metal organic frameworks. |
