Syntheses, Structures And Properties Of Coordination Polymers Constructed From Multi-carboxylic Acid Ligands

Up to now, thousands of coordination polymers (CPs) have been synthesized.The design and synthesis of CPs have attracted widespread interest not only becauseof their appealing structural and topological novelty but also owing to theirtremendous potential applications in heterogeneous catalysis, gas storage, molecularmagnet, chemical separations and nonlinear optics. With development of thetechnology and the introduction of many new methods, more and more polymers withnovel architecture and function have been synthesized, however, it is still a greatchallenge to achieve target product with special structure and property.CPs include two sections, inorganic and organic sections. Among all factors,these two sections are major factors influencing the synthesis of CPs. We can get CPswith diverse structure using different organic ligands, which have small changes incoordination atoms, flexibility, functional group position, length and symmetry. In thispaper, we select multi-carboxylic acid as organic ligands in view of its followingcharacteristics:(i) It has many carboxyl groups that may be completely or partiallydeprotonated, inducing rich coordination modes and achieving interesting structureswith higher dimensionalities.(ii) It can act as not only hydrogen-bond acceptor butalso hydrogen-bond donor, depending upon the degree of deprotonation, which aregood for stabilizing and extending the solid-state structures. Coordination polymersusing rare-earth metal (ReCPS) have attract upsurging interest because of propertiesin exceptional optical, for example, Eu3+, Tb3+, Sm3+and Tm3+emit red, green, orangeand blue light, respectively, Yb3+, Nd3+and Er3+display the well-known near -infrared luminescence, which can be used for biological medicine. Moreover, Sc(III)compounds are the good candidates for catalyst because of its good stability.Compared with rare-earth metal, In(III) compounds, which have good stability, can bedisplayed as catalyst. In this paper, we synthesize coordination polymers underhydro(solve)thermal conditions, using rare-earth metal and indiumas inorganic section,by changing orginic ligands, template, metal–ligand ratio, pH value and rection time.We synthesize new compounds and discuss their structure and properties. The majorcontributions in this work are listed as follows:1、Two ScCPs and a InCP:[Sc2(L1)3](H2L1=5-hydroxyisophthalic acid)(1),[Sc3O(CH3COO)7(H2O)]·H2O(2),[In3(L1)3(HL1)(OH)]·2H2O (3), have beensynthesized under hydro(solve)thermal conditions. Compound1can be described as anew3D structure,while compound3showing a3D super molecule structure with a1D channel. Compound2form a1D helix chain. The catalytic performance ofcompound1,2and3have been carried out. Interestingly, compound1,2and3exhibit active heterogeneous catalilivity in hydrosilylation. The luminescenceperformances of compound1and3have been tested, which can attribute to the π-π*transition among the ligands.2、Seven LnCPs,[Ln3(BPTC)2(NO3)·H2O]·2H2O·2CH3CN(Ln=Eu(4), Tb (5),Dy(6), Er(7), Tm(8), Y(9))(BPTC=2，2’，5，5’-biphenyltetracarboxylic acid),[Eu3(OOCCO O)4] NO3·H2O (10) have been synthesized under hydro(solve)thermalconditions. Compounds4-9are isostructural, demonstrate a3D superolecule structurewith a1D quadrilateral channel.Compound10is three dimensional structure withtriangle pores. We also investigate the photoluminescence of compound4-8and10atroom temperature, because of the sensitization of organic ligands. They exhibittypical emission bands of the corresponding Ln3+ions. Compounds4-6and10displaystrong characteristic emission in the visible region, while7and8exhibitcharacteristic near infrared spectra, Compounds6,7and8present millisecondluminescence lifetime and compound4,5and10exhibit microsecond luminescencelifetime.