Construction, Crystal Structure And Properties Of Coordination Polymers Based On Rigid Polyphenyl And N-heterocyclic Carboxyl Ligand

Coordination polymers (CPs) are crystalline materials with infinite network arrays formed by the linking of metal centers and organic linkers though coordinative bonding. In particular, Metal-organic frameworks (MOFs) depend largely on the ability to synthesize multi-functional porous materials possessing distinct structural features. The nowadays works on MOFs/CPs mainly focus on their potential application instead of diverse structure. However, MOFs are very attractive due to their modular nature, e.g., chemical and topological versatility, structural diversity, exceptionally large surface areas and controlled pore textures, which offer potential in various applications. Synthetic approaches to MOFs which consider the topological characteristics of these organic and inorganic secondary building units (SBUs) to rationally construct ’default’ structures, have attracted significant scientific interest over the last decades. Structural diversity and multi-function of MOFs depend mainly on their inorganic and organic units, however, many external factors in synthesis processing have a crucial influences on structure and function of CPs. One of the major challenges for the implementation of this technology is to efficiently adjust and control these uncertainty factors. Taking these considerations, phenyl aromatic and N-heterocyclic carboxylic ligand containing different coordinative groups have been chosen as organic linkers owing to their unique features, such as, symmetry, size, number and distribution of functional group, at el. Therefore, suitable ligand is an essential component for obtaining target products with expected properties. In the dissertation, the work has been divided in five chapters as follows:Chapter 1 provides a brief introduction of origin, evolution, background, synthetic strategies and valuable application.Chapter 2 represent two microporous metal-organic frameworks, [Zn2(HDDCBA)]·2DMF·2H2O (1) and [Cd2(DDCBA)·DMA·H2O]·H2N(Me)2 (2) have been synthesized under solvo thermal condition by using a less-exploited symmetrical pentacarboxylate ligand,3,5-di(3’,5’-dicarboxylphenyl)benozoic acid (H5 DDCBA). Both compounds 1 and 2 reveal a (5,5)-connected net based on binuclear metal clusters and organic linkers. The desolvated structure of 1 (la) contains two shapes of 1D channel with suitable pore size and polar system decorated by uncoordinated carboxylate groups. As a result, la possesses not only high CO2 loading but also excellent CO2/CH4 selectivity at 273 and 298 K. In addition, both compounds display solid-state luminescence stemming from the ligand-centered fluorescence of H5 DDCBA.Chapter 3 reported four porous metal-organic frameworks, Cd2(DDCPB)-2DMF-H2O (3), [Zn2(DDCPB)-2DMA]DMA (4), [Mn4(DDCPB)2(DMA)2]·(DMA)2·H2O (5) and [Mn2(DDCPB)·(DMF)3·H2O] ·3DMF (6). Noteworthy, two homologous luminescent metal-organic frameworks (LMOFs), Cd2(DDCPB)·2DMF·H2O (3) and [Zn2(DDCPB)-2DMA]DMA (4), have been constructed to explore sensing mechanisms series of nitro aromatic compounds. Among various kinds of organic compounds, both 3 and 4 only response to copper(II) ions and a series of nitro aromatic compounds through luminescence quenching with distinct analytes concentration in vapour and liquid phase. Quantitative experiments in solution have been conducted to confirm the higher quenching efficiency dynamic quenching and to calculate constants quenching. Importantly, the relationship between the sensing efficiency and the inherent structure of polymers the sensing mechanisms have been discussed and studied in detail. In addition, gas adsorption on 5 has been investigated.In chapter 4, there are eight new MOFs based on 6-(3’-pyridyl) isophthalic acid (H2PIA) have been constructed under hydro(solvo) thermal condition, such as, Zn(PIA) (7), Zn2(PIA)2 (8), Zn(PIA)·H2O (9), [Cd(PIA)H2O]·2H2O (10), Cd(PIA)(bpe)0.5(11), Cd(PIA) (12), Pb(PIA) (13) and Mn(PIA) (14). Single crystal analysis indicated that 7 contains classic paddle-wheel SBUs in structure in order to enhance the stability.12,13 and 14 possess chiral space group and have similar structures. The luminescent properties of 7-13 have been investigated in solid state at room temperature. In addition, the magnetic properties of 14 have been discussed.Chapter 5 give three new solvent-directed three-dimensional (3D) lead(II) coordination polymers, Pb2(HPIMA)2 (15), Pb3(HPIMA)3 (16) and [Pb(HPIMA)]·H2O (17) [H3PIMA= 2-(pyridine-2-yl)-1H-imidazole-4,5-dicarboxylic acid], have been synthesized solvothermally. As influenced by different solvent systems, compounds 15 and 17 exhibit varying architectures from a multi-nodal 3,3,4,4-connected to a uninodal 3-connected net, while 16 with helices represents a binodal 3,4-connected topological net. Moreover,17 possesses a micropore which is decorated with pyridyl systems and uncoordinated carboxylate oxygen atoms. In addition, the small-sized and highly polar pores enable 17 to attract CO2 strongly, leading to a high sorption heat for CO2 and significant selectivity for CO2 over H2 and N2 at room temperature. The luminescent behaviors of 15-17 are also discussed.Finally, a brief summary of this work is given.