| In recent decades, scientists have been synthesised numbers of novel coordination polymers, containing aromatic carboxylate coordination polymers, throgh designing or selecting various ligands and metal ions. It has gathered considerable attention not only because of their intriguing diversity of architectures and topologies, but also due to their diverse and novel structural characteristics, as well as potential applications, such as in porous materials, catalysis, sensing, and magnetism. There are distinctive features in biphenyltetra-carboxylic acids, such as (?) due to availability of more coordination sites and fexible space orientations, they can bond to a great number of metal ions, thereby forming different structures; (?) the carboxylic groups can assume many kinds of bridging or multitooth chelating modes (syn-syn, syn-anti, anti-anti, and ?-Oxo) to construct diverse MOFs; and (?) they can act as hydrogen-bond acceptors or donors to form supramolecular structures by hydrogen bonding interactions. Hence, the number of aromatic multicarboxylate complexes have been reported. The ligands with aromatic multicarboxyliate acids are also chemically modified to obtain special function groups, which can be designed and synthesised target coordination polymers with specific functions.In the text, novel twenty-five compouns have been synthesized based on bi-and triphenyltetracarboxylic acid ligands under hydrothermal or solvothermal conditions. All strucrues of the complexes were characterized by IR, single-crystal X-ray diffraction, elemental analysis, and X-ray powder diffraction. In additon, the thermal properties, magnetic and luminescent properties of the complexes have been studied as well below.Firstly, coordination polymers based on 2,2',4,4'-biphenyltetracarboxylic acidA series of 3D carboxylate coordination polymers [MH2(o,p-bpta)]n (H4(o,p-bpta)= 2,2',4,4'-biphenyltetracarboxylic acid, M=Fe(?) (1), Ni(?) (2), Cu(?)(3) and Zn(?) (4)), have been synthesized in H2O/CH3CN or H2O solvents, respectively. Structurally, the M(?) sites are linked by double syn-anti carboxylates to form chains. The H2(o,p-bpta)2- ligand connects five M(?) atoms by ?3-?1:?1:?1:?1-bridging/chelating for 2,2'-COO-, and ?2-?1:?0:?1:?0 fashion for 4,4'-COO-. Complexes 1-4 with (5,5)-connected 3D framework are isostructural. Due to the 3d orbits of Fe (?), Ni (?) and Cu (?) ions being occupied with unpaired electrons, the magnetic properties of the complexes are explored. Magnetically, the isostructural polymers show different magnetic behaviors due to different spins of central ions. Theoretical analysis indicates that couplings between magnetic ions obey uniform chain models. The magnetic susceptibility of 1 and 2 in the range of 1.8-300 K are perfectly fitted by the modified Fisher model with an effective intra-chain exchange coupling constant of -0.81(1) and 3.67(2) cm-1, respectively. For 3, a Heisenberg ferromagnetic S=1/2 chain included the intrachain magnetic exchange interaction (J=9.28(1)cm-1) reports weak ferromagnetic interactions in intrachains and weak antiferromagnetic interactions between interchains. The phenomena of 1-3 accord with the common view that the exchange interaction between two magnetic M(?) ions bridged by the syn-anti carboxylate bridge is dominantly weak ferro- or antiferromagnetic interactions. In addition, the M-O-C-O-M spin exchange interactions |J| of M2(CO2)2 (M= Mn(3d5), Fe(3d6), Co(3d7), Ni(3d8), Cu(3d9)) decrease strengthes with Cu2(CO2)2> Ni2(CO2)2> Co2(CO2)2> Fe2(CO2)2> Mn2(CO2)2, consistent with the orbits order.Further, the coordination polymer [Pb2(o,p-bpta)(H2O)2]n (5) was constructed by H4(o,p-bpta) ligand and Pb(?) with 6s25d10 electron configuration in the hydrothermal reaction, which shows a unique 3D open framework with alternating round and rectangular channels. In the structure, two crystallographically independent Pb(?) cations exhibit different coordination geometries. The (o,p-bpta)4-ligand connects eight Pb(?) atoms by adopting the ?8-bridging mode. The carboxylate groups (2,2'-COO-) are in ?4-?1:?2:?2:?2-chelating/bridging, and the other two (4,4'-COO) are in ?4-?1:?2:?1:?2 fashion. In addition, the structure of 5 consists of 1D chains built by carboxylate groups bridging a pair of quad-core cluster [Pb4O4] units. It shows that H4(o,p-bpta) ligand has good coordination ability to form metal chains, ascribing to suitable distance of the ortho-carboxylates of benzene rings. Photoluminescence property of 5 in solid state was investigated in the fine powder sample at room temperature. The peaks of the complex 5 exhibits an emission band at 391 nm with excitation at 312 nm, attributing to the ligand-to-metal charge transfer (LMCT) between the delocalized ?-bond of carboxylate groups and p orbitals of Pb(?) centers.Secondly, coordination polymers based on terphenyltetracarboxylic acidsA new series of water-bridged Co(?)/Ni(?) chains compounds have been prepared under hydrothermal conditions. Structurally, these complexes contain 1D chains based on single water bridging, and ultimately exhibit 1D or 3D unique architectures. Such the chain formed based on single water bridging are very rare, and the magnetic couplings of metal Co(?) and Ni(?) chains are also very interesting, which provide an option for analysis of multiple-bridged magnetic interaction involving ?-oxo bridge. Magnetically, Magnetostructural analyses indicate that the magnetic coupling through ?2-O of aqua is strong antiferromagnetic in the Ni(II) compounds. There is a common general trend with the strength of antiferromagnetic interaction (-24.47<-21.76<-20.56 cm-1) increasing with wider Ni-Ow-Ni angles (134.91> 133.34> 132.29°). However, the octahedral Co(II) complexes with a uniform chain model show different magnetism, in which two terminal water molecules in cis-oriented coordination sites complete the octahedral coordination of the Co(II) ions, and the water bridges assume an equatorial-equatorial disposition between metal ions in compound 6 as opposed to 8 with axial-axial water-bridged mode. Hence, two systems with two Co(II) centers adopting different orbits, exhibit different magnetic characteristic. Complex 6 shows strong antiferromagnetic interactions between the Ni(?) centers, whereas 8 is spin-canted magnetic phenomenon.Thirdly, coordination polymers based on biphenyltetracarboxylic acids and 1,4-bib ligandsHydrothermal or solvothermal methods of metal salts M(?) (Ni(?), Co(?), Mn(?), or Cd(?)) with different deprotonated biphenyltetracarboxylates (H4(o,m-bpta),H4(m,m-bpta), or H4(m,p-bpta)) and N-donor (1,4-bib) give seven novel coordination polymers in H2O/DMF or H2O. The framework of 11 is constructed by a 3D interpenetration structure with a (4.62)2(42.62.82) topology. Complex 12 exhibits a 3D framework assembled by 1D Cd(?) metal chains. Complex 13 exhibits a 3D supramolecular framework assembled by 1D mutual interpenetration chains. Complex 14 shows a (4,4)-connected 2D layers. In complex 15, the (m,m-bpta)4- ligand connects six Mn(?) ions by adopting the ?1-?1:?1:?1:?1-chelating mode for (3,3-COO-) and ?4-?1:?2:?1?2-bridging fashion for (5,5'-COO-), which is further extended to form a 3D porous network structure by 1,4-bib ligand. Complexes 16 and 17 are isomorphism, having 2D sheet structures with (4,4)-grid units. The variable attachment position of carboxylic groups plays a vital role in the formation of the different structures. Magnetic susceptibility measurements indicate the presence of weak ferromagnetic exchanges between adjacent Ni(II) ions for 11 and 16. Magnetic studies show the presence of a antiferromagnetic behavior for the compounds 13,14 (J=-0.1164(1) cm-1) and 17(J=-0.100(1) cm-1).Fourthly, coordination polymers based on 3,3',5,5'-biphenyltetracarboxylic acid and neutral N-ligandsThe reactions of the H4(m,m-bpta) ligand and differernt neutral N-ligands (phen,2,2'-bipy, and 4,4'-bipy) in the presence of metal(II) salts lead to a series of dimer M(II) complexes under hydrothermal or solvothermal conditions. As expected on the basis of the geometry, the syn-syn configuration favors the formation of dimer complexes. The reactions for the synthesis of 18-21 were carried out by adding terminal N-ligands (phen/2,2'-bipy), the octahedral dimeric SBUs were formed. The dinuclear unit is bridged through the double syn-syn COO groups and ?-Oxo configuration. It was anticipated that the linking of the H4bpta ligand that acts as only spacer to connect SBUs in 18-21, resulted in the formation of similar 3D nets due to the skeleton containing potential cavities. When the terminal N-ligands were substituted with the extendable 4,4'-bipy to form a series of penta-coordinated dimeric structures, H4bpta and 4,4'-bipy ligands commonly connect dimeric SBUs to yield different 2D and 3D nets. Complex 22 is constructed by (m,m-bpta)4- and 4,4'-bipy ligands and presents a unique 3D networks, which consists of zigzag chains based on the subunits of the different [Mn2(O4N)2]. Complex 23 exhibits a 2D layer structure. Complex 24 features a fascinating heterotwofold pseudo-interpenetration architecture. Complex 25 is a 3D network structure with an 1D stair-like chain. The H4(m,m-bpta) ligand is mainly fully deprotonated and partly deprotonated (trans-H2(m,m-bpta)2-) between the functional groups. However, partly deprotonated cis-H2(m,m-bpta)2- firstly emerges in this work. Magnetic susceptibility measurements indicate the presence of weak ferromagnetic exchanges between adjacent Ni(II) ions with J=1.44(1) and 2.44(1) cm-1 for 19 and 21, respectively. Magnetic studies indicate the presence of an antiferromagnetic behavior for the compounds 18,20,22 and 24. In addition, the fluorescence properties of Zn(II) coordination polymer attribute to the ligand-to-metal charge transfer (LMCT). |
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