| Metal-organic frameworks?MOFs?are an emerging class of porous materials constructed from metal ions and organic ligands.This promising materials have a variety of applications such as adsorption,catalysis,sensing optics and electrics because of their fascinating topological structures.Semi-rigid tetracarboxylic ligands can act as one kinds of significantly excellent linker to design helical structures based on its strong deformation ability and abundant coordinated modes.We choose 3,3?,5,5?-biphenyltetracarboxylic acid and1,3-di?3',5'-dicarboxylphenyl?benzene as ligands with different transition metals to generate eight new porous or helical MOFs by organic solvent tempting role.Furthermore,systematic studying the impact of metal ions,organic ligands and solvents on the structure of the target compounds is a very worthwhile work.All of compounds have been comprehensively characterized by single X-ray crystallography,powder X-ray crystallography,element analyses,infrared spectroscopy,thermal gravimetric analysis,fluorescence spectrum,second nonlinear optics,capacitorperformance and so on.The main contents include three parts as follows:In the first part,four novel helical coordination polymers{[Me2NH2][Zn?Hbptc??DMF?]}n?1?,{[H3O]2[Zn?H2bptc?2]}n?2?,{Co2?bptc??DMPU?4}n?3?,{[EMIM]2[H3O]2[Ni4?bptc?3?H2O?4]}n?4?were synthesized by 3,3',5,5'-biphenyl tetracarboxylate and Zn???,Co???,Ni???metal ions under solvethermal conditions.A careful investigation reveal that compounds 1,3,4 exhibit alternate arrangement of left-handed and right-handed helical chain in pairs which lead to a racemic compound with the centrosymmetric space group P21/n.We also develop the electric capacitance of 3 and 4.However,complex 2 is a 2-fold interpenetrated?2,4?-net 3D structure with 42 helical chain,which exhibits similar SHG efficiency as KDP.Secondly,two 3D isostructural MOFs formulated as{[MeNH3]3.3[Zn4.34?0.66?bptc?3]?13NMF}n?5?and{[MeNH3]2[Zn5?bptc?3?H2O?2]?13NMF}n?6?based on 3,3',5,5'-biphenyl tetracarboxylate has been constructed under solvothermal condition,which exhibit excellent adsorption property.Lastly,we replace the C-C of L1 with benzene to obtain a more flexible rotary and triangle ligand of 1,3-di?3',5'-dicarboxylphenyl?benzene?L2?.We use this ligand and Zn???metal ion to construct two helical and porous MOFs {[Zn2?L2??H2O?]?DMF?}n?7?and{Zn2?L2??NMP??EtOH?}n?8?.7 shows three-dimensional structure with nested ring pattern like “Olympic rings” which expanded by left and right 21 spiral chain arranged alternately.Noticeably,complex 8established only by left 21 helical chain forms left handed channel ofthree-dimensional structure,and SHG efficiency is 1.5 times that of KDP. |
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