Synthesis Of New Amide-Based Complexes And Optimization Of Their Photocatalytic Activities

Transition metal-organic complexes(TMOCs)are considered to be a new class of functional materials,which are built from transition metal ions and adjustable organic ligands.The design and synthesis of new TMOCs are of contemporary interest within the last decade not only because of their interesting topologies but also their potential applications in gas separation and storage,chemical sensors and heterogeneous catalysis.However,the design and synthesis of complexes with target structures and properties is still a challenge.This is mainly because many factors can be attributed to the structures of complexes,such as metal ions,organic ligands and reaction conditions.Therefore,it is important to study the relationship between the coordination characteristics of components and the structures of target complexes,to offer theoretical and experimental basis for developing new functional materials.In the present work,21 unreported complexes were synthesized by self-assembly of three types of diamides as neutral organic ligands,a series of organic aromatic carboxylic acids as anionic ligands and a series of transition metal ions under hydrothermal/solvent thermal conditions as follows.Two O-/S-bridged diamide ligands[N,N'-bis(pyridine-3-yl)-2,5-(thiophenyl)dicarboxamide(L1)and N,N'-bis(pyridine-3-yl)-4,4'-oxybis(benzoic-yl)dicarboxamide(L2)]and eight organic di-/tricarboxylic acids[1,2-benzenedicarboxylic acid(1,2-H2BDC),isophthalic acid(H2IP),5-methylisophthalic acid(5-H2MIP),5-nitroisophthalic acid(5-H2NIP),5-aminoisophthalic acid(5-H2AIP),1,3,5-benzenetricarboxylic acid(1,3,5-H3BTC),1,4-benzenedicarboxylic acid(1,4-H2BDC)and 5-hydroxyphthalic acid(5-H2HIP)]were selected to combine with Ni2+/Cu2+/Zn2+.As a result,ten new complexes(1-10)from zero to three dimensions were synthesized.[Ni2(L1)4(1,2-BDC)2(H2O)2](1)[Ni(L1)(IP)(H2O)2]·H2O(2)[Ni(L1)(5-MIP)(H2O)2]·H2O(3)[Ni(L1)(5-NIP)(H2O)](4)[Ni(L1)(5-AIP)]-2H2O(5)[Ni2(OH)(L1)(1,3,5-BTC)]·DMA·5H2O(6)[Cu(L1)(5-AIP)(H2O)0.25]·H2O(7)[Cu(L1)(1,3,5-HBTC)](8)[Cu(L1)(1,4-BDC)]·H2O(9)[Zn(L2)(5-HIP)]·2.8H2O(10)On the basis of the characterizations of IR,TG and PXRD,the structures of complexes 1-10 were determined by single crystal X-ray diffraction analysis.The results indicate that metal ions show an obvious effect on the structures of complexes.The photocatalytic degradation of methylene blue(MB)by complexes 6 and 8 were studied under ultraviolet light.Composite materials 6/ppy and 8/ppy were prepared by oxidative polymerization with polypyrrole(ppy).Photocatalytic degradation activities of 6/ppy and 8/ppy for MB were studied.The results show that the modification of ppy is beneficial to improve the photocatalytic properties of the complexes.Two methylene-bridged diamide ligands[N,N'-bis(4-methylenepyridin-4-yl)-1,4-benzenedicarboxamide(L3)and N,N'-bis(4-methylenepyridin-3-yl)-4,4'-oxybis(benzoic-yl)dicarboxamide(L4)]and nine organic single-/dicarboxylic acids[2-nitrobenzoic acid(2-HNB),4-nitrobenzoic acid(4-HNB),2-methoxybenzoic acid(2-HMOB),3-chlorobenzoic acid(3-HCB),3-nitrophthalic acid(3-H2NP),2-carboxyphenylacetic acid(2-H2CP),5-nitroisophthalic acid(5-H2NIP),1,4-benzenedicarboxylic acid(1,4-H2BDC),isophthalic acid(H2IP)]were selected to combine with Ni2+/Cd2+/Zn2+.As a result,nine new complexes(11-19)from one to three dimensions were obtained.[Ni(L3)(2-NB)2(H2O)2](11)[Ni(L3)(4-NB)2(H2O)2](12)[Ni(L3)2(2-MOB)2](13)[Ni(L3)2(3-CB)2](14)[Ni(L3)(2-CP)(H2O)](15)[Ni(L3)(5-NIP)(H2O)2]·2H2O(16)[Ni(L3)(3-NP)(H2O)2](17)[Cd(L4)(IP)(H2O)]·2H2O(18)[Zn(L4)(1,4-BDC)](19)The systematic characterizations based on IR,TG,PXRD and single crystal X-ray diffraction show that organic carboxylates exhibit obvious effect on the structures of complexes.The photocatalytic degradation of MB by complexes 11 and 17 were studied under ultraviolet light.Composite materials 11/PA and 17/PA were prepared by oxidative polymerization with polyaniline(PA).Photocatalytic degradation activities of 11/PA and 17/PA for MB were studied.The results show that the modification of PA is beneficial to improve the photocatalytic properties of the complexes.Two 5-substituent-type diamide ligands[N,N'-bis(pyridin-3-yl)-5-hydroxybenzene-1,3-dicarboxamide(L5)and N,N'-bis(pyridine-3-yl)-5-methylbenzene-1,3-dicarboxamide(L6)]and one organic dicarboxylic acids[1,4-benzenedicarboxylic acid(1,4-H2BDC)]were used to react with Zn2+.As a result,two new complexes(20 and 21)with different interlocking arrays were prepared.[Zn(L5)(1,4-BDC)]·H2O(20)[Zn(L6)(1,4-BDC)]·H2O(21)The systematic characterizations demonstrate that uncoordinated groups of N-donor ligands show an obvious effect on the structures of complexes.Ag@20 and Ag@21 composite materials were synthesized by ultraviolet light reduction and the modification of Ag on the complexes is beneficial to improve the photocatalytic activity for the degradation of MB under ultraviolet light.