| In this work,several benzonitrile-based bifurcate compounds were selected as original ligands to in-situ transform into new tridentate ligands,and to assemble with various polyoxomatalates(POMs)and transition metal ions under hydrothermal conditions.Ten POM-based metal-organic complexes with novel structures have been synthesized.All the complexes have been characterized by single-crystal X-ray diffractions,PXRD,IR,XPS,TG and so on.The structures of compounds 1-10 have also been further described to investigate the influences of the configurations of ligands,metal ions,polyoxoanions on the final structures.Meanwhile,the electrochemical and photocatalytic properties of all these complexes have also been investigated.1.Choosing 3,5-di(1H-imidazol-1-yl)benzonitrile(DICN)as original ligands,four POM-based metal-organic complexes 1-4 modified by in situ transformed ligands have been obtained by changing POMs and metal ions under hydrothermal condition.The effects of the pH,metal ions,polyoxoanions on the structures have been discussed.[Cu2(DIBA)4](H3PMo12O40)·6H2O(1)[Cu2(DIBA)4](H4SiW12O40)·6H2O(2)[Ag(HDIBA)2](H2PMo12O40)·2H2O(3)[Ag3(HDIBA)2(H2O)][(P2W18O62)1/2]·4H2O(4)(DIBAH=3,5-di(1,2,4-triazol-1-yl)benzoic acid)The 3,5-di(1,2,4-triazol-1-yl)benzoic acid(DIBAH)ligand was generated in situ from 3,5-di(1H-imidazol-1-yl)benzonitrile,and coordinates with metal ions to construct novel POM-based hybrids.Both 1 and 2 display 3D 2-fold interpenetrating frameworks containing two kinds of channels.The bigger channels are occupied by Keggin polyoxoanions and crystallization water molecules,but only crystallization water molecules in the smaller ones.Compound 3 displays a 3D supramolecular structure constructed from {Ag(HDIBA)2} segments and[PMo12O40]3-polyoxoanions through hydrogen bonding interactions.Compound 4 shows a 3D 2-fold interpenetrating framework based on(3,3,4)-connected network,which is constructed from {Ag3(HDIBA)2}n chains and[P2W18O62]6-polyoxoanions.The structural analysis indicates that different metal ions and POMs have important effects on the connected modes of ligand and the final structures of title complexes.Compounds 1-4 show good electrocatalytic activities toward the reduction of bromate,as well as excellent photocatalytic activities for the degradation of MB.2.To investigate the effects of the functional groups of ligands on the structures,3,5-di(1Hbenzoimidazol-1-yl)benzonitrile(DBICN),3,5-di(1H-imidazol-1-yl)benzonitrile(DICN)and 3,5-di-[1,2,4]triazol-1-yl-benzonitrile(DTCN)were chosen as the initial reaction ligands,respectively,and four POMs-based complexes 5-7 have been obtained in the same Cu/Mo8O26 reaction system under hydrothermal condition.[Cu?3(DBIBA)3][?-HMo8O26](5)[Cu?2(H2O)(DIBA)(DIBAH)(?-HMo8O26)]·2H2O(6)[Cu?(DTBA)(Mo2O6)](7)(HDBIBA = 3,5-di(1Hbenzoimidazol-1-yl)benzoic acid,HDIBA =3,5-di(lH-imidazol-1-yl)benzoic acid,HDTBA=3,5-di-[1,2,4]triazol-1-yl-benzoic acid)When the N-donor group is benzimidazolyl,compound 5 with a 3D(6,8)-connected framework is constructed from {Cu3(DBIBA)3} hexagonal ring building units and[?-Mo8O26]4-polyoxoanions.Replacing the benzimidazolyl group of the ligand with imidazolyl group,a 3D(3,4,6)-connected framework containing two types of {(?-Mo8O26)(DIBA)2} building blocks of compound 6 was obtained.When the triazolyl group is introduced,compound 7 displays a 3D framework,which is constructed from {(Mo4O13)(DTBA)2}n chains bridged by Cu(I)atoms.It is noted that the carboxyl oxygen atoms from the in situ ligands parcitipate in the construction of isopolymolybdates in compounds 6 and 7.In other words,the N-donor groups of in situ ligands show important effect on the final architectures of compounds 5-7.Compounds 5-7 also exhibit excellent electrocatalytic activities for the reduction of hydrogen peroxide and good photocatalytic activities for the degradations of organic dyes.3.To investigate the effects of metal ions on structures of complexes,different metal ions are introduced into the same reaction system based on DICN and polymolybdates to construct POMs-based complexes,respectively,and three isopolymolybdate-based complexes 8-10 were have been obtained.[Ag?(DTBA)(Mo2O6)](8)[Cu?3(DTBA)2(?-Mo8O26)(H2O)6]·7H2O(9)[Co?3(DTBA)2(DTBAH)2(?-Mo8O26)(H2O)2]·4H2O(10)(HDTBA=3,5-di-[1,2,4]triazol-1-yl-benzoic acid)Interestingly,all isopolymolybdates in the structures of compounds 8-10 are directly grafted by the in situ ligand DTBA.When Ag+ ion was presented,a 3D framework of compound 8 is constructed from {[Mo4O13](DTBA)2} building blocks.Replacing Ag+ with Cu2+ ion,compound 9 shows a(2,4,8)-connected framework based on {(?-Mo8O26)(DTBA)2} building units.A{(?-Mo8O26)(DTBA)2} building unit-based(4,4,8)-connected 3D framework of compound 10 is obtained in the presence of Co2+ ion.That is to say,the metal ions may play key roles in tuning the various structures of compounds 8-10.In addition,the title compounds 8-10 show good electrocatalytic activities for hydrogen peroxide reduction and photocatalytic activities for the degradation of MB. |
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