| In recent years,metal-organic crystalline network complexes constructed from flexible bispyridyl ligands have gained widely concern of chemical researchers.At present,the research of flexible bispyridyl ligands mainly focused on the length of spacers,rigid/flexible properties and structural types.In comparison,only few reports concerned on the crystalline network structures based on flexible bispyridines with chiral chelating spacers.This is mainly attributed to the strong deformation ability of asymmetric flexible bispyridyl molecules,which brings certain difficulties to the prediction of crystalline network structures.If the chiral chelating spacers stably coordinate to metal ions,it can not only increase the coordination sites of flexible bispyridyl ligands and the controllability of networks,but also reduce the uncertain factors and crystallization symmetry during the construction of crystalline networks.Meanwhile,the combination of rigidity and flexibility makes the flexible bispyridyl ligands show a variety of conformations,thus enriching the topological types of crystalline networks,such as helixes and even chiral crystal networks.Therefore,it is still a great challenge to design flexibly asymmetric bispyridyl building blocks with chiral chelating spacers,and further realize the regulation of design,syntheses and performances of metal-organic crystalline networks.In this thesis,according to the summary on the structures and properties of metal-organic crystal networks constructed from flexible bipyridines,two asymmetric flexible bis?pyridyl?diamine ligands with chelating spacer were synthesized in view of principles of coordination chemistry and crystal engineering,namely,N,N'-bis?pyridin-4-ylmethyl?propane-1,2-diamine?L1?and N,N'-bis?pyridin-3-ylmethyl?propane-1,2-diamine?L2?,involving a chiral carbonin the chelating spacer.Accordingly,thirty-two Zn???/Cd???/Ag?I?based crystalline network complexes were synthesized by the reaction of L1/L2,d100 metal salts and aliphatic/aromatic dicarboxylic acids through liquid phase diffusion and hydro/solvothermal methods.These complexes have been characterized by elemental analysis,IR,PL,luminescent lifetime,TG,CD,powder and single-crystal X-ray diffraction.Meanwhile,the effects of metal salts,synthetic methods,ligand conformations and different counter anions on the structures and properties of target complexes were also investigated.The main research results are listed as follows:1.Thirteen Cd???based complexes were synthesized by the reaction of L1/L2,different Cd???salts and fouraliphatic/aromatic dicarboxylic acids,namely,[Cd?L1??C4H4O4?]n?1?,[Cd?L2??C4H4O4?0.5]n·nOH·8nH2O?2?,[Cd?L1??C4H2O4?]n?3?,[Cd?L1??C4H2O4?]n?4?,[Cd2?L2??C4H2O4?2?H2O?2]n·nH2O?5?,[Cd2?L1??m-BDC?2?H2O?2]n?6?,[Cd2?L2??m-BDC?2?H2O?2]n?7?,[Cd3?L1?2?p-BDC?3?H2O?4]n·2nH2O?8?,[Cd?L2??p-BDC?0.5Cl]n?9?,[Cd?L2??p-BDC?0.5?H2O?]n·n?ClO4?·nH2O?10?,[Cd3?L2?2?p-BDC??SO4?2?H2O?6]n·4nH2O?11?,[Cd?L2??p-BDC?]n·nH2O?12?and[Cd?L2??p-BDC?]n·nMeOH?13??m-BDC=m-benzene dicarboxylate dianion,p-BDC=p-benzene dicarboxylate dianion?.Structure analyses indicate that the conformations of flexible bispyridines and the properties of organic dicarboxylic acids have an important effect on the topological structure of complexes.Ligands L1 and L2 in these complexes exhibit diverse conformations of cis-I-P,cis-O-P,trans-I-P and trans-O-P,which connect adjacent Cd???cations with four dicarboxylates in bis-monodentate and bis-chelating modes to form 1D chain?2?,2D?4,4?layer?1,3,8?,?6,3?layer?9,10?,2-period?6,3?layer?7?,?63??65.8?layer?6?,as well as 3D vma?4?,irl?5?,cds?11,12?and eca?13?nets.Furthermore,these complexes present blue emissions between 403and 433 nm in solid state at room temperature.The emission intensity of aromatic dicarboxylate complexes is stronger than that of aliphatic dicarboxylate complexes.2.Six mono/double-layered 2D and three 3D Zn???based complexes were synthesized by the reaction of L1/L2,different Zn???salts and four aliphatic/aromatic dicarboxylic acids,namely,[Zn?L1??C4H2O4?0.5?H2O?]n·0.5n?C4H2O4?·2nH2O?14?,[Zn2?L2??C4H2O4?2]n·2nH2O?15?,[Zn?L1??m-BDC?]n?16?,[Zn2?L2??m-BDC?2]n·2nH2O?17?,[Zn3?L1?2?p-BDC?3?H2O?4]n·2nH2O?18?,[Zn2?OH??L2??p-BDC?1.5]n?19?,[Zn2?L1??p-BDC?2]n·5nH2O?20?,[Zn2?L2??p-BDC?2]n·3nH2O?21?,[Zn2?L1??C4H4O4?1.5?H2O?]n·n?ClO4?·nH2O?22?.Structure analyses indicate that L1 and L2 exhibit diverse conformations to join adjacent Zn???cations into tetranuclear cluster,linear chain,wave-like chain,and?4,4?layer motifs,which are further extended by organic dicaboxylates into diverse architectures.The trans-conformational L1/L2 ligand tends to form double-layer?14?and mono-?4,4?layer structure?15-19?with different thickness of 5.815.0?,while the cis-conformational L1/L2 ligand tends to form 3D networks,that is,different binodal networks with?4,4?-c net?20?,pts?21?and 2-fold interpenetrated?5,5?-c net?22?.It should be noted that complexes 20 and 22 present Schl?fli symbols of?4.52.83??4.53.72?and?32.44.52.62??3.43.52.64?which are not reported so far.Moreover,these complexes present luminescent emissions in the range of402449 nm in solid state at room temperature.The luminescent lifetimes of the complexes 14,16 and 18-21 are 8.8116.30 ns.3.Ten Zn???,Cd???and Ag?I?based complexes with helical?or chiral?structures were synthesized by the self-assembly reaction between L1/L2 and different d100 metal salts,namely,[M2?L2?Cl4]n[M=Zn?23 and 24?or Cd?25?],[Cd?L2??SO4?]n?26?,[Cd?L2??X??H2O?]n·nX[X=ClO4?27?or NO3?28?],[Ag?L1?]n·nClO4?29?,[Ag?L1?]n·nNO3·nH2O?30?,[Ag?L2?]n·nClO4?31?and[Ag?H2L2?]n·3nNO3·2nH2O?32?.Structural analyses indicate that except for the wavelike chain structure of complex 32originated from the protonated H2L22+ligand,the other complexes 23-31 all contain helical chain or helical layer structures with the pitches falling in the range of7.9719.76?.Especially,complexes 25 and 26 present different 3D sqc and uog nets,which construct from?Cd-Cl?n helical layers and?Cd-L2?n helical chains,respectively.Complexes 29 and 30 exhibit the same?4,4?layer incorporating homo-helical chains.In addition,the circular dichroism?CD?spectrum further confirmed the chiral characteristics of complexes 26,27,29 and 30.Meanwhile,luminescent investigation reveals that complexes 23-28 exhibit blue emission maxima varying from 417 to 483nm in the solid state at room temperature.Moreover,complexes 26 and 28 show average luminescence lifetimes of 8.87?26?and 24.28 ns?28?,respectively.These experimental results not only confirm the original research idea of this paper,but also provide a good strategy for the design and synthesis of metal-organic crystalline network complexes with helical and chiral structures. |
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