Synthesis, Crystal Structure, Properties Studies Of Metal Complexes Of Three Types Of Ligands

Three series of complexes have been prepared under hydrothermal conditions. The first ones are transition metal complexes of ciprofloxacin and enoxacin, which display bioactivity or fluorescent properties; the second ones are coordination compounds with 3-cyanobenzoate anion and isophthalate anion; the third ones are rare earth metal complexes with nitrilotriacetic acid ions. Elemental analysis, Infrared spectra, fluorescent spectra, single crystal X-Rays, and bioactivity tests were performed to study the structures and properties of the complexes.1. The first series of metal complexes with quinoline drug ligandsHydrothermal treatment of ciprofloxacin with Ni(NO₃)₂·2H₂O and Mn(ClO₄)₂·6H₂O generate [Ni(H-CIP)₂(H₂O)₂]₂(NO₃)₂·2H₂O(1) and [Mn(H-CIP)₂(H₂O)₂]₂(ClO₄)₂ 2H₂O(2), which are characterized by single crystal x-ray diffraction,.IR., respectively. The result of Tests of in vitro antibacterial activity against E. coli, P. aeruginosa, S. aureus and Candidaalbicans, show that complex 2 shows almost the same antibacterial abilities as ciprofloxacin against Staphylococcus aureas, E.coli, Candidaalbicans, but the former is superior to the later against Pseudomonas aeruginos. The susceptibility of complex 1 is weaker than ciprofloxacin, and loses the antibacterial capability against Staphylococcus aureas, Pseudomonas aeruginos. The in vitro antibacterial activity of the ligand can be improved by coordination with Mn(II).The hydrothermal treatment of ciprofloxacin, oxalic acid with Sm₂O₃ yields a novel two-dimensional coordination polymer of Sm(III), C₂₀H₂₀FN₃O₁₀Sm (3). The results of X-ray crystallographic analysis of 3 indicates that each Sm(III) atom is coordinated by six oxygen atoms from three oxalate ligands and two oxygen atoms from carboxylate group and carbonyl of the quinoline ring of ciprofloxacin, respectively, to form a square antiprism geometric coordination environment. The adjacent Sm(III) atoms are bridged through oxalate, and the chelating ciprofloxacin ligands point up and down alternative. Six Sm(III) centersconstructs a cavity, resulting in 2D polymeric structure . Time-resolved spectrum of the complex indicated that the processes of fluorescent decay consists of two components, of which corresponding lifetimes x,=5.14ns, T2=0.40ns, and the amplitudes Ai=2.85%, A2=97.15%,under the condition: Ex=250nm, Em=606nm. Complex 3 can emit strong red-orange fluorescence, has the potential application in optical materials. Three two-dimensional coordination polymers, C30H34F2M11N8O10 (4) C32H38CoF2N8O7 (5) and C32H38F2N8O7Zn (6) (H-Enox = 1 -ethyl-6-fluoro-1,4-dihydro-4-oxo-7-( 1 -pierazinyl)-1,8-naphtyridine-3-c arboxylic acid), have been rationally designed and synthesized under hydrothermal conditions. The structures of three complexes are self-assembled from trifunctional drug ligand Enoxacin and transition metal ion Mn(II), Co(II) and Zn(II) through covalent coordination bonds and hydrogen bond. 2D molecular square grid was formed among the three complexes, but the sizes of the cavities and the solvent molecule in the cavities are different. The size of the cavity of complex 4 is 13.549 x 13.549 A2, and the solvent molecule in the cavity is H2O; The sizes of the cavity of complex 5 and complex 6 are 13.389 x 13.389 A2, 13.399 x 13.399 A2, respectively, and the solvent molecule in the cavity is C2H5OH.The fluorescent properties of the complex 6 were investigated, the results indicated that the solid complex 6 can emit strong blue fluorescence. The emission of complex 6 (^ max=512nm)is neither MLCT nor LMCT in nature, and can be assigned to the intraligand n-n transition, while complex 6 may be influenced by the rigid polymeric structure. Time-resolved spectra of the complex 6 indicated that the processes of fluorescent decay consists of two components, of which corresponding lifetimes ti=5.13ns, x2=0.75ns, and the amplitudes Ai=11.08%, A2=88.92%. The complex 6 with high thermal stability and strong blue fluorescent emission has the potential application in optical material.2. The second series of metal complexes with benzoic acidThe hydrothermal reaction of Gd(ClO4)3-6H2O, Er(ClO4)3-6H2O, Sm(ClO4)3-6H2O, and Dy(ClO4)3-6H2O with 1,3dicyanobenzene, give rise to four 1D chain complexes C48H24N6Dy2Oi6 ( 7 ), C48H24N6Er2Oi6 ( 8 ) ,C48H24N6 Gd2O16 (9) and C48H24N6Nd2O,6 (10), in the presence of ethanol and water. In the reactions, 1, 3-dicyanobenzene was hydrolyzed to give 3-cyanobenzoate anion. Single crystal X-ray diffraction analysis reveals that four complexes are isomorphous with the isostructure [C48H24M2N6O16] unit. Fluorescent spectra characterization were performed; the complex 7 in solid state can emit characteristic fluorescence of Dy3+excited by the ultra-light of 330nm. The characteristic blue fluorescent emission of 478nm and yellow fluorescent emission can be assigned to energy transition of 4F9/2—6Hi5/2 and 4F9/2^"6Hi3/2. The complex 8 in solid state emitted characteristic fluorescence of Er3+excited by the ultra-light of 310nm. The characteristic blue fluorescent emission of 500nm can be assigned to energy transition of 4F7/2—115/2. The solid complex 9 can emit strong blue fluorescence, the emission (XTOax=465nm) is neither MLCT nor LMCT in nature, and can be assigned to the intraligand tt-tt transition, because the 4f7 electronic configuration of Gd3+ is very stable. The solid complex 10 can emit red fluorescence(Amax=690nm) excited by ultra-light of 333nm.Time-resolved fluorescent spectrum characterizations were performed, the processes of fluorescent decay consists of two components, of which corresponding lifetimes are 8.81ns and 0.45ns, and the amplitudes A are 7.31% and 92.69% for Gd(III) chelate; the lifetimes are 0.76ns and 3.25ns, and the corresponding amplitudes A are 87.77% and 12.23% for Nd(III) chelate; the lifetimes are 48.28ns, 0.55ns and 2.71ns, the corresponding amplitudes A are 15.14% , 59.90% and 24.96% for Dy(III) chelate; the lifetimes are 1.89ns and 0.44ns, and the corresponding amplitudes A are 18.30% and 81.70% for Er(III) chelate. The complexes with the characteristic fluorescence have the potential application in optical material.The hydrothermal reaction of Ca(OH)2 with 1, 3dicyanobenene generated a triple helical Calcium based one-dimensional coordination polymer C20H25Ca2.50O1g.50 (11)(where L=Isophthalate anion) with strong blue fluorescent emission. In the reaction 1, 3-dicyanobenzene was hydrolyzed to give isophthalate anion. Its crystal structure was determined by single crystal X-ray diffraction. Crystal structure analysisindicates that in the molecular structure of 11, there are three crystallographically independent Ca2+ ions. ID chains are formed by Ca (II)-0 coordination bond, while 2D network supramolecular structure is built up by the 71-71 stacking interaction of the adjacent benzene rings with an approximate separation of 3.947-3.982 A. The fluorescent spectrum characterizations were performed, the complex 11 in the solid state can emit strong blue fluorescence ( A max=419nm) excited by ultra-light of 316nm, The emission can be assigned to the intraligand ti-7c transition. The complex with strong blue fluorescent emission can be applied as potential optical material.3. The third series of complexes with nitrilotriacetic acidThe hydrothermal reactions of Nd(ClO4)3-6H2O, Er2O3 and Gd(ClO4)3-6H2O with H3NTA (nitrilotriacetic acid) produce three novel coordination polymers C6H12NNdO9 (12), C6H,2GdNO9(13), C6Hi0ErNO8(14), respectively, in the presence of ethanol and water. Despite similar synthesis condition, compounds 12 to 14 show different molecular structures, due to the lanthanide contraction. Ln(III) in 12, 13, 14, is eight or nine coordinated and bridged by NTA to form two-dimensional or three-dimensional network structure. The processes of fluorescent decay consists of two components, of which corresponding lifetimes are 1.20ns and 6.22ns, and the amplitudes A are 63.4% and 37.6% for Nd(III) Chelate; the corresponding lifetimes are 1.50ns and 0.14ns, and the amplitudes A are 9.32% and 90.68% for Er(III) chelate; The corresponding lifetimes are 4.01ns and 0.94ns, and the amplitudes A are 15.61% and 84.39% for Nd(III) chelate. The Er(III) complex, which forms 3D chiral coordination polymer with nan-sized chiral cavities, has the potential application in asymmetric catalysis and separation.