| In recent years,considerable interest has been focused on molecule-based materials because of their fascinating structures and potential applications in catalysis,electronics,magnetic materials,nonlinear optics and so on.Many research groups have made great pregresses in inorganic-organic hybrid materials,and functional studies.Aiming at new molecule-based functional materials,this thesis focused on the crystal engineering of coordination complexes by choosing divalent counter-cations,solvents,and suitable central metal ions,while utilizing maleonitriledithiolate(mnt)and anthraquinone-1,4,5,8-tetracarboxylic acid(H4AQTC)ligands as primary ligands in the preparation.18 new coordination complexes are obtained.Their structures and properties are systematically investigated as well.The main achievements are listed as follows:1.Effects of divalent counter-cations upon coordination complexation with[Ni(mnt)2]-anion.(1)Tuning the structures and properties of[(Py)2CH2][Ni(mnt)2]2·Solvent complexes by solvents.We choose[(Py)2CH2]2+ as counter-ion to prepare four pseudo-isomorphism complexes[(Py)2CH2][Ni(mnt)2]2·2CH3CN(1),[(Py)2CH2]2[Ni(mnt)2]4·3CH3NO2(2),[(Py)2CH2]2.5[Ni(mnt)2]5·0.5(C3H7NO2)(3),and[(Py)2CH2][Ni(mnt)2]2·2(C3H60)(4)by using different solvents(such as acetonitrile,nitromethane,2-nitroprooane,and acetone).The stacking pattern of complex 1 is similar to that of 4,where the cations and anions pack into 1-D columns separately through intermolecular Ni…Ni,S…S,Ni…S,π…π,and C-H…N interactions.In complex 2,there are two types of[Ni(mnt)2]-stacking columns.One possesses a nickel-over-nickel arrangement and form a heptamer chain,while the other lies approximately vertical to the original one.The anion connects neighboring cations to form a 2-D network via Ni…S interaction.The structure of 3 is similar to that of 2,where a hexamer chain was formed.To the best of our knowledge,the stacking modes of complexes 2 and 3 have not been reported before.Complex 5[(NH2Py)2CH2][Ni(mnt)2]2·2(CH3CN)was obtained by modifying pyridine rings of the cations.The[Ni(mnt)2]-stacking mode is alsosimilar to that of 2,where π…π interactions are observed between cations.3-D supramolecular framework is formed through the intermolecular weak-interactions.Magnetic properties of these complexes are investigated.Complexes 1 and 3 exhibit the characteristics of a spin gap system.And the overall magnetic behaviors of 2 and 5 correspond to a paramagnetic system.(2)Tuning the stacking of[Ni(mnt)2]-by cations.Our results show that the size and volume of cations may greatly affect the stacking patterns of[Ni(mnt)2]-anions in coordination complexes,and thus tune their properties.On the basis of previous work,four complexes[(Py)2(CH2)3][Ni(mnt)2]2(6),[(Py)2(CH2)4][Ni(mnt)2]2(7),[1,3-BMPB]1.5(Ni(mnt)2]3·CH3CN(8),and[1,4-BMPB][Ni(mnt)2]2(9)were prepared by using different cations[(Py)2(CH2)3]2+,[(Py)2(CH2)4]2+,[1,3-BMPB]2+,and[1,4-BMPB]2+[1,3-BMPB = 1,3-bis(methylpyridinium benzene),1,4-BMPB = 1,4-bis(methylpyridinium benzene)].Single crystal X-ray diffraction analysis revealed that 1-D alternating chain is formed in complex 6,where the Ni…Ni distances are 3.973 and 4.280 A respectively.The structures of 7 and 8 are similar to that of complex 2,where 2-D layer structures are observed.A sandwich-type structure is formed from mixed cations and cations stacks in 9,where the anion…πinteraction is observed and 3-D supramolecular framework is formed through the intermolecular weak-interactions.Magnetic property investigations show that complex 6exhibits the characteristics of a spin gap system.And the overall magnetic behaviors of 7 and 8 correspond to a paramagnetic system.2.Studies on the syntheses and properties of coodination polymers based on anthraquinone-1,4,5,8-tetracarboxylic acid(H4AQTC).(1)Co(II)and Ni(II)complexes.{[Co2(AQTC)(H2O)6]·6H2O}n(10),and{[M2(AQTC)(bpym)(H2O)6]·6H20}n(M = Co(11),Ni(12))have been synthesized under solvo-thermal conditions and structurally characterized.Single crystal X-ray diffraction analysis revealed that complex 10 crystallizes in monoclinic space group P21/c.Four deprotonated carboxylate groups of H4AQTC are all involved in coordination,where they adopts monodentate mode to form a 2-D sheet in the ab plane.The neighbouring Co(Ⅱ)ions along c axis are bridged by oxygen atoms of water molecules to form[Co(H2O)]n chains,crosslinking pillared metal-organic layers to a 3-D framework.Complexes 11 and 12 are isomorphous and display 1-D chain structures.Only two diagonal carboxylate groups participate in coordination.Carboxylate oxygen atom adopts monodentate bridging mode,and 2,2’-bipyrimidine functions as a μ2-bridge.3-D supramolecular structures are formed through hydrogen-bonding interactions.Magnetic properties of these complexes are investigated.Compound 10 shows canted antiferromagnetism and slow relaxation below 4 K.For complexes 11 and 12,dominant antiferromagnetic interactions are observed.The luminescence of these complexes mainly originates from ligands and the emissions can be tentatively assigned to intraligand transitions at the excited state.(2)Lanthanide complexes.Six isostructural two-dimensional lanthanide complexes with the formula[Ln(HAQTC)(H2O)4·xH2O]n(Ln = Nd,13;Sm,14;Eu,15;Tb,16;Dy,17;Er,18.)were synthesized by treating H4AQTC with lanthanide(Ⅲ)salts under hydrothermal conditions.Only two diagonal carboxylate group participate in coordination.Carboxylate oxygen atom adopts monodentate bridging mode.Each AQTC3-anion ligand takes the syn-anti bidentate bridging mode,generating a two-dimensional layer structure.3-D supramolecular structurs are formed through hydrogen-bonding interactions.Magnetic susceptibility measurements of complexes 16 and 17 in temperature range 2-300 K were performed,which showed dominant weak ferromagnetic interactions in 16 and weak frequency dependence below 3 K in 17.In order to further explore the magnetic properties of complex 17,its anhydrous form(complex 17’)was investigated as well.Ac(alternating-current)susceptibility measurements of 17’ showed clear frequency dependence below 10 K.The result indicated that water molecules have some effect on the magnetization process. |
