Studies On The Synthesis, Structures And Properties Of Metal Coordination Compounds (Polymers) Based On Rigid/flexible Ditopic Multidentate Ligands

Chiral coordination polymers show promising application in respect of asymmetric catalysis, chiral separation, nonlinear opticals and ferroelectric materials. Although a number of chiral coordination polymers have been reported in recent years, it is still a challenge for scientists to design and synthesize a desired architecture in a truly predictable manner. It has been reported that some chiral coordination polymers can be constructed by self-resolution from the reaction of racemic ligand with metal salts. However, such examples of success are still very seldom. Therefore, it is necessary to investigate the coordination fashion and self-assembly rules of more racemic ligands, which will help to reveal details of self-assembly of chiral materials and the mechanisms of the self-recognization in the construction of chiral supramolecular systems, and to control effectively the spontaneous resolution procedures of the racemates.Due to their superiority of the rigid/flexible ditopic multicarboxylate ligands and N-acyl-salicylhydrazide ligands in the construction of functional coordination compounds, in this thesis we focus our attention on the studies of the synthesis and the coordination action of ditopic multicarboxylate ligands with axial axes or chiral centers and containing hydroxyl or amino groups, and the ligands of their multiacyl-multisalicylhydrazide derivatives. The effect of the rigidity and flexiblility, the functional groups and the location of the coordination sites of the ligands on the construction and the architectures of the complexes will be inverstigated. For this purpose, four ditopic ligands, including three racemic axial chiral ligands, 2,2’-dihydroxy-[1,1’]-binaphthalene-3,3’-dicarboxylate (L1), [1,1’]Binaphthalenyl-2,2’-diamine-N,N,N’,N’-tetraacetic acid (L2), N,N’-disalicylacyl-(BINOL)-3,3’)-diformylhydrazide (L3), and one optical pure chiral ligand (R,R)-N,N’-(disalicylacyl)- tartaric diformylhydrazide (L4) were prepared, among them L2, L3 and L4 are new.32 coordination compounds (polymers) were obtained by the reactions of these ligands with transition metal ions or lanthanide ions. The effects of the factors such as the metal ions, the pH value, the type of the base, the temperature on the structures of the final products were investigated. The magnetic and luminescent properties of some coordination compounds were studied. This dissertation is comprised of six parts:1. Five metal coordination compounds (polymers) were synthesized by racemic ditopic ligand 2,2’-dihydroxy-[1,1’]-binaphthalene-3,3’-dicarboxylate (L1) and transition metal salts. The magnetic properties of some compounds were investigated.Five coordination compounds (polymers) were obtained from the reaction of L1 ligand with transition metal salts:{[M(L1)(DMF)2(H2O)2]-DMF}n [M=Co (1), Mn(2), Ni (3), Cu(4); Cu2(L1)-(phen)2·(CH3OH)2 (5). Ligand L1 adopted two new coordination modes to form coordination polymers of 1-4 with similar 1D 21 helical chains, and a binuclear copper complex of 5. Helical structures have not been reported in the complexes of ligand L1, the formation of the helical compounds of 1-4 may be related to the hinge framework and new coordination modes of the ligands. It is very interesting that the 1D helical chain is constructed by the ligands with same configuration, which demonstrates that the orientation of the helices was determined by the axial chirality of the ligand. It was found that the helical chains are further linked into chiral layer through hydrogen-bonded interaction.2. Eight 2D lanthanide coordination polymers were synthesized with L1. The luminescent properties of these compounds were investigated.Eight coordination polymers were synthesized by the reaction of L2 ligand and lanthanide salts,{[M(L1)(H2O)]·N+H2(CH3)2}n [M= La (6a), Sm(6b), Eu (6c), Gd(6d), Tb(6e), Dy(6f), Er (6g), Y(6h). The eight compounds show similar 2D network with a Schlafli symbol of (46·64)(46). The structures of the compounds don’t change along with the lanthanide contraction effect, which may be attributed to the flexibility of ligand. Luminescent properties of 6a-6h show that the emissions of 6a and 6d-6h are assigned to intraligand π�'π* transition. The emission spectrum of 6c shows mainly the characteristic emission of Eu(Ⅲ) ion with infinitesimal disturbance of L1 ligand, while the emission spectrum of 6b shows not only the intraligand π�'π* transition and but also the characteristic emission of the Sm(Ⅲ) ion.3. Rigid and flexible racemic aminopolycarboxylic acids ditopic ligand [1,1’]Binaphthalenyl-2,2’-diamine-N,N,N’,N’-tetraacetic acid (L2) was synthesized. Eight transition metal and one 3d-4f heteronuclear coordination compounds were obtained with L2 ligand. The magnetic properties of some compounds were investigated.Nine coordination compounds were synthesize by the reaction of L2 ligand with transition metal salts or the mixture of transition metal and lanthanide salts:[Mn2(L2)(H2O)6] [Mn2(L2)(H2O)5]·7H2O (7), [Fe(L2)](Et3N+H)] (8), [Co2(L2)(H2O)4]·2.25H2O]n (9), [Ni2(L2)(H2O)4]·2H2O]n (10), [Co2(L2)(phen)2(H2O)]·2H2O (11), [Cu(C2O4)2-(bpy) (H2O)]·2H2O (12), [CuNa2(L2)(H2O)5]·(H2O)]n (13), Cu2(binam)2Cl4 (14) and {[Ni2Nd(L2)2(H2O)5] [Ni2Nd(L2)2(H2O)6] [Ni(L2)] [Ni(H2O)6]}·11H2O (15). Among them,7 and 8 display OD structures,9 and 10 show 1D chain structure linked by bidentate syn-trans and trans-trans carboxylate bridgings, and 13 exhibits a 3s-3d heteronuclear 2D network, showing interesting structural variability depending on the ions. It is noteworthy that the ID zigzag chain of 9 and 10 is racemic, two axial enantiomer ligands are alternatively aligned in the chain, which is different from the helical chain in 1-4.15 is a 3d-4f heteronuclear coordination compound. Four independent molecules are observed in its unit cell, which is very rare in the literature. The magnetic studies of compounds 7,9-11 indicate that the syn-trans and trans-trans mode of the carboxylate bridge transfer antiferromagnetic coupling and ferromagnetic coupling interaction, respectively.4. Five metal coordination compounds were synthesized from the reaction of L2 ligand with Zn(Ⅱ) and Cd(Ⅱ) salts. The luminescent properties of these compounds were investigated.Solvothermal reaction of Zn(Ⅱ) or Cd(Ⅱ) salts with L2 produce five metal coordination compounds:[Cd2(L2)(phen)2(H2O)](H2O)2 (16), [Cd4(L2)2(phen)2(H2O)7](CH3OH)·(H2O)10 (17), {[Cd5(L2)2(H2O)3(OH)2](H2O)}n (18), [Zn2(L2)(phen)2(H2O)](H2O)2 (19), {[Zn2(L2)(H2O)4](H2O)2.25}n (20). The structure of 16 is dinuclear, and that of 17 is tetranuclear. The structural difference of 16 and 17 indicates a temperature-dependence of the formation of the two complexes. In 17, every couple tetranuclear enantiomers are linked into a elliptic R22(28) dimer by intermolecular hydrogen-bonded interaction with a long axis of 16.53 A and a short axis of 12.63 A for the elliptic cavity. Complex 18 is a complicated 2D polymer constructed by a novel pentanuclear cadmium(II) repeating units. The structure of 19 is similar to that of 16,20 is a 1D chain polymer. Six distinct kinds of coordination modes for L4- ligands were found in five complexes. To the best of our knowledge, four coordination modes have not been observed in other metal complexes based on aminopolycarboxylic acids ligand reported in the literatures. The five complexes are found to display various architectures from 0D to 2D, which is related to the rigidity/flexibility of the ligand and the diversity of the coordination modes, and the reaction conditions such as the reaction temperature, the types of base, pH value. The complexes display structure-dependent photoluminescence properties in the solid state with interesting red-shift or blue-shift or extinction behaviour.5. Rigid and flexible racemic ditopic ligand N,N’-disalicylacyl-(BINOL)-3,3’)-diformylhydrazide (L3) was synthesized. One helical coordination polymer was obtained by the reaction of L3 and Cu(OAc)2.A 1D helical coordination polymer{[Cu4(L3)2(Py)4]·1.5DMF}n (21) was constructed by weak coordination-driven assembly via conventional reaction of copper salts and L3. This represents the first example of helical structure based on disalicylhydrazide ligand. It is very interesting that the helical chain is chiral, namely the orientation of the helices was correlated with the axial chirality of the ligand. Ligand L3 uses all of its twelve coordination atoms to coordinate with copper ions. It was shown that the rigidity/flexibility of the parent framework, the functional groups and the location of the coordination sites of the ditoptic disalicylhydrazide ligand affect greatly the structure of the complex obatined. The magnetic study indicates that the complex shows antiferromagnetic coupling interaction among the copper centers.6. Four coordination compounds (polymers) were synthesized from a new flexible chiral ligand (R,R)-N,N’-(disalicylacyl)-tartaric diformylhydrazide (L4). The magnetic properties of some compounds were investigated.Conventional reaction or low temperature solvothermal reaction of transition metal salts with L4 produce four metal coordination compounds:[Ni3(L4)(Py)2(DMF)2]·DMF (22), [Cu3(L4)(Py)2]·2DMF]n (23), Mn2(bshz4-)(acac-)2(Py)2 (24), [Co6(fshz3-)(Py)6]·DMF (25).22 and 23 exhibit planar trinuclear structure and 1D chiral chain structure with trinuclear repeating units, respectively. The CD spectrum of 23 shows positive signals. The Flack parameter is 0.007(12). The ligand L4 has decomposed in the reaction with Mn and Co salts. The complex 23 shows antiferromagnetic coupling interaction among the copper centers.