Syntheses And Folded Structures Of Novel Pendant-armed [1+1] And [2+2] Schiff-base Macrocyclic Zinc (?) Complexes

Macrocyclic ligand and their metal complexes have attracted much attention due to their potential applications in the field of applied chemistry.Schiff-base macrocycle is one type of the earliest macrocycles that were synthesized artificially.There has been growing interests and intensified research in Robson-type Schiff-base macrocyclic complexes since they were first reported in 1970 because of their special properties and functions in the study of the fields such as molecular recognization,bio-enzyme mimic,catalytic and functional material.Due to their significant status in macrocyclic and supramolecular chemistry,many efforts were made to find out the most efficient approach of forming this type of Schiff-base macrocyclic complexes,and as a result large numbers of such complexes have been synthesized and characterized.The introduction of functional pendant arms into macrocycles' skeleton is a useful way to improve their properties and functions such as the ability to complex with more kinds of metals which cannot be ligated before.It is an efficient method to change the structures of macrocycles as well.Therefore,much attention has been focused in this branch of Shciff-base macrocyclic ligand/complexes.In the majority of related research,pendant arms are often introduced into the amine components to construct corresponding macrocyclic ligands.In contrast,the expansion of dialdehyde components with functional pendant arms is much more challenging and has been less studied up till now.Our motivation is to design and prepare novel flexible Schiff-base macrocyclic ligands bearing extended pendant-armed dialdehyde components,and to use them to build up macrocyclic complexes in the presence of certain templates.In this dissertation,two new pendant-armed dialdehydes are synthesized and are used to form several macrocyclic complexes.Corresponding details are shown as follows:1.Two new pendant-armed dialdehydes la/lb have been synthesized by a one step reaction between 5-chloro-3-(chloromethyl)-2-hydroxybenzaldehyde/5-methyl-3-(chloromethyl)-2-hydroxybenzaldehyde and cyclohexylamine with a molar rate of 2:1.They have been used to form Schiff-base macrocyclic complexes by reacting with 1,3-propanediamine in the template agent ZnX2(X = Cl,Br,and I).As a result,six[1+1]Schiff-base macrocyclic Zn(II)complexes have been obtained.All of them are characterized by elemental analysis,FI-IR,UV-Vis spectra,H NMR and X-ray single crystal structural analysis.According to the X-ray single crystal structural analysis,dialdehyde la and six Schiff-base macrocyclic complexes were all folded structures with strong ?-? intramolecular effect between one pair of benzene units.It is found that among the six complexes,five are dinuclear(2a,2b,3b,4a,and 4b and one is mononuclear(3a).What the complexes have in common is that the zinc ions are all four-coordinated,forming distorted tetrahedra.In the five dinuclear complexes,each zinc ion is coordinated by one halide atom,one oxygen atom from the bridging water/ethanol molecule,one imine nitrogen atom from the azomathine group,and one phenolic oxygen atom.In the mononuclear complex 3a,the central zinc ion is coordinated by two bromide atoms,one phenolic oxygen atom,and one imine nitrogen atom from the azomathine group.2.By reacting the dialdehydes 1a/1b with 2,3-diaminomaleonitrile,1,2-diaminobenzene and 2,2'-(ethane-1,2-diylbis(oxy))diethanamine in the presence of zinc salts(anions = NO3-,Cl-,Br-,I-),eight[2+2]Schiff-base macrocyclic zinc complexes(5a,5b,6a,6b,6c,7a,7b and 7c)have been obtained.According to the diamines used,the eight complexes were divided into three series,that is,5,6 and 7.One complex of each series were successfully characterized by X-ray single crystal structural analysis,namely,three complexes(5a,6c and 7b)were structurally characterized while the other five were not obtained by single crystals suited for X-ray single-crystal structural analysis.But their structures were proved to be similar to those already structurally analyzed by other ways of analyses,including ESI-MS,FT-IR and UV-Vis spectra.Through X-ray single-crystal structural analysis,it is found that 5a,6c and 7b crystallize in the monoclinic space group P21/c,triclinic space group R3-and tetragonal space group 142d respectively.Each structure is folded with the benzene-benzene dihedral angles 19.0(2)°,18.4(2)°and 59.7(2)°,respectively.Every zinc ion is five-coordinated,forming distorted pyramidal and trigonal biyramidal geometry,respectively.In 5a both zinc ions are in the N2O2 ligating center,and are coordinated with one oxygen from water/ethanol,respectively.6c was obtained with ZnI2 as the template agent,and both zinc ions are coordinated with N2O2 and one I-ion.7b was obtained using ZnBr2 as template agent,however,no Br-ions are involved in the coordination.Besides,there was strong intramolecular ?-? effect in 5a and 6c.while in 7b there does not exist intramolecular ?-? effect.