Design And Construction Of Schiff Base Macrocycles Based On Dynamic Recersible Imine Bond

Schiff-based macrocyclic ligands and their complexes,as the first one to achieve through artificial synthesis,have been catched the widespread of attention because of their important role in the tradition of the macrocyclic ligand chemistry,supramolecular chemistry and functional materials,As an important part of interdisciplinary between macrocyclic chemistry and supramolecular chemistry,imine macrocycles possessed with excellent performance in the fields of host-guest recognition,biological process simulation,catalysis and materials ordered supramolecular self-assemble and other land.As in host-guest chemistry,it is very important that macrocyclic cavity and the may be site of active place must match the guest molecules in space.A lot of progression in the ressearch of Schiff base macrocycles and the corresponding host-guest chemistry has been achieved,but there also exist some limitations.Since the ring size of Schiff base macrocycles are small,makes to the identification of the guest molecules are mostly simple ions or small organic molecules and the like.Simlarily,that also results in the limitation of macromolecules recognition and catalysis researches.To this end,the selectively synthesis of large-sized Schiff base macrocycle becomes a big challenge.In addition to the cation template method to expand the size of the macrocycle,there are many other effects,including counterions and pendent-armed effects,gust molecular effects,solvent effects.With the successful examples on constractions of large-sized macrocycles emerging constantly,researches in this field catched much more attention.The main work of this paper are:1.Template-directed reactions between extended dialdehydes with different pendant arms and chiral or racemic 1,2-diaminocyclohexane in the presence of ZnCl₂ and Zn（NO₃）·6H₂O result in the production of 68-membered[4+4]Schiff-base macrocyclic tetranuclear Zn（Ⅱ）complexes 1-3 and 34-membered[2+2]Schiff-base macrocyclic dinuclear Zn（Ⅱ）complexes 4-10.It is noted that the construction of macrocyclic tetrazinc or dizinc complexes could be regulated by two additional variables,i.e.,counterions（Cl-and NO₃^-）and pendant arms（-CH₂CH₂C₆H₄OH and一CH₂CH₂C₆H₅）,besides the common Zn（Ⅱ）ion template effects for forming reversible covalent imine bonds.In our experiments,chiral and racemic[4+4]macrocyclic zinc（Ⅱ）complexes 1-3 are obtained in the presence of chloride ion and-CH₂CH₂C₆H₄OH pendant arm,which could be further verified by a rare single-crystal structure of 3 with the large 68-membered[4+4]Schiff-base macrocyclic skelton.In contrast,the use of Zn（NO₃）·6H₂O could only yield[2+2]macrocyclic complexes 4-9 no matter what pendant arms were employed.Furthermore,the treatment of ZnCl₂ and dialdehyde with-CH₂CH₂C₆H₅ pendant arm would also give[2+2]macrocyclic complex 10.2.A new extended dialdehyde was successful synthesized at room temperature according to the former publication.The condensation between this new extended dialdehyd CH2CH2C4H3S pendant-arm and three different diamine,i.e.,l,2-b iamine,phenylenediamine collar and crown ether diamine obtained[2+2]dinuclear macrocyclic complexes 12-22 In the presence of ZnX₂（X=Cl,Br）or Zn（NO₃）·6H₂O.Schiff-based condensation products were characterized by IR.ESI-MS and H NMR spectrum,X-ray crystal diffraction.Compare with of dialdehyde precursor 11 and imine macrocylic products in IR,ESI-MS and 1H NMR spectrum,it is noticed that the peaks of dialdehyde grop completely vanished,instead of a new set of peaks appear,proved the formation of C=N bond in this kind of imine condesation.Meanwhile,complexes 13-14 and 16 have successfully obtained the crystal structure,although all of Zn（Ⅱ）are five coordinated,but to complex 16,molecule π-π effect is weaker and the distance between the two metal centers is also farther than that in 13-14.