Controlling The Local Conformation Of Two Types Of Polymers By Intramolecular Hydrogen Bonding Of Aromatic Amides

Hydrogen bonding is a non-covalent interaction with directionality.Hydrogen bond can be used to control the whole or local conformation of molecules during molecular recognition and self-assembly for preparing materials with special structure and properties.Based on the understanding of hydrogen bonds and literature investigation,we designed and synthesized two compounds containing aromatic amide that can form intramolecular hydrogen bonds,and used them in preparing single crystals of seven coordination polymers.In addition,we designed and synthesized a polyamide material,in each structural unit of which intramolecular hydrogen bonds can form,and characterized the mechanical properties of the material.The effect of intramolecular hydrogen bonding on conformational control was analyzed and summarized.When preparing coordination polymer crystals,flexible ligands are difficult to predict due to their conformation diversity.In the second chapter,inspired by the control of the conformation of the polymers and foldamers via intramolecular hydrogen bonding,we synthesized two kinds of arylamide ligands,4,6-dimethoxy-N,N'-di(4-carboxyphenyl)isophthalamide(designated as L1)and 4,6-dimethoxy-N,N'-di(pyridin-4-yl)isophthalamide(designated as L2),which can form intramolecular hydrogen bonds.Seven coordination polymers were prepared from L1 and L2 and their single-crystal structures were analyzed.Of which,six coordination polymers have interpenetrating network structures.When L1 formed coordination polymers,neither the metal nor the solvent affected the conformation of the ligand in the crystals.As for the five different coordination polymer crystals(crystal 1~crystal 5)prepared from L1,the dihedral angles between the aromatic rings of the ligands are less than 15°,and only one approximately planar conformation is found in the crystals.Intramolecular hydrogen bonding in the coordination polymer crystal 6 and crystal 7 prepared by L2 limits the conformational freedom of the ligand,and the dihedral angle between the aromatic rings of the ligand is less than 5°.It's proved that our design idea that intramolecular hydrogen bonds in coordination polymers can be used to control the conformation of a ligand is feasible.The Raman spectra of crystal 1 and crystal 5 were recorded under different pressures(atmospheric pressure to 3.2 GPa).It was found that the spectra did not change significantly,indicating that the two crystals were stable under a certain range of pressure.It was inferred that the interpenetrating structure gives the crystal a high stability.In the third chapter,we designed and synthesized two new polyamides(P2 and P3)containing aromatic groups,which were obtained by interfacial polymerization of the corresponding diacid chloride and octanediamine.The presence of intramolecular hydrogen bonds in P2 was confirmed by NMR,indicating that the local conformation of o-alkoxybenzamide of the polymer is the same as we predicted.The solubility of P2 is better than P3 that cannot form intramolecular hydrogen bonding.In the case of adding ethylparaben(E4HB)as a plasticizer,the elongation at break of the P2 film can reach about 325%.The cyclic tensile test shows that the P2 film containing the plasticizer has a certain elasticity.