Crystal Structures of Optically Active Polyamides Derived from Di-O-methyl-l-tartaric Acid and 1,n-Alkanediamines:  A Study Combining Energy Calculations, Diffraction Analysis, and Modeling Simulations

Abstract

The crystal structures of a series of optically active polyamides derived from l-tartaric acid and 1,n-alkanediamines (n = 2, 4, 6, and 8) have been investigated. Experimental data provided by X-ray diffraction of powders and fibers as well as by electron diffraction of single crystals were used to determine the lattice parameters for each polymer. A triclinic unit cell with space group P1 was found to be shared by the whole series. Semiempirical quantum mechanical calculations revealed that the preferred conformation for these polytartaramides entailed the tartaric acid moiety in a gauche arrangement with the amide groups rotated out of the plane containing the all - trans polymethylene segment. Crystal models compatible with the crystallographic data were built and refined against X-ray diffraction intensities with the linked-atom least-squares (LALS) methodology. The favored structure appeared to consist of hydrogen-bonded pleated sheets packed with a stagger similar to that found in the α-form of nylon 66. Modeling performed with CERIUS, a program enabling on-line observation of the simulated X-ray and electron scattering as the molecular model is adjusted, led to substantially similar results.

Alternating Copoly(ester amide)s derived from Amino Alcohols andL-Tartaric and Succinic Acids

“…This is a remarkable feature displayed by tartaric acid based polyamides that has previously been noticed in similar studies carried out on related systems. [19] The carbon spectrum contains all the peaks arising for every magnetically different carbon present in the repeating unit. A reliable complete assignment of peaks could be done with the help of two-dimensional techniques which revealed that, contrary to expectations, the resonance due to the amide carbons are those appearing downfield to ester carbons.…”

“…Although no detailed structural analysis has been carried out on any poly(ester amide)s containing tartaric acid, diffraction data recorded from random poly(tartarester amide)s of 1,6-hexanediol and 1,6-hexanediamine containing up to 20% of succinic acid [15] have proved that they adopt a crystal structure close to the triclinic structure described for the homopolyamide poly(hexamethylene di-O-methyl-L-tartaramide). [19] In such a structure the polyamide chains are somewhat contracted due to the gauche conformation adopted by the tartaric moiety and hydrogen bonds are aligned along one unique direction.…”

Poly(ester amide)s derived fromL-tartaric acid and amino alcohols. II. Aregic polymers

“…A common type of crystal structure seems to be adopted by all a-PEAT6(a : b) poly(tartarester amide)s, regardless of the chemical composition and regicity, and this structure is very close to that adopted by the polyamide P6DMLT. 4 The crystal structure of this polyamide was investigated in detail by us a few years ago and was determined to be a structure made of hydrogenbonded sheets with chains in a slightly contracted conformation. The structure is similar to that described for the well-known ␣ form of nylon-6,6.…”

“…3 Among them, poly(hexamethylene-di-O-methyl-L-tartaramide) (P6DMLT), which is made from 1,6-hexanediamine and L-tartaric acid, is particularly interesting. 3,4 This poly(tartaramide) is highly crystalline, melts at 230°C, and may absorb up to 10% water when exposed to a humid atmosphere. However, it degrades very slowly in neutral water, losing less than 10% of its initial weight after 1 year of incubation.…”

Advances in synthetic optically active condensation polymers - A review

“…Progress in polymer chemistry has allowed the synthesis of entirely different condensation polymers which one of them is optically active polyamides (PA)s [47]. Many studies concerned with the synthesis and characterization of optically active PAs have been undertaken [48][49][50][51][52][53][54][55], mainly polypeptides and proteins which have been extensively investigated. Synthesis and optical properties of asymmetric PAs derived from composed of optically active cyclic dicarboxylic acids, (+)-(S)-and (-)-(R)-trans-1,2-cyclopropanedicarboxylic acids, (-)-(R)-trans-1,2-cyclobutanedicarboxylic acids, (+)-and (-)-trans-1,3-cyclopentanedicarboxylic acids and secondary diamines such as trans-2,5-piperazine, piperazine or N,N!-dimethylethylenediamine was reported by Overberger and Shimokawa [56].…”