Both self-organize their molecules in supramolecular systems, leading to functional units in highly oriented systems, exhibiting new properties. In 1988 Ringsdorf evidenced the parallelism between thermotropic and lyotropic liquid crystals (LCs) in materials science and lipids in life science, with common amphiphilic nature. Details of double-stranded PolyA-PolyT and Pol圜-PolyG are shown at the right-hand side. (a) Photograph 51 by (b) DNA crystal structure according to. The sequence of base pairs along the structure, without lateral periodic order, being convenient to endow DNA of their capacity to store genetic information. The concept of “aperiodic crystal” was surprisingly premonitory 9 years before the structure of DNA fibres was determined by x-ray diffraction as a helical structure by Franklin (“Photograph 51” in Figure 1(a)), Wilkins and Watson and Crick who reported the double helix with periodic order along the sugar-phosphate helical backbone, every 34 Å, and with the aleatory distribution of the complementary base pairs ( Figure 1(b)). He predicted there the concept of “aperiodic crystal”, to define a gene or perhaps the whole fibre of the chromosome, “that in my opinion, is the material carrier of life…,” “able to grow in aggregates bigger and bigger without the clumsy resource of repetition in three directions” as crystals do. In 1944, Erwin Schrödinger, one of the founders of quantum mechanics, completed in Dublin a small book entitled What Is Life? The Physical Aspect of the Living Cell. Similar new cationic cholesteric liquid crystal polyesters have also been synthesized in our laboratory. Besides being biocompatible, these synthetic polyesteramides have proved to act as non-viral vectors in gene therapy and be able to transfect DNA to the nucleus cell. Molecular models show helical polymeric chains with stereoregular head-tail, isotactic structure, explained as due to the higher reactivity of the primary hydroxyl with respect to the secondary one in the glycol through the polycondensation reaction. Morphology of powdered PNOBDME exhibits spherical clusters of about 5 μm in diameter homogeneously dispersed. Optical rotatory dispersion (ORD) is evaluated. The substitution of the ester groups in the mesogen by amide groups causes an increase of thermal stability with respect to the precursors. Thermal behaviour of the new compounds is studied by thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis. ![]() They have also been characterized by x-ray diffraction with synchrotron radiation source. ![]() The new compounds have been characterized by 1H and 13C-NMR, COSY and HSQC, exhibiting two 1H-independent sets of signals observed for each enantiomer, attributed to two diastereomeric conformers, gg and gt, of the torsion containing the asymmetric carbon atom in the spacer. Polyesteramides PNOBDME (C34H38N2O6)n, Poly, and PNOBEE (C26H22N2O6)n, Poly, have been designed and synthesized as cholesteric liquid crystals (LCs)-through a condensation reaction between 4- 4′-(terephthaloyl-diaminedibenzoic chloride) (NOBC) and racemic glycol, DL-1,2-dodecanediol or DL-1,2-butanediol, respectively-as chemical modifications of multifunctional cholesteric LC polyesters, involving new properties but holding the precursor helical macromolecular structures.
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