Chapters authored
Synthetic Cationic Cholesteric Liquid Crystal Polymers
We report the synthesis of six multifunctional cationic cholesteric liquid crystals polyesters functionalized with choline, amine, and amide groups to obtain new chemical formulations involving macromolecular features with new properties added to those of precursor chiral cholesteric polyesters. They are designed as PTOBDME-choline [(C34H36O8)n─C5H13N]; PTOBEE-choline [(C26H20O8)n─C5H13N]; PTOBDME-ammonium [(C34H36O8)n─C5H13N]; PTOBEE-ammonium [(C26H20O8)n─C5H13N]; PTOBUME-amide (C33H33O9N)n; and PTOBEE-amide (C26H19O9N)n. Structural characterization is performed by NMR. Thermal behavior is studied by thermogravimetry (TG) and differential scanning calorimetry (DSC), showing all the polymers endothermic transition from crystal phase to liquid crystal mesophase. Chirality is determined by optical rotatory dispersion (ORD). The cationic cholesteric liquid crystal polymers described here have proved to act as nonviral vectors in gene therapy, transfecting DNA to the nucleus cell.
Part of the book: Liquid Crystals
Cholesteric Liquid Crystal Polyesteramides: Non-Viral Vectors
Polyesteramides PNOBDME (C34H38N2O6)n, Poly[oxy(1,2-dodecane)-oxy-carbonyl-1,4-phenylene-amine-carbonyl-1,4-phenylene-carbonyl-amine-1,4-phenylene-carbonyl], and PNOBEE (C26H22N2O6)n, Poly[oxy(1,2-butylene)-oxy-carbonyl-1,4-phenylene-amine-carbonyl-1,4-phenylene-carbonyl-amine-1,4-phenylene-carbonyl], 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. 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. They have also been characterized by x-ray diffraction with synchrotron radiation source. Thermal behaviour of the new compounds is studied by thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis. The substitution of the ester groups in the mesogen by amide groups causes an increase of thermal stability with respect to the precursors. Optical rotatory dispersion (ORD) is evaluated. Morphology of powdered PNOBDME exhibits spherical clusters of about 5 μm in diameter homogeneously dispersed. 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. 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. Similar new cationic cholesteric liquid crystal polyesters have also been synthesized in our laboratory.
Part of the book: Liquid Crystals and Display Technology