Amino acid/crown ether hybrid materials: how charge affects liquid crystalline self-assembly.

摘要: To probe the influence of electrostatic interactions on mesomorphic self-assembly and phase behaviour hybrid liquid crystals a series crown ether/tyrosine systems was prepared by Steglich esterification alkyl N-(tert-butoxycarbonyl)-L-tyrosinates with 4-carboxybenzo[15]crown-5 4-carboxybenzo[18]crown-6. The obtained derivatives allowed further manipulations at NH functional group complexation ether unit NaI to give neutral or charged materials. All compounds were investigated differential scanning calorimetry (DSC), polarizing optical microscopy (POM) X-ray diffraction (XRD) measurements. Neither variation N-protecting group, introduction charge N-terminus nor anion exchange (Cl vs. I) resulted in mesomorphism. In contrast, N-Boc-protected unprotected hybrids formed rectangular columnar (Colr) mesophases widths up 35 K. switched these thermotropic into ionic (ILCs) induced change mesophase type from Colr smectic A (SmA). comparison experimentally layer distances theoretically calculated molecular lengths indicated bilayer SmA formation interdigitated chains. Packing models for both types are proposed discussed respect stabilizing interactions.