Search

Size exclusion chromatography and nuclear magnetic resonance studies demonstrated that 6,7-Bis(alkyloxy)-2,3-dihydrophthalazine-1,4-diones self-assemble into lactim-lactam trimeric disks in solution. The disks self-organized into a discotic, columnar and thermotropic phase in the presence of suitable substituents such as Phthal8, Phthal12 and Phthal16. The disubstituted phthalhydrazide unit represented a general motif for the generation of supramolecular, discotic liquid crystals by self-assembly.

The preparation of chloride and bromide derivatives of 1-methyl-3-[3,4-bis(alkoxy)benzyl]-4H-imidazolium is described. The results have shown high transfection efficacy of the formulated compounds and high silencing efficiency with more than 80% inhibition of the targeted gene at siRNA concentration.

The columnar mesophases of two series of hexacatenar palladium(II) mesogens are studied in detail by a combination of X-ray diffraction on aligned and unaligned samples and dilatometry. A model is proposed that differs from that generally accepted for the arrangement of polycatenar mesogens in columnar phases.

The thermal behavior and phase structure of two series of gemini fluorocarbon/hydrocarbon diblock amphiphiles with the general formula (CnF2n+1CH2)(Cm - 2H2m - 3)CH-CH(CnF2n+1CH2)(Cm - 2H2m - 3), with n = 8, 10 and m = 6, 12, 14, 16, 18, 20 (abbreviated as di(FnHm)), have been investigated by differential scanning calorimetry, polarized optical and freeze-fracture transmission electron microscopies, dilatometry, and small-angle X-ray scattering (SAXS). The various terms of the series exhibit the same thermal behavior, essentially composed of two exothermal transitions, a low-temperature event that corresponds to the melting of the hydrocarbon chains at TH and a high-temperature transition associated with the melting of the fluorocarbon chains at TF. Below TH, a disordered plastic rotator phase, MLT, and above TH, a lamellar phase, MHT, were determined by SAXS experiments. Above TF, the compounds eventually clear into the isotropic liquid. In the MHT phase, both the Fn and Hm blocks are segregated from each other, forming sublayers with sharp interfaces, as revealed by the five lamellar orders and remarkable sharpness of the SAXS peaks. In the MLT phase, the partial crystallization of the aliphatic blocks when the temperature is lowered leads to the disruption of the aliphatic sublayers into rows of ribbons arranged according to pseudohexagonal and/or rectangular arrangements with different lattice sizes (p2gg symmetry). The Fn segments form the fluorinated continuum. In support of SAXS, molecular packing models of the tetrablocks are proposed on the basis of the temperature/volume variations of di(F10H20) and di(F10H16) in both high- and low-temperature phases, as determined by dilatometry. It is notable that the arrangements found for di(FnHm) are completely different from those previously reported for FnHm diblocks, revealing the influence of the linker unit on the solid-state behavior of the tetrablocks.