A novel homologous series consisting of 11 homologues is reported. Liquid crystal properties commence from the hexyloxy homologue and continue up to the tetradecyloxy homologue as enantiotropic nematic mesomorphism only. The rest of the homologues (including hexadecyloxy homologue) are not liquid crystalline. None of the homologues show smectogenic mesophase formation. The texture of the nematic mesophase is of a threaded or Schlieren type. The transition temperatures of the homologues were determined by optical polarizing microscopy equipped with a heating stage. Transition curves of a phase diagram behave in normal manner except for the tetradecyloxy homologue which adopts an unexpected trend of propagation. An odd-even effect is absent for nematic-isotropic transition curve. Analytical and spectral data support the molecular structure of the homologues. The average thermal stability of the series is 78.8 • C. Mesomorphic/nematogenic phase length varies from 2.0 • C to 13.0 • C. The liquid crystal behavior of the present series is compared with structurally similar other known series. Thus, the present series is enantiotropically nematogenic only without exhibition of any smectogenic character with a low melting type, whose mesomorphic phase length is relatively short.
A novel homologous series: 4-(4 -n-alkoxy benzoyloxy)-4 -methoxy benzyl benzoates is studied with a view to understanding the effect of a central group on the phenomenon of mesomorphism. The novel homologous series consists of eleven compounds. Mesomorphism commences from the second member of a series. All the mesogenic homologues from ethoxy to hexadecyloxy exhibit nematogenic mesomorphism without the exhibition of smectogenic character. The nematic-isotropic transition curve of the phase diagram behaves in normal manner up to the dodecyloxy homologue and then deviated for the tetradecyloxy and hexadecyloxy homologues. The solid-isotropic or nematic transition curve adopts a normal behavior in a zigzag manner. The nematic-isotropic transition curve shows an odd-even effect and continues up to the octyloxy homologue. Transition and melting temperatures including the textures of mesophases are determined by an optical polarizing microscope, equipped with a heating stage. The textures of the nematic mesophase are threaded or Schlieren in type. Analytical data and spectral data support the molecular structures. The mesomorphic behavior of the present series is compared with structurally similar other known series of differing central group (viz. N N and CO CH CH ) keeping rest of a molecular part unchanged. The nematic thermal stability of the series is 236.8 • C of a high melting type present series whose nematogenic mesophase length varies between 27 • C and 98 • C. Thus, series is only nematogenic without exhibition of a smectic mesophase.
Charging the catalytic site! Incorporation of charged arm on the phenol has tremendous increase in the catalytic activity compared to its uncharged counterpart. We also performed NMR studies to understand the mechanism of the activity.
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