Herbert M. Rosenberg

Estimation of Nematic-Isotropic Points of Nematic Liquid Crystals

Abstract A survey has been made of reported nematic-isotropic points of nematic liqid crytals having the following structure: where X and Z are: R-, Ro-, RCO2-, ROCO2-, RCO-,ROCO-; R is n-alkyl varying form C1 to C6; andy is: The variation of the nematic-isotropic points with structure is sufficiently regular to permit the generation of sets of parameters for X, Y and Z that can be used to make resonable predictons of the namatic-isotropic points for all combinationf of X, Y and Z.

The Effect on Thermal Nematic Stability of Schiff's Bases Upon Reversal of Terminal Substituents

Abstract Nematic liquid crystals have been found to produce dynamic light scattering when subjected to an electric field.(1) This electro-optic effect has stimulated widespread interest in the development of liquid crystals for display devices. It is desirable that the nematic material exhibit the nematic phase around ambient temperature and have a large mesomorphic range. No reported single component system meets these requirements although bis-(4′-n-octyloxybenzal)-2-chloro-1,4-phenylenediamine has a reported 120° nematic range just above ambient temperature (59–179°C).(2)

Nuclear magnetic resonance analysis of 1- and 2-methylbenzotriazole

Abstract The NMR parameters of 1-methyl- and 2-methylbenzotriazole have been obtained from their high resolution spectra. LAOCOON III was used to iteratively refine the reported chemical shifts and coupling constants. Huckel molecular orbital calculations were performed in the hope of facilitating the choice of input parameters for the computer analysis of the complex ABCD spectrum of the 1-methylbenzotriazole. No useful correlation was found between the π-electron densities and chemical shifts of the aromatic protons. A deuteration experiment was performed to unambiguously assign the chemical shifts of the four protons. The NMR and MO data are tabulated and compared.

Self-consistent field molecular orbital calculation for anthranil, benzisoxazole, and benzoxazole

Abstract Energy transitions and oscillator strengths for the singlet and triplet states of anthranil, benzisoxazole, and benzoxazole have been calculated using self-consistent field molecular orbital methods. Agreement with experimental absorption data is quite good for benzisoxazole and benzoxazole, but less satisfactory for anthranil.

Liquid Crystals: Transition Point Studies of 4(4′)-Alkoxyformyloxy-4′(4)-alkylazoxybenzenes

Abstract A series of 4(4′)-alkoxyformyloxy-4′(4)-alkylazoxybenzenes has been prepared. The transition temperatures have been determined and the applicability of the spectral shift reagent Eu(fod)3 to determine the mole percent of six isomeric mixtures was demonstrated.