Liquid Crystal Formation in Binary Systems. IV. Induction of Smectic Phases in Mixtures of N-(p-Nitrobenzy lidene)-p-aminoazobenzene and Various Electron Donors of the Type N-(p-Substituted Benzylidene)-p-aminoazobenzene

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Abstract
A study of the phase diagrams of binary systems consisting of nematogenic N-(p-nitrobenzylidene)-p-aminoazobenzene and various electron donors of the type N-(p-X-benzylidene)-p-aminoazobenzene revealed the induction of a smectic A phase in the cases where X=MeO, EtO, n-PrO, Me2N, and Et2N and of a smectic B phase as well in the cases where X=EtO and n-PrO. The extent of thermal stability enhancement of the smectic A phase is larger with non-nematogenic dialkylamino derivatives than with nematogenic alkoxy derivatives; this supports our postulate that the smectic phases are stabilized by the intermolecular interaction of the electron donor-acceptor type. The induction of smectic A phases was shown also in all the combinations of the p′-ethoxy derivatives, including the cases where X=H, Me, and Ph.