- Cyano and Nitrobenzyloxy Derivatives: New Polymorphism Aspects
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Several polar molecules with three benzene rings and having the general formula: have been synthesized.All these compounds are built with the flexible -CH2O- linkage and provide rather low temperature mesomorphic phases easily accessible for physical investigations.The striking features of these six series are: The cyanobiphenyl series provides a rather classical polymorphism. The nitrobiphenyl series shows another example of the re-entrant nematic phase and furthermore a very spectacular transition Nre -> SG or H with complex spatial structuring. The cyanobenzoate series provides examples of the so-called SA1, AAd, SA2, S phases and also an interesting SAd-SA2 transition directly observable under the microscope. The nitrobenzoate series not only exhibits a classical re-entrant nematic phase, but also the inverted sequence K N SA I in a pure compound. The cyano-Schiff's base series presents the first example of a SB hexatic phase in polar systems. The nitro-Schiff's base series not only exhibits a new enantiotropic re-entrant sequence K SF SC Nre SA N I, but also the first example of the SF phase in polar compounds and the inverted sequence K SF SC N SA I.
- Tinh, Nguyen Huu,Gasparoux, H.,Destrade, C.
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p. 271 - 294
(2007/10/02)
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