Silver® stilbazole complexes

Another approach to get new liquid crystals is the lateral fluorination of the stilbazole ligands,337 which is a common and highly effective tool to exert control over mesomorphism, crystal phase stability, and physical properties. Other modifications include the use of more alkoxy substituents and other alkyl sulfate anions.338-344 Ionic silver amino complexes also display liquid crystalline behavior at rather low temperatures they are of the form [Ag(NH2 -CJl +OJX (X = N03, n = 6,8,10,12,14 X = BF4, = 8,10,12,14).345... 

The stilbazole complexes of these metals, Pd(II), Pt(II), Ag(I), and Au(I), are considered together because a good deal can be learned by looking at them in this way, particularly as we begin to look at more highly substituted stilbazoles. The liquid-crystal aspects of the silver... 

Figure 22 Phase diagram, for the stilbazole complexes of silver triflate.

The mesomorphism of silver(I) complexes of poly(alkoxy)stilbazoles has been reviewed recendy. However, it is appropriate to cover this work here in order to see the effect of an anion on mesomorphism in cationic complexes and to allow some comparison to be made with the complexes described in the preceding section. In these studies, there were two main variables, namely the substitution pattern of the stilbazole used and the nature of the anion. The former was varied in the same way as for the palladium and platinum complexes just described, while the latter was either triflate or an alkylsulfate whose chain length was varied. 

Characterisation by X-ray diffraction of the 84-phase of some silver(I)complexes of alkoxy-stilbazoles. 

Bruce, D.W. and Hudson, S.A. (1994) Mesomorphic complexes of silver trifluoromethane sulfonate and silver dodecylsulfate with 2- and 3-fluoro-4-alkoxy-4-stilbazoles. Journal of Materials Chemistry, 4, 479-486. 

Alkoxystilbazoles can react with a variety of silver salts, AgX, to yield the two-coordinate linear complexes (19). They show liquid crystalline behavior that strongly depends on the anion, the alkoxy chain length, and other substituents which may be present on the stilbazole.59-65... 

The greatest amount of work we have carried out with alkoxystil-bazoles is in the field of liquid crystals indeed, this is where our interest in stilbazoles started. After a brief and rather general introduction to liquid crystals, we will consider various types of complex that form liquid-crystal mesophases when complexed to stilbazoles, emphasizing patterns of behavior without delving into the subtleties. A more detailed discussion of the silver systems may be found elsewhere 24). Finally, although this article appears in a series that concentrates on inorganic chemistry, we offer an overview of some of our work with stilbazoles in hydrogen-bonded liquid crystals. 

More recently, 4-alkoxy-2- and 4-alkoxy-3-stilbazoles have been reported (Figure 85) and their silver complexes with AgDOS and AgOTf have been synthesized. While the ligands themselves are non-mesomorphic, the eomplexes show only SmA phases, although complexes of the 2-stilbazoles do not form readily. While the new complexes are Uquid crystalline, the use of the isomeric stilbazoles suppresses the polymorphism of the 4-stilbazole isomers. 

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