Rotationally fixed ferrocenophane extends the variety of possible molecular geometries in its derivatives in comparison with unbridged ferrocenes. In this respect molecular geometry-liquid crystalline properties relationship studies in ferrocenophane mesogens are of considerable interest. Different positional isomers of mono- and di-substituted ferrocenophanes which are obtained by incorporating one or two promesogenic building blocks into the cyclopentadienyl rings are reported in this article. A series of mono-substituted ferrocenophane-containing Schiff's bases was synthesized by condensing isomeric p-aminophenyl ferrocenophanes with appropriate aldehydes. Isomers of di-substituted ferrocenophane amines gave rise to a series of azomethines with two promesogenic substituents in the cyclopentadienyl rings. Besides, a β-enaminoketone was prepared from 3-(p-aminophenyl)ferrocenophane. Nematic and smectic mesophases were observed in the synthesized compounds under a polarizing optical microscope. The ferrocenophane-containing β-enaminoketone showed complex mesomorphic behaviour connected with occurrence of the keto-enamine and imino-enol tautomeric equilibrium in this compound. On the base of computational models obtained by semi-empirical quantum chemistry calculations the molecular geometry-phase behaviour relationships were examined. It was demonstrated that mesomorphism of ferocenophane azomethines depends on the spatial orientation of the substituents with respect to the propanediyl bridge in a case of mono-, and as well as to each other in a case of di-substituted derivatives.
Bibliographical noteFunding Information:
O.N. Kadkin acknowledges the Deutscher Akademischer Austauschdienst (DAAD). Special thanks to Prof. Dr. Willy Friedrichsen for his advising and encouraging this work. We are grateful to Mr. Elmar Schneider and Ms. Utta Oelbermann for mass, IR and UV spectroscopy measurements, and Mr. Dirk Mayer, Ms. Wiebke Delfs and Mr. Holger Franzen for recording 1 H NMR spectra. Financial support from Korean government program BK-21 is also gratefully acknowledged.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry
- Materials Chemistry