The lyomesomorphic behaviour in apolar organic solvents of members of two series 1 and 2 of disc-shaped palladium organyls-the syntheses of four of them are new (Id, f and 2a,e) and are described here-ach carrying twelve long lipophilic chains have been studied, Their lyomesomorphism appeared to be complex and has been observed here for the first time with metal organyls. As can be seen by polarizing microscopy, most' of the binary mixtures investigated here exhibit nematic properties. For two members of series 1-the chloro-bridged l b and its bromo-analogue lc-there is even evidence for the existence of two different nematic lyomesophases side by side showing reversible transitions between them. In ternary systems, i.e. after the addition of 2,4,7-trinitrofluorenone (TNF, a strong electron acceptor), the nematic phases are stabilized, suggesting that their mesophase structures are made up by columns with intercalated TNF molecules (charge transfer complex formation). Influences of structural features of the palladomesogens on the one hand and of the type of solvent on the other on the molecular self-aggregation in the observed types of lyotropic mesophase formed are discussed in detail.
The first non-calamitic/disc-shaped metal organyl series 3 and 6 containing two or even four palladium atoms and eight or twelve flexible side chains presented here have been synthesized via the novel roof-shapedlbent dirners 2 or (the thermomesomorphic) 5. respectively. In addition, from the chemical point of view the 'dodecaethers 5 and 6 a -c are the first derivatives of four novel, uniquely structured tetrapallado-macroheterocycles . Whereas the type of mesophase of 5 is still not distinctly clear yet those ones of 6a-c are enantiotropic disco+ hexagonal columnar (Dh) over a wide range of temperature. On the other hand, the dinuclear palladocompounds 3 a -d represent the first (monotropic) cases of metallomesogens exhibiting the nematic-discotic (ND) phase. This thermotropic nematic type of phase clearly gets stabilized by doping 3 C , d with a strong electron acceptor, under such circumstances mesophase conversions/inductions (ND+Dh) are observed in the cases of 3a-c. Finally, it is important t o emphasize that the very large, thermotropically Dh phase displaying rnacroheterocycles 6a-c are also /yotropic in various organic solvents exhibiting now a nematic phase,
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