Mesomorphism of di-ruthenium and di-rhodium alkoxybenzoates bearing aliphatic chains branched at assymetric carbons

M. A. CASTRO; A. ZELCER; M. RUSJAN; D. GUILLON; B. DONNIO; F. D. CUKIERNIK

Fortaleza (Brasil)

Congreso; XIII BRAZILIAN MEETING ON INORGANIC CHEMISTRY; 2006

Sociedad Brasileña de Quimica

Mesomorphism of di-ruthenium and di-rhodium alkoxybenzoates bearing aliphatic chains branched at assymetric carbons María A. Castro1, Andrés Zelcer1, Marca Rusjan1, Daniel Guillon2, Bertrand Donnio2 and Fabio D. Cukiernik1,3 1INQUIMAE, Faculltad de Ciencias Exactas y Naturales (UBA), Pabellón II – Cdad. Universitaria (Nuñez) C1428EHA, Capital Federal, Argentina – 2Gropue des Matériaux Organiques-IPCMStrasbourg (France)  - 3Instituto de Ciencias – UNGS (Argentina) Keyword: bimetallic carboxylates, metallomesogens, liquid crystals   Alkoxybenzoates bearing long aliphatic chains at 3,5- and 3,4,5 positions, have been recently used as equatorial ligands in bimetallic carboxylates as succesful promotors of room-temperature columnar mesomorphism (Rusjan et al Chem Mater. 2002, Langmuir 2002). With the aim of analyze the effect on mesomorphism of ramifications at near-core assymetric carbon atoms of these equatorial ligands, we synthesized and characterized some compounds derived from 3,5‑di(1-methylheptyloxy)benzoate (3,5-B2OC*8). The properties of racemic and enantiomerically pure Rh2(B2OC*8)4, polymeric Rh2(B2OC*8)4pz and polymeric Ru2(B2OC*8)4Cl, have been studied by optical microscopy, DSC and XRD. Poymeric compounds exhibited ColH mesophases. No evidence for helicity has yet been found in enantiomerically pure systems; the difference with the behaviour of non-branched analogs is explained in terms of steric effects.