TRANSITION-METALS COMPLEXED TO ORDERED MESOPHASES - SYNTHESIS, MESOMORPHISM, AND X-RAY AND EPR CHARACTERIZATION OF A HOMOLOGOUS SERIES OF N-(4-DODECYLOXYSALICYLIDENE)-4'-ALKYLANILINES COMPLEXED TO OXOVANADIUM (IV)
M. Ghedini et al., TRANSITION-METALS COMPLEXED TO ORDERED MESOPHASES - SYNTHESIS, MESOMORPHISM, AND X-RAY AND EPR CHARACTERIZATION OF A HOMOLOGOUS SERIES OF N-(4-DODECYLOXYSALICYLIDENE)-4'-ALKYLANILINES COMPLEXED TO OXOVANADIUM (IV), Chemistry of materials, 5(6), 1993, pp. 876-882
A number of mesogenic 4'-R(n)-phenyl)salicylideneiminato]oxovanadium(I
V) complexes (1-7, R(n) = CH3, C2H5, C3H7, C4H9, C6H13, OC6H13, C8H17,
respectively) have been synthesized and characterized by polarizing m
icroscope observations, DSC measurements, X-ray diffraction, and EPR s
pectroscopy. These compounds are thermally stable and to not decompose
on melting. Complexes 1-5 show two different solid phases K1 and K2.
In addition, 4 and 5 exhibit a liquid-crystalline smectic A phase (mon
otropic in 4 and enantiotropic in 5). On the other hand, 6 and 7 along
with a single solid phase, display a smectic C (enantiotropic in 6 an
d monotropic in 7) and an enantiotropic smectic A phase. Variable-temp
erature EPR spectra are accounted for on the basis of paramagnetic met
al ions experiencing different magnetic environments. For each mesopha
se, matching X-ray, and EPR data, the molecular packing mode is sugges
ted. Comparing 1-7 with the homologous copper complexes, the contribut
ion of the metallic center to the mesomorphic properties is discussed.