Copper
11
complexes of the fatty acids exhibit a thermotropic liquid crystalline phase of the columnar type. X-ray diffraction studies of this mesophase indicate that the spine of a column is made of regularly stacked dicopper tetracarboxylate cores, which are surrounded by disordered, liquid-like alkyl chains. In turn, the column axes occupy the nodes of a two-dimensional hexagonal lattice. Examination of the local environment of the copper atoms by Cu Ka
2
EXAFS spectroscopy reveals insignificant changes in bond lengths within the binuclear core upon the transition from the lamellar crystalline phase to the columnar mesophase. However, a slight, but sharp, decrease of the magnetic moment of the dicopper unit is observed at the solid-mesophase transition temperature (A/4eff « —0.04 ■ The columnar mesophase, and the crystalline phase alike, obey a Bleaney-Bowers relation. The singlet-triplet gap is higher in the former ( -2J = 310-330 cm
-1
against 290-300 cm
-1
). Dirhodium
11.11
complexes of selected fatty acids were prepared, and their thermal behaviour was investigated. They exhibit the same thermotropic columnar mesophase as their Cu
11
congeners, reflecting the presence of isostructural dimetallic cores in both series. The metal-metal single bond that is present in these dirhodium
11,11
mesogens is Raman active (iv
Rh
_
Rh
- 350 cm
-1
) ; it is a potential probe of the change in molecular and supramolecular structures of this class of compounds at their phase transition. Diruthenium
11.11
complexes of fatty acids were obtained by Cr
11
reduction of the mixed-valence chlorodiruthenium
11.111
tetrabutyrate, followed by ligand exchange with the appropriate carboxylic acid. Magnetic susceptibility studies indicate that these diruthenium
11.11
carboxylates have an
M
5
= 0 ground state and a thermally accessible M
8
= ± 1 excited state, suggesting a zero-field split (
D
= 300 cm
-1
} a
2
7i
4
5
2
(5*7t*)
4
configuration. The formation of a columnar liquid-crystalline phase is reflected by a sharp increase in the magnetic moment of these complexes at the phase transition (A ju,ef{% +0
Probing neutrino dipole portal at COHERENT experiment
