Probing magnetic interactions in columnar phases of a paramagnetic gold dithiolene complex

Abstract

A novel radical gold dithiolene complex exhibits a hexagonal columnar mesophase, as confirmed by optical microscopy, DSC analysis and X-ray diffraction. The extent of delocalization of the spin density in such a complex was analyzed by EPR. Temperature dependent magnetization measurements reveal that the global magnetic moment is remarkably affected at the liquid-crystalline phase transition with a marked hysteresis signature, rare behavior among the few described paramagnetic discotic phases. In addition, these molecules were found to strongly aggregate in solution into one-dimensional fibers with a mean diameter of 60 nm extending over micrometres, leading to the formation of gel-like structures. These fibers are stable and can be isolated on surfaces. The gelation of the system can also be detected by temperature-dependent magnetic measurements.

Nickel-Dithiolene Ion-Pair Compounds Showing Thermotropic Liquid Crystal Behaviors and Alkyl Chain Length Dependent Electrochemical Properties

“…Several research groups originally studied the mesomorphous properties for the neutral nickel-dithiolene complexes (42)(43)(44)(45)(46). Fourmigué and co-workers reported multifunctional neutral golddithiolene complexes, which showed the magnetic mesophase with strongly near infrared (NIR) absorption band around 1.5 µm (47), or a hexagonal columnar mesophase with a high sensitivity of magnetic interactions to external stimuli (48). Recently, we designed and synthesized a novel nickel-dithiolene ion-pair salt, [C 6 -Apy][Ni(mnt) 2 ] (where C 6 -Apy + = 4-amino-1hexylpyridinium).…”

(Photo)Thermal Stimulation of Functional Dithiolene Complexes in Soft Matter

“…Evolution of global magnetic moment as a function of temperature during heating and cooling cycles around the crystal/mesophase transition at a rate of 10 K min –1 (insert: DSC curves of compound [Au(dphedt) 2 ] 0 with n = 12 around the crystal/mesophase transition (2 nd heating curve (top) and 1 st cooling curve (bottom)). Reproduced from ref . Copyright (2011), with permission from The Royal Society of Chemistry.…”

“…Despite the absence of hydrogen‐bond donor fragments, the gelation properties of the paramagnetic (S = 1/2) neutral gold complex [Au(dphedt) 2 ] 0 with n = 12 have been evaluated . This compound was found to be able to form brittle gels in linear alkanes (C6–C12) (Figure a).…”

A charge transfer salt consisted of bis(maleonitriledithiolato)zincate dianion and 1,1'-didecyl-4,4'-bipyridinium exhibiting uncommon nematic mesophase behavior

“…The mesomorphous neutral nickel-dithiolene complexes, with focus on the aspect of mesophase with crystalline to liquid crystal transition behaviors, have been studied by . Most recently, Fourmigué et al have reported multifunctional neutral gold-dithiolene complexes, which show the magnetic mesophases with strongly near infrared (NIR) absorption band around 1.5 μm [21], or a hexagonal columnar mesophase with a high sensitivity of magnetic interactions to external stimuli [22]. For the neutral and mesogenic metal-dithiolene complexes, both mesophase and other functional properties arise from the metal-dithiolene unit, indicating that the tailoring of mesophase and other functional properties could be realized by singly alteration of the dithiolene ligands or metal ions.…”