207689-35-8Relevant academic research and scientific papers
(Pyrazolato)gold Complexes Showing Room-Temperature Columnar Mesophases. Synthesis, Properties, and Structural Characterization
Barbera, Joaquin,Elduque, Anabel,Gimenez, Raquel,Lahoz, Fernando J.,Lopez, Jose A.,Oro, Luis A.,Serrano, Jose L.
, p. 2960 - 2967 (2008/10/08)
Mesogenic (pyrazolato)gold complexes of formula [Au(pz)]3 (pz = 3,5-bis(3′,4′-di-n-decyloxyphenyl)pyrazole (1), 3-(3′,4′,5′-tri-n-decyloxyphenyl)-5-(3″,4″-di-n- decyloxyphenyl)pyrazole (2), 3-(2′,3′,4′-tri-n-decyloxyphenyl)-5-(3″,4″, 5″-tri-n-decyloxyphenyl)pyrazole (3), 3,5-bis(3′,4′,5′-tri-n-decyloxyphenyl)pyrazole (4)) have been prepared by reaction of the potassium salts of the nonmesogenic pyrazolate ligands with [AuCl(tht)] (tht = tetrahydrothiophene) in a 1:1 molar ratio. All these compounds show columnar mesophases that remain stable, at room temperature, for long periods of time. The formation of isomers for the nonsymmetrical derivatives - detected by spectroscopic studies - are suggested to be responsible for the subtle changes observed in the transition temperatures. Powder X-ray diffraction measurements show clearly that the supramolecular columnar arrangement appears in the crystalline solids as well as in the mesomorphic phase. An analogue of the mesogenic trinuclear complexes 1-4, having a methoxy group at the phenyl substituents of the pyrazolate ligands, [Au{3,5-(MeOPh)2Pz}]3 (5), has been synthesized and characterized by an X-ray single-crystal diffraction experiment. The molecular structure of 5 is based on a nine-membered metallacycle core. The whole molecule exhibits a rough planarity that favors a crystalline structure formed from columnar arrangements of trinuclear complexes. A simple and clear relationship could be established between the solid-state crystal structure of 5 and the X-ray-deduced structure of the mesophases.
