A banana-shaped spin-crossover (SCO) cobalt(II) complex [Co(C16-terpy)2](BPh4)2 (1) with long alkyl chains, based on a terpyridine frame, was synthesized. Compound 1 exhibited very gradual SCO behavior and changes in the dielectric constant. This shows a way in which SCO materials can be used in electronic devices.
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http://dx.doi.org/10.1021/ic051059f | DOI Listing |
JACS Au
December 2024
Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, IPCM, F-75005 Paris, France.
Metallogels built in a bottom-up approach by metal coordination and supramolecular interactions have important potential for the elaboration of smart materials. In this context, we present here the formation of supramolecular coordination polymers driven by the complexation of cobalt(II) or zinc(II) ions with polyoxometalate-based hybrids displaying two terpyridine ligands in a linear arrangement. Thanks to the electrostatic interactions between the polyoxometalate cores and metal nodes, the polymer chains self-assemble into fibers that physically cross-link to form gels above a critical concentration.
View Article and Find Full Text PDFJ Am Chem Soc
October 2024
Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin 53706, United States.
The phenomenon of spin crossover involves coordination complexes with switchable spin states. This spin state change is accompanied by significant geometric changes such that low and high spin forms of a complex are distinct isomers that exist in equilibrium with one another. Typically, spin-state isomers interconvert rapidly and are similar enough in polarity to prevent their independent separation and isolation.
View Article and Find Full Text PDFDalton Trans
June 2024
Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-909, Brazil.
In this contribution, a terpyridine-based ligand bearing a thioether functionality is used to prepare a new cobalt(II) spin crossover complex: [Co(TerpyPhSMe)](PF) (1), where TerpyPhSMe is 4'-(4-methylthiophenyl)-2,2':6',2''-terpyridine. Its structure, determined by single crystal X-ray diffraction, reveals a coordination of the tridentate terpyridine ligands, leading to a tetragonally compressed octahedron. Intermolecular interactions in the crystal lattice freeze the complex in the high spin state in the solid state at all temperatures, as indicated by magnetometry and Electron Paramagnetic Resonance (EPR) spectra.
View Article and Find Full Text PDFDalton Trans
June 2024
Department of Material Science, Graduate School of Science, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan.
This work investigated the spin states of the cobalt(II) complexes [Co()](X) (1·X; = 4'-(4-,'-diphenylaminophenyl)-2,2':6',2''-terpyridine, X = PF, BPh) and [Co()](X) (2·X; = 4'-(4-,'-dimethylaminophenyl)-2,2':6',2''-terpyridine, X = PF, BPh) in the solid state and in solution. In the solid state, and , both containing smaller PF counter anions, showed gradual spin-crossover. In contrast, and remained in the high-spin state over the temperature range of 5-400 K due to a lower degree of molecular cooperativity.
View Article and Find Full Text PDFDalton Trans
March 2024
Instituto de Ciencia Molecular (ICMol), Universitat de València, 46980 Paterna, València, Spain.
A novel family of cobalt(II) compounds with tridentate pyridine-2,6-diiminephenyl type ligands featuring electron-withdrawing substituents of general formula [Co(-XPhPDI)](ClO)·S [-XPhPDI = 2,6-bis(-halophenylformimidoyl)pyridine with = 4 (1-3) and 3 (4); X = I (1), Br (2 and 4) and Cl (3); S = MeCN (1 and 2) and EtOAc (3)] has been synthesised and characterised by single-crystal X-ray diffraction, electron paramagnetic resonance, and static (dc) and dynamic (ac) magnetic measurements combined with theoretical calculations. The structures of 1-4 consist of mononuclear bis(chelating) cobalt(II) complex cations, [Co(-XPhPDI)], perchlorate anions, and acetonitrile (1 and 2) or ethyl acetate (3) molecules of crystallisation. This unique series of mononuclear six-coordinate octahedral cobalt(II) complexes displays both thermally-induced low-spin (LS)/high-spin (HS) transition and field-induced slow magnetic relaxation in both LS and HS states.
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