261903-05-3Relevant articles and documents
Dinuclear cobalt complexes with a redox active biphenyl bridging ligand [Co2(BP)(tqa)2](PF6)2(H4BP = 4,4′-bis(3-tert-butyl-1,2-catechol), tqa = tris(2-quinolylmethyl)amine): structure and magnetic properties
Kuroda-Sowa, Takayoshi,Maekawa, Masahiko,Mibu, Takuto,Okubo, Takashi,Suenaga, Yusaku,Sugimoto, Kunihisa
, p. 9833 - 9841 (2021/07/28)
The biscatechol, H4BP (4,4′-bis(3-tert-butyl-1,2-catechol)) that can directly connect two redox active catechol moieties was synthesized. Also, tris(2-pyridylmethyl)amine (tpa), bis(2-pyridylmethyl)(2-quinolylmethyl)amine (bpqa), (2-pyridylmethyl)bis(2-quinolyl methyl)amine (pbqa), and tris (2-quinolylmethyl)amine (tqa) were synthesized as terminal ligands of the tetracoordinated tripod. In total, five different dinuclear Co complexes were synthesized from H4BP with various terminal ligands as follows, [Co2(BP)(tpa)2](PF6)2(1), [Co2(BP)(tpa)2](PF6)3(2), [Co2(BP)(bpqa)2](PF6)2(3), [Co2(BP)(pbqa)2](PF6)2(4), and [Co2(BP)(tqa)2](PF6)2(5). After a one-electron oxidation reaction of complex (1), complex (2), was isolated as a mixed valence state lsCoIII-[SQ-Cat]-lsCoIII, with an absorption intensity of about 1370 nm (intervalence charge transfer (IVCT) bands) in CH3CN solution. In addition, an investigation of the magnetic properties of the dinuclear Co complex (3) with SQUID showed that theχMTvalue gradually increased as the temperature increased from 280 to 380 K. Studies in the solid and solution states using electronic spectra, cyclic voltammetry and SQUID for the above complexes provide clear evidence for three different charge distributions: complexes (1) and (3) are CoIII-[Cat-Cat]-CoIII, complex (2) is CoIII-[Sq-Cat]-CoIII, complexes (4) and (5) are CoII-[Sq-Sq]-CoII. Of the five cobalt dinuclear complexes, only complex (3) shows evidence of the temperature dependence of the charge distribution, displaying a thermally induced valence tautomeric transition from the lsCoIII-[Cat-Cat]-lsCoIIIto hsCoII-[Sq-Sq]-hsCoIIin both solid and solution states. However, this valence tautomeric step is incomplete at 380 K, with the?χMT?value of hsCoII-[Sq-Sq]-hsCoII. This suggests that the steric hindrance of the quinolyl rings around the Co ion produces a coordination atmosphere that is weaker than that observed with pyridyl rings, which facilitates a change in the CoIIIions to CoII
Nitronyl nitroxide radicals as organic memory elements with both n- and p-type properties
Lee, Junghyun,Lee, Eunkyo,Kim, Sangkwan,Bang, Gyeong Sook,Shultz, David A.,Schmidt, Robert D.,Forbes, Malcolm D. E.,Lee, Hyoyoung
, p. 4414 - 4418 (2011/06/22)
Can't fight the SEEPR: Simultaneous electrochemical electron paramagnetic resonance reveals that a molecule containing the nitronyl nitroxide (NN) radical (structure and red layer) is redox-active, with switchability between oxidized and reduced states. An organic NN radical device utilizes the dual p- and n-type properties in a memory device. Copyright
