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Molecules ; 25(9)2020 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-32354044


Complexes [(dpp-BIAN)0CoIII2]·MeCN (I) and [(Py)2CoI2] (II) were synthesized by the reaction between cobalt(II) iodide and 1,2-bis(2,6-diisopropylphenylimino)acenaphthene (dpp-BIAN) or pyridine (Py), respectively. The molecular structures of the complexes were determined by X-ray diffraction. The Co(II) ions in both compounds are in a distorted tetrahedral environment (CoN2I2). The electrochemical behavior of complex I was studied by cyclic voltammetry. Magnetochemical measurements revealed that when an external magnetic field is applied, both compounds exhibit the properties of field-induced single ion magnets.

Molecules ; 24(24)2019 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-31847326


Vanadium(IV) complexes are actively studied as potential candidates for molecular spin qubits operating at room temperatures. They have longer electron spin decoherence times than many other transition ions, being the key property for applications in quantum information processing. In most cases reported to date, the molecular complexes were optimized through the design for this purpose. In this work, we investigate the relaxation properties of vanadium(IV) ions incorporated in complexes with lanthanides using electron paramagnetic resonance (EPR). In all cases, the VO6 moieties with no nuclear spins in the first coordination sphere are addressed. We develop and implement the approaches for facile diagnostics of relaxation characteristics in individual VO6 moieties of such compounds. Remarkably, the estimated relaxation times are found to be close to those of other vanadium-based qubits obtained previously. In the future, a synergistic combination of qubit-friendly properties of vanadium ions with single-molecule magnetism and luminescence of lanthanides can be pursued to realize new functionalities of such materials.

Complexos de Coordenação/química , Espectroscopia de Ressonância de Spin Eletrônica , Elementos da Série dos Lantanídeos/química , Fenômenos Magnéticos , Vanádio/química , Algoritmos , Complexos de Coordenação/síntese química , Hidrogênio , Modelos Teóricos , Conformação Molecular , Transição de Fase
Inorg Chem ; 56(3): 1599-1608, 2017 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-28072527


The tetranuclear heterometallic complex [Li2Zn2(piv)6(py)2] (1, where piv- = pivalate and py = pyridine) has been successfully employed as a presynthesized node for the construction of four porous metal-organic frameworks (MOFs) [Li2Zn2(R-bdc)3(bpy)]·solv (2-R, R-bdc2-; R = H, Br, NH2, NO2) by reaction with 4,4'-bipyridine (bpy) and terephthalate anionic linkers. The [Li2Zn2] node is retained in the products, representing a rare example of the rational step-by-step design of isoreticular MOFs based on complex heterometallic building units. The permanent porosity of the activated frameworks was confirmed by gas adsorption isotherm measurements (N2, CO2, CH4). Three compounds, 2-H, 2-Br, and 2-NH2 (but not 2-NO2), feature extensive hysteresis between the adsorption and desorption curves in the N2 isotherms at low pressures. The substituents R decorate the inner surface and also control the aperture of the channels, the volume of the micropores, and the overall surface area, thus affecting both the gas uptake and adsorption selectivity. The highest CO2 absorption at ambient conditions (105 cm3·g-1 or 21 wt % at 273 K and 1 bar for 2-NO2) is above the average values for microporous MOFs. The photoluminescent properties of the prototypic 2-H as well as the corresponding host-guest compounds with various aromatic molecules (benzene, toluene, anisole, and nitrobenzene) were systematically investigated. We discovered a rather complex pattern in the emission response of this material depending on the wavelength of excitation as well as the nature of the guest molecules. On the basis of the crystal structure of 2-H, a mechanism for these luminescent properties is proposed and discussed.