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Dalton Trans ; 48(20): 6960-6970, 2019 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-31041973


A coordination compound with the composition [CoLCl2]·H2O (L = bis-condensation product of diacetyl and 2-hydrazinyl-4,6-dimethylpyrimidine) was synthesized, in which the Co(ii) ion was hexacoordinated. Under applied DC fields, this compound exhibited single-ion magnet behavior. Two relaxation processes were observed when increasing the applied magnetic field from 1000 to 3200 Oe. The first relaxation (high-frequency) was observed both at 1000 Oe and 3200 Oe, while the second relaxation was only registered under a field of 3200 Oe at low frequencies (<1 Hz) and low temperatures (<5 K). Modeling of the magnetic DC properties using the Griffith Hamiltonian accompanied by quantum chemical calculations revealed easy-axis-type magnetic anisotropy with weak rhombic contributions.

Phys Chem Chem Phys ; 17(44): 29566-73, 2015 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-26457656


In order to enhance the electrical energy storage capabilities of nanostructured carbon materials, inter-particle spacer strategies are needed to maintain ion-accessible surface area between the nanoparticles. This paper presents a comparison between different classes of divalent, dinuclear coordination complexes which both show strong adsorption to SWCNTs and have molecular spacer properties that maintain electrochemical activity. We find that a novel, dinuclear zinc hydrazone complex binds as an ion-pair at very high loading while not inducing significant aggregation as compared to our previously studies of dinuclear ruthenium complexes. These conclusions are supported by conductivity and dispersion stability data. Moreover, since zinc is an earth abundant metal, these complexes can be used as components in sustainable energy storage materials. Binding kinetics and binding equilibrium data are presented. Modeling of the adsorption isotherm is best fit with the BET model. Kinetics data support an independent binding model. Preliminary capacitance and membrane resistance data are consistent with the complexes acting as molecular spacers between the SWCNTs in a condensed thin film.

Acta Crystallogr C ; 67(Pt 3): o85-8, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21368413


The structures of new oxaindane spiropyrans derived from 7-hydroxy-3',3'-dimethyl-3'H-spiro[chromene-2,1'-isobenzofuran]-8-carbaldehyde (SP1), namely N-benzyl-2-[(7-hydroxy-3',3'-dimethyl-3'H-spiro[chromene-2,1'-isobenzofuran]-8-yl)methylidene]hydrazinecarbothioamide, C(27)H(25)N(3)O(3)S, (I), at 120 (2) K, and N'-[(7-hydroxy-3',3'-dimethyl-3'H-spiro[chromene-2,1'-isobenzofuran]-8-yl)methylidene]-4-methylbenzohydrazide acetone monosolvate, C(27)H(24)N(2)O(4)·C(3)H(6)O, (II), at 100 (2) K, are reported. The photochromically active C(spiro)-O bond length in (I) is close to that in the parent compound (SP1), and in (II) it is shorter. In (I), centrosymmetric pairs of molecules are bound by two equivalent N-H...S hydrogen bonds, forming an eight-membered ring with two donors and two acceptors.

Acta Crystallogr C ; 65(Pt 12): o618-20, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19966444


A novel chelatofore functionalized spiropyran of the 2-oxaindane series, namely 8-formyl-7-hydroxy-3',3'-dimethylspiro[2H-chromene-2,1'(3'H)-2-benzofuran], C(19)H(16)O(4), is reported. In the crystalline state, dimers are formed as a result of the pi-pi stacking of aromatic groups of the 2H-chromene part of the molecule and C-H...O interactions. The C(spiro)-O bond length in the pyran ring is 1.4558 (10) A, which is longer than or equal to the bond length in thermo- and photochromic 2-oxaindane spiropyrans synthesized previously, except for the 7,8-benzo/6-NO(2) derivative, in which this bond length is 1.465 (2) A.

Spectrochim Acta A Mol Biomol Spectrosc ; 71(3): 1146-52, 2008 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-18550424


Six novel functionalized spiropyran's derivatives of 2H-1,3-benzoxazinone series were synthesized by introducing the substituents with chelating ability into 2H-chromene part of the 8'-formyl-7'-hydroxy-3-methyl-4-oxo-3,4-dihydro-2H-1,3-benzoxazine-2-spiro-2'-[2H]-chromene (I) by condensation with 2-aminophenol, 2-amino-4-methylphenol, 2-amino-4-nitrophenol, 2-amino-1-methylbenzimidazole, 4-amino-4H-1,2,4-triazole, N-(4-aminophenyl)acetamide. (1)H NMR, UV/vis, IR spectroscopy combined with quantum-chemical calculations employing density functional theory (DFT) were used to study their structure. All substances, except 2-amino-4-nitrophenol derivative exist in solid state and in solution solely in closed spiroform, while the mentioned one undergoes partial spiropyran ring opening. In DMSO solution NMR spectra show ratio of 2:1 of closed and opened form, correspondingly.

Benzopiranos/química , Benzopiranos/síntese química , Indóis/química , Indóis/síntese química , Nitrocompostos/química , Nitrocompostos/síntese química , Oxazinas/química , Oxazinas/síntese química , Quelantes/síntese química , Quelantes/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Teoria Quântica , Espectrofotometria , Espectrofotometria Infravermelho , Espectrofotometria Ultravioleta , Termodinâmica