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1.
Photoinduced magnetization of the cyano-bridged 3d-4f heterobimetallic assembly Nd(DMF)4(H2O)3(mu-CN)Fe(CN)5.H2O (1) (DMF = N,N-dimethylformamide) is described in this paper. The chiMT values are enhanced by about 45% after UV light illumination in the temperature range of 5-50 K. We propose that UV light illumination induces a structural distortion in 1. This small structural change is propagated by molecular interactions in the inorganic network. Furthermore, the cooperativity resulting from the molecular interaction functions to increase the activation energy of the relaxation processes, which makes observation of the photoexcited state possible. The flexible network structure through the hydrogen bonds in 1 plays an essential role for the photoinduced phenomenon. This finding may open up a new domain for developing the molecule-based magnetic materials. 相似文献
2.
New crystal structure of Eu(DMF)4(H2O)3Co(CN)6·H2O (DMF = N,N′-dimethylformamide) (Eu-Co) has been determined to be monoclinic, P2(1)/n, a = 19.796(12) Å, b = 8.862(11) Å, c = 17.525(10) Å, β = 96.26(5)°, V = 3056(5) Å3, Z = 4. The Eu(III) ion adopts an antiprismatic eight-coordination and forms a cyano bridge with r(Eu-N) = 2.496(7) Å and Θ(Eu-N-C) = 165.7(7)° to the Co(III) ion. The complex exhibits some common features with the Eu-Fe complex. Diffuse reflectance electronic spectra and magnetic susceptibility of Eu-Cr, Eu-Mn, Eu-Fe, and Eu-Co complexes were compared. By substituting the metal ions, both electronic and structural features affected the charge transfer bands and superexchange interactions concerning cyanide ligands. In addition, only Eu-Co exhibited 5 D 0 → 7 F 2 and 5 D 0 → 7 F 1 luminescence bands at 16300 cm?1 and 16900 cm?1, respectively at 298 K (λex = 360 nm (27000 cm?1)), because quenching by cyano-bridged ions did not prevent Eu(III) ion from exhibiting emission. Thus, only Eu-Co may be suitable for verification of an assumption of mechanism concerning drastic photoinduced magnetic changes for Nd-Fe. Merely small decrease of magnetization was observed for Eu-Co after UV light irradiation at 2.0 K. This result was attributed to slight structural changes around cyano bridges without transitions of spin states. 相似文献
3.
Takashiro Akitsu Yasuaki Einaga 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(4):m183-m186
The crystal structures of the title compounds, [Cu(C15H11N2O2)2(C14H15N)2] and [Cu(C15H11N2O2)2(C14H15N)2]·2CHCl3, respectively, have been determined. The red disolvate complex affords a square‐planar CuN4 coordination environment in which the CuII atom lies on a centre of symmetry. The blue solvent‐free complex affords a distorted square‐pyramidal CuN4O coordination environment and adjacent molecules form centrosymmetric dimers. A comparison of the different crystal structures focuses on the role of the solvent molecules in supramolecular assemblies of the copper(II) complexes. 相似文献
4.
Takashiro Akitsu Yasuaki Einaga 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(4):m162-m164
The title compound, [Cu(C4H12N2)2(C3H6O)2](ClO4)2, is the first structurally characterized CuII complex having acetone as axial ligands. The complex adopts an elongated octahedral trans‐[CuN4O2] coordination geometry, with the Cu atom having 222 site symmetry. The axial Cu—O(acetone) and in‐plane Cu—N bond lengths are 2.507 (5) and 2.041 (3) Å, respectively. 相似文献
5.
Yoshikazu AritakeTakashiro Akitsu 《Polyhedron》2012,31(1):278-284
Chiral Schiff base complexes containing azo-groups, bis(N-R-1-cyclohexylethyl-4-phenyldiazenylsalicydenaminato) nickel(II), copper(II) and zinc(II) complexes, and without azo-groups, bis(N-R-1-cyclohexylethyl-3,5-dichlorosalicydenaminato) nickel(II), copper(II) and zinc(II) complexes, affording a distorted square planar trans-[MN2O2] coordination geometry were prepared. Organic/inorganic hybrid materials in polymethylmethacrylate (PMMA) spincoat films of the complexes (both the azobenzene (AZ) containing type and the latter complexes of the AZ separated type) were assembled for a comparison of polarized UV light induced molecular arrangement caused by the Weigert effect. Investigation of the parameters for the optical anisotropy of the metal complexes as well as AZ suggested that the degree of increasing optical anisotropy of the containing type was higher than that of the separated type based on π-π∗ (of which a characteristic band appeared around 380 nm) and n-π∗ bands of polarized absorption electronic spectra. In the AZ containing type, the rigid nickel(II) or zinc(II) complexes easily increase the optical anisotropy compared to the flexible copper(II) complexes. In the AZ separated type, interestingly, enhancement of some CD bands suggests the role of chiral dopants of some complexes without azo-groups for AZ. 相似文献
6.
Cyprian M. Chunkang Iris E. Ikome Emmanuel N. Nfor Yuta Mitani Natsuki Katsuumi Tomoyuki Haraguchi Takashiro Akitsu 《Molecules (Basel, Switzerland)》2020,25(23)
Single crystals of two achiral and planar heterocyclic compounds, C9H8H3O(CA1) and C8H5NO2 (CA4), recrystallized from ethanol, were characterized by single crystal X-ray analysis, respectively, and chiral crystallization was observed only for CA1 as P212121 (# 19), whereas it was not observed for CA4 P21/c (# 14). In CA1, as a monohydrate, the hydrogen bonds were pronounced around the water of crystallization (O4), and the planar cyclic sites were arranged in parallel to slightly tilted positions. On the other hand, an anhydride CA4 formed a dimer by hydrogen bonds between adjacent molecules in the crystal, which were aggregated by van der Waals forces and placed in parallel planar cyclic sites. 相似文献
7.
New organic–inorganic hybrid material composed of typical single-molecule magnet [Mn12(CH3COO)16(H2O)4O12]·2CH3COOH·4H2O (Mn12-acetate) and photochromic azobenzene in PMMA cast films was prepared to observe novel photomagnetic phenomenon. We characterized it by means of UV–visible absorption and IR spectra to confirm photoisomerization of azobenzene even at room temperature. We measured temperature and field dependence of DC susceptibility, and temperature and frequency dependence of AC susceptibility as comparing with bulk precipitates of Mn12-acetate. We found some differences in hysteresis loops for them. After alternate illumination of UV or visible light for 3 min at 3 K, we could observe reversible decrease or increase of in-phase AC susceptibility (and little changes of DC susceptibility) for the hybrid materials accompanying cis–trans photoisomerization of azobenzene. 相似文献
8.
A new complex salt trans-[CrF2(2,3,2-tet)][ZnCl3(H2O)] (2,3,2-tet is 1,4,8,11-tetraazaundecane), is prepared and its structure is determined by single crystal X-ray diffraction using synchrotron data at 100 K. The complex crystallizes in the space group P21/c of the monoclinic system with two mononuclear formula units in a cell with dimensions a = 5.6360(11) Å, b = 17.120(3) Å, c = 17.020(3) Å, and β = 94.38(3)°. The chromium(III) ion is coordinated by four N atoms of the 2,3,2-tet ligand in the equatorial plane and two F atoms in a trans axial arrangement, displaying a slightly distorted octahedral geometry. The mean Cr–N(2,3,2-tet) and Cr–F bond distances are 2.0772(11) Å and 1.8930(8) Å, respectively. The crystal packing is stabilized by hydrogen bonding interactions between N–H groups of the 2,3,2-tet, O–H groups of the anion, the F atom, and the Cl atom of the anion. The FT-infrared, UV-visible spectra, and magnetic properties are also described. 相似文献
9.
10.
Takashiro Akitsu Chiaki Ishioka Tsubasa Itoh 《Central European Journal of Chemistry》2009,7(4):690-696
A series of organic/inorganic hybrid materials containing the single-molecule magnet [Mn12(CH3COO)16(H2O)4O12]·2CH3COOH·4H2O with the photochromic compounds azobenzene or disperse red 1 cast into polymethyl methacrylate films was prepared. To understand
the photomodulation of analogous mixtures’ AC susceptibility, we investigated the molecular alignment based on Weigert’s effect
accompanying cycles of cis-trans photoisomerization by alternate irradiations with polarized UV and visible light. Polarized
electronic spectra of the hybrid materials demonstrated gradually increasing anisotropy. These features suggest interactions
between photochromic compounds and the Mn12 complex in polymethyl methacrylate.
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