Field induced slow magnetic relaxation in a linear homotrinuclear manganese heterospin coordination compound with S = 7/2 ground state and intriguing spin density distribution.

We report a first example of field-induced (HDC = 2500 Oe) slow magnetization relaxation in the homotrinuclear linear heterospin manganese coordination compound with S = 7/2 ground state, based on the bidentate 3,5-di-tert-butyl-1,2-benzoquinone-1-monooxime (HL) ligand with composition {[MnL3]Mn[MnL3]}.

Copper(II) coordination compounds based on bis-hydrazones of 2,6-diacetylpyridine: synthesis, structure, and cytotoxic activity.

By reacting a series of 2,6-diacetylpyridine bis-hydrazones containing pyrimidine (H2L1), benzimidazole (H2L2) and phthalazine (H2L3) heterocyclic fragments with copper(II) chloride and bromide, a variety of pentacoordinated complexes of the composition [Cu(H2L1)X]X, [Cu(HL2)X] and [Cu(HL3)X], where X = Cl-, Br-, are formed. The properties and structure of the compounds were studied by means of NMR, IR, UV-vis, ESR, and X-ray absorption spectroscopy, cyclic voltammetry and X-Ray single crystal diffraction methods. It was shown that complexes of the cationic type [Cu(H2L1)X]X have an asymmetric structure with a distorted square-pyramidal geometry of the coordination unit. The coordination polyhedron of metal chelates [Cu(HL2)X] and [Cu(HL3)X] is an almost ideal square pyramid. Investigations of the cytotoxic activity of the obtained compounds in vitro on human hepatocellular carcinoma (HepG2) and non-tumor human lung fibroblast (MRC-5) cell lines demonstrated that complexes show higher activity compared with the well-known anticancer agent cisplatin. In addition, metal chelates [Cu(H2L1)Cl]Cl, [Cu(HL2)Cl], [Cu(HL2)Br] and [Cu(HL3)Cl] were less toxic to non-tumor cells MRC-5. A study of the binding of complexes to bovine serum albumin (BSA) protein using fluorescence spectroscopy showed that copper complexes are strongly bound to BSA. To study the mechanism of interaction of the complexes with the DNA of cancer cells, molecular dynamics simulation of the compound [Cu(HL3)Cl] was carried out. It was shown that the complex enters into π-stacking interactions predominantly with adenine and thymine bases.

A novel hybrid protein composed of superoxide-dismutase-active Cu(II) complex and lysozyme.

A novel hybrid protein composed of a superoxide dismutase-active Cu(II) complex (CuST) and lysozyme (CuST@lysozyme) was prepared. The results of the spectroscopic and electrochemical analyses confirmed that CuST binds to lysozyme. We determined the crystal structure of CuST@lysozyme at 0.92 Å resolution, which revealed that the His15 imidazole group of lysozyme binds to the Cu(II) center of CuST in the equatorial position. In addition, CuST was fixed in position by the weak axial coordination of the Thr89 hydroxyl group and the hydrogen bond between the guanidinium group of the Arg14 residue and the hydroxyl group of CuST. Furthermore, the combination of CuST with lysozyme did not decrease the superoxide dismutase activity of CuST. Based on the spectral, electrochemical, structural studies, and quantum chemical calculations, an O2- disproportionation mechanism catalyzed by CuST@lysozyme is proposed.

Field-induced SIM behaviour of a Co(II) complex with a 1,1'-diacetylferrocene-derived ligand.

Herein, we report the synthesis and magnetic properties of the Co(ii) coordination compound with the 1,1'-bis(1-((pyrid-2-ylmethylene)hydrazono)ethyl)ferrocene (L) ligand, having the general formula [CoLCl2]. The static magnetic data analysis supported by the CASSCF/NEVPT2 calculations revealed the presence of the triaxial magnetic anisotropy with Dexp = +35.2 cm-1 and large rhombicity (E/D = 0.31) in this complex (Dcalc = +34.5 cm-1, E/Dcalc = 0.30). The dynamic magnetic data confirm that the complex shows a slow field-induced (HDC = 1000 Oe) magnetic relaxation behaviour.

Field-induced single-ion magnet behaviour of a hexacoordinated Co(ii) complex with easy-axis-type magnetic anisotropy.

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.

Adsorption studies of divalent, dinuclear coordination complexes as molecular spacers on SWCNTs.

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.

Novel hydrazone derivatives of 7-hydroxy-3',3'-dimethyl-3'H-spiro[chromene-2,1'-isobenzofuran]-8-carbaldehyde.

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.

A novel chelatofore functionalized spiropyran of the 2-oxaindane series.

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.

Synthesis, IR, UV/vis-, (1)H NMR and DFT study of chelatophore functionalized 1,3-benzoxazinone spiropyrans.

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.