Haruo Akashi

Synthesis, Structures, and Magnetic Properties of Face-Sharing Heterodinuclear Ni(II)−Ln(III) (Ln = Eu, Gd, Tb, Dy) Complexes

Heterodinuclear [(Ni (II)L)Ln (III)(hfac) 2(EtOH)] (H 3L = 1,1,1-tris[(salicylideneamino)methyl]ethane; Ln = Eu, Gd, Tb, and Dy; hfac = hexafluoroacetylacetonate) complexes ( 1.Ln) were prepared by treating [Ni(H 1.5L)]Cl 0.5 ( 1) with [Ln(hfac) 3(H 2O) 2] and triethylamine in ethanol (1:1:1). All 1.Ln complexes ( 1.Eu, 1.Gd, 1.Tb, and 1.Dy) crystallized in the triclinic space group P1 (No. 2) with Z = 2 with very similar structures. Each complex is a face-sharing dinuclear molecule. The Ni (II) ion is coordinated by the L (3-) ligand in a N 3O 3 coordination sphere, and the three phenolate oxygen atoms coordinate to an Ln (III) ion as bridging atoms. The Ln (III) ion is eight-coordinate, with four oxygen atoms of two hfac (-)s, three phenolate oxygen atoms of L (3-), and one ethanol oxygen atom coordinated. Temperature-dependent magnetic susceptibility and field-dependent magnetization measurements showed a ferromagnetic interaction between Ni (II) and Gd (III) in 1.Gd. The Ni (II)-Ln (III) magnetic interactions in 1.Eu, 1.Tb, and 1.Dy were evaluated by comparing their magnetic susceptibilities with those of the isostructural Zn (II)-Ln (III) complexes, [(ZnL)Ln(hfac) 2(EtOH)] ( 2.Ln) containing a diamagnetic Zn (II) ion. A ferromagnetic interaction was indicated in 1.Tb and 1.Dy, while the interaction between Ni (II) and Eu (III) was negligible in 1.Eu. The magnetic behaviors of 1.Dy and 2.Dy were analyzed theoretically to give insight into the sublevel structures of the Dy (III) ion and its coupling with Ni (II). Frequency dependence in the ac susceptibility signals was observed in 1.Dy.

Isolation and X-ray structure determination of a sulphur-bridged incomplete cubane-type molybdenum(IV) aqua cluster, [Mo3S4(H2O)9](CH3·C6H4·SO3)4·9H2O

Abstract The title compound was isolated in high yield (72%) from 4 M HPTS solution, and the X-ray crystal structure has been determined. The cluster cation has an approximate C3ν, symmetry. The average MoMo distance (2.735[8] A) in the aqua complex is the shortest reported in complexes with Mo3S4 cores so far. Every SO3− moiety of the pts− anion faces towards the complex cation.

Ferromagnetic NiII–GdIII interactions in complexes with NiGd, NiGdNi, and NiGdGdNi cores supported by tripodal ligands

Dinuclear [(NiL)Gd(hfac)(2)(EtOH)](H(3)L = 1,1,1-tris(N-salicylideneaminomethyl)ethane, Hhfac = hexafluoroacetylacetone), trinuclear [(NiL)(2)Gd(NO(3))], and tetranuclear [(NiL)Gd(CH(3)CO(2))(2)(MeOH)](2) complexes, were prepared by treating [Ni(HL)] with [Gd(hfac)(3)(H(2)O)(2)], Gd(NO(3))(3).6H(2)O, and Gd(CH(3)CO(2))(3).4H(2)O, respectively, in the presence of Et(3)N. All the complexes show that ferromagnetic interactions occur between the Ni(II) and Gd(III) ions.

Antiferromagnetism induced by successive protonation of terminal phenol groups of a bis(μ-phenoxide)-bridged dicopper(II,II) complex

The reaction of a tripodal ligand (H2L = N,N-bis(2-hydroxybenzyl)-N′,N′-dimethylethylenediamine) with Cu(NO3)2·3H2O and Cu(ClO4)2·6H2O in methanol yielded [Cu2(HL)2](NO3)2·H2O (1) and [Cu2(HL)2](ClO4)2 (1′), respectively. When H2L was allowed to react with CuSO4·5H2O in the presence of triethylamine (1 ∶ 1 ∶ 2) in methanol, the neutral dicopper(II,II) complex [Cu2(L)2] (2) was obtained. The monopositive species [Cu2(L)(HL)]ClO4·CH3OH·H2O (3) crystallized on mixing 1′ and 2 (1 ∶ 1) in methanol–dichloromethane. The crystal structures of 1, 2, and 3 were determined by X-ray crystallography. All of the complexes consist of a discrete dinuclear molecule with bis(μ-phenoxide)-bridges. The tripodal ligand functions as a tetradentate ligand and one of the phenolic oxygen atoms serves as a bridging ligand. Protonation/deprotonation takes place at the terminal phenol moiety and as the phenol group is deprotonated the coordination geometry changes from a distorted square pyramid to a distorted trigonal bipyramid. The two copper ions in 1–3 are antiferromagnetically coupled with 2J = −714 (1), −19.9 (2), and −277 cm−1 (3). The results clearly demonstrate that protonation/deprotonation causes a change in coordination geometry, which in turn drastically affects magnetic exchange interactions.

A novel photodynamic therapy targeting cancer cells and tumor-associated macrophages

Tumor-associated macrophages (TAM) in cancer stroma play important roles for cancer cell growth, invasion, angiogenesis, and metastases. We synthesized a novel photosensitizer, mannose-conjugated chlorin (M-chlorin), designed to bind mannose receptors highly expressed on TAMs. We evaluated the newly available photodynamic therapy (PDT) with M-chlorin against gastric and colon cancer. We evaluated PDT with M-chlorin for in vitro cytotoxicity and apoptosis induction in cancer cells compared with chlorin alone and glucose-conjugated chlorin (G-chlorin). The subcellular localization of M-chlorin was observed by confocal microscopy, and the M-chlorin PDT effects against TAMs including THP-1–induced M2-polarized macrophages were evaluated. Anticancer effects were also investigated in an allograft model where cytotoxic effects against TAMs in the cancer cell stroma were analyzed by immunohistochemistry. M-chlorin PDT strongly induced cell death in cancer cells to almost the same extent as G-chlorin PDT by inducing apoptosis. M-chlorin was incorporated into cancer cells where it localized mainly in lysosomes and endoplasmic reticula. M-chlorin PDT revealed strong cytotoxicity for M2 macrophages induced from THP-1 cell lines, and it induced stronger cytotoxicity than G-chlorin PDT in the allograft model through killing both cancer cells and TAMs in the cancer stroma. The M-chlorin PDT produced strong cytotoxicity against cancer tissue by inducing apoptosis of both cancer cells and TAMs in the cancer stroma. This novel PDT thus stands as a new candidate for very effective, next-generation PDT. Mol Cancer Ther; 14(2); 452–60. ©2014 AACR.

Antitumor Effects in Gastrointestinal Stromal Tumors Using Photodynamic Therapy with a Novel Glucose-Conjugated Chlorin

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract. Except for surgical resection, no effective treatment strategies have been established. Photodynamic therapy (PDT) consists of intravenous administration of a photosensitizer, activated by a specific wavelength of light, which produces reactive oxygen species that directly kill tumor cells. We analyzed the efficacy of PDT using a newly developed photosensitizer, 5,10,15,20-tetrakis [4-[β-d-glucopyranosylthio-2,3,5,6-tetrafluorophenyl]-2,3,[methano[N-methyl] iminomethano] chlorin (H2TFPC-SGlc), for the GIST treatment. Various photosensitizers were administered in vitro to GIST (GIST-T1) and fibroblast (WI-38) cells, followed by irradiation, after which cell death was compared. We additionally established xenograft mouse models with GIST-T1 tumors and examined the accumulation and antitumor effects of these photosensitizers in vivo. In vitro, the expression of the glucose transporters GLUT1, GLUT3, and GLUT4, the cellular uptake of H2TFPC-SGlc, and apoptosis mediated by PDT with H2TFPC-SGlc were significantly higher in GIST-T1 than in WI-38 cells. In vivo, H2TFPC-SGlc accumulation was higher in xenograft tumors of GIST-T1 cells than in the adjacent normal tissue, and tumor growth was significantly suppressed following PDT. PDT with novel H2TFPC-SGlc is potentially useful for clinical applications about the treatment of GIST. Mol Cancer Ther; 13(4); 767–75. ©2014 AACR.

?-Methallylrhodium(III) supported on a vanadium oxide cluster: Synthesis, structure, and reaction

Reaction of [(η3-C4H7)2Rh(CH3CN)2]PF6(η3-C4H7 = β-methallyl) with [n-Bu4N](VO3) gives a new η3-allyl cluster [n-Bu4N]2[{(η3-C4H7)2Rh}2 (V4O12)] (I) which is readily converted into a diene cluster, [n-Bu4N]2 [{(η4-C8H14)Rh}2(V4O12)] (II) (C8H14=2,5-dimethyl-1,5-hexadiene) by reacting with CO or P(OEt)3;I andII have been characterized crystallographically.

Molybdenum–copper–sulfur Mo3CuS4 cubes

Abstract Reaction of the incomplete cubane-type cluster [Mo3S4(H2O)9]4+ (1) with CuCl in 2 M HCl gives a novel cubane-type cluster [Mo3CuS4Cl(H2O)9]4+ (2). The nitrilotriacetato complex [Mo3CuS4Cl(Hnta)3]2− (3), the derivative of 2, has been prepared. The crystallographic results obtained were as follows: K2[Mo3CuS4Cl(Hnta)3]·9H2O (3a), triclinic, P1, a=10.634(1), b=11.032(2), c=10.299(4) A, α=112.34(2), β=98.76(2), γ=81.91(1)°, V=1100.3(4) A3, Z=1, R=5.7%; (NH4)2[Mo3CuS4Cl(Hnta)3]·9H2O (3b), triclinic, P1, a=10.714(1), b=11.121(1), c=10.379(3) A, α=112.07(1), β=99.375(8), γ=81.168(7)°, V=1124.9(4) A3, Z=1, R=8.3%; (NH4)2[Mo3CuS4Cl(Hnta)3]·9H2O (3c) trigonal, R3m, a=16.332(2), c=14.301(2) A, V=3303.5(4) A3, Z=3, R=4.2%. Binding energies of Cu 2p3/2, Cu 2p1/2, Mo 3d5/2, and Mo 3d3/2 from X-ray photoelectron spectroscopy measurements are 933.35, 953.26, 230.07 and 233.24 eV for 3a, 933.47, 953.25, 230.18 and 233.31 eV for 3b, respectively (C1s=285.0 eV). The binding-energy values of Cu 2p3/2 for 3a and 3b and the absence of satellites indicate the Cu(I) oxidation state in the respective clusters. The comparison of [Mo3CuS4Cl(H2O)9]4+ (2) in hydrochloric acid with [Mo3CuS4(H2O)10]5+ (2′) in Hpts reveals that the coordination of chloride ion to copper atom increases very much the stability of 2 in hydrochloric acid solution. Air oxidation of [Mo3CuS4Cl(H2O)9]3+ (4) and [Mo3CuS4(H2O)10]4+ (4′) and the reaction and reaction products of [Mo3FeS4(H2O)10]4+ (5) with Cu(II) ion will be discussed.

Enantiopure Anthrylene−Ethynylene Cyclic Tetramer and Racemization via Rotation of Anthracene Unit about Acetylenic Axes1

Four anthracene and four acetylene units are used to construct a chiral pi-conjugate macrocycle, the chirality of which is due to the restricted rotation about acetylenic axes. Enantiomers were readily resolved by chiral HPLC and racemized slowly even at 70 degrees C.

Synthesis of [Cp*TiMo5O18]3−. Its unexpectedly high basicity and unexpected protonation site

Abstract A tetrabutylammonium salt of [Cp*TiMo5O18]3− (Cp* = η-C5(CH3)5) was synthesized by reacting [(C4H9)4N]2Mo2O7 with Cp*TiCl3 in CH3CN. The new polymolybdate is highly basic and readily reacts with [(η-C8H12)Ir]PF6 to form an adduct. The monoprotonated species [HCp*TiMo5O18]2− has also been isolated as a tetrabutylammonium salt and structurally characterized by a single crystal X-ray diffraction study.