Kinetic Formation of Pt-Pt Dimers of Cationic and Neutral Platinum(II) Complexes under Rapid Freeze Conditions in Solution.

We report the formation of M-M dimers (M = Pt or Pd) of cationic [M(dpb)(CHCN)] [dpbH = 1,3-di(2-pyridyl)benzene] and neutral [M(dpb)Cl] complexes resulting from the rapid freezing of solutions. Dimers based on M-M dz overlap were found to preferentially form rather than the thermodynamically favored head-to-tail π-stacking structures typically observed in the crystalline state. Kinetic dimers in glassy frozen solutions generated broad metal-metal-to-ligand charge-transfer emissions within the range of 600-800 nm at 77 K.

Design and synthesis of boron containing monosaccharides by the hydroboration of d-glucal for use in boron neutron capture therapy (BNCT).

Boron neutron capture therapy (BNCT) is one of the radiotherapies that involves the use of boron-containing compounds for the treatment of cancer. Boron-10 (B) containing compounds that can accumulate in tumor tissue are expected to be suitable agents for BNCT. We report herein on the design and synthesis of some new BNCT agents based on a d-glucose scaffold, since glycoconjugation has been recognized as a useful strategy for the specific targeting of tumors.

Stereospecific Synthesis of Tris-heteroleptic Tris-cyclometalated Iridium(III) Complexes via Different Heteroleptic Halogen-Bridged Iridium(III) Dimers and Their Photophysical Properties.

Herein, we report on the stereospecific synthesis of two single isomers of tris-heteroleptic tris-cyclometalated iridium(III) (Ir(III)) complexes composed of three different nonsymmetric cyclometalating ligands via heteroleptic halogen-bridged Ir dimers [Ir(tpy)(Fppy)(μ-Br)] 17b and [Ir(mpiq)(Fppy)(μ-Br)] 27b (tpyH: (2-(4'-tolyl)pyridine) and FppyH: (2-(4',6'-difluorophenyl)pyridine), and mpiqH: (1-(4'-methylphenyl)isoquinoline)) prepared by Zn-promoted degradation of Ir(tpy)(Fppy) 21 and Ir(mpiq)(Fppy) 26, as reported by us. Subsequently, 17b and 27b were converted to the tris-heteroleptic tris-cyclometalated Ir complexes Ir(tpy)(Fppy)(mpiq) 25 consisting of tpy, Fppy, and mpiq, as confirmed by spectroscopic data and X-ray crystal structure analysis. The first important point in this work is the selective synthesis of specific isomers among eight possible stereoisomers of Ir complexes having the same combination of three cyclometalating ligands.

Efficient Synthesis of Tris-Heteroleptic Iridium(III) Complexes Based on the Zn-Promoted Degradation of Tris-Cyclometalated Iridium(III) Complexes and Their Photophysical Properties.

We report on the efficient synthesis of tris-heteroleptic iridium (Ir) complexes based on the degradation of tris-cyclometalated Ir complexes (IrL, L: cyclometalating ligand) in the presence of Brønsted and Lewis acids such as HCl (in 1,4-dioxane), AlCl, TMSCl, and ZnX (X = Br or Cl), which affords the corresponding halogen-bridged Ir dimers (μ-complexes). Tris-cyclometalated Ir complexes containing electron-withdrawing groups such as fluorine, nitro, or CF moieties on the ligands were less reactive. This different reactivity was applied to the selective degradation of heteroleptic Ir complexes such as fac-Ir(tpy)(Fppy) (fac-12) (tpy: 2-(4'-tolyl)pyridine and Fppy: 2-(4',6'-difluorophenyl)pyridine), mer-Ir(tpy)(Fppy) (mer-12), and mer-Ir(mpiq)(Fppy) (mer-15) (mpiq: 1-(4'-methylphenyl)isoquinoline).

Regulation of the physiological effects of peroxidovanadium(V) complexes by the electronic nature of ligands.

Although the physiological effects of peroxidovanadium(V) complexes (pVs) have been extensively investigated both in vitro and in vivo with regard to their pharmacological activity, such as insulin-mimetic and antitumor activities, the relationship between the chemical and pharmacological properties of pVs is still unclear. Rational drug design with pVs depends on a full understanding of this relationship. Toward this end, the current report evaluates the physiological effects of 13 pVs were evaluated bound to a variety of ligand.

Preparation, structure, and properties of tetranuclear vanadium(III) and (IV) complexes bridged by diphenyl phosphate or phosphate.

Three novel tetranuclear vanadium(III) or (IV) complexes bridged by diphenyl phosphate or phosphate were prepared and their structures characterized by X-ray crystallography. The novel complexes are [{V(III)(2)(μ-hpnbpda)}(2){μ-(C(6)H(5)O)(2)PO(2)}(2)(μ-O)(2)]·6CH(3)OH (1), [{V(III)(2)(μ-tphpn)(μ-η(3)-HPO(4))}(2)(μ-η(4)-PO(4))](ClO(4))(3)·4.5H(2)O (2), and [{(V(IV)O)(2)(μ-tphpn)}(2)(μ-η(4)-PO(4))](ClO(4))(3)·H(2)O (3), where hpnbpda and tphpn are alkoxo-bridging dinucleating ligands.