V. D. Dolzhenko

Synthesis, photophysical and electrochemical properties of iridium(III) complexes with 2-aryl-1-phenylbenzimidazoles

A series of mixed-ligand cyclometalated iridium(III) complexes with 2-aryl-1-phenylbenzimidazoles (where aryl is phenyl, 4-chlorophenyl, 4-(N,N-dimethylamino)phenyl, 3,4-dimethoxyphenyl, and 2-thienyl) and 11-carboxydipyrido[3,2-a:2′,3′-c]phenazine have been synthesized and characterized by 1H NMR and 31P NMR spectroscopy and mass spectrometry. The electron absorption spectra (EASs) of the complexes are observed to contain charge-transfer bands in the low-energy region (below 600 nm, ɛ ≈ (1–3) × 103 mol/(L cm)). The bands experience appreciable bathochromic shifts as the electron-donating properties of a benzimidazole ligand strengthen. The complexes manifest luminescence in the yellow-red spectral region. According to alternating current voltammetry data, reversible and quasi-reversible redox transitions (Eox ≈ 1.2–1.7 V with respect to SHE, CH3CN) are observed in solutions of the studied complexes.

Properties of iron-containing nanohydroxyapatite-based composites

The paramagnetic properties of compounds resulting from the synthesis of nanohydroxyapatite in the presence of Fe(III) ions have been studied by electron paramagnetic resonance, Mössbauer spectroscopy, and magnetochemistry. Based on the obtained results on the mechanism of the reaction between an orthophosphoric acid solution and an aqueous calcium hydroxide suspension, we have found conditions for incorporating Fe(III) impurity ions into hydroxyapatite. We have studied samples differing in the sequence in which reagents were mixed and in hydroxyapatite crystallite formation conditions. It has been shown that, in all instances, the composition and properties of the iron-containing phases in the composites depend significantly on both synthesis and heat treatment conditions.

On existence and properties of plutonium(VIII) derivatives

Abstract The existence of Pu(VIII) was shown in alkaline solutions and in nonpolar solvents (CCl4 and CHCl3) on the ground of such experimental facts like extraction of plutonium species, obtained by means of ozonization of Pu(VI) alkaline solutions into CCl4 and CHCl3; volatility of Pu compounds out of aqueous alkaline solutions, and the mentioned solvents. The product of interaction between PuO3 · 0.8H2O and XeF2 in CCl4 and CHCl3 was of the same chemical form for both cases and identical with the form of the product of volatility of Pu out of these organic solutions. The electronic absorbance spectra of these products in CCl4 and CHCl3 were fairly similar to the ones for OsO4 and RuO4. The band of absorption in these spectra with the maximum at 332 nm corresponds to the charge transfer of metal-ligand type [π(O)→Pu], as the value of molar extinction coefficient ε was found to be higher than 2 · 103 L/mole cm. A satisfactory agreement between the energies for the transitions of PuO4 molecule designed by Xα-SW method and experimental data was observed. A similar accordance was observed for the designed vibration frequency (DFT-method) with the one found as result of analysis of the vibration structure of the experimental spectra.

Equilibria in solutions of rhodium(III) complex with ethylenediaminetetraacetic acid (EDTA)

Equilibria in the solutions of the rhodium(III) complex of EDTA (H4Y) are studied by means of electronic absorption spectrometry. Mathematical treatment of the spectra provided the estimation of the parameters of spectral bands for two complexes [Rh(Y)(H2O)]− (λmax = 302 ± 2 and 371 ± 2 nm; ɛmax = 265 ± 3 and 275 ± 3 L/(cm mole), respectively) and [Rh(Y)]− (λmax = 289 ± 2 and 353 ± 2 nm; ɛmax = 240 ± 3 and 415 ± 5, respectively). The equilibrium constant [Rh(Y)(H2O)]− ai [Rh(Y)]− is estimated at pKeq = −2.7 ± 0.2. The description of the calculation procedure is provided.

Overcoming the Inertness of Iridium(III) in a Facile Single-Crystal to Single-Crystal Reaction of Iodine Vapor with a Cyclometalated Chloride Monomer

Iridium(III) is often considered to be one of the most inert octahedral metal ions. Herein we present a phenanthroimidazole-based bis-cyclometalated iridium(III) chloride undergoing a facile chloro ligand exchange with iodine, in a gas-solid reaction under ambient conditions. Monitoring the progress of the reaction by X-ray diffraction analysis reveals the crystal-packing-induced exceptional stereoselectivity of this topochemical transformation. The results provide excellent opportunities to modulate the geometry and kinetic properties of cyclometalated iridium(III) complexes that may be very promising in catalysis and design of anticancer agents.

Synthesis, structure, and optical properties of lanthanum(III), cerium(III), praseodymium(III), and nickel(II) heterometallic complexes with glycine

New cluster complexes of lanthanides(III) and nickel(II) [Ln{Ni(Gly)2}6]3+[Ln(NO3)6]3– have been synthesized, where Ln = La (I), Ce (II), and Pr (III); and Gly is glycinate. The structures of compounds I–III are determined by X-ray diffraction. The icosahedral cavity in the complex cation, where the lanthanide ion resides, has a fixed size independent of the nature of the central Ln(III) ion. In the complex anion, on the contrary, the Ln–O distances naturally decrease from La(III) to Pr(III). The optical properties of cationanion complexes I–III are studied. Based on the assignment in the electronic absorption spectra of the complexes, it is shown that the absorption bands are caused by d–d electronic transitions.

Synthesis, structure, and optical properties of iridium(III) complex with 1-benzyl-2-phenylbenzimidazole and 4,4'-dicarboxy-2,2'-bipyridyne

A new cyclometalated iridium(III) complex [Ir(L)2(Hdcbpy)] (1) has been synthesized, where L is 1-benzyl-2-phenylbenzimidazole and Hdcbpy is monoprotonated 4,4′-dicarboxy-2,2′-bipyridine. The structure of complex 1 has been determined by X-ray diffraction. The optical properties of complex 1 have been studied, and the quantum yield of luminescence has been measured.