Electron affinity and substituent effects in radical anions

The first vertical electron affinities EA of 13 series of molecules and free radicals D(X _i ) _n are related to the inductive (σ _I ), resonance (σ _R ^? ), and polarization (σ_α) parameters of substituents X _i by the dependences EA = EA _H + aΣσ _I + bΣσ _R/? + cΣσ_α: In radical anions D^+·(X _i ) _n , compared to radical cations D^+·(X _i ) _n , the polarization interaction is weaker or similar in magnitude but has an opposite sign. The previously unknown resonance parameters σ _R ^? of substituents SiMe₃ and CH₂SiMe₃ bound to the radical anion center H₂C=CH^?· were calculated.     

Conjugates of polyhedral boron compounds with carbohydrates 7. Hydrolytic stability of closo-ortho-carborane glycoconjugates containing from one to three β-lactosylamine and β-d-galactopyranosylamine residues; estimation of their galectin-binding efficiency with galectin RCA120

The galectin-binding efficiency (Ricinus communis agglutinin, RCA) and the degree of deboronation at 37 °C of glycoconjugates of ortho-carboranylacetic acid containing from one to three β-lactosylamine or β-d-galactopyranosylamine residues were estimated; the glycoconjugates are potential agents for boron neutron capture therapy of cancer. Over a period of 24 h, up to ～15% of glycoconjugates underwent deboronation to give glycoconjugates of nido-ortho-carborane. With Lac-β-NH(COCH₂NH)₂COCH₂-o-CCHB₁₀H₁₀ as an example, it was demonstrated that the deboronation occurs at both 60 and 5 °C. Glycoconjugates with an O-linked β-galactose as a fragment of lactosylamine bind to galectin RCA₁₂₀ much more efficiently (up to ～40 times) than do the corresponding glycoconjugates with a N-linked β-galactose residue. The glycoconjugates containing one β-lactosylamine residue bind to galectin RCA approximately two times less efficiently than does lactose; however, introduction of the second and third β-lactosylamine residues into the glycoconjugate increases the binding efficiency by a factor of five to seven due to the cluster effect.     

Collision-induced nonadiabatic transitions in the second-tier ion-pair states of iodine molecule: experimental and theoretical study of the I2(f0g+) collisions with rare gas atoms

Nonadiabatic transitions induced by collisions with He, Ar, Kr, and Xe atoms in the I(2) molecule excited to the f0(g)(+) second-tier ion-pair state are investigated by means of the optical-optical double resonance spectroscopy. Fluorescence spectra reveal that the transition to the F0(u)(+) state is a dominant nonradiative decay channel for f state in He, Ar, and Kr, whereas the reactive quenching is more efficient for collisions with Xe atom. Total rate constants and vibrational product state distributions for the f-->F electronic energy transfer are determined and analyzed in terms of energy gaps and Franck-Condon factors for the combining vibronic levels at initial vibrational excitations v(f)=8, 10, 14, and 17. Quantum scattering calculations are performed for collisions with He and Ar atoms, implementing a combination of the diatomics-in-molecule and long-range perturbation theories to evaluate diabatic PESs and coupling matrix elements. Calculated rate constants and vibrational product state distributions agree well with the measured ones, especially in case of Ar. Qualitative comparison is made with the previous results for the second-tier f0(g)(+)-->F0(u)(+) transition in collisions with I(2)(X) molecule and the first-tier E0(g)(+)-->D0(u)(+) transition induced by collisions with the rare gas atoms.     

Synthesis of organophosphorus derivatives of 2,6‐di‐tert‐butyl‐4‐methylphenol

Convenient procedures for the synthesis of 2,6‐di‐tert‐butyl‐4‐methylphenol (ionol) mono‐, di‐, and triphosphorus derivatives, starting from the readily accessible 3,5‐di‐tert‐butyl‐4‐hydroxybenzaldehyde, are proposed, and some properties of the obtained compounds are presented. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:490–494, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20458     

Chronopotentiometric Method of Studying Electroosmosis in Systems with Ion-Exchange Membranes and Lysine Solutions

A new method of chronopotentiometric study of electroosmotic water transfer in the electromembrane system containing amino acid solution is elaborated. An electrodiffusion problem, which allows for a convective solvent transfer in the system, is formulated and solved. By comparing calculated and experimental transition times for MK-40 and MF-4SK cationite membranes in lysine monohydrochloride solutions, the electroosmotic permeability of the membranes and transport numbers of water through them are calculated. A considerably higher electroosmotic water transport through MK-40 as compared with MF-4SK is attributed to differences in their nature and structure.     

Synthesis of new derivatives of 2,4-dihydroxybenzoic acid and aldehyde and the study of the spectral-luminescent properties of their lanthanide complexes

4-Acylated derivatives of 2,4-dihydroxybenzoic acid and aldehyde were synthesized. It was found that 2-hydroxy-4-[(4-decyloxy)benzoyloxy]benzaldehyde coordinates to Eu(III) ion, and when the aldehyde group is replaced by the carboxy group, a complex with Tb(III) ions is formed. The photoluminescent properties of the resulting complexes in solution were studied.     

2-Hydroxybenzoic acid esters: Synthesis,complexes with Tb(III), and their luminescence characteristics

New esters of 2-hydroxybenzoic acid and 4-(4-alkoxybenzoyloxy)phenols, forming liquid crystals, were synthesized. These compounds in solution form complexes with Tb(III), exhibiting photoluminescence properties.     

β-nitro- and β-bromo-β-nitrostyrenes in the reactions with aminonitroguanidine

The conditions for the reactions of ??-nitro- and ??-bromo-??-nitrostyrenes with 1-amino-2-nitroguanidine resulting in the amination products, 1-nitro- and 1-bromo-1-nitro-2-aryl-2-(2-nitroguanidinoamino) ethanes, were found. Under the action of the basic catalysts or prolonged boiling, the adducts derived from the gem-bromonitrostyrenes undergo decomposition to form N-arylmethylidene-N-(2-nitroguanidino)amines.