Luminescence of the free bases of chelate-substituted tetraphenylporphyrin derivatives and their complexes with lutetium

The absorption and luminescence spectra of the free-base forms of some new tetrarphenylporphyrin derivatives bearing a chelating group or lutetium chelate as a substituent on the phenyl ring were studied with reference to the properties of unsubstituted tetrarphenylporphyrin. The fluorescence and phosphorescence quantum yields were measured for solutions of these compounds at various temperatures. The nature of the absorption and luminescence spectral bands of the complexes and their relation to the structure are discussed.     

Entanglement for two-atom Tavis–Cummings model with degenerate two-photon transitions in the presence of the Stark shift

The dynamics of atom–field entanglement for two two-level atoms with degenerate two-photon transitions interacting with one-mode radiation field with taking into account the Stark shift is investigated. Asymptotic solutions for system state vectors are obtained in the approximation of large initial coherent fields. The atom–field entanglement is investigated also on the basis of the linear atomic entropy dynamics. The possibility of the system being initially in a pure disentangled state to revive into this state during the evolution process is shown. Conditions and times of disentanglement are derived.     

Spectrophotometric determination of mangiferin

A spectrophotometric method is proposed for determining mangiferin in a crystalline powder and in sweetvetch herbage. The relative accuracy of the method is ± 0.34% for the powder and ± 2.63% for the herbage.     

Influence of the Nature of meso-Substituents and Extra-Ligands on the Luminescence of Ytterbium in Complexes with Porphyrins

Complexes of ytterbium with various meso-tetrasubstituted porphyrins have been obtained and their spectral-luminescent properties have been investigated. It is shown that the quantum yield and the lifetime of 4f-luminescence of the ytterbium ion are higher in complexes with porphyrins that contain aromatic and heteroaromatic meso-substituents (as compared to n-alkyl ones) and also in complexes with the acetylacetonate ion as an extra-ligand.     

Spectrophotometric determination of mangiferin

Summary A spectrophotometric method is proposed for determining mangiferin in a crystalline powder and in sweetvetch herbage. The relative accuracy of the method is ± 0.34% for the powder and ± 2.63% for the herbage.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 44–46, January–February, 1976.     

Effect of intramolecular energy transfer on the rate of unimolecular isomerization: HCN --HNC

This paper reports calculations of the rate of isomerization of HCN - HCN based on the theory of Gary and Rice as extended by Zhao and Rice. The major task is to determine the effect of intramolecular energy transfer on the prediction of the rate of isomerization. Both the full three-dimensional (3D) system and the reduced two-dimensional (2D) system obtained from freezing CN bond at 1.159 A are analyzed to check the validity of the freezing bond approximation. Meanwhile, RRKM rates are calculated to test RRKM choice of the transition state by comparing to Gary-Rice three-state model. The comparison shows that the rates from 2D model and 3D model are differing up to 20% with 2D rates consistently larger. The intramolecular energy transfer modifies the isomerization rate for HCN system up to 30% that is modestly small by the expectation. The isomerization rate predicted from RRKM theory is greater than those of Gary-Rice three-state model theory up to 65%, and it overstimates the rates under all consider     

Effect of tensor g-factor on the spectrum of eigen modes in magnetoactive plasma

The influence of the tensorial nature of the gyromagnetic coupling on a spectrum of eigen modes in magnetoactive plasma is studied. A dispersion equation for waves propagating in such a medium is obtained in the approximation of frigid hydrodynamics.     

Superparamagnetic gadonanotubes are high-performance MRI contrast agents

We report the nanoscale loading and confinement of aquated Gd3+n-ion clusters within ultra-short single-walled carbon nanotubes (US-tubes); these Gd3+n@US-tube species are linear superparamagnetic molecular magnets with Magnetic Resonance Imaging (MRI) efficacies 40 to 90 times larger than any Gd3+-based contrast agent (CA) in current clinical use.     

X-ray crystallographic investigation of 8,9,10,12-tetrachloro-1,2-di(hydroxymethyl)-o-carborane

State Scientific-Research Institute of Chemistry and Technology of Heteroorganic Compounds. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 5, pp. 147–150, September–October, 1990.