Lanthanide luminescence efficiency in eight- and nine-coordinate complexes: Role of the radiative lifetime

The photophysical parameters for the sensitization of metal-centred luminescence are analyzed in two series of complexes with tridentate and hexadentate ligands having N_xO_y chelating units. In particular, the radiative lifetime τ_rad is experimentally estimated for 29 nine-coordinate Eu^III complexes and 10 eight- and nine-coordinate Yb^III complexes. The known dependence of τ_rad on refractive index is substantiated by comparing data for solid-state samples and solutions. Moreover, a clear dependence of τ_rad with the coordination environment is evidenced and in the case of Eu^III, a comparison between τ_rad and the nephelauxetic effect generated by the ligands is attempted. Altogether, this extensive analysis points to the importance of having a handle on τ_rad when designing ligands for highly luminescent lanthanide-containing molecular edifices. This, in turn, should stimulate initiating theoretical considerations to unravel a reliable relationship between τ_rad and the electronic structure of the ligands.     

Ferrocene‐modified thiopyrimidines: synthesis,enantiomeric resolution,antitumor activity

Ferrocenylalkyl thiopyrimidines ( 6a–d to 9a–d ) were prepared via the reaction of the α‐(hydroxy)alkyl ferrocenes, FcCHR(OH) ( 1a–d ; Fc = ferrocenyl; R = H, Me, Et, Ph), with 2‐thiopyrimidines ( 2 – 5 ) in acetone at room temperature in the presence of TFA, yielding 50–95%. The resulting enantiomers were resolved using HPLC on modified cellulose as chiral selector. The antitumor activities of S‐ferrocenylethyl 2‐thiopyrimidine ( 6b ) against two murine solid tumor models, carcinoma 755 (Ca755) and Lewis lung carcinoma (LLC) were evaluated in vivo. The strong antitumor effect of compound 6b on Ca755 and LLC was demonstrated. The index of tumor growth inhibition on Ca755 equaled 95% in comparison with control. Copyright © 2010 John Wiley & Sons, Ltd.     

Natural radioactivity in springs of Sverdlovsk region,Middle Urals,Russia

Journal of Radioanalytical and Nuclear Chemistry - Activity concentrations of natural radionuclides were determined in water from 31 springs of Sverdlovsk region, Middle Urals, Russia. Activity...     

Prospects for making polar molecules with microwave fields

We propose a mechanism to produce ultracold polar molecules with microwave fields. It converts trapped ultracold atoms into vibrationally excited molecules by a single microwave transition and entirely depends on the existence of a permanent dipole moment in the molecules. As opposed to production of molecules by photoassociation or magnetic-field Feshbach resonances, our method does not rely on properties of excited states or existence of Feshbach resonances. We determine conditions for optimal creation of polar molecules in vibrationally excited states of the ground-state potential by changing frequency and intensity of the microwave field. We also explore the possibility to produce vibrationally cold molecules by combining the microwave field with an optical Raman transition or by applying a microwave field to Feshbach molecules. The production mechanism is illustrated for KRb and RbCs.