Improvements in diagnostic measures for biomedical applications have been investigated in various studies for better interpretations of biological abnormalities and several medical conditions. The use of imaging techniques, such as magnetic resonance imaging (MRI), is widespread and becoming a standard procedure for such specialized applications. A major avenue being studied in MRI is the use of magnetic nanoparticles (NPs) as contrast agents (CAs). Among various approaches, current research also incorporates use of superparamagnetic iron oxide NPs and manganese-based NPs with biocompatible coatings for improved stability and reduced biodegradation when exposed to a biological environment. In this review, recent advances with these types of magnetic NPs and their potential use as CAs in MRI are reported, as well as new insights into the selectivity and cellular transport mechanism that occurs following injection.

No abstract

Synthesis of 2-oxazolidinones from 2-aminoalcohols and carbon dioxide (CO2) in the presence of 1,3-dichloro-1,1,3,3-tetraalkyldistannoxanes (1) is reported. The influence of the change in substituent groups on the metal centers Sna and Snb of the catalyst (1) on the yields of the products was studied. Turnover numbers as high as 138 were obtained using the chlorostannoxane catalyst with all butyl substituents (1a) on both the metal centers. The activity of the catalyst 1a on various substrates was studied and reported.

No abstract

A series of amidoamine ligands (1) and their cobalt(III) complexes (2) were synthesized and characterized by various spectroscopic techniques including (1)H-NMR and X-ray crystallographic techniques. X-ray crystallography shows that one of the complexes, 2a, forms a chiral coordination polymer due to bridge formation with Li(+) associated with the complex, although the ligand is achiral. Complex 2 was employed for catalytic synthesis of cyclic carbonates from epoxides and carbon dioxide (CO2) in a solvent free condition. A strong influence of the substituents on the ligand 1 was revealed by the varied activity of complex 2. The presence of electron withdrawing groups such as chloro (2b) and nitro (2c) increases the Lewis acidity of the catalyst, which, in turn, enhances the catalytic activity of 2. An electron withdrawing group containing complexes (2b and 2c) showed exceptionally high catalytic activity with a turnover frequency (TOF) of 662 and 602 h(-1) respectively at 130 °C and 300 psig CO2 pressure. On the other hand, our studies indicate that a catalyst with an electron releasing group (2d) showed relatively lower activity with a TOF of 488 h(-1) under similar reaction conditions. Our results show that cobalt(iii) complexes follow the reactivity order of 2d < 2a < 2c < 2b.