Six-membered cyclic semiaminal as intermediate in the synthesis of thiazoles from thiosemicarhazide and α-haloketones

Cyclization of thiosemicarbazide with methyl 3-chloro-2-oxo-3-phenylpropionate in MeCN results in 5-hydroxy-2-imino-5-methoxycarbonyl-6-phenylperhydro-1,3,4-thiadiazine. The structure of the product has been confirmed using spectral (IR,1H,13C,13C{1H} NMR) methods and chemical transformations. © 1994 Plenum Publishing Corporation

Tuning the non-covalent confinement of Gd(III) complexes in silica nanoparticles for high T<inf>1</inf>-weighted MR imaging capability

© 2016 Elsevier B.V.The present work introduces deliberate synthesis of Gd(III)-doped silica nanoparticles with high relaxivity at magnetic field strengths below 1.5 T. Modified microemulsion water-in-oil procedure was used in order to achieve superficial localization of Gd(III) complexes within 40–55 nm sized silica spheres. The relaxivities of the prepared nanoparticles were measured at 0.47, 1.41 and 1.5 T with the use of both NMR analyzer and whole body NMR scanner. Longitudinal relaxivities of the obtained silica nanoparticles reveal significant dependence on the confinement mode, changing from 4.1 to 49.6 mM−1 s−1 at 0.47 T when the localization of Gd(III) complexes changes from core to superficial zones of the silica spheres. The results highlight predominant contribution of the complexes located close to silica/water interface to the relaxivity of the nanoparticles. Low effect of blood proteins on the relaxivity in the aqueous colloids of the nanoparticles was exemplified by serum bovine albumin. T1- weighted MRI data indicate that the nanoparticles provide strong positive contrast at 1.5 T, which along with low cytotoxicity effect make a good basis for their application as contrast agents

Nanoscale hydrophilic colloids with high relaxivity and low cytotoxicity based on Gd(III) complexes with Keplerate polyanions

© The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. The work introduces for the first time Mo-132-type Keplerates (Kp) and Gd 3+ ions as a basis for the one-pot synthesis of aqueous colloids with high longitudinal relaxivity (r 1 = 96.4 mM -1 s -1 at 20 MHz). The hydrophilic coating of small (3-5 nm) Gd x (Kp) y -based cores provides their colloid stabilization, protection from degradation and low cytotoxicity

Tuning the non-covalent confinement of Gd(III) complexes in silica nanoparticles for high T<inf>1</inf>-weighted MR imaging capability

© 2016 Elsevier B.V.The present work introduces deliberate synthesis of Gd(III)-doped silica nanoparticles with high relaxivity at magnetic field strengths below 1.5 T. Modified microemulsion water-in-oil procedure was used in order to achieve superficial localization of Gd(III) complexes within 40–55 nm sized silica spheres. The relaxivities of the prepared nanoparticles were measured at 0.47, 1.41 and 1.5 T with the use of both NMR analyzer and whole body NMR scanner. Longitudinal relaxivities of the obtained silica nanoparticles reveal significant dependence on the confinement mode, changing from 4.1 to 49.6 mM−1 s−1 at 0.47 T when the localization of Gd(III) complexes changes from core to superficial zones of the silica spheres. The results highlight predominant contribution of the complexes located close to silica/water interface to the relaxivity of the nanoparticles. Low effect of blood proteins on the relaxivity in the aqueous colloids of the nanoparticles was exemplified by serum bovine albumin. T1- weighted MRI data indicate that the nanoparticles provide strong positive contrast at 1.5 T, which along with low cytotoxicity effect make a good basis for their application as contrast agents

One-pot embedding of iron oxides and Gd(III) complexes into silica nanoparticles—Morphology and aggregation effects on MRI dual contrasting ability

© 2018 Elsevier B.V. The present work introduces one-pot synthetic route to join ultra-small iron oxides (6 nm) with Gd(III) complexes in small (∼30 nm) silica nanoparticles with high longitudinal and transverse relaxivity values (r1 = 34.7 mM−1 s−1 and r2 = 64.7 mM−1 s−1 at 0.47 T). The design of the nanoparticles is based on the core-shell morphology, where the Gd(III) complexes were doped into the exterior silica layer. The doping mode is the reason for an efficient interfacial hydration and the small suppressing of r1 by iron oxides. The measurements on the whole body scanner at 1.5 T confirm the high contrasting abilities of T1 (Gd) and T2 (iron oxide) components in the nanoparticles. Poor aggregation behavior of the nanoparticles in water is due to high electrokinetic potential value (−78 mV). Greater aggregation of the nanoparticles in the buffer solutions of bovine serum albumin enhances the disturbing effect of iron oxides on the longitudinal relaxation and facilitates the transverse relaxation. The higher surface activity of the nanoparticles results in their greater cytotoxicity versus the silica coated iron oxides, although the cytotoxicity is low in the concentration range which is within the region of interest for MRI technique

Six-membered cyclic semiaminal as intermediate in the synthesis of thiazoles from thiosemicarhazide and α-haloketones

Cyclization of thiosemicarbazide with methyl 3-chloro-2-oxo-3-phenylpropionate in MeCN results in 5-hydroxy-2-imino-5-methoxycarbonyl-6-phenylperhydro-1,3,4-thiadiazine. The structure of the product has been confirmed using spectral (IR,1H,13C,13C{1H} NMR) methods and chemical transformations. © 1994 Plenum Publishing Corporation

Six-membered cyclic semiaminal as intermediate in the synthesis of thiazoles from thiosemicarhazide and α-haloketones

Cyclization of thiosemicarbazide with methyl 3-chloro-2-oxo-3-phenylpropionate in MeCN results in 5-hydroxy-2-imino-5-methoxycarbonyl-6-phenylperhydro-1,3,4-thiadiazine. The structure of the product has been confirmed using spectral (IR,1H,13C,13C{1H} NMR) methods and chemical transformations. © 1994 Plenum Publishing Corporation

Six-membered cyclic semiaminal as intermediate in the synthesis of thiazoles from thiosemicarhazide and α-haloketones

Cyclization of thiosemicarbazide with methyl 3-chloro-2-oxo-3-phenylpropionate in MeCN results in 5-hydroxy-2-imino-5-methoxycarbonyl-6-phenylperhydro-1,3,4-thiadiazine. The structure of the product has been confirmed using spectral (IR,1H,13C,13C{1H} NMR) methods and chemical transformations. © 1994 Plenum Publishing Corporation