123-61-5Relevant articles and documents
Thermal- and pH-Dependent Size Variable Radical Nanoparticles and Its Water Proton Relaxivity for Metal-Free MRI Functional Contrast Agents
Morishita, Kosuke,Murayama, Shuhei,Araki, Takeru,Aoki, Ichio,Karasawa, Satoru
, p. 8351 - 8362 (2016)
For development of the metal-free MRI contrast agents, we prepared the supra-molecular organic radical, TEMPO-UBD, carrying TEMPO radical, as well as the urea, alkyl group, and phenyl ring, which demonstrate self-assembly behaviors using noncovalent bonds in an aqueous solution. In addition, TEMPO-UBD has the tertiary amine and the oligoethylene glycol chains (OEGs) for the function of pH and thermal responsiveness. By dynamic light scattering and transmission electron microscopy imaging, the resulting self-assembly was seen to form the spherical nanoparticles 10-150 nm in size. On heating, interestingly, the nanoparticles showed a lower critical solution temperature (LCST) behavior having two-step variation. This double-LCST behavior is the first such example among the supra-molecules. To evaluate of the ability as MRI contrast agents, the values of proton (1H) longitudinal relaxivity (r1) were determined using MRI apparatus. In conditions below and above CAC at pH 7.0, the distinguishable r1 values were estimated to be 0.17 and 0.21 mM-1 s1, indicating the suppression of fast tumbling motion of TEMPO moiety in a nanoparticle. Furthermore, r1 values became larger in the order of pH 7.0 > 9.0 > 5.0. Those thermal and pH dependencies indicated the possibility of metal-fee MRI functional contrast agents in the future.
Preferred Binding of Carboxylates by Chiral Urea Derivatives Containing α-Phenylethyl Group
Cortés-Hernández, Mayra,Rojas-Lima, Susana,Hernández-Rodríguez, Marcos,Cruz-Borbolla, Julián,López-Ruiz, Heraclio
, p. 416 - 424 (2016/07/06)
An efficient, simple protocol for the synthesis of a new family of chiral ureas 1 – 4 is described. The binding properties of 1 – 4 toward different anion (acetate, benzoate, fluoride, and chloride) have been studied by1H-NMR titration and have been observed in the case of 4 is a selective receptor for acetate. The theoretical calculation M06/6-311+G(d,p) helped us explain the binding properties observed. The most interesting observation is that this calculated structure is consistent with expected, based on the concept of allylic 1,3-strain (A1,3strain). When chiral caboxylates were studied, urea 1 was the best in discriminating between enantiomers.
Synthesis of isocyanates from nitroalkanes
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, (2008/06/13)
A process for the preparation of aromatic isocyanates from nitroalkanes. A nitromethyl aromatic compound of the general formula: STR1 wherein R and R1 represent hydrogen, halogen, a C1 -C5 alkyl radical, a C1 -C4 alkoxy radical, nitro, isocyanato, an alkoxycarbonylamino, or nitromethyl radical, with R and R1 being the same or different, is heated in the presence of an effective amount of a Lewis acid or Bronsted acid substance to effect a dehydrogenation-isomerization reaction to yield an aromatic isocyanate of the general formula: STR2 The product of the reaction may be recovered as the aromatic isocyanate or the alcohol adduct, a carbamate.
