Copper-catalyzed reaction of aziridine for the synthesis of substituted imidazolidine and imidazolidinone.

Herein we report a copper-catalyzed synthesis of imidazolidine by employing the reaction of aziridine with imine. The reaction smoothly provided a diverse range of 2-substituted imidazolidines with high compatibility with various functional groups. Moreover, during our investigation, we discovered that isocyanate also reacted with aziridine to yield substituted imidazolidinones efficiently. The versatility of these reactions was further demonstrated by their application in the synthesis of hybrid molecules derived from two pharmaceutical compounds. This approach opens new possibilities for the discovery of novel classes of bioactive molecules.

Comparison of atomic force microscopy force curve and solvation structure studied by integral equation theory.

Atomic force microscopy can observe structures of liquids (solvents) on solid surfaces as oscillating force curves. The oscillation originates from the solvation force, which is affected by the interaction between the probe, substrate, and solvents. To investigate the effects of the interactions on the force curve, we calculated the force curves by integral equation theory with various probe and substrate conditions. The probe solvophilicity affected the force curves more than the substrate solvophilicity in our calculation, and its reason is qualitatively explained by the amount of the desolvated solvents. We evaluated the probes and parameters in terms of the qualitative estimation of the number density distribution of the solvent on the wall. The negative of the force curve's derivative with respect to the surface separation reflected the number density distribution better than the force curve. This parameter is based on the method that is proposed previously by Amano et al. [Phys. Chem. Chem. Phys. 18, 15534 (2016)]. The normalized frequency shift can also be used for the qualitative estimation of the number density distribution if the cantilever amplitude is small. Solvophobic probes reflected the number density distribution better than the solvophilic probes. Solvophilic probes resulted in larger oscillation amplitudes than solvophobic probes and are suitable for measurements with a high S/N ratio.

Stratification of Colloidal Particles on a Surface: Study by a Colloidal Probe Atomic Force Microscopy Combined with a Transform Theory.

Colloidal probe atomic force microscopy (CP-AFM) can be used for measuring force curves between the colloidal probe and the substrate in a colloidal suspension. In the experiment, an oscillatory force curve reflecting the layer structure of the colloidal particles on the substrate is usually obtained. However, the force curve is not equivalent to the interfacial structure of the colloidal particles. In this paper, the force curve is transformed into the number density distribution of the colloidal particles as a function of the distance from the substrate surface using our newly developed transform theory. It is found by the transform theory that the interfacial stratification is enhanced by an increase in an absolute value of the surface potential of the colloidal particle, despite a simultaneous increase in a repulsive electrostatic interaction between the substrate and the colloidal particle. To elucidate the mechanism of the stratification, an integral equation theory is employed. It is found that crowding of the colloidal particles in the bulk due to the increase in the absolute value of the surface potential of the colloidal particle leads to pushing out some colloidal particles to the wall. The combined method of CP-AFM and the transform theory (the experimental-theoretical study of the interfacial stratification) is related to colloidal crystallization, glass transition, and aggregation on a surface. Thus, the combined method is important for developments of colloidal nanotechnologies.

Number Density Distribution of Small Particles around a Large Particle: Structural Analysis of a Colloidal Suspension.

Some colloidal suspensions contain two types of particles-small and large particles-to improve the lubricating ability, light absorptivity, and so forth. Structural and chemical analyses of such colloidal suspensions are often performed to understand their properties. In a structural analysis study, the observation of the number density distribution of small particles around a large particle (gLS) is difficult because these particles are randomly moving within the colloidal suspension by Brownian motion. We obtain gLS using the data from a line optical tweezer (LOT) that can measure the potential of mean force between two large colloidal particles (ΦLL). We propose a theory that transforms ΦLL into gLS. The transform theory is explained in detail and tested. We demonstrate for the first time that LOT can be used for the structural analysis of a colloidal suspension. LOT combined with the transform theory will facilitate structural analyses of the colloidal suspensions, which is important for both understanding colloidal properties and developing colloidal products.

Correction: Number density distribution of solvent molecules on a substrate: a transform theory for atomic force microscopy.

Correction for 'Number density distribution of solvent molecules on a substrate: a transform theory for atomic force microscopy' by Ken-ichi Amano et al., Phys. Chem. Chem. Phys., 2016, 18, 15534-15544.

Number density distribution of solvent molecules on a substrate: a transform theory for atomic force microscopy.

Atomic force microscopy (AFM) in liquids can measure a force curve between a probe and a buried substrate. The shape of the measured force curve is related to hydration structure on the substrate. However, until now, there has been no practical theory that can transform the force curve into the hydration structure, because treatment of the liquid confined between the probe and the substrate is a difficult problem. Here, we propose a robust and practical transform theory, which can generate the number density distribution of solvent molecules on a substrate from the force curve. As an example, we analyzed a force curve measured by using our high-resolution AFM with a newly fabricated ultrashort cantilever. It is demonstrated that the hydration structure on muscovite mica (001) surface can be reproduced from the force curve by using the transform theory. The transform theory will enhance AFM's ability and support structural analyses of solid/liquid interfaces. By using the transform theory, the effective diameter of a real probe apex is also obtained. This result will be important for designing a model probe of molecular scale simulations.