Synthesis and Properties of N,N′-Disubstituted Ureas and Their Isosteric Analogs Containing Polycyclic Fragments: III. Synthesis and Properties ofN-[2-(Adamantan-1-yl)ethyl]-N′-R-ureas

Russian Journal of Organic Chemistry - Methods have been developed for the synthesis of N,N′-disubstituted ureas containing an adamantane fragment separated from the urea nitrogen atom by an...     

Synthesis and Properties of N,N′-Disubstituted Ureas and Their Isosteric Analogs Containing Polycyclic Fragments: XIV. N-[(Adamantan-1-yl)(phenyl)methyl]-N′-substituted Ureas and Symmetrical Bis-ureas

Russian Journal of Organic Chemistry - A procedure has been developed for the synthesis of rac-1-[isocyanato(phenyl)methyl]adamantane from rac-2-(adamantan-1-yl)-2-phenylacetic acid in 95% yield....     

Synthesis and properties of symmetrical <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>'-Bis(R-adamantan-1-yl)ureas as target-oriented soluble epoxide hydrolase (sEH) inhibitors

Self-condensation of substituted adamantan-1-yl isocyanates in THF in the presence of DBU afforded 91–96% of symmetrical ureas as target-oriented soluble epoxide hydrolase (sEH) inhibitors. The described reaction avoids the use of the corresponding amine as counterpart. The obtained ureas are characterized by reduced melting points and improved solubility in water.     

Excitonic effects in low density electron-hole plasma in InGaAs/InP quantum wells under magnetic field

The magnetic-field and excitation-density dependencies of the photoluminescence of undoped In_0.53Ga_0.47As/InP single quantum well structures have been investigated. A clear transition from excitonic to free-carrier-like recombination has been observed while changing the electron-hole density from 10¹⁰ to 10¹² cm⁻². Excitonic correlations are found to be well pronounced for carriers at the upper partly occupied Landau levels.     

Pattern formation as a signature of quantum degeneracy in a cold exciton system

The development of a Turing instability to a spatially modulated state in a photoexcited electron-hole system is proposed as a novel signature of exciton Bose statistics. We show that such an instability, driven by kinetics of exciton formation, can result from stimulated processes that build up near quantum degeneracy. The stability of an electron-hole interface which describes recently observed exciton rings is analyzed. Interface instability occurs below a critical temperature, with a periodic 1D pattern developing via a continuous (type II) transition, in a qualitative agreement with observations.