Synthesis of N,N,N′,N′-tetrasubstituted 1,3-bis(4-aminophenyl)azulenes and their application to a hole-injecting material in organic electroluminescent devices

After a preliminary search of the reaction conditions for the Suzuki-Miyaura cross-coupling of haloazulenes with arylboronic acids, the title compounds were synthesized either by the direct coupling reaction between 1,3-dihaloazulene and the corresponding N,N-disubstituted 4-aminophenylboronic acids or by a two-step sequence involving the cross-coupling with 4-bromophenylboronic acid and subsequent Pd-catalyzed amination. Application of the title diamines to a hole-injecting material in organic electroluminescent devices was carried out to provide their prominent characteristics as a novel durable, non-cyanine and non-polyamine substance without color fade. The diamine derivatives, extended by an ethynyl unit between the azulenyl core and the 4-aminophenyl moiety, were also synthesized and found, unfortunately, unsuitable for vacuum deposition in preparing a multilayer composite.     

Synthesis and utility of 3-silylthiophenes having perfluoroalkyl groups

The synthesis of a novel class of 3-silyl substituted thiophenes possessing perfluoroalkyl groups on the silicon atom was investigated. The treatment of 3-bromothiophene with n-butyllithium followed by the reaction with halosilanes proceeded to afford the corresponding 3-silyl substituted thiophenes 1 in good yields. The chemical polymerization of the resulting 1 did not work well. However, the electropolymerization of 3-silylthiophenes 1a and 1b provided the corresponding polymers 5a and 5b with head-to-tail regioregularity. The cyclic voltammogram of the resulting polymers 5a and 5b indicated both n- and p-doping properties.     

Molecular Modeling of Human CCR2 Receptor within POPC Lipid Bilayer

Structural Chemistry - Chemokine receptor 2 (CCR2), a G-protein coupled receptor (GPCR), is a critical target for several inflammatory and autoimmune diseases. The main restriction on designing...     

The Eigenvalues of a Class of Elliptic Differential Operators

Consider $\left(M,g\right)$ as an $n$-dimensional compact Riemannian manifold. In this paper we are going to study a class of elliptic differential operators which appears naturally in the study of hypersurfaces with constant mean curvature and also the study of variation theory for $1$-area functional.     

Using a charging coordinate in studies of ionization induced partial unfolding

The ionization of groups in proteins may sometimes involve a partial unfolding and/or water penetration. Unfortunately the corresponding structural changes might not be captured by microscopic free energy perturbation (FEP) approaches due to activation barriers that are not surmounted in nanosecond FEP simulations. This problem is apparent, for example, from mutation experiments that introduced ionizable groups in protein interiors and from the difficulties to reproduce the corresponding pKa changes by microscopic approaches. Here we develop a new general approach for treating such challenging cases. Our approach drives the protein structural change by increasing the charge of the ionized group beyond its physical value and thus overcoming the barriers for the partial unfolding by a physically consistent process. The potential of our approach is illustrated by the evaluation of the pKa of the Val66Glu mutant of staphylococcal nuclease. In this case it is first demonstrated that standard FEP approaches give extremely disappointing results for this pKa. On the other hand, our "overcharging" approach gives a much more realistic result. We believe that the present approach represents a breakthrough in FEP studies of ionizable residues in proteins, and expect this strategy to be useful in studies of a wide range of challenging problems including simulations of hydrogen exchange processes.     

Solvation number and conformation of N,N-dimethylacrylamide and N,N-dimethylpropionamide in the coordination sphere of the cobalt(II) ion in solution studied by FT-IR and FT-Raman spectroscopy.

The solvation number and conformation of N,N-dimethylacrylamide (DMAA) in the coordination sphere of the cobalt(II) ion in solution were studied, and compared with those of N,N-dimethylpropionamide (DMPA) by means of FT-Raman and FT-IR spectroscopy. Both solvents are present as either the planar cis or nonplanar staggered conformer in equilibrium, and the former is more stable in the bulk. As these solvents solvate the metal ion through the carbonyl O atom of the acryl (DMAA) or propionyl (DMPA) group, the solvation structure around the metal ion is highly congested to reduce the solvation number and/or to lead to a conformational geometry change of solvent. It turns out that the solvation number of the cobalt(II) ion is 4 for both DMAA and DMPA at 298 K, and that DMPA changes its conformation upon solvation, whereas DMAA hardly changes. The enthalpy of conformational change DeltaH degrees for DMPA is 5 kJ mol(-1) in the bulk, and is -9 kJ mol(-1) in the coordination sphere of the cobalt(II) ion. On the other hand, the DeltaH degrees value for DMAA is 9 kJ mol(-1) in the bulk.     

Stereoselective hetero Diels-Alder reaction of selenoaldehydes with pentavalent phosphole chalcogenides

Stereoselective hetero Diels-Alder reaction of selenoaldehydes, generated by thermal retro Diels-Alder reaction of anthracene cycloadducts, with pentavalent 3,4-dimethylphosphole chalcogenides at 110 °C in toluene to give the corresponding [4+2] cycloadducts as a single diastereoisomer in good yields, accompanied by a slight scrambling of chalcogen atoms. Higher reaction temperature led to an increase of the scrambling between chalcogen atoms.     

An iridoid glucoside dimer and a non-glycosidic iridoid from the leaves of Lasianthus wallichii

A new iridoid glucoside dimer (1) and a non-glycosidic iridoid (2) was isolated together with the known compounds, asperuloside (3), paederoside (4), daphylloside (5), citroside A (6) and benzyl 6-O-alpha-L-rhamnopyranosyl-beta-D-glucopyranoside (7), from the leaves of Lasianthus wallichii. The structures of the new compounds were elucidated by spectroscopic and chemical evidence.