Synthesis of 2-phenylimidazo[2,1-b]benzothiazole derivatives as modulators of multidrug resistance for tumor cells

We have investigated 3-substituted-2-phenylimidazo[2,1-b]benzothiazole derivatives and herein we have discussed their pharmaceutical activities. We found that some 2-phenyl-5,6,7,8-tetrahydroimidazo[2,1-b]-benzothiazoles could overcome multidrug resistance for tumor cells. Among them, 2-phenyl-3-(N-methyl-3-piperidyl)carbonylammomiinomemyl-5,6,7,8-tetrahydVoimidazo[2,1-b]benzothiazole [N276-12] demonstrated the most potent activity for overcoming multidrug resistance.     

Conjugate additions of the crown-potassium enolate complexes

Achiral and chiral crowns complexed with potassium bases catalyze the Michael additions of enolates to cycloalkenones.     

Inclusion of Bisphenols by Cyclodextrin Derivatives

Complexation of various kinds of bisphenols (BPs) with cycloheptaamylose(β-cyclodextrin, β-CD) derivatives (β-CD, hydroxyethyl-β-CD (HE-β-CD), 2,6-di-O-methyl-β-CD (DM-β-CD) and polymerised β-CD (L-Poly-β-CD)) was examined fluorimetrically using2-anilinonaphthalene-6-sulfonic acid (2,6-ANS) as a probe. From the inhibitory effectof BPs on the inclusion of 2,6-ANS by the β-CD derivatives, the associationconstants (K_ass) of BPs with the β-CD derivatives were determined.The K_ass values for bisphenol B (BPB) with β-cyclodextrin derivatives except for L-Poly-β-CD were always larger than those for other BPs including bisphenol A (BPA), due to the interaction between the non-polar cavity and hydrophobic BPB. Thermodynamic parameters indicated that the entropy change was always largely negative (-90～ -120 J/mol...K in the β-CD system, for example), and the inclusion of bisphenols into the CD cavity was completely enthalpy-driven. The very largely negative entropy change might be mainly due to the tight fixation of guest molecules in the CD cavity, resulting in the loss of freedom of both CD and guest molecules. The effect of the structure of guest and host molecules on the association was also examined.     

Electronic-phase transition associated with instability of the Hartree–Fock solution of infinite one-dimensional system

Electronic-phase transition associated with the singlet instability problem of the Hartree-Fock solution of the extended system is studied employing the metallic trans-polyacetylene. Concerning the eigenstates of the stability matrix set up for the crystal orbitals at the Fermi level, classification of the electronic phases is attempted and the origin of their emergence in relation to the interelectronic interaction is discussed.     

Acid-induced conformational switching of aromatic N-methyl-N-(2-pyridyl)amides

Aromatic N-methyl amides containing N-(2-pyridyl) and 2-pyridinecarboxamide or 2,6-pyridinedicarboxamide moieties switch their conformation from cis to trans depending upon the addition of acid.     

Application of Pesticide Quantification in Unpolished Rice by LC-Dopant-Assisted Atmospheric Pressure Photoionization-MS

We applied liquid chromatography-dopant-assisted atmospheric pressure photoionization-mass spectrometry to quantify four distinct pesticides (isoprothiolane, fenitrothion, fthalide, and ethophenprox) in unpolished rice flour. Although the effect of acetone as a dopant on enhancement of ionization differed among the pesticides, the analytical results by LC-DA-APPI-MS with a dopant flow rate of 50 μL min^?1 were not only repeatable (relative SD < 9%, n = 3) but also comparable to those by gas chromatography–mass spectrometry.