Optical response of monolayer films of a metal-free sulfonamido-porphyrin

The influence of gaseous chlorine on monolayers of metal-free meso-tetra(4-amino sulfonyl)phenylporphyrin is discussed. These films exhibit characteristic intense optical absorption bands in the region 400-700 nm. Upon exposure to chlorine vapour in the concentration range 0.1-10 ppm, the Soret and Q-bands decrease in intensity and new bands at ~455 nm and ~660 nm appear. The rate of response has been measured as a function of deposition surface pressure and gas concentration. Repeated dosing experiments have shown that reversible and reproducible sensing action occurs provided that a threshold concentration is not exceeded. The recovery of the original optical spectrum can be accelerated with moderate heat treatment (60°C for 10 min). Ageing experiments have shown that the basic response of the monolayer is not effected over a time period of at least 5 months.http://www.sciencedirect.com/science/article/B6TW0-3VV0K4W-2D/1/d4a4ed344aa0216ef5d8648dd4c7102

Conformation analysis and binding affinity determination for host-guest complexation of alkali metal ion with Bis (Crown Ether)s by electrospray mass spectrometry and molecular modeling

[[abstract]]This study presents the application of electrospray ionization mass spectrometry (ESI/MS) to investigate the host–guest complexation phenomenon for an array of alkali metal ions with bis[(benzo-15-crown-5)-15-ylmethyl] pimelate (BBCP). The results have shown that potassium ions possess the best binding affinity with the BBCP, owing to formation of the very stable sandwich-type (1 : 1) complexes and the strong K+ cation-p electron interactions between the K+ ion and the benzene rings of BBCP. The results of the competition experiments indicate the selectivity for BBCP toward the alkali metal ions is K+ > Rb+ > Cs+ > Na+ > Li+. In addition, combining the results of ESI/MS and molecular mechanics conformational searches reveal that the formation of sandwich-type (1 : 1) complexes can be observed for larger metal ions including K+, Rb+ and Cs+. As for Na+ ions, both 1 : 1 and 1 : 2 complexes can be observed.[[notice]]補正完畢[[journaltype]]國

Cellular uptake of chloroquine is dependent on binding to ferriprotoporphyrin IX and is independent of NHE activity in Plasmodium falciparum.

Here we provide definitive evidence that chloroquine (CQ) uptake in Plasmodium falciparum is determined by binding to ferriprotoporphyrin IX (FPIX). Specific proteinase inhibitors that block the degradation of hemoglobin and stop the generation of FPIX also inhibit CQ uptake. Food vacuole enzymes can generate cell-free binding, using human hemoglobin as a substrate. This binding accounts for CQ uptake into intact cells and is subject to identical inhibitor specificity. Inhibition of CQ uptake by amiloride derivatives occurs because of inhibition of CQ-FPIX binding rather than inhibition of the Na+/H+ exchanger (NHE). Inhibition of parasite NHE using a sodium-free medium does not inhibit CQ uptake nor does it alter the ability of amilorides to inhibit uptake. CQ resistance is characterized by a reduced affinity of CQ-FPIX binding that is reversible by verapamil. Diverse compounds that are known to disrupt lysosomal pH can mimic the verapamil effect. These effects are seen in sodium-free medium and are not due to stimulation of the NHE. We propose that these compounds increase CQ accumulation and overcome CQ resistance by increasing the pH of lysosomes and endosomes, thereby causing an increased affinity of binding of CQ to FPIX

Synthesis, characterization and surface properties of 1-N-l-tryptophan-glycerol-ether surfactants

A novel homologous series of 1-N-L-tryptophan-glycerol-ether surfactants was synthesized and characterized. The precursor compounds, 3-alkyloxy-1-chloropropan-2-ols, were prepared from epichlorohydrin and aliphatic alcohols with alkyl chain lengths of 9-16 carbon atoms. Tryptophan was then attached to the monosubstituted glycerol backbone from its α-amino group through an α-NH-C bond. Structural assignment of the new compounds was made on the basis of elemental analysis and spectroscopic data. Critical micelle concentrations of the new surfactants, as well as the negative logs of the surfactant concentrations required to reduce the surface tension of the solvent by 20 mN/m (pC20) and the interfacial areas occupied by the surfactant molecules, were calculated from aqueous surface tension measurements using the Wilhelmy plate technique.Peer reviewe