Doped Soap Membranes Selectively Permeate a Chiral Isomer

Abstract

Soap films can not only be made with sub-μm thickness, they can have intrinsic permeabilities comparable to many commercial membranes, permitting very high transmembrane flux. Soap films readily incorporate a wide range of modifiers to allow highly tailored selectivity: We show that incorporating α-cyclodextrin in an 890 nm thick Triton-X-100 film allows, in a single stage, a high degree of chirally selective transport (1.6:1) of α(+)-pinene over α(-)-pinene.

Giant optical activity of sugar in thin soap films

“…Since analytical chemistry has been recently used to determine the composition of soap films [15] one may wonder whether films with sugar added could be probed by measuring the optical activity. The aim of the letter is thus to investigate the optical rotary power of glucose in thin soap films depending on the glucose concentration or on the film thickness and to get more insights into its conformation at the air/liquid interface.…”

Conductometric determination of ammonium ion with a mobile drop

“…The gas flow rate affects the exit humidity (very slow flow rates can lead to moisture supersaturation of the exit humidity, potential condensation on exit tube walls and wall losses) and collection efficiency by the drop [35] (at very high gas flow rates, not only the collection efficiency will be poor, the drop shape is distorted and in an extreme case can be dislodged from the electrode. We studied gas flow rates in the 50-600 mL/min range; at 50 mL/min, the observed signals from samples were barely discernible from that of a blank.…”

Nanometer-Thick Newton Black Film for Selective Formaldehyde Gas Detection

“…They also used doped soap films for chiral pinene selective transport. 32 These methods suggest good potential for soap film based assay, benefiting from the large surface area to volume ratio of the film. Inspired by these studies, we recently developed assays using fluorescent pH probe in common black films (CBF) for the detection of ppm level ammonia and ppb level acetic acid.…”

“…Recently, Kanyanee et al utilized a soap bubble to detect subppm levels of SO 2 by monitoring the bubble’s conductance after analyte uptake from the gas phase. They also used doped soap films for chiral pinene selective transport . These methods suggest good potential for soap film based assay, benefiting from the large surface area to volume ratio of the film.…”