Biomembranes constitute the boundary between the living organism and the external environment, and their function is essential for maintaining biological activities. Quantitative understanding and precise control of the transport and conversion of various substances across biomembranes are important issues in biophysics and cell biology, but dealing with biomembranes, which are multi-component, heterogeneous, and complex systems, is not an easy task. In the Current Topics, investigators who are boldly tackling this area of research introduce recent advances in biophysical and molecular biological aspects and technology.

The linear 1,3-diol structure is a common motif in biologically active molecules. C-H functionalization at an α-position of alcohols leads to efficient synthesis of sugars and polyols. However, regioselective conversions at the alcohol α-position of linear 1,3-diols have been limited. Nakao et al. developed secondary-alcohol-selective C-H alkylation of 1,3-butane diol by combining an acridinium photoredox catalyst and a thiophosphoric acid hydrogen atom transfer (HAT) catalyst. The use of DCM as a solvent with a relatively small dipole moment improved secondary α-alkoxy C-H selectivity by making the C-H abstraction process the rate-limiting step.

Hardness is a critical quality characteristic of pharmaceutical oral jelly. The purpose of this study is to determine the hardness using time-domain NMR (TD-NMR). After measurement of the T2 relaxation curves of the test jellies by TD-NMR, the acquired data were analyzed by partial least squares (PLS) regression analysis. Eventually, an accurate and reliable PLS model was created that enabled accurate assessment of the hardness of the test jellies. TD-NMR enables the measurement of samples nondestructively and rapidly with low cost, and so could be a promising method for evaluation of the hardness of pharmaceutical oral jellies.

This paper describes acid-mediated aryne generation from o-triazenylarylboronic acids. The authors previously reported these practical aryne precursors generate arynes by the treatment with silica gel. In this paper, they reported acids including Brønsted acids, Lewis acids, and solid acids are also effective for aryne generation from the precursors. In particular, the use of camphorsulfonic acid provided high yields in reactions with a range of arynophiles, and enabled chemoselective reaction with a furan in the presence of an amine. Hammett plot analyses revealed that an aryne generation mechanism induced by the acid is distinct from the mechanism induced by silica gel.