Perfluoroalkyl compounds are known to exhibit a hydrophobic character on the surface of the material, although the CF bond has a large dipole, which should make the molecular surface polar and hydrophilic. This inconsistency has long been a chemical matter to be solved. Herein, a stratified dipole‐arrays model is proposed: the molecular polar surface can be fully hidden by forming a two‐dimensional aggregate of perfluoroalkyl (Rf) groups; this aggregate is spontaneously induced by dipole–dipole interaction arrays owing to the helical structure of the Rf group. In this model, a ‘short’ Rf group should play the role of a single Rf group with a hydrophilic character, whereas a ‘long’ Rf group should spontaneously form a hexagonal aggregate. To examine this model, Rf‐containing myristic acids with various Rf lengths have been synthesized and their aggregation properties are analyzed by using the Langmuir monolayer technique aided by precise IR spectroscopic analysis.

Ligand-directed Ru(bpy)3 photocatalysts induce chromophore-assisted light inactivation (CALI) of target proteins under visible light irradiation in vitro and within cells. Here, histidine, methionine, and tryptophan residues were oxidized by the singlet oxygen ((1)O2) generated by Ru(bpy)3 with light. The addition of a tyrosyl radical trapper (TRT), such as N'-acyl-N,N-dimethyl phenylenediamine, inhibited peptide/protein oxidation and induced labeling on the tyrosine residue. This mechanistic study suggests that TRT scavenges (1)O2, concomitant with the coupling reaction to the tyrosyl radical generated by Ru(bpy)3. Both CALI and labeling can be regulated by the Ru(bpy)3 photocatalysts in the absence or presence of TRT. Ligand-conjugated Ru(bpy)3 photocatalysts (local environmental single-electron transfer catalysts: LSCs) were used not only for target-selective protein labeling, but also for protein knockdown by CALI.

The authors have performed distortionless atom imaging and force mapping experiments, under a large thermal drift condition at room temperature (RT), using frequency modulation atomic force microscopy (FM-AFM) that had been done previously only at low temperature. In the authors’ experimental scheme, three-dimensional position feedback with atom tracking detects the thermal drift velocity that is constant for a period of time at RT. The detected velocity is then used as the model for implementing the feedforward in order to compensate for the thermal drift. This technique can be expected to be used for precise positioning of the tip-sample in atom manipulation experiments using the FM-AFM at RT.

We have performed simultaneous scanning tunneling microscopy and atomic force microscopy measurements in the dynamic mode using metal-coated Si cantilevers at room temperature. Frequency shift (Δf) and time-average tunneling current (⟨It⟩) images are obtained by tip scanning on the Si(111)-(7×7) surface at constant height mode. By measuring site-specific Δf(⟨It⟩) versus tip-surface distance curves, we derive the force (tunneling current) at the closest separation between the sample surface and the oscillating tip. We observe the drop in the tunneling current due to the chemical interaction between the tip apex atom and the surface adatom, which was found recently, and estimate the value of the chemical bonding force. Scanning tunneling spectroscopy using the same tip shows that the tip is metallic enough to measure local density of states of electrons on the surface.

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