Abstract. The structure and protein resistance of oligo(ethylene glycol)-terminated self-assembled monolayers (OEG-SAMs) have intensively been studied by various techniques. However, their molecular-scale surface structure has not been well understood. In this study, we performed molecular-resolution imaging of OHterminated SAMs (OH-SAMs) and hexa(ethylene glycol) SAMs (EG 6 OH-SAMs) formed on a Au(111) surface in aqueous solution by frequency modulation atomic force microscopy (FM-AFM). The results show that most of the ethylene glycol (EG) chains in an EG 6 OH-SAM are closely-packed and well-ordered to present a molecularlyflat surface even in aqueous solution. In addition, we found that EG 6 OH-SAMs have nanoscale defects, where molecules take a disordered arrangement with their molecular axis parallel to the substrate surface. We also found that the domain size (50-200 nm) of an EG 6 OH-SAM is much larger than that of OH-SAMs (10-40 nm). These findings should significantly advance molecular-scale understanding on the surface structure of OEG-SAMs.

Self-sorting, in which multiple components selectively assemble themselves by recognising self from others, is an attractive approach to produce supramolecular assemblies with controlled structures. Lock-and-key type complementary physical interactions are required for self-sorting because selective affinity is necessary to distinguish self from others. Here we show self-sorting behaviour based on a principle of geometrical complementarity by shape during our investigation of assembly of pentagonal pillar[5]arenes and hexagonal pillar[6] arenes on a surface. In the homoassembly systems, anionic pillar[5]arenes and pillar[6]arenes are adsorbed onto positively charged layers of cationic pillar[5]arenes and pillar[6]arenes, respectively, through cationic-anionic electrostatic interactions. In contrast, ionic pillar[5] arenes are adsorbed onto layers constructed from oppositely charged pillar[5]arenes, but ionic pillar[6]arenes are not. Equally, for the reverse combination, ionic pillar[6]arenes are adsorbed onto layers constructed from oppositely charged pillar[6]arenes, but ionic pillar[5] arenes are not. The geometrical complementarity by shape realises effective self-sorting even in non-directional multivalent ionic interactions.

A simple methylenedioxy dibromoindole alkaloid, amakusamine (1), was isolated from a marine sponge of the genus Psammocinia, and its structure was determined from spectroscopic data, time-dependent density-functional theory calculations, and synthesis. Compound 1 inhibited the receptor activator of nuclear factor-κB ligand (RANKL)-induced formation of multinuclear osteoclasts with an IC 50 value of 10.5 μM in RAW264 cells. The structure−activity relationship of 1 was also investigated with synthetic derivatives.

Fifteen new isopimarane-type diterpenes, taichunins E–S (1–15), and a new 20-nor-isopimarane, taichunin T (16), together with four known compounds were isolated from Aspergillus taichungensis (IBT 19404). The structures of these new compounds were determined by NMR and mass spectroscopy, and their absolute configurations were analyzed by NOESY and TDDFT calculations of ECD spectra. Taichunins G, K, and N (3, 7, and 10) completely inhibited the receptor activator of nuclear factor-κB ligand (RANKL)-induced formation of multinuclear osteoclasts in RAW264 cells at 5 μM, with 3 showing 92% inhibition at a concentration of 0.2 μM.

No abstract