We have examined the interaction of the human immunodeficiency virustype 1 fusion peptide (23 amino acid residues) and of a Trp-containing analog with vesicles composed of dioleoylphosphatidylcholine, dioleoylphosphatidylethanolamine and cholesterol (molar ratio, 1:1:1). Both the native and the Trp-substituted peptides bound the vesicles to the same extent and induced intervesicular lipid mixing with comparable efficiency. Infrared reflection-absorption spectroscopy data are compatible with the adoption by the peptide of a main beta-sheet structure in a cospread lipid/peptide monolayer. Cryo-transmission electron microscopy observations of peptide-treated vesicles reveal the existence of a peculiar morphology consisting of membrane tubular elongations protruding from single vesicles. Tryptophan fluorescence quenching by brominated phospholipids and by water-soluble acrylamide further indicated that the peptide penetrated into the acyl chain region closer to the interface rather than into the bilayer core. We conclude that the differential partition and shallow penetration of the fusion peptide into the outer monolayer of a surface-constrained bilayer may account for the detected morphological effects. Such single monolayer-restricted interaction and its structural consequences are compatible with specific predictions of current theories on viral fusion.

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By the bridging action of the 6-chloro-2-hydroxypyridine (Hchp) ligand and the terminal coordination role of the homochiral ligand, (−)/(+)-3-trifluoroacetyl camphor (l-Htfc/d-Htfc), a pair of enantiomerically pure dysprosium­(III) dinuclear complexes, [Dy2(l-tfc)4(chp)2(MeOH)2] (l-1) and [Dy2(d-tfc)4(chp)2(MeOH)2] (d-1), was obtained. Their circular dichroism (CD) spectra verified their enantiomeric nature. Magnetic investigation indicated that they exhibit ferromagnetic interaction and good zero field single-molecule magnet (SMM) properties. The U eff/k values of l-1 and d-1 at 0 Oe are 180.5 and 181.3 K, respectively, which are large values for homochiral Dy­(III) SMMs. A reasonable explanation for the magnetic properties of l-1 and d-1 was supplied by ab initio calculations. Remarkably, magnetic circular dichroism (MCD) investigation revealed that the chiral Dy2 enantiomers show a strong magneto-optical Faraday effect at room temperature, suggesting potential applications in magneto-optical devices.

The ability to modulate the spin states of adsorbed molecules is in high demand for molecular spintronics applications. Here, we demonstrate that the spin state of a corrole complex can be tuned by expanding its fused ring as a result of the modification to the d–π interaction between the metal and ligand. A bicyclo[2.2.2]octadiene-fused copper corrole can readily be converted into a tetrabenzocorrole radical on an Au(111) substrate during the sublimation process. In the scanning tunnelling spectroscopy spectrum, a sharp Kondo resonance appears near the Fermi level on the corrole ligand of the tetrabenzocorrole molecule. In contrast, a non-fused-ring-expanded copper corrole molecule, copper 5,10,15-triphenylcorrole, shows no such Kondo feature. Mapping of the Kondo resonance demonstrates that the spin distribution of the tetrabenzocorrole molecule can be further modified by the rotation of the meso-aryl groups, in a manner that could lead to applications in molecular spintronics.