Chemodiversity in the fingerprint analysis of volatile organic compounds (VOCs) of 35 old and 7 modern apple cultivars determined by proton-transfer-reaction mass spectrometry (PTR-MS) in two different seasons.

Volatile organic compounds (VOCs) are chemical species that play an important role in determining the characteristic aroma and flavor of fruits. Apple (Malus × domestica Borkh.) cultivars differ in their aroma and composition of VOCs.

The effect of ligand denticity in size-selective synthesis of calix[n]arene-stabilized gold nanoparticles: a multitechnique approach.

A series of gold nanoparticles (AuNPs) stabilized by monodentate, bidentate, and tridentate thiolate calix[n]arene ligands 1-3 was prepared by using the Brust-Schiffrin two-phase direct synthesis and characterized with NMR spectroscopy, elemental analysis, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The experimental data show that the particular multidentate structure of calix[n]arene derivatives 2 and 3 introduces a control element in the preparation of the gold nanoparticles that allows, in the particular experimental conditions here reported, to obtain very small (≈1 nm) AuNPs. These are the first experimental findings that identify a role of ligand "denticity" in the determination of the nuclearity of nanoparticles.

Gold nanoparticle membranes as large-area surface monolayers.

An aqueous suspension of gold nanoparticles of sizes from 20 to 90 nm can be conjugated with mercaptosuccinic acid and exposed to a second phase of toluene containing an electrostatic coupler, tetraoctylammonium bromide, to organize the gold particles at the interface between water and toluene. The particles have an amphiphilic character similarly to Janus beads. The thus formed membrane can be transferred to a solid surface to yield centimeter-sized densely packed particle layers.