Organo-soluble photoresponsive azo thiol monolayer-protected gold nanorods.

Organo-soluble photoresponsive azo thiol monolayer-protected gold nanorods were synthesized; the resulting gold nanorods encapsulated by thiols on their entire surface with strong covalent Au-S linkages were very stable in both organic solvents and in the solid state without aggregation or decomposition.

A facile synthesis of aliphatic thiol surfactant with tunable length as a stabilizer of gold nanoparticles in organic solvents.

Three new aliphatic thiol surfactants were synthesized by reacting alkyl bromide with hexamethyldisilathiane under a mild condition. This approach provides an easy access for the direct synthesis of various different length thiol surfactants which play a crucial role in tuning the properties of gold nanoparticles. Gold nanoparticles encapsulated with one of our synthetic thiols were prepared and well characterized by H NMR, UV-vis, FT-IR, and TEM. The hybrid nanoparticles are very stable in both organic solvents and the solid state.

A colorimetric titration method for quantification of millimolar glucose in a pH 7.4 aqueous phosphate buffer.

3-Pyridinylboronic acid is identified as a key sensing element for reversible sugar complexation in an aqueous solution at the physiological pH. The utility of a sensing element has been demonstrated through a simple colorimetric titration of glucose using absorption spectroscopy in the visible region. The mechanism of the high diol/triol binding affinity of pyridine boronic acid in the neutral pH is discussed based on the 1H and 11B NMR spectroscopic studies.

Photochemical patterning of a self-assembled monolayer of 7-diazomethylcarbonyl-2,4,9-trithiaadmantane on gold films via Wolff rearrangement.

Photolithographic attachment of functional organic molecules via ester or amide linkages to self-assembled monolayers (SAMs) on gold thin films was achieved by employing a novel photoreactive surface anchor, 7-diazomethylcarbonyl-2,4,9-trithiaadmantane. The photoreactive SAM was prepared by the spontaneous physical adsorption of the photoreactive surface anchor onto gold surfaces. The alpha-diazo ketone moiety of the SAM was found to display the classical Wolff rearrangement reactivity to produce a ketene intermediate on the exposed area. Organic molecules such as alcohols and amines can thus be attached to the gold surfaces selectively by the facile in situ formation of ester or amide linkages. The structure and reactivity of the photoreactive surface anchor were characterized by real-time FT-IR, fluorescence, and polarization modulation infrared reflectance absorption spectroscopy (PM-IRRAS). The Wolff rearrangement reactivity of the SAM suggested that a "surface-isolated" carbonylcarbene may be generated when the SAM was exposed to 255-nm irradiation.