Multivalent interactions occur frequently between biological entities.1 When strong binding is not achievable with a single receptor-ligand pair, multivalency, or simultaneous binding between multiple receptors and ligands, becomes an effective strategy to enhance the binding. Significant efforts have been devoted in recent years to synthetic multivalent ligands and their interactions with biological hosts.2 Two of the most widely used scaffolds in multivalency are dendrimers and gold nanoparticles protected with functionalized thiols.

A single- and a double-tailed cationic surfactant with the triallylammonium headgroup formed reverse micelles (RMs) in heptane/chloroform containing a small amount of water. The reverse micelles were cross-linked at the interface upon UV irradiation in the presence of a water-soluble dithiol cross-linker and a photoinitiator. The resulting interfacially cross-linked reverse micelles (ICRMs) of the single-tailed surfactant aggregated in a solvent-dependent fashion, whereas those of the double-tailed were identical in size as the corresponding RMs. The ICRMs could extract anionic metal salts, such as AuCl(4)(-) and PtCl(6)(2-), from water into the organic phase. Au and Pt metal nanoparticles were produced upon reduction of metal salts. The covalent nature of the ICRMs made the template synthesis highly predictable, with the size of the metal particles controlled by the amount of the metal salt and the method of reduction. Nanoalloys were obtained by combining two metal precursors in the same reaction. Reduction of the ICRM-entrapped aurate also occurred without any external reducing agents, and the gold nanoparticles differed dramatically from those obtained through sodium borohydride reduction. The same template allowed the preparation of luminescent Au(4), Au(8), and Au(13)-Au(23) clusters, as well as gold nanoparticles several nanometers in size, simply by using different amounts of gold precursor and reducing conditions.

Hydrophobic guests such as pyrene could be readily trapped inside the micelles of an alkynylated surfactant in the presence of an azide-functionalized cross-linker using the click reaction. The cross-linker was designed to contain cleavable bonds such as geminal diol, disulfide, and acetal. The resulting pyrene-containing watersoluble nanoparticle was under electrostatic stress when diluted below the CMC of the surfactant. Extremely rapid (<1 >min) release of the hydrophobic content was observed when the cross-linker was cleaved. This method combines the ease of physical entrapment and the precision of chemical ligation, and potentially is highly useful in the delivery and controlled release of pharmaceutical agents. Disciplines Chemistry CommentsReprinted (adapted) Abstract: Hydrophobic guests such as pyrene could be readily trapped inside the micelles of an alkynylated surfactant in the presence of an azide-functionalized cross-linker using the click reaction. The cross-linker was designed to contain cleavable bonds such as geminal diol, disulfide, and acetal. The resulting pyrene-containing water-soluble nanoparticle was under electrostatic stress when diluted below the CMC of the surfactant. Extremely rapid (<1 min) release of the hydrophobic content was observed when the cross-linker was cleaved. This method combines the ease of physical entrapment and the precision of chemical ligation, and potentially is highly useful in the delivery and controlled release of pharmaceutical agents.

A novel class of helical nonracemic tubular coordination polymers, which can immobilize a wide range of solvents at very low concentrations, have been synthesized for the first time in the absence of chiral influences and appended groups.

We herein demonstrate a new gelation mechanism based on a readily available coordination polymer {Zn(bibp)(2)(OSO(2)CF(3))(2)}(n), in which ultrasound changes the morphology of the material from sheetlike microparticles into nanofibers, resulting in the immobilization of organic solvents.