Search

Abstract: One-dimensional (1D) silver oxide nanoparticle arrays were synthesized by illuminating the composite Langmuir–Blodgett monolayers of porphyrin derivatives/Ag+ and n-hexadecyl dihydrogen phosphate (n-HDP)/Ag+ deposited on carbon-coated copper grids with daylight and then exposing them to air. Transmission electron microscopy (TEM) observation shows that the nanoparticle size is around 3 nm, with the separation of about 2–3 nm. High-resolution TEM (HRTEM) investigation indicates that the particles are made up of Ag2O. Ag nanorods with the width of 15–35 nm and the length of several hundreds of nanometers were synthesized by irradiating the composite Langmuir monolayers of porphyrin derivatives/Ag+ and n-HDP/Ag+ by UV-light directly at the air/water interface at room temperature. HRTEM image and selected-area electron diffraction (SAED) pattern indicate that the nanorods are single crystals with the (110) face of the face-centered cubic (fcc) silver parallel to the air/water interface. The formation of the 1D arrays and the nanorods should be attributed to the templating effect of the linear supramolecules formed by porphyrin derivative or n-HDP molecules in Langmuir monolayers through non-covalent interactions. [Copyright &y& Elsevier]

Monolayers and Langmuir–Blodgett (LB) films of several kinds of porphyrin derivatives that have different substituted alkyl chain length, chain numbers and central metals were studied by π-A isotherms, UV–Vis, polarized UV–Vis and fluorescence spectroscopy and low angle X-ray diffractometry (LAXD). The orientation angles of porphyrin rings and alkyl chains were derived from the polarized UV–Vis spectra and LAXD patterns of the monolayers or LB films, respectively. The rings of the freebase porphyrins with different alkyl chain length or number have similar orientation angles in the films due to the same hydrophilic groups on the rings, and those of metal porphyrins have different orientation angles from each other. The orientation of the alkyl chains is related to the special positions of the chains on the rings and the orientation of the rings. The influences of the hydrophilicity of the hydrophilic groups and the alkyl chain number and length on the organization of the supramolecular assemblies of the porphyrin derivatives were discussed. [Copyright &y& Elsevier]

Abstract: Silver dendritic nanostructures and nanoplates were prepared at the solid/liquid interfaces via electroless deposition. Langmuir monolayers of 5,10,15,20-tetra-4-oxy(2-stearic acid) phenyl porphyrin (TSPP) and arachidic acid (AA) were formed at the air/AgNO3 aqueous solution interface. These nanostructures were produced when carbon-coated copper grids were covered on the Langmuir monolayers at lower (<20°C) and higher (20–50°C) temperature, respectively, and the branches are composed of parallel aligned nanobelts with their (110) face parallel to the interface. The formation of the nanostructures should be attributed to the galvanic reduction of Ag+ ions by copper, the electronic conductivity of the carbon layer, the templating effect of the Langmuir monolayer, and the non-equilibrium growth and aggregation of silver nanoparticles at the interface. This is a convenient avenue to produce metal nanostructures. [Copyright &y& Elsevier]