Structure and Dynamics in Self-Organized C60 Fullerenes
Abstract:This manuscript on 'structure and dynamics in self-organized C60 fullerenes' has three sections dealing with: (A) pristine C60 aggregate structure and geometry in solvents of varying dielectric constant. Here, using positronium (Ps) as a fundamental probe which maps changes in the local electron density of the microenvironment, the onset concentration for stable C60 aggregate formation and its phase behavior is deduced from the specific interactions of the Ps atom with the surrounding. (B) A novel methanofullerene dyad, based on a hydrophobic (acceptor C60 moiety)-hydrophilic (bridge with benzene and ester functionalities)-hydrophobic (donor didodecyloxybenzene) network is chosen for investigation of characteristic self-assembly it undergoes leading to supramolecular aggregates. The -electronic amphiphile, necessitating a critical dielectric constant ≥ 30 in binary THF–water mixtures, dictated the formation of bilayer vesicles as precursors for spherical fractal aggregates upon complete dyad extraction into a more polar water phase. (C) While the molecular orientation is dependent on the packing density, the ordering of the molecular arrangement, indispensable for self-assembly depends on the balance between the structures demanded by intermolecular and molecule-substrate interactions. The molecular orientation in a monolayer affects the orientation in a multilayer, formed on the monolayer, suggesting the possibility of the latter to act as a template for controlling the structure of the three dimensionally grown self-assembled molecular aggregation. A systematic study on the electronic structure and orientation associated with C60 functionalized aminothiol self-assembled monolayers on Au(111) surface is presented using surface sensitive Ultra-Violet Photoelectron Spectroscopy (UPS) and C-K edge Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. The results revealed drastic modifications to d-band structure of Au(111) and the electronic structure was found sensitive towards the S–Au interface and the C60 end functional moiety with formation of localized (S–Au) and (N–C) bonds, respectively. Upon binding C60 to the amine-terminated alkanethiol SAM, a drastically reduced HOMO-LUMO gap of 2.7 eV as compared to a large electronic gap of ∼8 eV in alkanethiols enables the SAM to be a potential electron transport medium.
Document Type: Review Article
Publication date: April 1, 2007
More about this publication?
- Journal for Nanoscience and Nanotechnology (JNN) is an international and multidisciplinary peer-reviewed journal with a wide-ranging coverage, consolidating research activities in all areas of nanoscience and nanotechnology into a single and unique reference source. JNN is the first cross-disciplinary journal to publish original full research articles, rapid communications of important new scientific and technological findings, timely state-of-the-art reviews with author's photo and short biography, and current research news encompassing the fundamental and applied research in all disciplines of science, engineering and medicine.
- Editorial Board
- Information for Authors
- Subscribe to this Title
- Terms & Conditions
- ingentaconnect is not responsible for the content or availability of external websites