Nanoscience and Nanotechnology

Anion-Templated Self-Assembly: Inorganic Compounds Part 1 (Nanotechnology)

INTRODUCTION The use of anions to template the formation of new supramolecular entities is a relatively new approach to self-assembly, but one that is expanding the available number of noncovalent and coordinate bonding motifs for the construction of new interlocked materials and new supramolecular nanoarchitectures.[1-5] Transition metal-directed approaches (e.g., using a transition metal to template […]

Anion-Templated Self-Assembly: Inorganic Compounds Part 2 (Nanotechnology)

Silver Steel and Sumby have recently reported the formation of cages and polymers with silver as the metallic com-ponent.[29,30] Using hexa(2-pyridyl)[3]radialene (22), prepared from reaction of diarylmethyl anions with tet-rachlorocyclopropene[31,32] and reaction of this with silver tetrafluoroborate produces [Ag(222)F(BF4)5-11H2O], a hexametallic cage, with each 22 acting in a hexapodalhexadentate mode (Scheme 4). Within the cavity […]

Atomic Force Microscopy Studies of Metal Ion Sorption Part 2 (Nanotechnology)

Fig. 3 Dynamic force-profile measurements during the adsorption of copper ions by a silica tip for a copper concentration of 1.5 x 10"6 M. Ionic strength = 0.005 M NaCl, pH=5.5, A = 5.43 x 10" 21 J. Metal ion sorption equilibrium using various metal ion concentrations is shown in Fig. 5. At equilibrium, a […]

Anion-Templated Self-Assembly: Organic Compounds Part 1 (Nanotechnology)

INTRODUCTION The field of self-assembly is an increasingly attractive area of supramolecular chemistry. With many principles derived from biological systems, it often enables the synthesis of large, complex structures that would be far too demanding using conventional covalent tech-niques.[1-3] Utilizing weak, reversible, noncovalent interactions, self-assembly can, through rational design of simple ligands, help minimize the […]

Anion-Templated Self-Assembly: Organic Compounds Part 2 (Nanotechnology)

Schalley et al.[54] have ascertained that low yields are often obtained with these rotaxane ”snapping” syntheses because the nucleophilic anion required for rotaxane formation is often buried within the wheel and thus protected against attack of the semiaxle. To circumvent this problem, Ghosh et al.[55] have designed a centerpiece, which contains a phenolate group and […]

Anodization Patterned on Aluminum Surfaces (Nanotechnology)

INTRODUCTION Novel nanofabrication techniques are being explored as alternatives to conventional lithographic techniques to mass produce structures with feature sizes smaller than 100 nm and to minimize costs.[1] Porous anodic aluminum oxide (AAO) is a self-ordered, hexagonal array of straight cylindrical pores with high densities (108-1011 pores/ cm2), tunable diameters (5-250 nm), and depths (a […]

Antibodies and Other Ligand-Receptor Systems with Infinite Binding Affinity (Nanotechnology)

INTRODUCTION Biological molecules such as antibodies show exquisite specificity in binding to target molecules. This binding is naturally reversible, and the stability of the antibody-target complex is often a matter of concern because experiments can be compromised if it dissociates or exchanges with other molecules. Here we describe the current state of molecular technology for […]

Atmospheric Nanoparticles: Formation and Physicochemical Properties Part 1 (Nanotechnology)

INTRODUCTION Atmospheric nanoparticles, defined as particles with spherical equivalent diameters smaller than 50 nm, are either directly emitted from combustion sources, or are formed in the atmosphere by a process called nucleation. They then quickly grow by the condensation of gas monomers or clusters, or by coagulation with other particles, to become a critical participant […]

Atmospheric Nanoparticles: Formation and Physicochemical Properties Part 2 (Nanotechnology)

In reality, there are no pure particles in the atmosphere. If the particle contains a soluble material, then during evaporation it will experience two competing effects: the Kelvin effect, which would require an increase in vapor pressure to stop evaporation, and the solute effect, in which the increase in solute concentration in the particle reduces […]

Atomic Force Microscope Nanolithography on Organized Molecular Films Part 1 (Nanotechnology)

INTRODUCTION The ongoing miniaturization in size and integrity of electronic and mechanic devices has led to an interest in fabrication of nanometer-sized uniform structures on surfaces. With the device downscaling dimensions to the nanometer range, current interest is focused on the state-of-the-art lithographic development such as electron beam lithography, extreme UV lithography, imprint lithography, and […]