Suitably modified linear conjugated poly(arylene ethynylene)s are able to assist effective debundling and dispersion of crude as-prepared single-walled carbon nanotube powders in organic solvents, the dispersion of which is effected via a surface coating mechanism and, to some extent, in a size-selective fashion.

We present and analyze a method to improve the morphology and mechanical properties of gold thin films for use in optical sensors or other settings where good adhesion of gold to a substrate is of importance and where controlled topography/roughness is key. To improve the adhesion of thermally evaporated gold thin films, we introduce a gold deposition step on SU-8 photoresist prior to UV exposure but after the pre-bake step of SU-8 processing. Shrinkage and distribution of residual stresses, which occur during cross-linking of the SU-8 polymer layer in the post-exposure baking step, are responsible for the higher adhesion of the top gold film to the post-deposition cured SU-8 sublayer. The SU-8 underlayer can also be used to tune the resulting gold film morphology. Our promoter-free protocol is easily integrated with existing sensor microfabrication processes.

The bonding in an unusual nickel carbide polymer network synthesized by Musanke and Jeitschko is analyzed using qualitative, band-structure calculations in the framework of extended Hiickel tight-binding theory. The carbide features infinite, one-dimensional, vertex-sharing chains of Ni squares. Each square is centered by a carbon and flanked by C₂ units. - In this electron-rich polymer, the Ni atoms act as electron acceptors through their s and p orbitals. The orbital interaction schemes reveal that there is little Ni-Ni bonding and essentially no Ni to C₂ back-donation. Molecular orbital interaction diagrams of some molecular models are used to describe the bonding in ¹ _∞[Ni₃Cs]^8-. We also discuss the stability of the planar building block of the polymer, (CNi₄)^4- (which resembles planar CH₄) with respect to a “tetrahedral” alternative and we do so for the extended ¹ _∞[ Ni₃C]^4-and ¹ _∞[Ni₃C₅]^8-chains. In each model case the tetrahedral alternative is favored, and there is no sign of stabilization of a crucial CL₄ orbital. Such stabilization is partially achieved through bonding to two Ca axial to the C in the center of the Ni₄ ring, but it takes the entire inter-chain calcium network to effect the observed stabilization.

We show that a simple approach to building small computationally inexpensive clusters offers insights on specific structural motifs that stabilize the electronic structure of ZnO. All-electron calculations on Zn_iO_i needle (i = 6, 9, 12, 15, and 18) and plate (i = 9 and 18) clusters within the density functional theory (DFT) formalism show a higher stability for ZnO needles that increases with length. Puckering of the rings to achieve a more wurtzite-like structure destabilizes the needles, although this destabilization is reduced by going to infinite needles (calculated using periodic boundary conditions). Calculations of density of states (DOS) curves and band gaps for finite clusters and infinite needles highlight opportunities for band-gap tuning through kinetic control of nanocrystal growth.