Anthony C. Coleman

Dispersion of graphene in ethanol using a simple solvent exchange method

A dispersion of graphene in ethanol was achieved using solvent exchange from N-methyl-2-pyrrolidone (NMP) that enables broader application of dispersed graphene.

One-Pot Functionalization of Graphene with Porphyrin through Cycloaddition Reactions

Two types of graphene-based hybrid materials, graphene-TPP (TPP=tetraphenylporphyrin) and graphene-PdTPP (PdTPP=palladium tetraphenylporphyrin), were prepared directly from pristine graphene through one-pot cycloaddition reactions. The hybrid materials were characterized by thermogravimetric analysis (TGA), by TEM, by UV/Vis, FTIR, Raman, and luminescence spectroscopy, and by fluorescence/phosphorescence lifetime measurements. The presence of the covalent linkages between graphene and porphyrin was confirmed by FTIR and Raman spectroscopy and further supported by control experiments. The presence of TPP (or PdTPP) in the hybrid material was demonstrated by UV/Vis spectroscopy, with TGA results indicating that the graphene-TPP and graphene-PdTPP hybrid materials contained approximately 18 % TPP and 20 % PdTPP. The quenching of fluorescence (or phosphorescence) and reduced lifetimes suggest excited state energy/electron transfer between graphene and the covalently attached TPP (or PdTPP) molecules.

Light-induced disassembly of self-assembled vesicle-capped nanotubes observed in real time

Molecular self-assembly is the basis for the formation of numerous artificial nanostructures. The self-organization of peptides, amphiphilic molecules composed of fused benzene rings and other functional molecules into nanotubes is of particular interest. However, the design of dynamic, complex self-organized systems that are responsive to external stimuli remains a significant challenge. Here, we report self-assembled, vesicle-capped nanotubes that can be selectively disassembled by irradiation. The walls of the nanotubes are 3-nm-thick bilayers and are made from amphiphilic molecules with two hydrophobic legs that interdigitate when the molecules self-assemble into bilayers. In the presence of phospholipids, a phase separation between the phospholipids and the amphiphilic molecules creates nanotubes, which are end-capped by vesicles that can be chemically altered or removed and reattached without affecting the nanotubes. The presence of a photoswitchable and fluorescent core in the amphiphilic molecules allows fast and highly controlled disassembly of the nanotubes on irradiation, and distinct disassembly processes can be observed in real time using fluorescence microscopy.

Visible light driven room temperature Pauson-Khand reaction†

Visible light driven decarbonylation of [(mu(2)-alkyne)Co(2)(CO)(6)] complexes enables the formation of cyclopentenones in good yields at ambient temperatures.

Evidence for cobalt-cobalt bond homolysis and wavelength-dependent CO loss in (mu(2)-Alkyne)Co-2(CO)(6) complexes

Time-resolved infrared spectroscopy was used to probe the photochemistry of three (μ(2)-alkyne)Co(2)(CO)(6) complexes. The data indicate the formation of a triplet diradical species, with lifetimes in the range 38-71 ps. Theoretical calculations support these experimental findings. No evidence for the CO loss species, (μ(2)-alkyne)Co(2)(CO)(5), was observed, and this is rationalized by the low quantum yield for this process at the excitation wavelengths used.

Optically induced cis-trans isomerisation of (η6-cis-stilbene)Cr(CO)3

The femto- and picosecond time resolved spectroscopy of (eta(6)-cis-stilbene)Cr(CO)(3) provides evidence for three optically accessible excited states one leading to cis-trans isomerisation of the coordinated stilbene ligand and another which results in a slow release of CO.