This review describes recent developments in the chemistry of both first and second generation 99m-technetium-based imaging agents. The material is presented according to the biological target for the agent, and where possible actual images are presented to indicate the type of information available to the clinician. Beta emitting isotopes of rhenium offer a possible method for the in situ treatment of cancerous tissue using analogous targeting strategies to those for technetium. Recent developments in the relevant coordination chemistry of rhenium and their extension to in vitro and in vivo studies are presented.

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The ubiquitous challenge of plastic waste has led to the modern descriptor 'plastisphere' to represent the human-made plastic environment and ecosystem.Here we report a straightforward, rapid method for the deconstruction of various plastic feedstocks into hydrogen and high-value carbons. We use microwaves together with abundant and inexpensive iron-based catalysts as microwavesusceptors to initiate the catalytic deconstruction process. The one-step process typically takes some 30-90 seconds to transform a sample of mechanically-pulverised commercial plastic into hydrogen and (predominantly) multi-walled carbon nanotubes. A high hydrogen yield of 55.6 mmol• − is achieved, with over 97 % of the theoretical mass of hydrogen being extracted from the deconstructed plastic. The approach is demonstrated on widely used, real-world plastic waste. This proof-of-concept advance highlights the potential of plastics waste itself as valuable energy feedstocks for the production of hydrogen and high-value carbon materials.

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Copper diacetyl-bis(N4-methylthiosemicarbazone), Cu(II)ATSM, is a promising agent for imaging hypoxic tissue. Here we present results that provide insight into the chemical and electronic properties underlying previously observed structure-activity relationships. Density functional theory (DFT) calculations on the electronic structures and molecular orbitals of a series of 13 Cu(II)bis(thiosemicarbazone) analogues with different alkylation patterns and with fixed geometries based on the known structure of Cu(II)PTSM showed that the LUMO and the next lowest orbital were very close in energy, and their energy order was strikingly dependent on the ligand alkylation pattern in a way that correlated with hypoxia-selectivity and redox potentials. The LUMOs of Cu(II)ATSM and other hypoxia-selective analogues were predominantly metal-based (leading to a singlet reduced species) while the LUMOs of Cu(II)PTSM and other nonselective analogues were predominantly ligand-based (leading to a triplet reduced species). Upon relaxation of the geometric constraint and full optimization in both Cu(II)ATSM and Cu(II)GTS, the metal-based orbital became the LUMO, and the singlet was the thermodynamically preferred form of the reduced species. Chemical and electrochemical investigation showed that all Cu(II) complexes were reducible, but Cu(I)PTSM and other nonselective analogues dissociated immediately upon reduction with release of ligand (detected by UV-vis) while Cu(I)ATSM and other hypoxia-selective analogues did not. Instead they were rapidly re-oxidized to the Cu(II) complex by molecular oxygen. The reversible electrochemical reduction of nonselective complexes Cu(II)PTSM and Cu(II)GTS became irreversible in the presence of weak acid, whereas that of Cu(II)ATSM was unaffected. In light of these results we present a model to explain the structure-activity relationships on the basis of electronic structure and molecular vibrations.