The analysis of atom-to-atom and/or residue-to-residue contacts remains a favoured mode of analysing the molecular packing in crystals. In this contribution, additional tools are highlighted as methods for analysis in order to complement the `crystallographer's tool', PLATON [Spek (2009). Acta Cryst. D65, 148–155]. Thus, a brief outline of the procedures and what can be learned by using Crystal Explorer [Spackman & Jayatilaka (2009). CrystEngComm11, 19–23] is presented. Attention is then directed towards evaluating the nature, i.e. attractive/weakly attractive/repulsive, of specific contacts employing NCIPLOT [Johnson et al. (2010). J. Am. Chem. Soc. 132, 6498–6506]. This is complemented by a discussion of the calculation of energy frameworks utilizing the latest version of Crystal Explorer. All the mentioned programs are free of charge and straightforward to use. More importantly, they complement each other to give a more complete picture of how molecules assemble in molecular crystals.
A new era of metal-based drugs started in the 1960s, heralded by the discovery of potent platinum-based complexes, commencing with cisplatin [(H3N)2PtCl2], which are effective anti-cancer chemotherapeutic drugs. While clinical applications of gold-based drugs largely relate to the treatment of rheumatoid arthritis, attention has turned to the investigation of the efficacy of gold(I) and gold(III) compounds for anti-cancer applications. This review article provides an account of the latest research conducted during the last decade or so on the development of gold compounds and their potential activities against several cancers as well as a summary of possible mechanisms of action/biological targets. The promising activities and increasing knowledge of gold-based drug metabolism ensures that continued efforts will be made to develop gold-based anti-cancer agents.
Despite being disparaged for their malodorous and toxic demeanour, compounds of selenium, a bio-essential element, and tellurium, offer possibilities as therapeutic agents. Herein, their potential use as drugs, for example, as anti-viral, anti-microbial, anti-inflammatory agents, etc., will be surveyed along with a summary of the established biological functions of selenium. The natural biological functions of tellurium remain to be discovered.
Crystal structures of transition and main group element 1,1-dithiolates are shown to be partially sustained by C–H⋯π(chelate) interactions. For the planar binary bisdithiocarbamates, C–H⋯π(MS2C) interactions lead to aggregation patterns ranging from a 0-D four molecule aggregate to a 3-D architecture but with the majority of structures featuring 1-D or 2-D supramolecular assemblies.
Au⋯π interactions whereby the electron-rich π-system of C6-aromatic rings interact with gold are shown to exist in the crystal structures of both gold(I) and gold(III) complexes, and have been revealed to occur between neutral/neutral, cationic/cationic, and cationic/anionic systems. Supramolecular aggregation facilitated by Au⋯π interactions leads to the formation of 0-dimensional aggregates, e.g. arising from an interaction between a gold complex and a solvent molecule, loosely associated spherical aggregates, e.g. cooperative interactions between centrosymmetrically related gold complexes, and even extended supramolecular polymeric chains of variable topology (e.g. linear, step ladder, and helical). The described Au⋯π interactions represent a new synthon in structural gold chemistry that should be considered in any complete analysis of their crystal structures.