Nanographites, their compounds, and film structures

The influence of an adsorbate and edge covalent bonds on topological zero modes in few-layer nanographenes

The existence of zero-energy edge π-electronic states (zero modes) in turbostratic few-layer nanographenes (nanographites) has been established and the sensitivity of their characteristics to the presence of adsorbed chlorine molecules and covalent bonds of halogen with dangling edge carbon orbitals has been studied using a combination of wide- and small-angle X-ray diffraction, Raman spectroscopy, XPS, EPR and magnetic susceptibility experiments. The reversible change in density of the edge π-electronic states found under the influence of an adsorbate has been explained by their spin-splitting initiated with the transfer of a small part of the electron density from the nanographites to the adsorbate. The change of the sign of the temperature coefficient of the current carrier spin relaxation rate caused by the adsorbate has also been accounted for in the framework of this model as a consequence of interaction of mobile spins with edge spin-split (magnetically ordered) states. Our investigations have shown the preservation of π-electronic states with zero energy on chlorine saturation of free (dangling) σ-orbitals of edge carbon atoms.

Hybrid metal complexes with opposed biological modes of action – promising selective drug candidates

The oxidative stress is considered to be involved in the pathogenesis of many diseases. The antioxidative defense system in the living organism regulates the toxic impact of ROS and there is strong evidence that the antioxidants prevent some pathologies including cancer. The specific chemical properties of metal-based drugs impart innovative pharmacological profiles to this type of therapeutic agents, most likely in relation to novel biomolecular mechanisms. This review will focus on a novel approach to design polyfunctional metal-based physiollogically active compounds with opposed modes of action – prooxidant metal center and antioxidant 2,6-dialkylphenol group. The synthesis and anti/prooxidant activity and cytotoxicity studies of novel organometallic/coordination compounds (ferrocenes, complexes with di-(2-picolyl)amine ligand, porphyrins, pyridines, thiols, carboxylates) based on either biogenic metals (Fe, Mn, Co, Cu, Zn, Ni) or exogenic metals (Sn, Au, Rh) are presented and discussed. The results allow us to conclude that combining in one molecule a redox active metal center and cytoprotective functional organic moiety with antioxidative function is a promising way to rational metallodrug design in modern medicinal chemistry.