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In many established methods, identification of hydrogen bonds (H-bonds) is primarily based on pairwise comparison of distances between atoms. These methods often give rise to systematic errors when sulfur is involved. A more accurate method is the non-covalent interaction index, which determines the strength of the H-bonds based on the associated electron density and its gradient. We applied the NCI index on the active site of a single-cysteine peroxiredoxin. We found a different sulfur hydrogen-bonding network to that typically found by established methods and we propose a more accurate equation for determining sulfur H-bonds based on geometrical criteria. This new algorithm will be implemented in the next release of the widely-used CHARMM program (version 41b) and will be particularly useful for analyzing water molecule-mediated H-bonds involving different atom types. Furthermore, based on the identification of the weakest sulfur-water H-bond, the location of hydrogen peroxide for the nucleophilic attack by the cysteine sulfur can be predicted. In general, current methods to determine H-bonds will need to be reevaluated, thereby leading to better understanding of the catalytic mechanisms in which sulfur chemistry is involved.

After Heitler and London published their pioneering work on the application of quantum mechanics to chemistry in 1927, it became an almost unquestioned dogma that chemistry would soon disappear as a discipline of its own rights. Reductionism felt victorious in the hope of analytically describing the chemical bond and the structure of molecules. The old quantum theory has already produced a widely applied model for the structure of atoms and the explanation of the periodic system. This paper will show two examples of the entry of quantum physics into more classical fields of chemistry: inorganic chemistry and physical chemistry. Due to their professional networking, George Hevesy and Michael Polanyi found their ways to Niels Bohr and Fritz London, respectively, to cooperate in solving together some problems of classical chemistry. Their works on rare earth elements and adsorption theory throws light to the application of quantum physics outside the reductionist areas. They support the heuristic and persuasive value of quantum thinking in the 1920–1930s. Looking at Polanyi’s later oeuvre, his experience with adsorption theory could be a starting point of his non-justificationist philosophy.

Textbooks and encyclopedias represent different genres of scientific literature. Textbooks help the students to prepare for their examinations in various subjects taught at schools, such as logic, metaphysic, chemistry. In the 17th Century some Calvinist professors, mostly in Germany, thought that a universal wholeness should be taught for the students. Encyclopedias adequately expressed this vision. Some of these professors, including Johannes Alsted, were invited to Hungary, Transylvania, to introduce the encyclopedic spirit to the local schools. This act fostered the first textbook in Hungarian language written by Janos Apaczai Csere. This book was an encyclopedia born mostly in the Netherlands where the author studied. The Cartesian philosophy combined with a Ramist system served as the basis of the book. Its history shows how the local conditions influence the content of knowledge incorporated into a textbook.

The UV absorption of KCl crystals grown at different rates from aqueous solutions containing SnCl2 and PbCl2 in various concentrations was investigated as a function of the concentration of dopants built-in into the crystal. With increasing dopant concentration characteristic changes were observed in the absorption spectra at about 10−2 mole% concentration in the case of the non-isomorphic Sn dopant, and at 2×10−1 mole% in the case of the isomorphic Pb. The changes indicate that the manner in which the dopants are incorporated into and distributed within the crystal differs from that at lower dopant concentrations.