Conformational studies of 2-anilino-substituted 1,3,2-oxazaphospholanes

A series of 2-anilino-2-thio-1,3,2-oxazaphospholanes derived from ephedrine has been synthesized and conformationally studied by proton NMR and X-ray crystallography. The NMR data can be interpreted in terms of twist-envelope conformations in which the anilino substituents on phosphorus adopt predominantly equatorial positions. X-ray crystal structures of (2R,4S,5S)-2-anilino-2-thio-3,4-dimethyl-5-phenyl-1,3-2-oxazaphospholane, (2R,4S,5S)-2-(4-fluoroanilino)-2-thio-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholane, and (2R,4S,5S)-2-(4-methoxyanilino)-2-thio-3,4-dimethyl-5-phenyl-1,3,2-oxazaphosholane have been carried out, and these compounds adopt envelop, twist-envelope, and twist-envelope conformations, respectively, with the anilino moieties equatorial.     

Conformational analysis of 1,4,7-trithiacyclodecane and related compounds: Synthesis and complexation studies of mesocyclic and macrocyclic polythioethers VI

Molecular mechanics (MM2) calculations have been carried out on the ten-membered ring trithioethers, 1,4,7-trithiacyclodecane (10S3) and 1,4,7-trithiacyclodecan-9-one (keto-10S3). The lowest energy conformations according to these calculations are a [1333] and a [2233] conformation, respectively. The crystal and molecular structure of the ketone, 1,4,7-trithiacyclodecan-9-one, has been determined by a single-crystal X-ray study. The compound crystallizes in the monoclinic space group P2₁, with two molecules per unit cell of dimensions a = 7.176(1) Å, b = 5.3447(6) Å, c = 12.0914(6) Å, and β = 96.486(7)⁰, and R = 0.048. The conformation adopted by the compound in the crystalline state is a [2323] or boat-chair-boat conformation with two sulfur atoms endodentate and one sulfur atom exodentate.     

Achieving Digital Catalysis: Strategies for Data Acquisition,Storage and Use

Heterogeneous catalysis is an important area of research that generates data as intricate as the phenomenon itself. Complexity is inherently coupled to the function of the catalyst and advance in knowledge can only be achieved if this complexity is adequately captured and accounted for. This requires integration of experiment and theory, high data quality and quality control, close interdisciplinary collaboration, and sharing of data and metadata, which is facilitated by the application of joint data management strategies. This Viewpoint Article first discusses the potential of a digital transition in catalysis research. Then, a summary of the current status in terms of data infrastructure in heterogeneous catalysis is presented, defining the various types of (meta-) data, from catalyst synthesis to functional analysis. Finally, an already implemented working concept for local data acquisition and storage is introduced and the benefits and further development directions for catalysis data use and sharing are discussed.     

Encapsulation of magnetic self-assembled systems in thermoreversible gels

We describe two different ways of encapsulating within the fibrils of thermoreversible polymer gels the filaments of a supermolecular polymer formed by self-assembly of a bicopper complex. Heterogeneous nucleation is brought about with gels made from isotactic poly(styrene) while compound formation occurs with gels made from poly(hexyl isocyanate). These ways depend upon the interaction between the wings of the supermolecular polymer and the side groups of the polymer. In all cases, the filaments retain their 1-D structure. Preliminary results from magnetic susceptibility measurements show a striking difference between the pure and the encapsulated supermolecular polymer.     

Lessons Learned from the Grouping of Chemicals to Assess Risks to Human Health

In analogy to the periodic system that groups elements by their similarity in structure and chemical properties, the hazard of chemicals can be assessed in groups having similar structures and similar toxicological properties. Here we review case studies of chemical grouping strategies that supported the assessment of hazard, exposure, and risk to human health. By the EU-REACH and the US-TSCA New Chemicals Program, structural similarity is commonly used as the basis for grouping, but that criterion is not always adequate and sufficient. Based on the lessons learned, we derive ten principles for grouping, including: transparency of the purpose, criteria, and boundaries of the group; adequacy of methods used to justify the group; and inclusion or exclusion of substances in the group by toxicological properties. These principles apply to initial grouping to prioritize further actions as well as to definitive grouping to generate data for risk assessment. Both can expedite effective risk management.