C-H⋯O contacts in the crystal structure of 1,3-di-thiane 1,1,3,3-tetra-oxide.

The crystal structure of 1,3-di-thiane 1,1,3,3-tetra-oxide, C4H8O4S2, has been determined to examine the inter-molecular C-H⋯O hydrogen bonds in a small mol-ecule with highly polarized hydrogen atoms. The crystals are monoclinic, space group Pn, with a = 4.9472 (5), b = 9.9021 (10), c = 7.1002 (7) Šand ß = 91.464 (3)° with Z = 2. The mol-ecules form two stacks parallel to the a axis with the molecules being one a translation distance from each other. This stacking involves axial hydrogen atoms on one mol-ecule and the axial oxygen atoms on the adjacent mol-ecule in the stack. None of these C-H⋯O contacts is particularly short (all are > 2.4 Å). The many C-H⋯O contacts between the two stacks involve at least one equatorial hydrogen or oxygen atom. Again, no unusually short contacts are found. The whole crystal structure basically consists of a complex network of C-H⋯O contacts with no single, linear C-H⋯O contacts, only contacts that involve two (bifurcated), and mostly three or four neighbors.

A Transdisciplinary Methodology for Introducing Solar Water Disinfection to Rural Communities in Malawi-Formative Research Findings.

Despite the increasing volume of evidence demonstrating the efficacy of solar water disinfection (SODIS) as a household water treatment technology, there still appear to be significant barriers to uptake in developing countries. The potential of SODIS is often treated with skepticism in terms of effective treatment, volume, and safety, and is dismissed in preference for more accepted technologies such as ceramic filters and dose chlorination. As part of WATERSPOUTT (EU H2020 688928), our study used a transdisciplinary methodology to cocreate an innovative SODIS system in rural Malawi. The formative work focused on the design of 1) an appropriate and acceptable system and 2) a context-specific intervention delivery program using a behavior-centered design. Initial research identified specific water needs and challenges, which were discussed along with a cocreation process with potential end users, through a series of shared dialogue workshops (SDWs). Specifications from end users outlined a desire for higher volume systems (20 L) that were "familiar" and could be manufactured locally. Development of the "SODIS bucket" was then undertaken by design experts and local manufacturers, with input from end users and subject to controlled testing to ensure efficacy and safety. Concurrent data were collated using questionnaires (n = 777 households), water point mapping (n = 121), water quality testing (n = 46), and behavior change modeling (n = 100 households). These identified specific contextual issues (hydrogeology, water access, gender roles, social capital, and socioeconomic status), and behavioral determinants (normative, ability, and self-regulation factors) that informed the development and delivery mechanism for the implementation toolkit. Integr Environ Assess Manag 2020;16:871-884. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Comparison of the C-H⋯O bonding in two crystalline phases of 1,4-di-thiane 1,1,4,4-tetra-oxide.

The crystal structures of two crystalline phases of 1,4-di-thiane 1,1,4,4-tetra-oxide, C4H8O4S2, have been determined in order to examine the nature of possible inter-molecular hydrogen bonds. Phase 1 is monoclinic, space group C2/m, with unit-cell dimensions of a = 9.073 (8), b = 7.077 (6), c = 5.597 (5) Šand ß = 105.89 (1)°. The mol-ecule adopts 2/m symmetry and all of the mol-ecules are related by translation and thus have the same orientation. Phase 2 is also monoclinic but in space group P21/n with unit-cell dimensions of a = 7.1305 (5), b = 5.7245 (4), c = 8.3760 (6) Šand ß = 91.138 (2)°. In this phase, the mol-ecule sits on an inversion center and the mol-ecules within the unit cell adopt quite different orientations. In both phases, examination of the potential C-H⋯O hydrogen bonds around each of the independent oxygen atoms (one axial and the other equatorial) shows the general O⋯H patterns to be quite similar with each oxygen atom in contact with four neighboring H atoms, and each H atom contacting two neighboring O atoms. While none of the H⋯O contacts is particularly short (all are greater than 2.5 Å), each mol-ecule has 32 such contacts that form an extensive inter-molecular network. A 1H NMR spectrum of the compound dissolved in DMSO shows a singlet of 8H at δ 3.677 which indicates that the C-H bonds are only moderately polarized by the single adjacent -SO2- moiety: strongly polarized C-H bonds have δ values in the 5-6 range [Li & Sammes (1983 ▸). J. Chem. Soc. Perkin Trans. 1, pp. 1303-1309]. The phase 1 crystal studied was non-merohedrally twinned.

Troublesome Crystal Structures: Prevention, Detection, and Resolution.

A large number of incorrect crystal structures is being published today. These structures are proving to be a particular problem to those of us who are interested in comparing structural moieties found in the databases in order to develop structure-property relationships. Problems can reside in the input data, e.g., wrong unit cell or low quality intensity data, or in the structural model, e.g., wrong space group or atom types. Many of the common mistakes are, however, relatively easy to detect and thus should be preventable; at the very least, suspicious structures can be flagged, if not by the authors then by the referees and, ultimately, the crystallographic databases. This article describes some of the more common mistakes and their effects on the resulting structures, lists a series of tests that can be used to detect incorrect structures, and makes a strong plea for the publication of higher quality structures.