Synthesis of unsymmetrical NCN′ and PCN pincer palladacycles and their catalytic evaluation compared with a related SCN pincer palladacycle

1-(3-(Pyridin-2-yl)phenyl)methanamine derivatives have been synthesized and underwent C–H bond activation to afford unsymmetrical NCN′ pincer palladacycles, which were characterised in the solid state. 2-Pyridinyl-phenol and -benzyl alcohols were then used as precursors to unsymmetrical PCN pincer palladacycles. Catalytic applications, where the palladacycle remains in the Pd(II) state, have been carried out and show good activity and selectivity

Rationalization of the mechanism of in situ Pd(0) formation for cross-coupling reactions from novel unsymmetrical pincer palladacycles using DFT calculations

Density functional theory (DFT) is used to determine the mechanism for Pd(0) generation from pincer palladacycle pre-catalysts. The elucidated mechanisms comprise two key steps, transmetallation and reductive elimination. It is found that the presence of a base in the pre-catalyst activation step serves to significantly lower the Gibbs free energy barrier of the transmetallation step and the Gibbs free energy of the overall pre-catalyst activation. The DFT results are used to rationalize the catalytic activity of a number of pincer palladacycles in the Suzuki-Miyaura coupling of sterically demanding and electronically deactivated aryl bromides with 2-tolyboronic acid. A strong correlation exists between the Gibbs free energy barrier of the transmetallation step and/or overall pre-catalyst activation energy and the percentage conversions of the Suzuki- Miyaura coupling in the presence of the novel pre-catalysts. The data presented suggest that the slow, controlled release of the “true, active catalyst,” Pd(0), from the pincer palladacycle pre-catalysts provides the optimum reaction conditions and may be achieved by a high transmetallation energy barrier or overall pre-catalyst activation energy or both

Sustainable recreational trails in Sweden : Is it possible to talk about ROI for hiking trail investments?

Spending time in nature is becoming increasingly popular in Sweden, as in many other countries, following the pandemic. In the Swedish context, the issue of funding investments and regular maintenance of recreational trails in nature is a challenge given the Allemansrätten (public access to private land), which hinders the closing of land and charging of entrance fees. Still, high-quality trails are demanded to serve as a driver for attracting visitors to destinations.  This report looks into aspects that are relevant for a discussion on return on investment (ROI) for investments in trails, and especially hiking trails. The first section offers an outlook to a few international cases that discuss access and funding types for hiking trails. Another section uses a mini-case to evaluate a few larger trail networks in relation to guidelines for the Swedish national framework for hiking trails.  This report highlights that people’s use of trails bring a number of benefits to society, mainly economic, environmental, and public health benefits. The economic benefits originate from spending by the visitors and direct investments during construction of trails, while environmental benefits come from reduced CO2 emissions and the public health benefits derive from reductions in health care spendings. Finally, quality of life and happiness values arise from the increased relationship between individuals and nature and social aspects.  The report notes that a proper evaluation of ROI for trails can be conducted, with consideration of the many loopholes. The benefit side incorporates such needs as considering visitors’ potential multiple purpose of trips and how to properly value and include the non-monetary effects coming from improved health, interaction with nature, and socializing with other people. Finally, the report discusses the benefits of trail use in relation to the fulfillment of the United Nations’ sustainable development goals (SDGs). We find that investments would contribute to decent work for all and sustainable economic growth, as well as a reduction in inequalities. A key point to emerge from this report is that, to properly use ROI for trail investments in practice, there is a need to further analyze the economic impact of hiking trail users in Sweden.

Novel multiplex strategy for DNA methylation-based age prediction from small amounts of DNA via Pyrosequencing

DNA methylation-based age estimation is a promising new tool for forensic molecular biology. There is growing understanding of the best predictive CpG loci and their performance in various sample types. Since forensic samples usually provide only small amounts of DNA, the sensitivity of the method is crucial. Pyrosequencing is one of the most sensitive methods but only capable to analyze different target regions separately. Thus, multiple input DNA samples are required for investigations of different target regions, which is required for all current age estimation models. To overcome this limitation, we developed a novel multiplex strategy for Pyrosequencing, which allows the investigation of different target regions from a single small amount of input DNA. A pre-amplification step was introduced to increase the amount of target-specific template for the subsequent sequencing PCR step. We tested this multiplex strategy for eight target regions including 15 age CpGs associated with the genes of ELOVL2, FHL2, CCDC102B, C1orf132, KLF14, EDARADD, PDE4C and SST. Except for FHL2, all target regions were successfully sequenced with the multiplex strategy and the precision in terms of reproducibility of the measurements was equal to the singleplex strategy. The measured methylation values at the age CpGs displayed borderline significant differences between both analytical strategies for six out of 14 CpG sites whereas both strategies delivered equal methylation values for the remaining eight age CpGs. In total, our results indicate that the multiplex strategy can act as a promising alternative for age estimation studies in cases when only limited amounts of DNA samples are available

Crystal structure of (piperidine-1-carbo-di-thio-ato-κ(2) S,S)[2-(pyridin-2-yl)phenyl-κ(2) C (1),N]palladium(II).

The title compound, [Pd(C11H8N)(C6H10NS2)], crystallizes with three similar and discrete mol-ecules in the asymmetric unit. The CNS2 donor set defines a distorted square-planar geometry around the Pd(II) atom, with very small deviations from planarity. The bidentate nature of the ligands gives fairly large deviations from the ideal 90° angles; the C-Pd-N angles are all around 81° and the S-Pd-S angles are around 75°. Mol-ecules pack via dispersion inter-actions

Cyclometallated phenyl-pyridine palladium species. Monomeric complex formation with potentially bridging ligands

The cyclometallated dinuclear (2-phenyl-pyridine) palladium acetate and chloride [{PdCl(phpy)}(2)] and [{PdOAc(phpy)}(2)] were reacted with potentially bridging N- and S-donor ligands. The N,N-ligands bind with only one nitrogen and form monomeric products. The S,S-ligand binds in a chelate mode, also forming a monomeric complex. 3,3-Dimethyl glutarate, on the other hand, binds in a bridging mode. An X-ray structure of the complex with naphthyridine is presented. (C) 2016 Elsevier B.V. All rights reserved

Allotwinning in a molecular crystal: (1R,3S)-dimethyl 2-oxocyclohexane-1,3-dicarboxylate.

Two polytypic modifications of (1R,3S)-dimethyl 2-oxocyclohexane-1,3-dicarboxylate intergrow to form allotwins. One phase shows monoclinic symmetry, Cc, while the other is orthorhombic Pmc21. The structures may be considered as two different modes of superstructure ordering of an underlying, disordered structure. Considered in the same metrically orthorhombic unit cell a = 37.8883, b = 4.7233, c = 11.6835 Å, the two can be conveniently distinguished by their non-standard centering, Cc being represented as Xc with the centering vectors (0 0 0); (½ 0 ½); (¼ ½ ¾); (¾ ½ ¼); and Pmc21 as Xmc21 with the centering vectors (0 0 0); (½ 0 0). The difference between the allotwin domains lies only in the relationship between next-nearest neighbors along the stacking direction 100 and hence the conformations and packing efficiencies are identical for both phases and all three domains. The stacking sequences for the two phases correspond to ABAB for the orthorhombic stacking and ABA'B'/AB'A'B for the two (equivalent) monoclinic stackings. The monoclinic phase dominates comprising ca 80% of the total volume. Within the monoclinic phase, the ratio between the two possible orientations is highly unbalanced (6:1) indicating relatively large domains. The allotwinning detected in this sample may appear exotic in molecular compounds, but we suggest that the rarity of such examples in the literature is a reflection of the paucity of software that can identify and handle such cases. It is easy to overlook the possibility that a complex diffraction pattern originates from allotwinning and assume that normal mono-component twinning is the cause. The underlying mechanism in this case is the formation of two-dimensional layers of molecules that allow for two equivalent, but in terms of absolute geometry, different, ways of stacking

Aromatic PCN pincer palladium complexes : Forming and breaking CC bonds

Through a salt metathesis reaction, ( t-BuPCN)Pd-ONO2 (2) was prepared and used as a precursor for producing ( t-BuPCN)Pd-OH (3) and ( t-BuPCN)Pd-aryl acetylide complexes 4 (phenyl acetylide) and 5 (p-tolyl acetylide). The aryl acetylide complexes could also be prepared through another synthetic route: by condensation of 3 with the corresponding aryl acetylene. The reactivity of complexes 3 and 4 toward carbon dioxide was studied and it was found that both reactions give the hydrogen carbonate complex (6). The low reactivity of the Pd-acetylide bond was further confirmed by the fact that the propiolate complex undergoes decarboxylation to give 4. PCN palladium complexes are good catalysts for the decarboxylative cross coupling reactions between acetylene carboxylic acids and aryl halides. The yield of the cross coupling product was improved by adding a catalytic amount of CuI

Progress in the implementation of massively parallel sequencing for forensic genetics: results of a European-wide survey among professional users

A European-wide online survey was conducted to generate an overview on the state-of-the-art using massively parallel sequencing (MPS) platforms for forensic DNA analysis and DNA phenotyping among forensic practitioners in Europe. The survey was part of the dissemination activities of the VISible Attributes through GEnomics - VISAGE Horizon 2020 funded European research project [30], in preparation of a series of educational training activities. A total of 105 replies from 32 European countries representing participants from police, governmental, academic, and private laboratories providing professional services in the field of forensic genetics were included in the final analysis. Of these, 73% already own an MPS platform or are planning to acquire one within the next 1-2 years. One-third of the participants have already carried out MPS-based STR sequencing, identity, or ancestry SNP typing. A total of 23-40% of participants are planning to explore all FDP applications showing the overall very high interest in using MPS for the whole range of forensic MPS markers and applications. About 50% of the participants have previously gathered experience using forensic DNA phenotyping (FDP) markers based on conventional (i.e., not MPS-based) DNA typing methods. A total of 55% of the participants have attended training on the general use of MPS technology, but 36% have received no training whatsoever. Accordingly, 90% have expressed high or medium interest to attend training on the analysis and interpretation of DNA phenotyping data for predicting appearance, ancestry, and age. The results of our survey will provide valuable information for organizing relevant training workshops on all aspects of MPS-based DNA phenotyping for the forensic genetics scientific community