| 1. |
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| 2. |
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| 3. |
- Clark, Andrew G., et al.
(författare)
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Evolution of genes and genomes on the Drosophila phylogeny
- 2007
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 450:7167, s. 203-218
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Tidskriftsartikel (refereegranskat)abstract
- Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.
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| 4. |
- Gao, Hong, et al.
(författare)
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The landscape of tolerated genetic variation in humans and primates
- 2023
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 380:6648
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Tidskriftsartikel (refereegranskat)abstract
- Personalized genome sequencing has revealed millions of genetic differences between individuals, but our understanding of their clinical relevance remains largely incomplete. To systematically decipher the effects of human genetic variants, we obtained whole-genome sequencing data for 809 individuals from 233 primate species and identified 4.3 million common protein-altering variants with orthologs in humans. We show that these variants can be inferred to have nondeleterious effects in humans based on their presence at high allele frequencies in other primate populations. We use this resource to classify 6% of all possible human protein-altering variants as likely benign and impute the pathogenicity of the remaining 94% of variants with deep learning, achieving state-of-the-art accuracy for diagnosing pathogenic variants in patients with genetic diseases.
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| 5. |
- Kattge, Jens, et al.
(författare)
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TRY plant trait database - enhanced coverage and open access
- 2020
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Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Tidskriftsartikel (refereegranskat)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 6. |
- Kuderna, Lukas F. K., et al.
(författare)
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A global catalog of whole-genome diversity from 233 primate species
- 2023
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 380:6648, s. 906-913
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Tidskriftsartikel (refereegranskat)abstract
- The rich diversity of morphology and behavior displayed across primate species provides an informative context in which to study the impact of genomic diversity on fundamental biological processes. Analysis of that diversity provides insight into long-standing questions in evolutionary and conservation biology and is urgent given severe threats these species are facing. Here, we present high-coverage wholegenome data from 233 primate species representing 86% of genera and all 16 families. This dataset was used, together with fossil calibration, to create a nuclear DNA phylogeny and to reassess evolutionary divergence times among primate clades. We found within-species genetic diversity across families and geographic regions to be associated with climate and sociality, but not with extinction risk. Furthermore, mutation rates differ across species, potentially influenced by effective population sizes. Lastly, we identified extensive recurrence of missense mutations previously thought to be human specific. This study will open a wide range of research avenues for future primate genomic research.
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| 7. |
- Kuderna, Lukas F. K., et al.
(författare)
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Identification of constrained sequence elements across 239 primate genomes
- 2024
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Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 625:7996, s. 735-742
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Tidskriftsartikel (refereegranskat)abstract
- Noncoding DNA is central to our understanding of human gene regulation and complex diseases1,2, and measuring the evolutionary sequence constraint can establish the functional relevance of putative regulatory elements in the human genome3,4,5,6,7,8,9. Identifying the genomic elements that have become constrained specifically in primates has been hampered by the faster evolution of noncoding DNA compared to protein-coding DNA10, the relatively short timescales separating primate species11, and the previously limited availability of whole-genome sequences12. Here we construct a whole-genome alignment of 239 species, representing nearly half of all extant species in the primate order. Using this resource, we identified human regulatory elements that are under selective constraint across primates and other mammals at a 5% false discovery rate. We detected 111,318 DNase I hypersensitivity sites and 267,410 transcription factor binding sites that are constrained specifically in primates but not across other placental mammals and validate their cis-regulatory effects on gene expression. These regulatory elements are enriched for human genetic variants that affect gene expression and complex traits and diseases. Our results highlight the important role of recent evolution in regulatory sequence elements differentiating primates, including humans, from other placental mammals.
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| 8. |
- Jensen, Axel, et al.
(författare)
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Complex Evolutionary History With Extensive Ancestral Gene Flow in an African Primate Radiation
- 2023
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Ingår i: Molecular biology and evolution. - : Oxford University Press. - 0737-4038 .- 1537-1719. ; 40:12
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the drivers of speciation is fundamental in evolutionary biology, and recent studies highlight hybridization as an important evolutionary force. Using whole-genome sequencing data from 22 species of guenons (tribe Cercopithecini), one of the world's largest primate radiations, we show that rampant gene flow characterizes their evolutionary history and identify ancient hybridization across deeply divergent lineages that differ in ecology, morphology, and karyotypes. Some hybridization events resulted in mitochondrial introgression between distant lineages, likely facilitated by cointrogression of coadapted nuclear variants. Although the genomic landscapes of introgression were largely lineage specific, we found that genes with immune functions were overrepresented in introgressing regions, in line with adaptive introgression, whereas genes involved in pigmentation and morphology may contribute to reproductive isolation. In line with reports from other systems that hybridization might facilitate diversification, we find that some of the most species-rich guenon clades are of admixed origin. This study provides important insights into the prevalence, role, and outcomes of ancestral hybridization in a large mammalian radiation.
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| 9. |
- Kelley, Steven P., et al.
(författare)
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Benchtop access to anhydrous actinide N-donor coordination complexes using ionic liquids
- 2020
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 56:30, s. 4232-4235
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Tidskriftsartikel (refereegranskat)abstract
- By dehydrating actinide salts with an ionic liquid containing a common anion and subsequent reaction with N-heterocyclic ligands, we challenge the concept that actinides prefer O- over N-donors; rather the acidic hydrogen atoms of protic solvents hinder the formation of more elusive f-element N-donor coordination complexes.
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| 10. |
- Adranno, Brando, et al.
(författare)
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The 8-hydroxyquinolinium cation as a lead structure for efficient color-tunable ionic small molecule emitting materials
- 2023
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Ingår i: Advanced Photonics Research. - : John Wiley & Sons. - 2699-9293. ; 4:3
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Tidskriftsartikel (refereegranskat)abstract
- Albeit tris(8-hydroxyquinolinato) aluminum (Alq3) and its derivatives are prominent emitter materials for organic lighting devices, and the optical transitions occur among ligand-centered states, the use of metal-free 8-hydroxyquinoline is impractical as it suffers from strong nonradiative quenching, mainly through fast proton transfer. Herein, it is shown that the problem of rapid proton exchange and vibration quenching of light emission can be overcome not only by complexation, but also by organization of the 8-hydroxyquinolinium cations into a solid rigid network with appropriate counter-anions (here bis(trifluoromethanesulfonyl)imide). The resulting structure is stiffened by secondary bonding interactions such as pi-stacking and hydrogen bonds, which efficiently block rapid proton transfer quenching and reduce vibrational deactivation. Additionally, the optical properties are tuned through methyl substitution from deep blue (455 nm) to blue-green (488 nm). Time-dependent density functional theory (TDFT) calculations reveal the emission to occur from which an unexpectedly long-lived S-1 level, unusual for organic fluorophores. All compounds show comparable, even superior photoluminescence compared to Alq3 and related materials, both as solids and thin films with quantum yields (QYs) up to 40-50%. In addition, all compounds show appreciable thermal stability with decomposition temperatures above 310 °C.
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| 11. |
- Bousrez, Guillaume, et al.
(författare)
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Ready Access to Anhydrous Anionic Lanthanide Acetates by Using Imidazolium Acetate Ionic Liquids as the Reaction Medium
- 2021
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 27:52, s. 13181-13189
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Tidskriftsartikel (refereegranskat)abstract
- Access to lanthanide acetate coordination compounds is challenged by the tendency of lanthanides to coordinate water and the plethora of acetate coordination modes. A straightforward, reproducible synthetic procedure by treating lanthanide chloride hydrates with defined ratios of the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C(2)mim][OAc]) has been developed. This reaction pathway leads to two isostructural crystalline anhydrous coordination complexes, the polymeric [C(2)mim](n)[{Ln(2)(OAc)(7)}(n)] and the dimeric [C(2)mim](2)[Ln(2)(OAc)(8)], based on the ion size and the ratio of IL used. A reaction with an IL : Ln-salt ratio of 5 : 1, where Ln=Nd, Sm, and Gd, led exclusively to the polymer, whilst for the heaviest lanthanides (Dy-Lu) the dimer was observed. Reaction with Eu and Tb resulted in a mixture of both polymeric and dimeric forms. When the amount of IL and/or the size of the cation was increased, the reaction led to only the dimeric compound for all the lanthanide series. Crystallographic analyses of the resulting salts revealed three different types of metal-acetate coordination modes where eta(2)mu kappa(2) is the most represented in both structure types.
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| 12. |
- Fazey, Ioan, et al.
(författare)
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Transforming knowledge systems for life on Earth : Visions of future systems and how to get there
- 2020
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Ingår i: Energy Research & Social Science. - : Elsevier. - 2214-6296 .- 2214-6326. ; 70
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Tidskriftsartikel (refereegranskat)abstract
- Formalised knowledge systems, including universities and research institutes, are important for contemporary societies. They are, however, also arguably failing humanity when their impact is measured against the level of progress being made in stimulating the societal changes needed to address challenges like climate change. In this research we used a novel futures-oriented and participatory approach that asked what future envisioned knowledge systems might need to look like and how we might get there. Findings suggest that envisioned future systems will need to be much more collaborative, open, diverse, egalitarian, and able to work with values and systemic issues. They will also need to go beyond producing knowledge about our world to generating wisdom about how to act within it. To get to envisioned systems we will need to rapidly scale methodological innovations, connect innovators, and creatively accelerate learning about working with intractable challenges. We will also need to create new funding schemes, a global knowledge commons, and challenge deeply held assumptions. To genuinely be a creative force in supporting longevity of human and non-human life on our planet, the shift in knowledge systems will probably need to be at the scale of the enlightenment and speed of the scientific and technological revolution accompanying the second World War. This will require bold and strategic action from governments, scientists, civic society and sustained transformational intent.
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| 13. |
- Hiti, Ethan A., et al.
(författare)
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Exploring the Role of Neutral 4-Amino-1,2,4-triazole in the Formation of Hexanuclear f-Element Hydrolysis Products
- 2024
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Ingår i: Crystal Growth & Design. - 1528-7483 .- 1528-7505. ; 24:2, s. 834-842
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Tidskriftsartikel (refereegranskat)abstract
- Our recent observations of an unexpected Ce(III) hydrolysis product from the reaction of 4-amino-1,2,4-triazole (4-NH2-1,2,4-Triaz) with CeCl3·7H2O, [Ce6(μ3-O)4(μ3-OH)2(μ3-Cl)2(Cl)6(μ2-4-NH2-1,2,4-Triaz)12]·7H2O, the first high-nuclearity lanthanide complex where all Ln atoms are connected pairwise through 12 N-donor ligands or 12 neutral bridging ligands of any type, prompted us to explore the utility of this ligand in trapping additional f-element examples. Reactions of LnCl3·6H2O (Ln = Nd, Eu, Ho) with a large excess of 4-NH2-1,2,4-Triaz (20 equiv) and with the addition of small amounts of water to help solubilize the metal salts led to the isolation of the unique hydrolysis products [Nd6(μ3-OH)8Cl6(μ2-4-NH2-1,2,4-Triaz)12][Cl4]·2H2O, [Eu6(μ6-Cl)0.23(μ3-O0.77)4(μ3-O)2.6(μ3-Cl)0.4Cl6(μ2-4-NH2-1,2,4-Triaz)12], and [Ho6(μ6-Cl)0.21(μ3-O0.79)4(μ3-OH)2Cl6(μ2-4-NH2-1,2,4-Triaz)12][Cl]3.4. We also report a Ce(III) analogue prepared in glassware contaminated with Pb(OAc)2, namely, [Ce6(μ3-OH)8(BrPbBr5)(μ2-4-NH2-1,2,4-Triaz)11.5(OH2)6][Pb0.84Br4.2][Br]3.8·2(4-NH2-1,2,4-Triaz)·3.6H2O. The Nd(III) complex is the structurally most ordered with a clear [Nd6(μ3-OH)8] cluster core, while the Eu(III) and Ho(III) compounds contain partial occupancy of a μ6 position and thus result in an incomplete Ln6O9 cluster core formation. The crystallographic results suggest that the 4-NH2-1,2,4-Triaz ligand brings Ln(III) ions together, followed by the formation of an Ln6O8 or Ln6O9 core with whatever remaining anions or ligands can be incorporated. Given the complexity of the hydrolysis products of nuclear waste, we expect to continue to find a myriad of closely related complex structures of these types for the f-elements.
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| 14. |
- Hiti, Ethan A., et al.
(författare)
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Isolation of anhydrous tetrabutylphosphonium lanthanide hexa- and penta-nitrates from ionic liquids
- 2023
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Ingår i: Polyhedron. - : Elsevier BV. - 0277-5387 .- 1873-3719. ; 232
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Tidskriftsartikel (refereegranskat)abstract
- Our attempts to use an ionic liquid strategy to force f-element coordination of soft donor adenine and 4,5-dicyanoimidazole using 1-pot reactions in water using hydrated lanthanide salts failed, instead resulting in the isolation of anhydrous lanthanide nitrate salts. Reactions of previously ground mixtures of 40 % aq. [P4444][OH] and adenine with Nd(NO3)3·6H2O or Sm(NO3)3·6H2O followed by hand grinding and heating to 90 °C for 10 h led to hot crystallization of anhydrous [P4444]2[Nd(NO3)5] and [P4444]2[Sm(NO3)5]. The same reaction with 4,5-dicyanoimidazole and Nd(NO3)3·6H2O but without heating (10 h, room temperature) to prevent ligand decomposition, led to crystallization of anhydrous [P4444]3[Nd(NO3)6]. [P4444]3[Nd(NO3)6] could also be isolated by conducting the first reaction without using adenine. The single crystal X-ray diffraction structures of the three new anhydrous salts were examined to provide clues to the observed behavior. The [P4444]+ cations allow charge balance while forming box-type encapsulations around the anionic counterpart which has been previously reported in similar structures. The fact that these anhydrous salts were prepared from water with hydrated starting materials and no precautions taken to keep the crystal growing process anhydrous, suggests synthetic strategies that can potentially be beneficial for more advanced separations procedures.
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| 15. |
- Kelley, Steven P., et al.
(författare)
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Dehydration of UO2Cl2 center dot 3H(2)O and Nd(NO3)(3)center dot 6H(2)O with a Soft Donor Ligand and Comparison of Their Interactions through X-ray Diffraction and Theoretical Investigation
- 2020
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 59:5, s. 2861-2869
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Tidskriftsartikel (refereegranskat)abstract
- We investigated whether the relatively Lewis basic imidazole-2-thiones could be used to substitute water ligands bound to f-element cations and generate f-element soft donor complexes. Reactions of 1,3-diethylimidazole-2-thione (C(2)C(2)ImT) with Nd(NO3)(3)center dot 6H(2)O and UO2Cl2 center dot 3H(2)O led to the isolation of the anhydrous thione complexes Nd(NO3)(3)(C(2)C(2)ImT)(3) and UO2Cl2(C(2)C(2)ImT)(2), characterized by single crystal X-ray diffraction. Differences in the strength of metal-thione interactions have been examined by means of the crystal structure analysis and density functional theory (DFT) calculations. The C(2)C(2)ImT ligands were found to be affected by both coordination and noncovalent interactions, making it impossible to deconvolute the effects of one from the other. Calculated partial atomic charges indicated greater ligand-to-metal charge transfer in the [UO2](2+) complex, indicative of a stronger interaction. The reactivity of C(2)C(2)ImT demonstrates its usefulness in the preparation of f-element soft donor complexes from readily available hydrates that could be useful intermediates for promoting the coordination and studying the effects of soft donor anions.
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| 16. |
- Kelley, Steven P., et al.
(författare)
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Structural analysis of mono-substituted N-butyl-pyridinium salts : in search of ionic liquids
- 2021
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Ingår i: Journal of coordination chemistry (Print). - : Informa UK Limited. - 0095-8972 .- 1029-0389. ; 74:1-3, s. 117-128
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Tidskriftsartikel (refereegranskat)abstract
- Four mono-substituted N-butylpyridinium salts, 1-butyl-4-dimethylaminopyridinium chloride [b4dmapy]Cl, 1-butyl-4-methylpyridinium bromide [b4mpy]Br, 1-butyl-4-methylpyridinium hexafluorophosphate [b4mpy][PF6], and 1-butyl-3-methylpyridinium hexafluorophosphate [b3mpy][PF6] were synthesized and characterized using single crystal X-ray diffraction. The crystal structures were examined with the intent of identifying ion interactions leading to higher melting points of the halide salts with respect to the [PF6]– salts. The changes in hydrogen bonding, C–H⋅⋅⋅π, and van der Waals interactions have been analyzed with respect to anion, functional groups, and the symmetry of the cation to establish interdependence with the compound’s physicochemical properties. It has been observed that the cation–anion interactions are represented by highly directional hydrogen bonds and show strong preference to positions of interaction depending on the anion. The cations of the halide salts show strong tendency towards higher dimensional formations, while those of the [PF6]– salts prefer low dimensional assemblies both being based mainly on the weaker van der Waals interactions. These interactions depend on the shape of the cation but may offer certain structure-ordering rigidity accommodating variable anions.
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| 17. |
- Kelley, Steven P., et al.
(författare)
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Structural Consequences of Halogen Bonding in Dialkylimidazolium : A New Design Strategy for Ionic Liquids Illustrated with the I-2 Cocrystal and Acetonitrile Solvate of 1,3-Dimethylimidazolium Iodide
- 2020
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 20:1, s. 498-505
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Tidskriftsartikel (refereegranskat)abstract
- The reaction of 1,3-dimethylimidazolium-2-carboxylate with elemental iodine in acetonitrile rapidly affords crystalline iodide salts of the 1,3-dimethy1-2-iodoimidazolium cation ([C(1)mim-2-I](+)), [C(1)mim-2-I]I.0.5I(2), and [C(1)mim-2-1]I-0.5CH(3)CN, depending on the temperature. Analysis of the two structures shows the significant role of halogen bonding interactions between the cation and anion in the [C(1)mim-2-I]I salts, which reduces the ionicity of the compounds. This observation is backed by theoretical calculations revealing the importance of halogen bonding as a design strategy for ionic liquids (ILs), which, so far, has been underestimated. The halogen bonding is also analyzed in terms of this new design concept for ILs.
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| 18. |
- Mishra, Manish Kumar, et al.
(författare)
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CO2 capture from ambient air via crystallization with tetraalkylammonium hydroxides
- 2022
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 51:46, s. 17724-17732
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous solutions of a series of short carbon chain tetra(n-alkyl)ammonium hydroxides, [Nnnnn][OH] with n = 2: n-ethyl, 3: n-propyl, 4: n-butyl, have been serendipitously found to be potential candidates for direct air carbon capture (DAC) when being used as reagents in more complicated reactions. Aqueous solutions of [N3333][OH], [N2222][OH], or [N3333][OH] with UO2SO4·3H2O and 1,4-diamidoximylbenzene, and [N4444][OH] with cytosine (HCyt) directly absorb CO2 from the atmosphere upon mild heating in the open atmosphere crystallizing in complexes reaching up to 2 : 1 CO2/[Nnnnn]OH ratio. [N2222][HCO3]·3H2O (1), [N2222]2[H(HCO3)3]·5H2O (2), [N3333][HCO3]·0.5H2O (3), [N3333][H(HCO3)2] (4), [N3333]2[(tpa)(H2CO3)2] (5; tpa = terephthalate), [N4444][H(Cyt)(HCO3)]·H2O (6) and [N4444][H2(Cyt)2(HCO3)]·H2O (7) have been isolated in crystalline form and structurally characterized by single crystal X-ray diffraction. The compounds are characterized by complex polyanionic formations from bicarbonate dimers ([(HCO3)2·(H2O)]24−) or chains ([H(HCO3)2]nn− or [H2(tpa)(HCO3)2]n2n−) to water-bicarbonate associates ([(HCO3)2·6H2O]2− and [(H2CO3·(HCO3)2)2·6H2O·2H2O]2−) and three-component anionic layers ([H(Cyt)(HCO3)·H2O]nn− and [H2(Cyt)2(HCO3)·H2O]nn−) frequently showing proton sharing. While some hydroxides themselves can maintain a high CO2/[Nnnnn][OH] ratio, particularly 2 and 4, the presence of secondary hydrogen bond donors/acceptors may increase the sorption efficiency through decreased solubility and enhanced crystallization.
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| 19. |
- Mishra, Manish Kumar, et al.
(författare)
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Crystallographic evidence of Watson-Crick connectivity in the base pair of anionic adenine with thymine
- 2020
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 117:31, s. 18224-18230
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Tidskriftsartikel (refereegranskat)abstract
- Utilizing an ionic liquid strategy, we report crystal structures of salts of free anionic nucleobases and base pairs previously studied only computationally and in the gas phase. Reaction of tetrabutylammonium ([N-4444](+)) or tetrabutylphosphonium ([P-4444](+)) hydroxide with adenine (HAd) and thymine (HThy) led to hydrated salts of deprotonated adenine, [N-4444][Ad]center dot 2H(2)O, and thymine, [P4444][Thy]center dot 2H(2)O, as well as the double salt cocrystal, [P-4444](2)[Ad][Thy]center dot 3H(2)O center dot 2HThy. The cocrystal includes the anionic [Ad-(HThy)] base pair which is a stable formation in the solid state that has previously not even been suggested. It exhibits Watson-Crick connectivity as found in DNA but which is unusual for the free neutral base pairs. The stability of the observed anionic bases and their supramolecular formations and hydrates has also been examined by electronic structure calculations, contributing to more insight into how base pairs can bind when a proton is removed and highlighting mechanisms of stabilization or chemical transformation in the DNA chains.
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| 20. |
- Nayak, Amrita, et al.
(författare)
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Anhydrous vs Hydrated f-Element Acetate Polymers Dictated by the Stoichiometry of Protic Acidic/Basic Azole Mixtures
- 2021
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 21:4, s. 2516-2525
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Tidskriftsartikel (refereegranskat)abstract
- Continuing our investigations of ionic liquid (IL) based routes to a library of f-element/soft donor complexes which could be studied crystallographically, we have explored the dissolution of f-element salts in protic imidazole-based ILs containing only soft donors at high temperatures to drive off volatiles, including water and carboxylic or mineral acids. Here we present our results, reacting acidic and basic azoles in 1:3 or 1:1 stoichiometric compositions at elevated temperature, followed by saturation with Nd(OAc)(3)center dot xH(2)O or Ce(OAc)(3)center dot xH(2)O, which led to 13 new metal-acetate polymeric complexes identified by single-crystal X-ray diffraction. We found that the diversity in coordination modes of the simple acetate ligand that interfere with substitution of the softer N donors led to several readily crystallizable complexes forming two distinct groups with respect to f-element interaction with the ionic liquid precursors. When the acidic/basic azole ratio was 1:3, acetate and a neutral basic azole were found to be coordinated to the metal centers but no water, although in one case (2) water was observed in the secondary coordination sphere: [Ce(mu(2)-OAc)(3)(C(1)im)](n) (1, C(1)im = 1-methylimidazole), [Nd(mu(2)-(OAc)(3)(C(1)im)](n)center dot nH(2)O (2), [Ce(mu(2)-OAc)(3)(C(2)im)](n) (3, C(2)im = 1-ethylimidazole), [Ln(mu(2)-OAc)(3)DMF](n) (Ln = Nd (4), Ce (5); dimethylformamide (DMF) was substituted for the azole mixture), and [Nd(mu(2)-OAc)(3)(C(4)im)](n) (6, C(4)im = 1-butylimidazole). However, when the stoichiometric ratio was 1:1, water was always observed coordinated to the metal ions with the acidic azole included in the structure as a solvate or cocrystal, despite a higher reaction temperature: [Nd(mu(2)-OAc)(3)(OH2)](n)center dot n(1,2,3-Taz) (7,1,2,3-Taz = 1,2,3-triazole), [Ln(mu(2)-OAc)(3)(OH2)](n)center dot n(4,5-DCim) (Ln = Nd (8), Ce (9), 4,5-DCim = 4,5-dicyanoimidazole), [Ln(mu(2)-OAc)(3)(OH2)](n)center dot n(3,5-diNH(2)-1,2,4-Taz) (Ln = Nd (10), Ce (11), 3,5diNH(2)-1,2,4-Taz = 3,5-diamino-1,2,4-triazole), [Ce(mu(2)-OAc)(3)(OH2)](n)center dot n(3-NH2-1,2,4-Taz) (12, 3-NH2-1,2,4-Taz = 3-amino-1,2,4-triazole), and [Nd(mu(2)-OAc)(3)(OH2)](n)center dot n(5-NH2-Tz) (13, 5-NH2-Tz = 5-aminotetrazole). All of the compounds retain the Ln:OAc- ratio of 1:3 and form 1D polymeric chains; however, they exhibit a variety of coordination modes affecting the degree of chain condensation. The isolation of both hydrated and anhydrous products revealed different abilities of the investigated soft N-donors to compete with O-donors finding their place in the coordination sphere of the lanthanide or in the crystal lattice.
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| 22. |
- Renier, Olivier, et al.
(författare)
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Investigation of the role of hydrogen bonding in ionic liquid-like salts with both N- and S-soft donors
- 2023
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 25:4, s. 530-540
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Tidskriftsartikel (refereegranskat)abstract
- In search of ionic liquids (ILs) with multiple types of soft donor atoms capable of preferentially complexing a range of soft metal ions over harder ions, we investigated structural clues to the role of hydrogen bonding in IL behavior through a series of salts with anions containing both N- and S-donor atoms based on azole thiolates. Reaction of equimolar amounts of triethylamine (Et3N) or diisobutylamine (DBA) with 1-phenyl-1H-tetrazole-5-thiol (PhTzSH), 1-methyl-1H-tetrazole-5-thiol (MeTzSH), or 5-methyl-1,3,4-dithiazole-2-thiol (MeDiTSH) yielded [Et3NH][MeTzS] (1), a yellow liquid, and the low melting yellow solids [DBAH][MeTzS] (2), [Et3NH][PhTzS] (3), [DBAH][PhTzS] (4), [Et3NH][MeDiTS] (5), and [DBAH][MeDiTS] (6). Thermal analysis revealed that all of them qualify as ILs with melting points below 100 °C. Single crystal X-ray structure analysis of 2–6 revealed the presence of an extensive H-bonding network that includes the rare N–H⋯S hydrogen bonds in 3, 4, and 6. These weaker interactions appear to significantly influence thermal behavior, where strong bonding leads to higher melting temperatures and lower decomposition points.
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| 23. |
- Renier, Olivier, et al.
(författare)
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Shape Preserving Single Crystal to Amorphous to Single Crystal Polymorphic Transformation Is Possible
- 2021
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 143:48, s. 20202-20206
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Tidskriftsartikel (refereegranskat)abstract
- Many crystalline materials form polymorphs and undergo solid–solid transitions between different forms as a function of temperature or pressure. However, there is still a poor understanding of the mechanism of transformation. Conclusions about the transformation process are typically drawn by comparing the crystal structures before and after the conversion, but gaining detailed mechanistic knowledge is strongly impeded by the generally fast rate of these transitions. When the crystal morphology does not change, it is assumed that crystallinity is maintained throughout the process. Here we report transformation between polymorphs of ZnCl2(1,3-diethylimidazole-2-thione)2 which are sufficiently slow to allow unambiguous assignment of single crystal to single crystal transformation with shape preservation proceeding through an amorphous intermediate phase. This result fundamentally challenges the commonly accepted views of polymorphic phase transition mechanisms.
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| 24. |
- Smetana, Volodymyr, et al.
(författare)
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A fivefold UO22+ node is a path to dodecagonal quasicrystal approximants in coordination polymers
- 2020
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 6:5
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Tidskriftsartikel (refereegranskat)abstract
- Aperiodic formations continue to focus interest in areas ranging from advanced scientific theories to practical everyday applications. Starting from diverse and tightly bonded intermetallic compounds, this world showed an important breakthrough toward the so-called soft systems of meso/macroscale: liquid crystals, thin films, polymers, proteins, etc. This work opens a route for making bulk quasicrystals (QC) in an unprecedented but very common area, with molecular ligands. Since these systems are, to a large extent, transparent, they extend the possible areas of QC application to previously unreachable corners, e.g., photonics. We combined efficient bridging ligands with uranyl pentagonal bonding centers and, unexpectedly, brought the unique attributes of f-element coordination chemistry to an interdisciplinary area of aperiodic formations. Taking advantage of the planar coordination of uranyl ions, we were able to direct the structure expansion solely in two directions with a characteristic snub square tiling, a predicted but previously unobtainable dodecagonal approximant.
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| 25. |
- Smetana, Volodymyr, et al.
(författare)
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Sandwiched Kagomé Lattices in a Coordination Polymer Based on Mixed-Valent Uranium
- 2021
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 21:3, s. 1727-1733
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Tidskriftsartikel (refereegranskat)abstract
- The metal-organic material (UO)-O-V((UO2)-O-VI)(2)(OH)(5)-(Triaz)(2) (Triaz = 1,2,4-triazolate) has been isolated from the reaction of UO2(NO3)(2)center dot 6H(2)O with 1,2,4-triazole in the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C(2)mim][OAc]). The compound's crystal structure is comprised of planar inorganic layers interconnected by organic linkers into a 3D framework. These layers represent a uranium-based coordination polymer with a Kagome topology that to the best of our knowledge has never been recognized in f-element coordination chemistry.
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