Acta crystallographica Section B, Structural science, crystal engineering and materials最新文献_第10页

Competition of interactions and a new high-temperature phase of selenourea. 相互作用的竞争和硒脲的新高温相。

IF 1.9 3区化学

Acta crystallographica Section B, Structural science, crystal engineering and materials Pub Date : 2023-02-01 DOI: 10.1107/S2052520622011623

Kinga Roszak, Andrzej Katrusiak

{"title":"Competition of interactions and a new high-temperature phase of selenourea.","authors":"Kinga Roszak, Andrzej Katrusiak","doi":"10.1107/S2052520622011623","DOIUrl":"https://doi.org/10.1107/S2052520622011623","url":null,"abstract":"The aggregation of molecules is usually associated with a specific type of interaction, which can be altered by thermodynamic conditions. Under normal conditions, the crystal structure of selenourea, SeC(NH2)2, phase α is trigonal, space group P31, Z = 27. Its large number of independent molecules (Zα' = 9) can be associated with the formation of an NH...N hydrogen bond substituting one of 36 independent NH...Se hydrogen bonds, which prevail among intermolecular interactions. Phase α approximates the trigonal structure with a threefold smaller unit cell (Z = 9), which in turn approximates another still threefold smaller unit cell (Z = 3). The temperature-induced transformations of selenourea have been characterized by calorimetry and by performing 21 single-crystal X-ray diffraction structural determinations as a function of temperature. At 381.0 K, phase α undergoes a first-order displacive transition to phase γ, with space group P3121 and Z reduced to 9, when the NH...N bond is broken and an NH...Se bond is formed in its place. Previously, an analogous competition was observed between NH...N and NH...O hydrogen bonds in high-pressure phase III of urea. The lattice vectors along the (001) plane in low- and high-temperature phases of selenourea are related by a similarity rule, while the lattice dimensions along direction c are not affected. This similarity rule also applies to the structures of phase γ and hypothetical phase δ (Z = 3). The thermally controlled transition between enantiomorphic phases of selenourea contrasts with its high-pressure transition at 0.21 GPa to a centrosymmetric phase β, where both the NH...Se and NH...N bonds are present. The compression and heating reduce the number of independent molecules from Z' = 9 in phase α, to Z' = 2 in phase β and to Z' = 1.5 in phase γ.","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10663487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Pervasive approximate periodic symmetry in organic P1 structures. 有机P1结构的普遍近似周期对称性。

IF 1.9 3区化学

Acta crystallographica Section B, Structural science, crystal engineering and materials Pub Date : 2022-08-01 Epub Date: 2022-07-05 DOI: 10.1107/S2052520622004929

Carolyn Pratt Brock

{"title":"Pervasive approximate periodic symmetry in organic P1 structures.","authors":"Carolyn Pratt Brock","doi":"10.1107/S2052520622004929","DOIUrl":"https://doi.org/10.1107/S2052520622004929","url":null,"abstract":"The goal of this project was to identify the prevalence of approximate symmetry in organic P1 structures. In the November 2019 version of the Cambridge Structural Database (CSD), there are 2592 organic, P1, R ≤ 0.050 structures; complete, unique entries are available for 1407 Z = Z' > 1 and 1049 Z = Z' = 1 structures. All the Z > 1 structures can have approximate symmetry; the Z = 1 structures were scanned to find those composed of molecules or ions that might lie on a special position and those that have two or more large molecules or ions that are very similar. The number of Z = 1 structures so identified was 285, of which 49 were grouped with the Z > 1 structures because Zeffective > 1. The packing in each of the 1407 + 285 = 1692 structures was investigated. The 144 that should almost certainly have been described in a smaller or higher-symmetry unit cell were removed from the list; 120 of the 144 are composed of achiral or racemic material. (About half of the Z = 1 and 89% of the Z > 1 structures are composed of enantiopure material.) Approximate periodic symmetry was found in 86% of the 1337 remaining Z > 1 structures and in 72% of the 211 remaining Z = 1 structures. About a third of the enantiomerically pure structures mimic inversion symmetry; 38% have approximate rotational symmetry. For the structures of achiral and racemic material, distorted glide or mirror symmetry is more common than is distorted inversion symmetry. Approximate rotational and glide symmetry was found to be periodic in two dimensions considerably more often than in three. In 4% of the structures, different layer types alternate or layers are related by approximate local rotations, as well as by small translations. In 5% of the structures, different parts of the molecule are segregated into two-dimensional regions that have different approximate symmetries. More than a third of the structures that are a distorted version of a higher-symmetry structure were determined at T ≥ 288 K.","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40704076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Analytic description of nanowires II: morphing of regular cross sections for zincblende- and diamond-structures to match arbitrary shapes. 纳米线的解析描述II:锌闪锌矿和金刚石结构的规则截面变形以匹配任意形状。

IF 1.9 3区化学

Acta crystallographica Section B, Structural science, crystal engineering and materials Pub Date : 2022-08-01 DOI: 10.1107/S2052520622004942

Dirk König, Sean C Smith

{"title":"Analytic description of nanowires II: morphing of regular cross sections for zincblende- and diamond-structures to match arbitrary shapes.","authors":"Dirk König, Sean C Smith","doi":"10.1107/S2052520622004942","DOIUrl":"https://doi.org/10.1107/S2052520622004942","url":null,"abstract":"Setting out from our recent publication [König & Smith (2021). Acta Cryst. B77, 861], we extend our analytic description of the regular cross sections of zincblende- and diamond-structure nanowires (NWires) by introducing cross section morphing to arbitrary convex shapes featuring linear interfaces as encountered in experiment. To this end, we provide add-on terms to the existing number series with their respective running indices for zinc-blende- (zb-) and diamond-structure NWire cross sections. Such add-on terms to all variables yield the required flexibility for cross section morphing, with main variables presented by the number of NWire atoms NWire(dWire[i]), bonds between NWire atoms Nbnd(dWire[i]) and interface bonds NIF(dWire[i]). Other basic geometric variables, such as the specific length of interface facets, as well as widths, heights and total area of the cross section, are given as well. The cross sections refer to the six high-symmetry zb NWires with low-index faceting frequently occurring in the bottom-up and top-down approaches of NWire processing. The fundamental insights into NWire structures revealed here offer a universal gauge and thus enable major advancements in data interpretation and the understanding of all zb- and diamond-structure-based NWires with arbitrary convex cross sections. We corroborate this statement with an exact description of irregular Si NWire cross sections and irregular InGaAs/GaAs core-shell NWire cross sections, where a radially changing unit-cell parameter can be included.","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9370210/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9101986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Formation and crystallization of TiO₂ nanostructures on various surfaces. 不同表面上TiO2纳米结构的形成和结晶。

IF 1.9 3区化学

Acta crystallographica Section B, Structural science, crystal engineering and materials Pub Date : 2022-08-01 Epub Date: 2022-07-07 DOI: 10.1107/S2052520622005042

Ghulam Hassnain Jaffari, Tanvir Hussain, Asad Muhammad Iqbal, Yawar Abbas

{"title":"Formation and crystallization of TiO2 nanostructures on various surfaces.","authors":"Ghulam Hassnain Jaffari, Tanvir Hussain, Asad Muhammad Iqbal, Yawar Abbas","doi":"10.1107/S2052520622005042","DOIUrl":"https://doi.org/10.1107/S2052520622005042","url":null,"abstract":"A comparative study of the synthesis of TiO2 nanorods on fluorine-doped tin oxide (FTO) glass, Si, SiO2, Si/Ta, Si/TiN, Si/TiN/Ti and Si/HFO2 substrates by hydrothermal reaction is presented. Detailed analysis on the growth of TiO2 on pre-annealed Si/TiN/Ti and HfO2 (HFO) surfaces is also given. For Si/TiN/Ti, a pre-annealing procedure led to the transformation of Ti to a TiO2 layer which acts as a seed for aligned growth of TiO2 nanorods. In contrast, Si/HFO does not provide a nucleation site for the formation of aligned nanorods. Various samples were prepared by varying the synthesis conditions, i.e. pre- and post-annealing temperatures and hydrothermal reaction time to figure out the optimum conditions which lead to unidirectional and highly aligned nanorods. X-ray diffraction, scanning electron microscopy, ultraviolet-visible spectroscopy and Raman spectroscopy were used to study structural, morphological and optical properties of synthesized samples. It is found that TiO2 nanorods exhibit a rutile phase on the Si/Ti/TiN and Si/HFO substrates, but highly oriented vertical growth of nanorods has been observed only on pre-annealed Si/TiN/Ti substrates. On the other hand, TiO2 nanorods form dandelion-like structures on Si/HFO substrates. Growth of vertically oriented TiO2 nanorods on Si/TiN/Ti is attributed to the TiO2 seed layer which forms after the process of pre-annealing of substrates at a suitable temperature. Variation in hydrothermal reaction time and post-annealing temperature brings further improvement in crystallinity and morphology of nanorods. This work shows that the pre-annealed Si/TiN/Ti substrate is the optimal choice to achieve vertically oriented, highly aligned TiO2 nanorods.","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40704078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

The bond valence model as a prospective approach: examination of the crystal structures of copper chalcogenides with Cu bond valence excess. 键价模型作为一种前瞻性方法:铜键价过剩的硫族铜晶体结构的研究。

IF 1.9 3区化学

Acta crystallographica Section B, Structural science, crystal engineering and materials Pub Date : 2022-08-01 Epub Date: 2022-07-12 DOI: 10.1107/S2052520622006138

Yves Moëlo, Aurelian Florin Popa, Vincent Dubost

{"title":"The bond valence model as a prospective approach: examination of the crystal structures of copper chalcogenides with Cu bond valence excess.","authors":"Yves Moëlo, Aurelian Florin Popa, Vincent Dubost","doi":"10.1107/S2052520622006138","DOIUrl":"https://doi.org/10.1107/S2052520622006138","url":null,"abstract":"Bond valence analysis has been applied to various copper chalcogenides with copper valence excess, i.e. where the formal valence of copper exceeds 1. This approach always reveals a copper bond valence excess relative to the unit value, correlated to an equivalent ligand bond valence deficit. In stoichiometric chalcogenides, this corresponds to one ligand electron in excess per formula unit relative to the valence equilibrium considering only CuI. This ligand electron in excess is 50/50 shared between all or part of the Cu-atom positions, and all or part of the ligand-atom positions. In Cu3Se2, only one of the two Cu positions is involved in this sharing. It would indicate a special type of multicentre bonding (`one-electron co-operative bonding'). Calculated and ideal structural formulae according to this bond valence distribution are presented. At the crystal structure scale, Cu-ligand bonds implying the single electron in excess form one-, two- or three-dimensional subnetworks. Bond valence distribution according to two two-dimensional subnets is detailed in covellite, CuS. This bond valence description is a formal crystal-chemical representation of the metallic conductivity of holes (mixing between Cu 3d bands and ligand p bands), according to published electronic band structures. Bond valence analysis is a useful and very simple prospective approach in the search for new compounds with targeted specific physical properties.","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40420475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Insights into isostructural and non-isostructural crystals of esters of oleanolic acid and its 11-oxo derivatives. 齐墩果酸酯及其11-氧衍生物的同构和非同构晶体研究。

IF 1.9 3区化学

Acta crystallographica Section B, Structural science, crystal engineering and materials Pub Date : 2022-08-01 Epub Date: 2022-07-07 DOI: 10.1107/S2052520622005972

Dominik Langer, Barbara Wicher, Wioletta Bendzinska-Berus, Barbara Bednarczyk-Cwynar, Ewa Tykarska

引用次数: 1

Role of lone-pair electron localization in temperature-induced phase transitions in mimetite. 孤对电子定位在温度诱导的麦饭石相变中的作用。

IF 1.3 3区化学

Acta crystallographica Section B, Structural science, crystal engineering and materials Pub Date : 2022-08-01 Epub Date: 2022-07-09 DOI: 10.1107/S2052520622006254

Georgia Cametti, Mariko Nagashima, Sergey V Churakov

{"title":"Role of lone-pair electron localization in temperature-induced phase transitions in mimetite.","authors":"Georgia Cametti, Mariko Nagashima, Sergey V Churakov","doi":"10.1107/S2052520622006254","DOIUrl":"10.1107/S2052520622006254","url":null,"abstract":"The crystal structure of mimetite Pb5(AsO4)3Cl, a phosphate with apatite structure-type has been investigated in situ at 123, 173, 273, 288, 353 and 393 K. A careful inspection of the diffraction pattern and subsequent structure refinements indicated that mimetite transforms from the monoclinic to the hexagonal polymorph with increasing temperature. At 123 K, a monoclinic superstructure, mimetite-2M, with cell parameters a = 20.4487 (9), b = 7.4362 (2), c = 20.4513 (9) Å, β = 119.953 (6)°, V = 2694.5 (2) Å3 and space group P21 was observed. From 173 to 353 K, the reflections of the supercell were evident only along one direction of the corresponding hexagonal apatite-cell and the structure transforms to the polymorph mimetite-M with space group P21/b and unit-cell parameters a = 10.2378 (3), b = 20.4573 (7), c = 7.4457 (2) Å, β = 120.039 (5)°, V = 1349.96 (9) Å3. Only at higher temperature, i.e. 393 K, does mimetite adopt the hexagonal space group P63/m characteristic of apatite structure-types. The role of the electron lone pairs of Pb atoms in the phase transition was investigated through the analysis of the electron localization function (ELF) calculated based on the DFT-geometry optimized structures of the three polymorphs. The changes in spatial distribution of the 6s2 electron density during the phase transitions were explored by means of the Wannier Function Centres (WFCs) derived from ab initio molecular dynamics trajectories. In the high-temperature hexagonal structure the 6s2 electrons are spherically symmetric relative to the position of Pb atoms. At low temperature the maximum of 6s2 electron density is displaced relative to the position of Pb atom contributing to the polar interaction in the monoclinic polymorphs.","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9370212/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40704080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The tetrel bonding role in supramolecular aggregation of lead(II) acetate and a thiosemicarbazide derivative. 四元键在醋酸铅和氨基硫脲衍生物的超分子聚集中的作用。

IF 1.9 3区化学

Acta crystallographica Section B, Structural science, crystal engineering and materials Pub Date : 2022-08-01 Epub Date: 2022-07-22 DOI: 10.1107/S2052520622005789

Ghodrat Mahmoudi, Isabel García-Santos, Michael Pittelkow, Fadhil S Kamounah, Ennio Zangrando, Maria G Babashkina, Antonio Frontera, Damir A Safin

{"title":"The tetrel bonding role in supramolecular aggregation of lead(II) acetate and a thiosemicarbazide derivative.","authors":"Ghodrat Mahmoudi, Isabel García-Santos, Michael Pittelkow, Fadhil S Kamounah, Ennio Zangrando, Maria G Babashkina, Antonio Frontera, Damir A Safin","doi":"10.1107/S2052520622005789","DOIUrl":"https://doi.org/10.1107/S2052520622005789","url":null,"abstract":"A new PbII coordination complex [PbL(OAc)], which was readily synthesized from a mixture of Pb(OAc)2·3H2O and 1-(pyridin-2-yl)benzylidene-4-phenylthiosemicarbazide (HL) is reported. The crystal structure analysis of [PbL(OAc)] showed that the PbII cation is N,N',S-chelated by the tridentate pincer-type ligand L and by the oxygen atoms of the acetate anion. In addition, the metal centre forms Pb...O and Pb...S tetrel bonds with an adjacent complex molecule, yielding a 1D zigzag polymeric chain, which is reinforced by N-H...O hydrogen bonds and π...π interactions. These chains are interlinked by C-H...py non-covalent interactions, realized between one of the acetate hydrogen atoms and the pyridine rings. According to the Hirshfeld surface analysis, the crystal packing is mainly characterized by intermolecular H...H, H...C and H...O contacts, followed by H...N, H...S, C...C, C...N, Pb...H, Pb...O and Pb...S contacts. The FTIR and 1H NMR spectra of [PbL(OAc)] testify to the deprotonation of the parent ligand HL, while the acetate ligand exhibits an anisobidentate coordination mode as established by means of single-crystal X-ray diffraction and FTIR spectroscopy. Lastly, theoretical calculations at the PBE0-D3/def2-TZVP level of theory have been used to analyze and characterize the Pb...O and Pb...S tetrel bonds observed in the crystal of [PbL(OAc)], using a combination of QTAIM (Quantum Theory of Atoms in Molecules) and NCIPlot (Non-Covalent Interaction Plot) computational tools.","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40420479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Structure stabilization effect of vacancies and entropy in hexagonal WN. 空位和熵对六方WN结构的稳定作用。

IF 1.9 3区化学

Acta crystallographica Section B, Structural science, crystal engineering and materials Pub Date : 2022-08-01 Epub Date: 2022-07-16 DOI: 10.1107/S2052520622006096

Yingna Han, Wandong Xing, Rong Yu, Fanyan Meng

引用次数: 0

Synthesis, chiral crystal structure, and magnetic properties of Ba₃Ga₂O₅Cl₂. Ba3Ga2O5Cl2的合成、手性晶体结构及磁性能。

IF 1.9 3区化学

Acta crystallographica Section B, Structural science, crystal engineering and materials Pub Date : 2022-08-01 Epub Date: 2022-07-05 DOI: 10.1107/S2052520622004723

Jeremy Rine, Yongqi Yang, Zhixue Shu, Jianda Zhao, Weiwei Xie, Tai Kong

引用次数: 0