Acta crystallographica Section B, Structural science, crystal engineering and materials最新文献

{"title":"Comparative study of conventional and synchrotron X-ray electron densities on molecular crystals.","authors":"Emilie S Vosegaard,&nbsp;Jakob V Ahlburg,&nbsp;Lennard Krause,&nbsp;Bo B Iversen","doi":"10.1107/S2052520623006625","DOIUrl":"10.1107/S2052520623006625","url":null,"abstract":"<p><p>Five different electron density datasets obtained from conventional and synchrotron single crystal X-ray diffraction experiments are compared. The general aim of the study is to investigate the quality of data for electron density analysis from current state-of-the-art conventional sources, and to see how the data perform in comparison with high-quality synchrotron data. A molecular crystal of melamine was selected as the test compound due to its ability to form excellent single crystals, the light atom content, and an advantageous suitability factor of 3.6 for electron density modeling. These features make melamine an optimal system for conventional X-ray diffractometers since the inherent advantages of synchrotron sources such as short wavelength and high intensity are less critical in this case. Data were obtained at 100 K from new in-house diffractometers Rigaku Synergy-S (Mo and Ag source, HyPix100 detector) and Stoe Stadivari (Mo source, EIGER2 1M CdTe detector), and an older Oxford Diffraction Supernova (Mo source, Atlas CCD detector). The synchrotron data were obtained at 25 K from BL02B1 beamline at SPring-8 in Japan (λ = 0.2480 Å, Pilatus3 X 1M CdTe detector). The five datasets were compared on general quality parameters such as resolution, ⟨I/σ⟩, redundancy and R factors, as well as the more model specific fractal dimension plot and residual density maps. Comparison of the extracted electron densities reveals that all datasets can provide reliable multipole models, which overall convey similar chemical information. However, the new laboratory X-ray diffractometers with advanced pixel detector technology clearly measure data with significantly less noise and much higher reliability giving densities of higher quality, compared to the older instrument. The synchrotron data have higher resolution and lower measurement temperature, and they allow for finer details to be modeled (e.g. hydrogen κ parameters).</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10552600/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10515174","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}

{"title":"In data we trust: X-ray diffraction experiments for charge density investigations.","authors":"Regine Herbst-Irmer","doi":"10.1107/S205252062300776X","DOIUrl":"10.1107/S205252062300776X","url":null,"abstract":"<p><p>A short commentary is given on the paper by Vosegaard et al. [Acta Cryst. (2023), 79, 380-391], which compares charge density models derived from four datasets measured on conventional diffractometers with the results of a high-quality dataset from SPring-8.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10552599/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10361476","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}

{"title":"Structural insight into the cooperativity of spin crossover compounds.","authors":"H Shahed,&nbsp;N Sharma,&nbsp;M Angst,&nbsp;J Voigt,&nbsp;J Perßon,&nbsp;P Prakash,&nbsp;K W Törnroos,&nbsp;D Chernyshov,&nbsp;H Gildenast,&nbsp;M Ohl,&nbsp;G Saffarini,&nbsp;A Grzechnik,&nbsp;K Friese","doi":"10.1107/S2052520623005814","DOIUrl":"10.1107/S2052520623005814","url":null,"abstract":"<p><p>Spin-crossover (SCO) compounds are promising materials for a wide variety of industrial applications. However, the fundamental understanding of their nature of transition and its effect on the physical properties are still being fervently explored; the microscopic knowledge of their transition is essential for tailoring their properties. Here an attempt is made to correlate the changes in macroscopic physical properties with microscopic structural changes in the orthorhombic and monoclinic polymorphs of the SCO compound Fe(PM-Bia)₂(NCS)₂ (PM = N-2'-pyridylmethylene and Bia = 4-aminobiphenyl) by employing single-crystal X-ray diffraction, magnetization and DSC measurements. The dependence of macroscopic properties on cooperativity, highlighting the role of hydrogen bonding, π-π and van der Waals interactions is discussed. Values of entropy, enthalpy and cooperativity are calculated numerically based on the Slichter-Drickamer model. The particle size dependence of the magnetic properties is probed along with the thermal exchange and the kinetic behavior of the two polymorphs based on the dependence of magnetization on temperature scan rate and a theoretical model is proposed for the calculation of the non-equilibrium spin-phase fraction. Also a scan-rate-dependent two-step behavior observed for the orthorhombic polymorph, which is absent for the monoclinic polymorph, is reported. Moreover, it is found that the radiation dose from synchrotron radiation affects the spin-crossover process and shifts the transition region to lower temperatures, implying that the spin crossover can be tuned with radiation damage.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10552598/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10044857","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}

{"title":"An approach to investigate the crystallographic unit cell of human tooth enamel.","authors":"Jose Reyes-Gasga,&nbsp;Samuel Tehuacanero-Núñez,&nbsp;Francisco Sánchez-Ochoa","doi":"10.1107/S2052520623006777","DOIUrl":"10.1107/S2052520623006777","url":null,"abstract":"<p><p>Human tooth enamel (HTE) is the hardest tissue in the human body and its structural organization shows a hierarchical composite material. At the nanometric level, HTE is composed of approximately 97% hydroxyapatite [HAP, Ca₁₀(PO₄)₆(OH)₂] as inorganic phase, and of 3% as organic phase and water. However, it is still controversial whether the hexagonal HAP phase crystallizes in P6₃/m or another space group. The observance in HTE of Ca²⁺, Mg²⁺ and Na⁺ ions using X-ray characteristic energy-dispersive spectroscopy in the scanning electron microscope has been explained by substitutions in the HAP unit cell. Thus, Ca²⁺ can be replaced by Na⁺ and Mg²⁺ ions; the PO₄^3- group can be replaced by CO₃^2- ions; and the OH^- ions can also be replaced by CO₃^2-. A unit-cell model of the hexagonal structure of HTE is not fully defined yet. In this work, density functional theory calculations are performed to study the hexagonal HAP unit cell when substitution by OH^-, CO₃^2-, Mg²⁺ and Na⁺ ions are carried out. An approach is presented to study the crystallographic unit cell of HTE by examining the changes resulting from the inclusion of these different ions in the unit cell of HAP. Enthalpies of formation and crystallographic characteristics of the electron diffraction patterns are analysed in each case. The results show an enhancement in structural stability of HAP with OH defects, atomic substitution of Mg²⁺, carbonate and interstitial Na⁺. Simulated electron diffraction patterns of the generated structures show similar characteristics to those of human tooth enamel. Hence, the results explain the indiscernible structural changes shown in experimental X-ray diffractograms and electron diffraction patterns.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10597250","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}

{"title":"Effect of pre-rolling aging treatment on evolutions of the microstructure and the texture of aluminium alloy 7005 subjected to heavy cold rolling.","authors":"Mohammad Hassan Farshidi,&nbsp;Hiroyuki Miyamoto,&nbsp;Haruka Ito","doi":"10.1107/S2052520623007011","DOIUrl":"10.1107/S2052520623007011","url":null,"abstract":"<p><p>Aluminium alloy 7005 is widely used for structural purposes because of its attractive properties such as good weldability and age-hardening capability. However, since the workability of this alloy falls after a short period of natural aging, the application of cold rolling for the production of strain-hardened sheets of this alloy is a challenge. Two solutions proposed to overcome this challenge are as follows: (a) immediate rolling of the alloy after solution treatment and (b) rolling of the alloy after artificial aging. However, there is no comprehensive study comparing the effect of pre-rolling aging treatments on the evolutions of microstructure and texture of the alloy through heavy cold rolling. This subject is the aim of the present study. For this purpose, different pieces of the alloy are subjected to three different heat treatments before rolling, and afterward, they are rolled to obtain a thickness reduction of 80%. Scanning electron microscopy with electron backscattered diffraction observations are applied to study the evolutions of the microstructure and the texture of the alloy. Results show that the progression of pre-rolling aging decreases the incidence of micro-scaled shear bands by rolling. In addition, the rolling texture intensity decreases with the advancement of pre-rolling aging. Mechanisms responsible for this effect are discussed.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10597249","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}

{"title":"The hydrogen-bond network in sodium chloride tridecahydrate: analogy with ice VI.","authors":"Keishiro Yamashita,&nbsp;Kazuya Nakayama,&nbsp;Kazuki Komatsu,&nbsp;Takashi Ohhara,&nbsp;Koji Munakata,&nbsp;Takanori Hattori,&nbsp;Asami Sano-Furukawa,&nbsp;Hiroyuki Kagi","doi":"10.1107/S2052520623007199","DOIUrl":"10.1107/S2052520623007199","url":null,"abstract":"<p><p>The structure of a recently found hyperhydrated form of sodium chloride (NaCl·13H₂O and NaCl·13D₂O) has been determined by in situ single-crystal neutron diffraction at 1.7 GPa and 298 K. It has large hydrogen-bond networks and some water molecules have distorted bonding features such as bifurcated hydrogen bonds and five-coordinated water molecules. The hydrogen-bond network has similarities to ice VI in terms of network topology and disordered hydrogen bonds. Assuming the equivalence of network components connected by pseudo-symmetries, the overall network structure of this hydrate can be expressed by breaking it down into smaller structural units which correspond to the ice VI network structure. This hydrogen-bond network contains orientational disorder of water molecules in contrast to the known salt hydrates. An example is presented here for further insights into a hydrogen-bond network containing ionic species.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10579265","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}

{"title":"Crystal structure refinement, low- and high-temperature X-ray diffraction and Mössbauer spectroscopy study of the oxoborate ludwigite from the Iten'yurginskoe deposit.","authors":"Yaroslav P Biryukov,&nbsp;Almaz L Zinnatullin,&nbsp;Irina O Levashova,&nbsp;Andrey P Shablinskii,&nbsp;Rimma S Bubnova,&nbsp;Farit G Vagizov,&nbsp;Valery L Ugolkov,&nbsp;Stanislav K Filatov,&nbsp;Igor V Pekov","doi":"10.1107/S2052520623006455","DOIUrl":"10.1107/S2052520623006455","url":null,"abstract":"<p><p>This paper reports an investigation of the chemistry, crystal structure refinement and thermal behavior (80-1650 K) of ludwigite from the Iten'yurginskoe deposit (Eastern Chukotka, Russia). Its chemical composition was determined by electron microprobe analysis, giving an empirical formula (Mg_1.70Fe²⁺_0.29Mn_0.01)_Σ2.00(Fe³⁺_0.90Al_0.08Mg_0.02)_Σ1.00O₂(BO₃). A refinement of the crystal structure from single-crystal X-ray diffraction data (SCXRD) was provided for the first time for ludwigite from this deposit (R = 0.047). The structure can be described as a framework composed of [MO₆]^n- octahedra and isolated [BO₃]^3- triangles located in triangular interstices of the framework. Based on a comprehensive analysis of SCXRD and Mössbauer spectroscopy data, the M1 site is occupied by Mg, M2 and M3 by Mg and Fe²⁺, M4 by Fe³⁺, Mg and Al. There are also oxo-centered [O4M₄]ⁿ⁺ and [O2M₅]ⁿ⁺ polyhedra building up a framework with the [BO₃]^3- triangles located in its hexagonal interstices. No indications of magnetic ordering are found in the temperature range investigated. The Fe²⁺ → Fe³⁺ oxidation occurs above 600 K, and is accompanied by a decrease of the unit-cell parameters and subsequent incomplete solid-phase decomposition with the formation of hematite, warwickite and magnetite. The mineral melts at temperatures above 1582 K. The thermal expansion of ludwigite is slightly anisotropic, which is explained by a dense packing of the [MO₆]^n- octahedra as well as a virtually perpendicular orientation of the oxo-centered double chains to each other. At room temperature, maximum expansion is along the c axis (α_c = 9.1 × 10^-6 K^-1) and minimum expansion is in the ab plane (α_a = 8.6 × 10^-6, α_b = 7.6 × 10^-6 K^-1), which is due to the preferred orientation of the [BO₃]^3- triangles. A comparison of the thermal behavior of three oxoborates of the ludwigite group, namely azoproite (Mg,Fe²⁺)₂(Fe³⁺,Ti,Mg,Al)O₂(BO₃), vonsenite (Fe²⁺,Mg)₂(Fe³⁺,Mn²⁺,Sn,Al)O₂(BO₃) and ludwigite (Mg_,Fe²⁺_,Mn)₂(Fe³⁺_,Al_,Mg)O₂(BO₃), is provided.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10515176","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}

{"title":"Bromine versus chlorine substituent in breathing crystals of a copper(I) coordination compound with a triazolamine Schiff base.","authors":"Emilia Ganczar,&nbsp;Agata Białońska","doi":"10.1107/S205252062300673X","DOIUrl":"10.1107/S205252062300673X","url":null,"abstract":"<p><p>It is known that N-[4-(chlorobenzylidene)-4H-1,2,4-triazol-4-amine in reaction with copper(I) perchlorate(VII) forms metastable breathing crystals built up of X-shaped binuclear units containing copper(I) ions in a trigonal coordination sphere. Using trifluoromethanesulfonate instead of perchlorate(VII) affects the self-assembly of the X-shaped units and the breathing function of the resulting crystals. The latter are not breathing crystals. Copper(I) trifluoromethanesulfonate with N-[4-(bromobenzylidene)-4H-1,2,4-triazol-4-amine crystallizes in two forms: open (with the presence of 1D channels) and closed (without 1D channels). Both are characterized by the presence of X-shaped binuclear cationic units and the trigonal coordination sphere of copper(I) ions. The open form has the ability to engage in reversible sorption. The desorption process is associated with the large reorientation of the binuclear units and the reorganization of the intermolecular interactions leading to the closure of the channels. The post-synthetically obtained channel-less form differs from the channel-less form obtained by direct crystallization, the latter being incapable of sorption. The mechanism of the desorption process of the open form is governed by the general principle of dense packing, and the main reason for the sorption process is the formation of directional halogen-halogen interactions. The halogen atom in the para position of the ligands influences the formation of different crystalline forms and also a different mechanism for the desorption process.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10597251","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}

{"title":"Crystal and magnetic structures of R₂Ni₂In compounds (R = Tb and Ho).","authors":"Stanisław Baran,&nbsp;Aleksandra Deptuch,&nbsp;Andreas Hoser,&nbsp;Bogusław Penc,&nbsp;Janusz Przewoźnik,&nbsp;Andrzej Szytuła","doi":"10.1107/S2052520623006315","DOIUrl":"10.1107/S2052520623006315","url":null,"abstract":"<p><p>Crystal and magnetic structures of R₂Ni₂In (R = Tb and Ho) have been studied using powder neutron diffraction at low temperatures. The compounds crystallize as orthorhombic crystal structures of the Mn₂AlB₂ type. At low temperatures, the magnetic moments localized solely on the rare earth atoms form antiferromagnetic structures. The Tb magnetic moments, equal to 8.8 (4) μ_B and parallel to the c axis, form a collinear magnetic structure described by the propagation vector k = [½ , ½ , ½]. This magnetic structure is stable up to the Néel temperature T_N = 40 K. For Ho₂Ni₂In a complex, temperature-dependent magnetic structure is detected. In the temperature range 6.1-8.6 K, an incommensurate sinusoidal magnetic structure, described by the propagation vector k₁ = [0.24, 1, 0.52] is observed, while in the temperature interval 2.2-2.5 K a square-modulated magnetic structure, related to k₂ = [0.17,{{5} over {6}},{{1} over {2}}] (the component along the a axis slightly differs from the commensurate value) and its third harmonics 3k₂ = [0.50,{{5} over {2}},{{3} over {2}}] is found. At 3.1-3.7 K as well as below 2 K, a coexistence of both detected magnetic structures is observed. The Ho magnetic moments remain parallel to the c axis in both the sine- and square-modulated magnetic structures. The low-temperature heat capacity data confirm a first-order transition near 3 K.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10044862","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}

{"title":"The structure of magnesium stearate trihydrate determined from a micrometre-sized single crystal using a microfocused synchrotron X-ray beam.","authors":"Mikkel Herzberg,&nbsp;Toms Rekis,&nbsp;Anders Støttrup Larsen,&nbsp;Ana Gonzalez,&nbsp;Jukka Rantanen,&nbsp;Anders Østergaard Madsen","doi":"10.1107/S2052520623005607","DOIUrl":"https://doi.org/10.1107/S2052520623005607","url":null,"abstract":"<p><p>Crystalline magnesium stearate has been extensively used as an additive in pharmaceutical and other industries for decades. However, the lack of suitably large crystals has hindered the determination of the crystal structure and thereby a more fundamental understanding of the structure-functionality relationship. Presented here is the structure of magnesium stearate trihydrate as determined from X-ray diffraction data of a micrometre-sized single crystal measured at a fourth-generation synchrotron facility. Despite the small size of the single crystals and the weak diffraction, it was possible to determine the positions of the non-hydrogen atoms reliably. Periodic dispersion-corrected density functional theory calculations were used to obtain the positions of the hydrogen atoms playing an important role in the overall organization of the structure via a hydrogen-bond network.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10410307/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9973550","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}