Design of higher valency in covalent organic frameworks

Science ◽  
2020 ◽  
Vol 370 (6515) ◽  
pp. eabd6406 ◽  
Author(s):  
Cornelius Gropp ◽  
Tianqiong Ma ◽  
Nikita Hanikel ◽  
Omar M. Yaghi
Keyword(s):  
Single Crystals ◽  
Powder Diffraction ◽  
Covalent Organic Frameworks ◽  
X Ray

The valency (connectivity) of building units in covalent organic frameworks (COFs) has been primarily 3 and 4, corresponding to triangles and squares or tetrahedrons, respectively. We report a strategy for making COFs with valency 8 (cubes) and “infinity” (rods). The linker 1,4-boronophenylphosphonic acid—designed to have boron and phosphorus as an isoelectronic combination of carbon-group elements—was condensed into a porous, polycubane structure (BP-COF-1) formulated as (–B4P4O12–)(–C6H4–)4. It was characterized by x-ray powder diffraction techniques, which revealed cubes linked with phenyls. The isoreticular forms (BP-COF-2 to 5) were similarly prepared and characterized. Large single crystals of a constitutionally isomeric COF (BP-COF-6), composed of rod units, were also synthesized using the same strategy, thus propelling COF chemistry into a new valency regime.

scholarly journals Crystal structures of the triple perovskites Ba2K2Te2O9and Ba2KNaTe2O9, and redetermination of the double perovskite Ba2CaTeO6

2018 ◽  
Vol 74 (7) ◽  
pp. 1006-1009 ◽  
Author(s):  
Matthias Weil
Keyword(s):  
Solid State ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Perovskite Structure ◽  
Double Perovskite ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Group Type

Single crystals of Ba2K2Te2O9(dibarium dipotassium nonaoxidoditellurate), (I), Ba2KNaTe2O9(dibarium potassium sodium nonaoxidoditellurate), (II), and Ba2CaTeO6(dibarium calcium hexaoxidotellurate), (III), were obtained from KNO3/KI or KNO3/NaNO3flux syntheses in platinum crucibles for (I) and (II), or porcelain crucibles for (III). (I) and (II) are isotypic and are members of triple perovskites with general formulaA2[12co]A′[12co]B2[6o]B′[6o]O9. They crystallize in the 6H-BaTiO3structure family in space-group typeP63/mmc, with theA,A′,BandB′ sites being occupied by K, Ba, Te and a second Ba in (I), and in (II) by mixed-occupied (Ba/K), Ba, Te and Na sites, respectively. (III) adopts theA2[12co]B′[6o]B′′[6o]O6double perovskite structure in space-group typeFm-3m, with Ba, Ca and Te located on theA,B′ andB′′sites, respectively. The current refinement of (III) is based on single-crystal X-ray data. It confirms the previous refinement from X-ray powder diffraction data [Fuet al.(2008).J. Solid State Chem.181, 2523–2529], but with higher precision.

scholarly journals Use of Imaging Plates in X-Ray Analysis

1997 ◽  
Vol 29 (1-2) ◽  
pp. 89-101 ◽  
Author(s):  
M. Ermrich ◽  
F. Hahn ◽  
E. R. Wölfel
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Polycrystalline Materials ◽  
Imaging Plate ◽  
Two Dimensional ◽  
X Ray ◽  
Working Principle ◽  
Imaging Plates

Two-dimensional detectors have opened a new area for the investigation of both single crystals and polycrystalline materials. The working principle of Imaging Plates is described. Some characteristics and the advantages of an Imaging Plate are discussed using the STOE Imaging Plate Diffraction System for different kinds of X-ray analysis: (i) single crystal diffractometry, (ii) powder diffraction and (iii) stress and texture investigations.

Powder X-ray diffraction data for Ba4ZnTi11O27 and Ba2ZnTi5O13

1994 ◽  
Vol 9 (1) ◽  
pp. 56-62 ◽  
Author(s):  
C. G. Lindsay ◽  
C. J. Rawn ◽  
R. S. Roth
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
Powder Samples ◽  
Unit Cell Dimensions

Single crystals and powder samples of Ba4ZnTi11O27 and Ba2ZnTi5O13 have been synthesized and studied using single-crystal X-ray precession photographs and X-ray powder diffraction. Unit cell dimensions were calculated from a least-squares refinement with a final maximum Δ2θ of 0.05°. Both phases were found to have monoclinic cells, space group C2/m. The refined lattice parameters for the Ba4ZnTi11O27 compound are a= 19.8687(8) Å, b=11.4674(5) Å, c=9.9184(4) Å, β= 109.223(4)°, and Z=4. The refined lattice parameters for the Ba2ZnTi5O13 compound are a= 15.2822(7) Å, b=3.8977(1) Å, c=9.1398(3) Å, β=98.769(4)°, and Z=2.

Analysis of an industrial production suspension ofBacillus lentussubtilisin crystals by powder diffraction: a powerful quality-control tool

2014 ◽  
Vol 70 (4) ◽  
pp. 1115-1123 ◽  
Author(s):  
Christian G. Frankaer ◽  
Olga V. Moroz ◽  
Johan P. Turkenburg ◽  
Stein I. Aspmo ◽  
Majbritt Thymark ◽  
...  
Keyword(s):  
Quality Control ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Quality Control Tool ◽  
Control Tool

A microcrystalline suspension ofBacillus lentussubtilisin (Savinase) produced during industrial large-scale production was analysed by X-ray powder diffraction (XRPD) and X-ray single-crystal diffraction (MX). XRPD established that the bulk microcrystal sample representative of the entire production suspension corresponded to space groupP212121, with unit-cell parametersa= 47.65,b= 62.43,c= 75.74 Å, equivalent to those for a known orthorhombic crystal form (PDB entry 1ndq). MX using synchrotron beamlines at the Diamond Light Source with beam dimensions of 20 × 20 µm was subsequently used to study the largest crystals present in the suspension, with diffraction data being collected from two single crystals (∼20 × 20 × 60 µm) to resolutions of 1.40 and 1.57 Å, respectively. Both structures also belonged to space groupP212121, but were quite distinct from the dominant form identified by XRPD, with unit-cell parametersa= 53.04,b = 57.55,c= 71.37 Å anda= 52.72,b= 57.13,c= 65.86 Å, respectively, and refined toR= 10.8% andRfree= 15.5% and toR= 14.1% andRfree= 18.0%, respectively. They are also different from any of the forms previously reported in the PDB. A controlled crystallization experiment with a highly purified Savinase sample allowed the growth of single crystals of the form identified by XRPD; their structure was solved and refined to a resolution of 1.17 Å with anRof 9.2% and anRfreeof 11.8%. Thus, there are at least three polymorphs present in the production suspension, albeit with the 1ndq-like microcrystals predominating. It is shown how the two techniques can provide invaluable and complementary information for such a production suspension and it is proposed that XRPD provides an excellent quality-control tool for such suspensions.

Powder Diffraction Data of Some Acentric Tartrates and Tartrato-Antimonates

1991 ◽  
Vol 6 (2) ◽  
pp. 107-110
Author(s):  
Markus Garsche ◽  
Ekkehart Tillmanns ◽  
Thomas Bauer ◽  
Reinhard X. Fischer ◽  
Ladislav Bohaty
Keyword(s):  
Aqueous Solutions ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Crystal Data ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Optical Effects ◽  
Diffraction Patterns

AbstractSix acentric tartrates and tartrato-antimonates have been investigated by means of X-ray powder diffraction. Single crystals were obtained by evaporation from aqueous solutions. The compounds have attracted attention because of their electrostrictive and electro-optical effects. Complete crystal data for the six compounds are reported. X-ray powder diffraction patterns for Rb2C4H4O6 and Ca [Sb2{C4H2O6}2]·2H2O are given.

scholarly journals The growth of sapphire single crystals

2001 ◽  
Vol 66 (6) ◽  
pp. 411-418 ◽  
Author(s):  
Aleksandar Golubovic ◽  
Slobodanka Nikolic ◽  
Stevan Djuric ◽  
Andreja Valcic
Keyword(s):  
Crystal Growth ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Chemical Polishing ◽  
Published Data ◽  
Czochralski Technique ◽  
Critical Rate ◽  
Etching Solution ◽  
X Ray ◽  
Crystal Diameter

Sapphire (Al2O3) single crystals were grown by the Czochralski technique both in air and argon atmospheres. The conditions for growing sapphire single crystals were calculated by using a combination of Reynolds and Grash of numbers. Acritical crystal diameter dc = 20 mm and the critical rate of rotation c = 20 rpm were calculated from the hydrodynamics of the melt. The value of the rate of crystal growth was experimentally found to be 3.5 mm/h. According to our previous experiments, it was confirmed that three hours exposures to conc. H3PO4 at 593 K was suitable for chemical polishing. Also, three hours exposure to conc.H3PO4 at 523Kwas found to be a suitable etching solution. The lattice parameters a = 0.47573 nm and c = 1.29893 nm were determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

Amorphization of quartz-type structures and a new high-pressure phase of AlAsO4

1996 ◽  
Vol 211 (2) ◽  
Author(s):  
H. Sowa ◽  
H. Ahsbahs
Keyword(s):  
High Pressure ◽  
Single Crystals ◽  
Powder Diffraction ◽  
High Pressure Phase ◽  
X Ray ◽  
Pressure Phase

AbstractX-ray powder diffraction measurements and investigations on single crystals of AlAsO

Identification of two lead perovskites, Pb2ScTaO6 and Pb(Sc0.5Nb0.5)O3, by X-ray powder diffraction patterns

1993 ◽  
Vol 8 (3) ◽  
pp. 191-193 ◽  
Author(s):  
C. Caranoni ◽  
P. Lampin ◽  
C. Boulesteix
Keyword(s):  
Single Crystals ◽  
Powder Diffraction ◽  
Perovskite Structure ◽  
Room Temperature ◽  
Stoichiometric Mixture ◽  
High Quality ◽  
Space Group ◽  
X Ray ◽  
Diffraction Patterns ◽  
Degree Of Order

Substituting cations in materials with the formula Pb2B′B″O6 is more or less ordered on the B sites. High-quality single crystals of Pb2ScTaO6 (PST) and Pb(Sc0.5Nb0.5)O3 (PSN) were prepared from two thermal cycles. A stoichiometric mixture of the constituent oxides was prefired at up to 1000 °C, and then crystals were grown from a PbO–B2O3–PbF2 flux mixture, starting at a temperature of 1100 °C for PSN and 1200 °C for PST. At room temperature, X-ray examination showed that PSN had a perovskite structure with a cubic unit-cell and a refined parameter a = 4.080(1 ) Å, space group Pm3m and Z = 1, whereas PST formed a well-ordered superlattice with a = 8.136(1) Å, Z = 4 and space group Fm3m. In each case a fully indexed powder pattern is presented. The degree of order is estimated to be close to 80% for PST and less than 10% for PSN.

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