Trigonal Space Group P3 Research Articles

Synthesis and crystal structure of acentric anhydrous beryllium carbonate Be(CO3).

The anhydrous alkaline earth metal carbonate Be(CO3) was synthesized in a laser-heated diamond anvil cell at moderate pressures and temperatures (20(2) GPa and 1500(200) K) by a reaction of BeO with CO2. It crystallizes in the acentric, trigonal space group P3121 with Z = 3. The crystal structure was obtained from synchrotron single crystal X-ray diffraction data and confirmed by density functional theory-based calculations in combination with Raman spectroscopy. Second harmonic generation measurements were employed to verify the acentric space group symmetry. The crystal structure of Be(CO3) is characterized by the presence of isolated [CO3]2--groups and BeO4-tetrahedra. This is a new structure type and such a topology has not been observed in carbonates before. Be(CO3) can be recovered to ambient conditions and is not undergoing a phase transition during decompression.

Two trinuclear cluster metal–organic frameworks: syntheses, structures, highly fluorescent sensing and magnetic properties

Two new metal–organic frameworks [Zn3(TCPB)2(H2O)2]·3DMF·2H2O (1) and [Mn1.5(TCPB)(DMF)(H2O)]·DMF(2)(H3TCPB = 1,3,5-tri(4-carboxyphenoxy)benzene), have been successfully constructed by solvothermal methods and structurally characterized by single crystal X-ray diffraction, elemental analyses, IR spectra, Raman spectra, 1H NMR spectra, powder X-ray diffraction and thermogravimetric analyses. Single-crystal X-ray diffraction analyses reveal that complex 1 crystallizes in the trigonal space group P3¯ 1c and possesses a 2D network, whereas complex 2 crystallizes in the triclinic space group P1¯ and also possesses a 2D network. TOPOS analyses reveal that both complexes 1 and 2 have a (3,6)-connected network topology with the Schläfli symbol of (43·612) (43)2 for 1 and {43}2{46·66·83} for 2. Notably, further investigation indicates that complex 1 can be employed as a bi-functional fluorescent sensor for highly sensitive and selective detection of ferric ions (Fe3+) and 2,4,6-trinitrophenol (TNP), with the detection limit of 0.11 μM for Fe3+ and 0.14 μM for TNP. Furthermore, the possible fluorescence quenching mechanisms are explained as: (a) photo-induced electron transfer (PET) caused by the HOMO-LUMO energy gap through DFT and (b) fluorescence resonance energy transfer (FRET). Besides, the magnetic property measurement indicated that complex 2 shows antiferromagnetic interactions between trinuclear {Mn3(COO)6} SBUs.

Strategic design of a rare trigonal symmetric luminescent covalent organic framework by linker modification

We designed a trigonal symmetric imine-linked covalent organic framework (COF), TFPC-DAB, with control over the angularity of the building units, where a bent C2-symmetric diamine, such as 1,3-diaminobenzene (1,3-DAB or DAB), with an exo-angle of 120° was used instead of those with an exo-angle of 180°, in combination with a C3-symmetric trialdehyde, such as tri(4-formylphenoxy)cyanurate (TFPC). Its synthesis was accomplished by reacting the building units in a mixture of mesitylene/dioxane/6 M acetic acid under solvothermal conditions. The phase purity, thermal stability, and porosity of TFPC-DAB were established by various analytical techniques. Utilizing the Density Functional Tight Binding (DFTB+) simulation and Pawley refinement, the best fit of the small angle x-ray pattern was found to have an AA stacking of TFPC-DAB in the trigonal space group P3 with low refinement parameters. Such smart materials are in huge demand to detect hazardous corrosive chemicals, such as HCl and NH3. The dual features of electron deficient π-acidic triazine moiety and heteroatoms (N/O) from TFPC and electron rich phenyl units from DAB embodied in the framework enhance its luminescent property and thereby make it suitable for solvent-based HCl and NH3 sensing. The detection limits for HCl and NH3 in methanol were found to be 14 and 82 ppb, respectively. The effect of solvent polarity on the sensing studies was observed with much lower detection limits in dioxane: 2.5 and 11 ppb for HCl and NH3, respectively. A detailed theoretical calculation using density functional theory and configurational bias Monte Carlo modules was conducted for understanding interactions between the COF and HCl or NH3 analytes.

SrCl2·6H2O: An Alkaline-Earth-Metal Chloride Hexahydrate as Deep-Ultraviolet Nonlinear-Optical Crystal with the {[Sr(H2O)6]2+}∞ Cationic Framework.

Exploring deep-ultraviolet (DUV) nonlinear-optical (NLO) materials is significant for the conversion of high-frequency laser. Herein, two alkali-earth-metal halide hexahydrates, SrX2·6H2O (X = Cl, Br), were obtained, and the centimeter-sized single crystals of SrCl2·6H2O were grown by a slow evaporation method. Both of them crystallize in the trigonal space group P321, and their crystal structures show {[Sr(H2O)6]2+}∞ cationic chains, with isolated Cl- or Br- anions interspersed between the chains. SrCl2·6H2O exhibits a moderate second-harmonic-generation response (0.4 × KDP) at 1064 nm and can realize phase matching. Importantly, SrCl2·6H2O has a short ultraviolet cutoff edge (<200 nm). Crystal growth, crystal structures, optical performances, and theoretical calculations of the title and related compounds have been discussed in this work. This study enriches the understanding of metal halide hydrates as NLO materials in the DUV region.

Structures of Three Alkaline-Earth Metal Germanides Refined from Single-Crystal X-ray Diffraction Data

The calcium- and strontium- alumo-germanides SrxCa1–xAl2Ge2 (x ≈ 0.4) and SrAl2Ge2 have been synthesized and structurally characterized. Additionally, a binary calcium germanide CaGe has also been identified as a byproduct. All three crystal structures have been established from single-crystal X-ray diffraction methods and refined with high accuracy and precision. The binary CaGe crystallizes with a CrB-type structure in the orthorhombic space group Cmcm (no. 63; Z = 4; Pearson symbol oC8), where the germanium atoms are interconnected into infinite zigzag chains, formally [Ge]2−. The calcium atoms are arranged in monocapped trigonal prisms, centered by Ge atoms. SrxCa1−xAl2Ge2 (x ≈ 0.4) and SrAl2Ge2 have been confirmed to crystallize with a CaAl2Si2-type structure in the trigonal space group P3¯m1 (no. 164; Z = 1; Pearson symbol hP5), where the germanium and aluminum atoms form puckered double-layers, formally [Al2Ge2]2−. The calcium atoms are located between the layers and reside inside distorted octahedra of Ge atoms. All presented structures have a valence electron count satisfying the octet rules (e.g., Ca2+Ge2− and Ca2+[Al2Ge2]2−) and can be regarded as Zintl phases.

Synthesis and characterization of a novel alkali mixed magnesium-aluminum phosphate with a layered structure–KMgAl(PO4)2

A novel phosphate compound - potassium magnesium-aluminum double phosphate with chemical formula KMgAl(PO4)2 - has been synthesized. Platelet-shaped single crystals have been grown from the flux using K2Mo2O7 as a solvent. The powder form has been obtained through a sol-gel reaction. It has been characterized by X-ray diffraction, differential thermal analysis, vibrational spectroscopy and electronic structure calculations. KMgAl(PO4)2 crystallizes in the trigonal centrosymmetric space group P3¯m1 (No. 164) with unit cell parameters a = b = 5.347(1) Å, c = 7.903(10) Å, γ = 120° (Z = 1). The main characteristic of the crystal is the two-dimensional (2D) lamellar framework formed by Mg|AlO4 and PO4 tetrahedrons sharing their vertices of oxygen atoms, with the K+ cations located within the interlayer space. The sample morphology and chemical composition were revealed by the scanning electron microscopy – energy-dispersive X-ray spectroscopy analysis. The IR spectroscopy of KMgAl(PO4)2 confirmed the existence of a single PO4 group in agreement with the structural study. A relatively large indirect band gap of 3.86 eV was determined.

Thermally Induced Reversible Metal-to-Metal Charge Transfer in Mixed-Valence {Fe III 4 Fe II 4 } Cubes

Thermally Induced Reversible Metal-to-Metal Charge Transfer in Mixed-Valence {Fe ^III ₄ Fe ^II ₄ } Cubes

Computational approach for determining the zero-field splitting terms and magnetic coupling strength of in a trigonal Mn3III complex

This study reports on the synthesis, X-ray structure, magnetic properties, and computational studies of the complex [Mn3O(mhaep)3(MeOH)3](ClO4) (1), where the ligand H2mhaep is a 2-N,N-[methyl(2-hydroxymethyl)aminoethyl]phenol moiety. Compound 1 crystallizes in the trigonal space group P3-. The most significant structural characteristic is that the Jahn-Teller axes of the MnIII ions tilt to an angle of 47.6°. Calculations using the ORCA program, combined with irreducible representation methods indicate that, the leading terms of the molecular zero-field splitting (zfs), D and E terms, are largely quenched. The conclusion was confirmed by reduced magnetization measurements, which indicate that the magnitude of the D term is very limited. All of the magnetic data and the computational calculations point to a conclusion that compound 1 is ferromagnetically coupled with a total molecular spin of S = 6.

Synthesis, Crystal Structure, and Nonlinear Optical Properties of Zn(II) Complex with 4,4',4''-Tri-tert-Butyl-2,2':6',2''-Terpyridine: A Dual Exploration

The metal complexes are getting immense importance as hi-tech functional materials. In the present investigation, a new Zn(II) complex [Zn(C27H35N3)Cl2] (1) has been synthesized by using 4,4′,4″-tri-tert-butyl-2,2′:6′,2″-terpyridine ligand. The synthesized compound 1 is characterized by X-ray crystallography, IR spectroscopy as well as elemental analysis. The X-rays structure revealed that compound 1 crystallizes in trigonal space group P3221 in which Zn(II) atom is penta coordinated having highly distorted trigonal bipyramidal geometry. The compound 1 has a 2-fold rotational axis parallel to the b axis, which is passing through two opposite N and C atoms in the central pyridine ring, and the Zn atom. Moreover, quantum computational study has been performed to get insights into the optical and nonlinear optical response properties of compound 1. The geometrical structure of compound 1 has been optimized with M06-2X functional and LANL2DZ/6-311G** basis set and it shows good resemblance with the experimental coordinates. The linear polarizabilities including isotropic (αiso) and anisotropic (αaniso) polarizability amplitudes are found to be 69.44 × 10−24 and 34.99 × 10−24 esu, respectively. Similarly, the NLO polarizability (❬γ❭) amplitude for compound 1 is found to be 104.19 × 10–36 esu at M06-2X method, which is ~5 times greater than the p-NA (a model NLO molecule). Additionally, frontier molecular orbitals, molecular electrostatic potentials and Hirshfeld analysis are used to explore the structure-property relationship of compound 1. Thus, the indigenously synthesized compound 1 might be a reasonable candidate for its possible applications as optical and NLO material.

Analysis of solvent-accessible voids and proton-coupled electron transfer of 2,6-bis(1H-imidazol-2-yl)pyridine and its hydrochloride.

The crystal structures of the solid form of solvated 2,6-bis(1H-imidazol-2-yl)pyridine (H2dimpy) trihydrate, C11H9N5·3H2O·[+solvent], I, and its hydrate hydrochloride salt 2-[6-(1H-imidazol-2-yl)pyridin-2-yl]-1H-imidazol-3-ium chloride trihydrate, C11H10N5+·Cl-·3H2O, II, are reported and analysed in detail, along with potentiometric and spectrophotometric titrations for evaluation of the acid-base equilibria and proton-coupled electron-transfer reactions. Compound I crystallizes in the high-symmetry trigonal space group P3221 with an atypical formation of solvent-accessible voids, as a consequence of the 32 screw axis in the crystallographic c-axis direction, which are probably occupied by uncharacterized disordered solvent molecules. Additionally, the trihydrated chloride salt crystallizes in the conventional monoclinic space group P21/c without the formation of solvent-accessible voids. The acid-base equilibria of H2dimpy were studied by potentiometric and spectrophotometric titrations, and the results suggest the formation of H3dimpy+ (pKa1 = 5.40) and H4dimpy2+ (pKa2 = 3.98), with the electrochemical behaviour of these species showing two consecutive irreversible proton-coupled electron-transfer reactions. Density functional theory (DFT) calculations corroborate the interpretation of the experimental results and support the assignment of the electrochemical behaviour.

The new tellurium compounds: Na1.5Te2Mo0.5O6.25 and K6(Te94+Te6+)Mo6O42

The new ternary compounds Na1.5Te2Mo0.5O6.25 and K6(Te94+Te6+)Mo6O42 have been revealed by the study of the phase relation in the systems Na2O–TeO2–MoO3 and K2O–TeO2–MoO3. The structure of the compounds has been investigated by X-ray Single-Crystal Analysis. The Na1.5Te2Mo0.5O6.25 compound belongs to anti-glass tellurium phase with fluorite-type structure and space group Fm3‾m, Z = 1, a = 5.4087 Å, where the oxygen atoms are strongly disordered near the 8a site. The K6(Te94+Te6+)Mo6O42 mixed-valence tellurium compound possesses trigonal space group P3‾, Z = 1, a = 12.0074 Å, c = 7.8979 Å. The K6(Te94+Te6+)Mo6O42 structure contains rare units of two [TeO6] octahedron sharing three common oxygen. The decomposition temperatures are 378 °C and 410 °C for Na1.5Te2Mo0.5O6.25 and K6(Te94+Te6+)Mo6O42, respectively.

Room-temperature synthesis of a new stable (N2H4)WO3 compound: a route for hydrazine trapping.

A new (N2H4)WO3 compound has been obtained by mixing WO3 and aqueous hydrazine solution at room temperature for 24 h. The reaction is catalyzed by the presence of lithium. X-ray, synchrotron and neutron diffraction techniques have shown that the material crystallizes in trigonal space group P3221 (No. 154). Chains of distorted WO4 tetrahedra extend along the a axis of the unit cell, linked by a corner-sharing oxygen atom: the N2H4 are in the voids between them. The thermal characterization shows that this new compound is stable up to 220°C, greatly beyond the boiling point of N2H4 (114°C); thus making it a promising candidate for catalysis or trapping applications.

Synthesis, Characterization, and Crystal Structure Analysis of New Mixed Metal Sulfate NaPr(SO4)2(H2O)

A crystalline mixed-metal sulfate compound NaPr(SO4)2(H2O) is synthesized under hydrothermal conditions and thoroughly characterized. Sodium bisulfite (NaHSO3) and piperazine are used with praseodymium acetate to obtain this sulfate-based structure. The single crystal structural analysis shows that the compound has the NaCe(SO4)2 · H2O structure type and crystallizes in the trigonal space group P3221 (No. 154) with a = 6.9872(2) A, c = 12.8935(8) A, and V = 545.14(4) A3. The compound has three-dimensional connectivity formed by the sulfate units with Pr and Na centers. Tricapped trigonal prismatic PrO9 units and square-antiprismatic NaO8 units link to the SO4 tetrahedron for building the three-dimensional structure. The compound is also characterized by PXRD, TGA, and FT-IR spectroscopy. The present study illustrates the usefulness of the bisulfite anion and secondary amine for the chiral structure building.

Synthesis, characterization, and crystal structure analysis of new mixed metal sulfate NaPr(SO4)2(H2O)

A crystalline mixed-metal sulfate compound NaPr(SO4)2(H2O) is synthesized under hydrothermal conditions and thoroughly characterized. Sodium bisulfite (NaHSO3) and piperazine are used with praseodymium acetate to obtain this sulfate-based structure. The single crystal structural analysis shows that the compound has the NaCe(SO4)2×H2O structure type and crystallizes in the trigonal space group P3221 (No. 154) with a = 6.9872(2) Å, c = 12.8935(8) Å, and V = 545.14(4) Å3. The compound has three-dimensional connectivity formed by the sulfate units with Pr and Na centers. Tricapped trigonal prismatic PrO9 units and square-antiprismatic NaO8 units link to the SO4 tetrahedron for building the three-dimensional structure. The compound is also characterized by PXRD, TGA, and FT—IR spectroscopy. The present study illustrates the usefulness of the bisulfite anion and secondary amine for the chiral structure building.

RE4Ba2[Si12O2N16C3]:Eu2+ ( RE = Lu, Y): Green-Yellow Emitting Oxonitridocarbidosilicates with a Highly Condensed Network Structure Unraveled through Synchrotron Microdiffraction.

The oxonitridocarbidosilicates RE4Ba2[Si12O2N16C3]:Eu2+ ( RE = Lu, Y) were synthesized by carbothermal reactions starting from RE2O3, graphite, Ba2Si5N8, Si(NH)2, and Eu2O3. The crystal structure of Lu4Ba2[Si12O2N16C3]:Eu2+ was elucidated on a submicron-sized single crystal by a combination of transmission electron microscopy and microfocused synchrotron radiation. The compound crystallizes in trigonal space group P3 (no. 143) with a = 16.297(4) Å, c = 6.001(2) Å, and Z = 3 ( R1 = 0.0332, wR2 = 0.0834, GoF = 1.034). According to Rietveld refinements on powder X-ray diffraction data, Y4Ba2[Si12O2N16C3]:Eu2+ is isotypic with a = 16.41190(6) Å and c = 6.03909(3) Å. The crystal structures are built up of vertex-sharing SiC(O/N)3 tetrahedra forming star-shaped units [C[4](Si(O/N)3)4] with carbon atoms in fourfold bridging positions. Energy-dispersive X-ray spectroscopy and CHNS analysis correspond to the sum formula, lattice energy, and charge distribution calculations support the assignment of O/N/C atoms. When excited with UV to blue light, Eu2+-doped samples show green luminescence for RE = Lu (λem ≈ 538 nm, full width at half-maximum (fwhm) ≈ 3600 cm-1) and yellow emission in the case of RE = Y (λem ≈ 556 nm, fwhm ≈ 4085 cm-1).

Conducting Anilate-Based Mixed-Valence Fe(II)Fe(III) Coordination Polymer: Small-Polaron Hopping Model for Oxalate-Type Fe(II)Fe(III) 2D Networks.

The mixed-valence FeIIFeIII 2D coordination polymer formulated as [TAG][FeIIFeIII(ClCNAn)3]·(solvate) 1 (TAG = tris(amino)-guanidinium, ClCNAn2- = chlorocyanoanilate dianionic ligand) crystallized in the polar trigonal space group P3. In the solid-state structure, determined both at 150 and at 10 K, anionic 2D honeycomb layers [FeIIFeIII(ClCNAn)3]- establish in the ab plane, with an intralayer metal-metal distance of 7.860 Å, alternating with cationic layers of TAG. The similar Fe-O distances suggest electron delocalization and an average oxidation state of +2.5 for each Fe center. The cation imposes its C3 symmetry to the structure and engages in intermolecular N-H···Cl hydrogen bonding with the ligand. Magnetic susceptibility characterization indicates magnetic ordering below 4 K and the presence of a hysteresis loop at 2 K with a coercive field of 60 Oe. Mössbauer measurements are in agreement with the existence of Fe(+2.5) ions at RT and statistic charge localization at 10 K. The compound shows semiconducting behavior with the in-plane conductivity of 2 × 10-3 S/cm, 3 orders of magnitude higher than the perpendicular one. A small-polaron hopping model has been applied to a series of oxalate-type FeIIFeIII 2D coordination polymers, providing a clear explanation on the much higher conductivity of the anilate-based systems than the oxalate ones.

MSMEG_6292, a Mycobacterium smegmatis RNA polymerase secondary channel-binding protein: purification, crystallization and X-ray diffraction analysis.

The transcriptional activity of RNA polymerase (RNAP) is controlled by a diverse set of regulatory factors. A subset of these regulators modulate the activity of RNAP through its secondary channel. Gre factors reactivate stalled elongation complexes by enhancing the intrinsic cleavage activity of RNAP. In the present study, the protein MSMEG_6292, a Gre-factor homologue from Mycobacterium smegmatis, was expressed heterologously in Escherichia coli and purified using standard chromatographic techniques. The hanging-drop vapour-diffusion crystallization method yielded diffraction-quality crystals. The crystals belonged to the trigonal space group P3121 (or its enantiomorph P3221), with unit-cell parameters a = b = 83.15, c = 107.07 Å, α = β = 90, γ = 120°. The crystals diffracted to better than 3.0 Å resolution. Molecular-replacement attempts did not yield any phasing models; hence, platinum derivatization was carried out with K2PtCl4 and derivative data were collected to 3.4 Å resolution.

Crystallization and X-ray crystallographic analysis of recombinant TylP, a putative γ-butyrolactone receptor protein from Streptomyces fradiae.

TylP is one of five regulatory proteins involved in the regulation of antibiotic (tylosin) production, morphological and physiological differentiation in Streptomyces fradiae. Its function is similar to those of various γ-butyrolactone receptor proteins. In this report, N-terminally His-tagged recombinant TylP protein (rTylP) was overproduced in Escherichia coli and purified to homogeneity. The rTylP protein was crystallized from a reservoir solution comprising 34%(v/v) ethylene glycol and 5%(v/v) glycerol. The protein crystals diffracted X-rays to 3.05 Å resolution and belonged to the trigonal space group P3121, with unit-cell parameters a = b = 126.62, c = 95.63 Å.

Spin Frustration in an Organic Radical Ion Salt Based on a Kagome-Coupled Chain Structure.

Electro-oxidation of the quinoidal bisdithiazole BT in dichloroethane in the presence of [Bu4N][GaBr4] affords the 1:1 radical ion salt [BT][GaBr4], crystals of which belong to the trigonal space group P3. The packing pattern of the radical cations provides a rare example of an organic kagome basket structure, with S = 1/2 radical ion chains located at the triangular corners of a trihexagonal lattice. Magnetic measurements over a wide temperature range from 30 mK to 300 K suggest strongly frustrated AFM interactions on the scale of J/kb ∼ 30 K, but reveal no anomalies that would be associated with magnetic order. These observations are discussed in terms of the symmetry allowed magnetic interactions within and between the frustrated layers.

Sequence similarity network analysis, crystallization, and X-ray crystallographic analysis of the lactate metabolism regulator LldR from Pseudomonas aeruginosa

The FadR subfamily of regulators plays essential roles in the regulation of diverse metabolic pathways in bacteria. LldR, an FadR-type regulator, regulates lactate utilization in Pseudomonas aeruginosa. Sequence network analysis of the LldR proteins from different bacterial species showed that LldR proteins from Pseudomonas sp. and Escherichia coli were separated into different clusters, suggesting that LldRs are derived from two ancestors that functionally diverged. Then, the recombinant PLldR protein (LldR of P. aeruginosa) was expressed, purified, and crystallized. Preliminary X-ray diffraction analysis of LldR protein crystals was performed. The PLldR crystal diffracted to 2.55 A resolution and belonged to the trigonal space group P3, with unit-cell parameters a = 68.5 A, b = 68.5 A, and c = 237.0 A. These results will facilitate further understanding of the regulatory mechanism and the adaptation to sensing of both l -lactate and d -lactate of LldR proteins from Pseudomonas sp. in lactate metabolism.