Acta Crystallographica Section C Structural Chemistry最新文献

Three new thiosemicarbazide derivatives are described in terms of synthesis, structure and biological activity. N'-(Morpholine-4-carbonothioyl)-4-(4-phenylpiperazin-1-yl)picolinohydrazonamide 2-methyltetrahydrofuran hemisolvate, 2C₂₁H₂₇N₇OS·C₅H₁₀O, 1, determined at 100 K, has orthorhombic (Pca2₁) symmetry and exhibits disorder. 4-(4-Phenylpiperazin-1-yl)-N'-(piperidine-1-carbonothioyl)picolinohydrazonamide-dimethylformamide-water (1/1/0.285), C₂₂H₂₉N₇S·C₃H₇NO·0.285H₂O, 2, determined at 100 K, has monoclinic (P2₁/c) symmetry. 4-(4-Phenylpiperazin-1-yl)-N'-(pyrrolidine-1-carbonothioyl)picolinohydrazonamide, C₂₁H₂₇N₇S, 3, determined at 100 K, has triclinic (P1) symmetry and exhibits disorder. Compounds 1 and 2 contain solvent molecules in their structure. All three studied compounds adopt the zwitterionic form and were tested for their microbiological activity on a model panel of Gram-positive and Gram-negative bacteria, as well as selected yeasts.

In recent years, molecular-based ferroelectric materials have attracted widespread research interest due to their excellent performance. Among them, host-guest-type crown ether inclusion compounds composed of organic ammonium cations, crown ether molecules and corresponding anions have become a star component in the design of molecular-based ferroelectric materials because they are prone to order-disorder phase transitions. Many anions have been studied extensively as counter-ions, such as bis(trifluoromethanesulfonyl)amidate (TFSA^-), PF₆^- and [FeCl₄]^-. However, crown ether inclusion compounds with di(methanesulfonyl)amidate (DMSA) as the anion have been rarely investigated. Here, we converted TFSA to DMSA to obtain 3,4-difluoroanilinium di(methanesulfonyl)amidate-18-crown-6 (1/1), C₆H₆F₂N⁺·C₂H₆NO₄S₂^-·C₁₂H₂₄O₆ or [(3,4-DFA)(18-crown-6)][DMSA]. At both 100 and 300 K, the crystal falls into the space group P2₁/c. The 3,4-DFA cation forms three well-defined N-H...O hydrogen bonds, positioned at the perching position of the crown ether ring. In contrast to the distinct packing configuration observed in the [(3,4-DFA)(18-crown-6)][TFSA] crystals, where TFSA exhibits a disordered structure, the [(3,4-DFA)(18-crown-6)][DMSA] complex features a staggered arrangement, with DMSA existing in an ordered fashion.

A new twofold interpenetrated 3D metal-organic framework (MOF), namely, poly[[μ-aqua-diaqua{μ₄-2,2'-[terephthaloylbis(azanediyl)]diacetato}barium(II)] dihydrate], {[Ba(C₁₂H₁₀N₂O₆)(H₂O)₃]·2H₂O}_n, (I), has been assembled through a combination of the reaction of 2,2'-[terephthaloylbis(azanediyl)]diacetic acid (TPBA, H₂L) with barium hydroxide and crystallization at low temperature. In the crystal structure of (I), the nine-coordinated Ba^II ions are bridged by two μ₂-aqua ligands and two carboxylate μ₂-O atoms to form a 1D loop-like Ba-O chain, which, together with the other two coordinated water molecules and μ₂-carboxylate groups, produces a rod-like secondary building unit (SBU). The resultant 1D polynuclear SBUs are further extended into a 3D MOF via the terephthalamide moiety of the ligand as a spacer. Two intramolecular dihydrogen bonds (DHBs) between the imine H atoms and the arene H atoms contribute to maintaining the 3D structure. In the crystal, two independent MOFs interpenetrate each other, thereby producing a twofold interpenetrated 3D architecture with a 4-connected PtS-X topology. Intermolecular hydrogen bonding and π-π interactions contribute to the stability of the twofold interpenetrated 3D architecture. The noncovalent interactions in the coordination polymer (CP) were further investigated by Hirshfeld surface analysis and the results show that the prominent interactions are H...O (39.6%) and H...H (34.4%), as well as Ba...O (9.8%), contacts. The 3D CP (I) exhibits a fluorescence emission with a quantum yield of 0.134.

Prompted by visionary political leaders and a flowering economy, the University of La Plata was founded in 1905, the third Argentinian university after the Universities of Cordoba (1613) and Buenos Aires (1821). Differing from the older universities, more prone to professional formation, the new university was oriented towards teaching and scientific research following western European academic tradition. Along with the university was created the Institute of Physics, the first of its kind in Latin America. To pursue the foundational plan, the university recruited distinguished German physicists, some of whom became the first directors. From the start, the institute became acquainted with Röntgen rays, their generation and use, initially for radiographic images and later in occasional diffraction studies. The first dedicated crystallographic X-ray diffraction laboratory was set up in the early 1970s, when it solved the first molecular structures. Soon the fascination brought about by a methodology that afforded the visualization of atoms, molecules and crystals lured the local and national physical chemistry communities. In close partnership with an equally oriented laboratory at the University of Sao Paulo, Brazil, and in collaboration with several physical chemistry laboratories from Argentina and the Latin American region, and also from Europe, we undertook studies on the crystal structures and physicochemical and spectroscopic properties of a wide range of materials, including inorganic, organic, bioinorganic, metal-organic, organic-metal, supramolecular, pharmaceutical, organic minerals and liquid crystals. The present essay is a personal account of the origin and development of structural X-ray crystallography at the University of La Plata and its impact on the scientific research of Argentina and Latin America.

Taurine is part of the cysteine cycle and is one of the few naturally occuring organosulfur-based molecules in the human body. As implied by modern studies, protonated taurine is of biological impact. The first attempts to isolate its protonated species in the binary superacidic system HF/SbF₅ were performed by Hopfinger, resulting in the isolation of monoprotonated taurine. Since the chosen conditions seemed rather harsh, investigations in less acidic systems were performed at room temperature to explore the involved protonated species. Herein, we present the structure of 2-[dihydroxy(oxo)sulfanyliumyl]ethanaminium bis[hexafluoridoarsenate(V)], [H₂O₃SC₂H₄NH₃][AsF₆]₂, the diprotonated form of 2-aminoethanesulfonic acid (taurine). It was synthesized in the binary superacidic system HF/AsF₅ and crystallizes as colourless needles. Diprotonated taurine was structurally characterized by single-crystal X-ray diffraction analysis, low-temperature vibrational spectroscopy and NMR spectroscopy.

The reactions of oxalyl chloride were investigated in the binary superacidic systems HF/SbF₅ and DF/SbF₅. O-Monoprotonated oxalyl chloride was isolated and represents the first example of a protonated acyl chloride. Diprotonated oxalyl chloride is only stable in solution. Salts of the ClCO⁺ cation were synthesized from the reactions of oxalyl chloride or COClF with SbF₅ in 1,1,1,2-tetrafluoroethane (R-134a, CF₃CFH₂). The colourless salts were characterized by low-temperature vibrational spectroscopy, NMR spectroscopy and single-crystal X-ray diffraction. (1,2-Dichloro-2-oxoethylidene)oxidanium hexafluoridoantimonate(V), [C₂O(OH)Cl₂][SbF₆], crystallizes in the monoclinic space group P2₁ and carbonyl chloride hexadecafluoridotriarsenate(V) [ClCO][Sb₃F₁₆], in the trigonal space group P3₁, with two and three formula units per unit cell, respectively. Monoprotonated oxalyl chloride and the ClCO⁺ cation both display very short C-Cl bonds with a strong double-bond character.

A new crystalline compound, catena-poly[hexa-μ-acetato-(acetic acid)-μ₃-oxido-triangulo-triiron(III)]-μ-acetato], [Fe₃(C₂H₃O₂)₇O(C₂H₄O₂)]_n, incorporating the basic ferric acetate unit, has been obtained from an acetic anhydride solution of hydrated iron(III) nitrate. The crystals have the composition Fe₃O(OAc)₇(HOAc) (HOAc is acetic acid) and include the well-known [Fe₃O(OAc)₆]⁺ unit, in which the Fe^III centres are linked to a central coplanar μ₃-oxido ligand. Acetate ions provide bridges between pairs of Fe^III centres. These individual [Fe₃O(OAc)₆]⁺ units are linked by additional bridging acetate anions to form zigzag chains. The bridging acetate ions coordinate to a position trans to the oxido group on two of the Fe^III centres. Remarkably, the trans site on the third Fe^III centre is occupied by the carbonyl group of an acetic acid molecule. This is the first reported case of an acetic acid molecule coordinating to an Fe^III centre. Not surprisingly, the acetic acid molecule is only weakly coordinating, resulting in a short Fe-O(oxido) bond trans to the carbonyl group. The trans influence apparent in this structure provides an interesting contrast with the structurally similar Mn^III analogue, in which the corresponding pair of trans bonds are both elongated because of the Jahn-Teller effect.

The synthesis, single-crystal X-ray structure determination and thermal analysis are reported for a novel heteronuclear oxalate compound synthesized from a mixture of Fe and Na salts, oxalic acid and N,N-dimethylformamide (DMF) in aqueous solution. The new metallooxalate compound was obtained and identified as a dimethylammonium tris(oxalato)ferrate(III), namely, poly[[bis(dimethylammonium) [tri-μ-oxalato-sodium(I)iron(III)]]-dimethylamine-water (3/1/1)], [NH₂(CH₃)₂]₂[NaFe(C₂O₄)₃]·0.33NH(CH₃)₂·0.33H₂O, which crystallizes in the orthorhombic noncentrosymmetric space group C222₁. In this novel structure, each Fe atom is hexacoordinated by three non-equivalent bidentate oxalate ligands, while the four Na atoms adopt different coordination numbers, i.e. 6, 7 and 8. The structure consists of bimetallic anionic A layers, {[NaFe(C₂O₄)₃]^2-}_n, displaying a layered structure with infinitely linked Fe₂Na₂ tetramers on the ab plane. Two kinds of bimetallic parallel layers (A1 and A2) are present alternately and are found to be staggered, while only the A2 layer is crossed by a twofold axis parallel to the a axis through two Na atoms. The [NH₂(CH₃)₂]⁺ (HDMA) cations occupy the voids between the anionic layers, while the free molecules, i.e. NH(CH₃)₂ (DMA) and H₂O, are located between two different anionic layers. In addition to ionic bonds, the stability of the structure is ensured by hydrogen-bond interactions involving the oxalate ligands and the nitrogenous and water molecules. The layered structure appears to be different in the family of oxalate-bridged Na^I-Fe^III compounds. It is in agreement with the predicted 2D or layered structure of bimetallic complexes containing anionic tris(oxalato)metallate(III) with the [XR₄]⁺ counter-ion template (X = N, P or S, and R = alkyl group or H). The thermal decomposition of the compound shows the final residual product to be NaFeO₂.

Two novel Cu-based metal-organic frameworks (MOFs), namely, poly[[aquadichlorido[μ₄-4'-(pyridin-4-yl)-[2,2':6',2''-terpyridine]-4,4''-dicarboxylato][μ₃-4'-(pyridin-4-yl)-[2,2':6',2''-terpyridine]-4,4''-dicarboxylato]tricopper(II)] monohydrate], {[Cu₃(C₂₂H₁₂N₄O₄)₂Cl₂(H₂O)]·H₂O}_n or {[Cu₃(PTP)₂Cl₂(H₂O)]·H₂O}_n, (I), and poly[[diaquabis[μ₂-4'-(pyridin-3-yl)-[2,2':6',2''-terpyridine]-4,4''-dicarboxylato]bis(μ₂-terephthalato)tricopper(II)] dihydrate], {[Cu₃(C₂₂H₁₂N₄O₄)₂(C₈H₄O₄)₂(H₂O)₂]·2H₂O}_n or {[Cu₃(BDC)₂(MTP)₂(H₂O)₂]·2H₂O}_n, (II), have been synthesized successfully with 4'-(pyridin-4-yl)-[2,2':6',2''-terpyridine]-4,4''-dicarboxylic acid (H₂PTP) and 4'-(pyridin-3-yl)-[2,2':6',2''-terpyridine]-4,4''-dicarboxylic acid (H₂MTP) as the ligands, respectively. Crystal structure analysis reveals that (II) possesses a 2D coordinated layer structure, in which adjacent 2D coordination layers are linked into 3D frameworks through π-π interactions, while the structure of (I) displays dual coordination layers, in which adjacent coordination layers are connected into a 3D framework through hydrogen-bonding interactions. The photophysical properties of the two MOFs were investigated by fluorescence spectroscopy. Complex (II) shows an obvious `turn-on' fluorescence enhancement effect towards flazasulfuron and its potential application for sensing flazasulfuron in water with high selectivity and sensitivity was also investigated in detail.

The effects of Eu³⁺ doping on the crystal structure and charge distribution of Bi₄Si₃O₁₂ (BSO) bisilicate, based on first principles and density functional theory (DFT), were calculated and analyzed using Materials Studio software. The effect of different proportions (1/12, 1/6 and 1/3) of Eu³⁺ doping on BSO crystals was investigated using the virtual crystal approximation method. Through Mulliken charge analysis, it is found that a high proportion of Eu³⁺ doping will destroy the symmetry of the crystal structure. With an increase of the Eu³⁺-doping ratio, the Eu-O bond length first increased and then decreased, showing the characteristics of covalent bonds, and the Eu-O bond length reached the minimum value when the Eu³⁺-doping ratio was increased to 1/3. With an increase in the Eu³⁺-doping ratio, the Bi-O bond length decreases sequentially and also reaches the minimum value when the Eu³⁺-doping ratio was increased to 1/3. This indicates that the covalence between the Eu-O and Bi-O atoms is enhanced when the doping ratio is 1/3 when BSO crystals are doped with Eu³⁺.