Single-crystal X-ray Diffractometry Research Articles

Monometallic and mixed-valence bimetallic Rh(I/III) complexes: Synthesis, structure, electrochemistry and application in 1-octene hydroformylation

Two mononuclear rhodium complexes, Rh(I)-1,5-cyclooctadiene and Rh(III)-pentamethylcyclopentadienyl, and a bimetallic Rh(I)-Rh(III) mixed-valence complex were synthesised. The complexes were fully characterised using an array of analytical techniques which included NMR and infrared spectroscopy, single-crystal X-ray diffractometry, elemental analysis, and mass spectrometry. These complexes were evaluated as catalyst precursors in the hydroformylation of olefins. All catalyst precursors were active in the hydroformylation of 1-octene under optimised conditions. The rhodium complexes generally showed chemoselectivity towards the formation of linear aldehydes. The electrochemical behaviour of the rhodium complexes was examined using cyclic voltammetry.

Carbazole-based aggregation-induced emission (AIE)-active gold(I) complex: Persistent room-temperature phosphorescence, reversible mechanochromism and vapochromism characteristics

A carbazole-based gold(I) complex 1 has been successfully synthesized. Its structure was characterized by nuclear magnetic resonance spectroscopy, elemental analysis and single crystal X-ray diffractometry. Its aggregation-induced emission behavior was studied by ultraviolet/visible, photoluminescence spectroscopy and scanning electron microscope. Its solid-state mechanochromic and thin-film vapochromic luminescence behaviors were also investigated by photoluminescence spectroscopy. The results demonstrated that luminogen 1 showed obvious aggregation-induced emission property. Furthermore, 1 also exhibited reversible high-contrast mechanochromic and vapochromic luminescence behaviors. More interestingly, 1 can emit persistent room-temperature phosphorescence with a solid-state emission lifetime up to 86.84 ms, which is the highest lifetime value among all the reported gold(I) complexes so far. To the best of our knowledge, the gold(I) complex is the first example of an AIE-active luminogen with persistent room-temperature phosphorescence, reversible mechanochromism and vapochromism characteristics.

Globular molecular platinum carbonyl nanoclusters: Synthesis and molecular structures of the [Pt26(CO)32]− and [Pt14+x(CO)18+x]4− anions and their comparison to related platinum “browns”

The thermal decomposition of [Pt3n(CO)6n]2− (n=2–10) Chini clusters results in the formation of globular molecular platinum carbonyl clusters, whose nature depends of the nuclearity of the parent cluster as well as the counter-ion and solvent employed. Among these, the new [Pt14+x(CO)18+x]4− (x=0,1) and [Pt44(CO)45]n−, as well as the previously reported [Pt15(CO)19]4−, [Pt19(CO)22]4−, [Pt24(CO)30]2−, [Pt26(CO)32]2−, [Pt33(CO)38]2− and [Pt38(CO)44]2− have been identified. Oxidation of [Pt14+x(CO)18+x]4− (x=0,1) with HBF4·Et2O affords [Pt26(CO)32]2−, which is further oxidized to the related [Pt26(CO)32]− mono-anion. Oxidation of [Pt19(CO)22]4−, under similar conditions, affords the unstable [Pt19(CO)22]2− di-anion, that rearranges during crystallization into the new [Pt36(CO)44]2−. Conversely, the reduction of [Pt19(CO)22]4− with Na/naphthalene results in the [Pt19(CO)22]5− penta-anion which, after work-up, is transformed into the new [Pt23(CO)27]2−. The new clusters [Pt14+x(CO)18+x]4− (x=0,1) and [Pt26(CO)32]− have been fully characterized by means of single crystal X-ray diffractometry as their [NEt4]4[Pt14+x(CO)18+x]·MeCN (x=0.18) and [NEt4][Pt26(CO)32]·2.12thf·0.38C6H14 salts. Conversely, in the case of the new [Pt23(CO)27]2−, [Pt36(CO)44]2− and [Pt44(CO)45]n−, due to the poor quality of their crystals, only a partial structural determination has been possible. [Pt14+x(CO)18+x]4− (x=0,1) displays a distorted bcc structure, [Pt26(CO)32]− and [Pt23(CO)27]2− adopt hcp structures, [Pt36(CO)44]2− presents a distorted ccp metal core, whereas [Pt44(CO)45]n− possesses a twinned hcp/ccp ABCBA structure. The structures of the metal cores of these clusters is compared to previously reported globular platinum carbonyl nanoclusters (“platinum browns”).

Synthesis and characterization of two new trans palladium (II) complexes containing benzylamine ligand: DNA/BSA interactions, molecular docking and in vitro cytotoxic activity

Two new trans Pd (II) complexes with formulas Pd(PhCH2NH2)2Cl2 (1) and [Pd(PhCH2NH2)2(L)2](NO3)2 (2) (L=Letrozole drug; 4,4′-((1H-1,2,4-triazol-1-yl)methylene)dibenzonitrile) have been synthesized and characterized by elemental analysis, FT-IR and NMR spectroscopy. Single crystal X-ray diffractometry has been used to determine the crystal structure of 1. UV–Vis spectroscopy, emission titration, circular dichroism and helix melting methods have been used to study the binding interaction of Pd (II) complexes with Calf Thymus deoxyribonucleic acid (CT-DNA). The analysis results show that 1 can interact with DNA via groove binding and 2 binds to DNA through partial intercalation mode.It was found that the binding constants (Kb) of the complexes toward BSA were (1.4×104M−1) and (1.68×104M−1) for 1 and 2, respectively. Competitive binding using Warfarin, Ibuprofen and Digoxin site markers with definite binding sites demonstrated that the complexes bind to more than one site on BSA. In the presence of Ibuprofen, the binding constant was surprisingly not fixed, while a smaller influence was observed in the presence of Warfarin and Digoxin on 1. The results indicated that the binding site for 1 was mainly located within site II of BSA. The result of the competitive titration of 2 was different. In the presence of Warfarin, the Kb value decreased, showing a competition between 2 and Warfarin. In addition, molecular docking studies have been conducted to determine the binding site of the DNA and BSA with 1. Finally, In vitro cytotoxicity of 1, 2 and cisplatin were carried out against leukemia cancer (Raji), lung cancer (A549) and breast cancer (MCF7) cell lines. According to the IC50 values, the cytotoxicity of 2 was more than 1.

Use of Stable Amine-Capped Polyynes in the Regioselective Synthesis of Push-Pull Thiophenes.

The reactions of a series of 1-halopolyynes with secondary amines led to novel amine end-capped polyynes exhibiting surprisingly high stability toward moisture. The new compounds were characterized by NMR spectroscopy, ESI-MS spectrometry, and X-ray single-crystal diffractometry. The use of amine end-capped polyynes as precursors to substituted push-pull thiophenes was next presented. The results show the first-to the best of our knowledge-transformation of ynamine to thiophene and the first regioselective transformation of a longer polyynes to butadiyne-substituted thiophene. Photophysical studies of the resulting compounds show that some of the substituted thiophenes have high quantum yield photoluminescence upon UV light irradiation.

Heteroleptic tris-chelate ruthenium(II) complexes of N,N-disubstituted-N′-acylthioureas: Synthesis, structural studies, cytotoxic activity and confocal microscopy studies

Ruthenium complexes have been assessed as anti-tumor agents against cancer cells. In this project, new heteroleptic ruthenium(II) complexes with general formulae [Ru(L)(bipy)(dppb)](PF6) (where L=N,N-disubstituted-N′-acylthiourea, bipy=2,2′-bipyridine and dppb=1,4-bis(diphenylphosphino)butane) were synthesized and characterized by elemental analysis, IR and NMR (1H and 31P{1H}) spectroscopies, molar conductivity measurements and single crystal X-ray diffractometry. The IR and NMR data suggest the coordination of the ligands to the Ru(II) metal center through the thiocarbonyl and carbonyl groups. The structures of the new complexes were further studied by X-ray crystallography, which confirmed the coordination of the ligands with the metal through the sulfur and oxygen atoms, leading to the formation of distorted octahedral complexes. The N,N-disubstituted-N′-acylthioureas and their complexes were screened with respect to their in vitro cytotoxicity. All compounds exhibited considerable antiproliferative activity against MCF-7 (human breast tumor cells ATCC HTB-26), DU-145 (human prostate tumor cells ATCC HTB-26), and relatively low toxicity against fibroblast L929 cells (health cell line from mouse ATCC CCL-1). A preliminary study regarding the mechanism of action of these compounds by confocal microscopy shows alterations of the actin filaments leading to modifications in cytoskeletal supporting the cell death and that the cell nucleus is not main target of these complexes.

Minerals In Food: Crystal Structures of Ikaite and Struvite From Bacterial Smears On Washed-Rind Cheese

Abstract Food contains inorganic elements and compounds that are important for human nutrition and human health. Although these substances have been investigated and characterized in many foods for their nutritive value, little is known about the crystal phases that form in foods. In this study, we investigated crystals that form in the bacterial smears on the surface of washed-rind cheese. Washed-rind cheeses have been consumed for centuries, but the crystals that often contribute detectable grittiness to the surface of these cheeses have never been identified. The crystals were characterized with petrographic microscopy and identified with single crystal X-ray diffractometry as ikaite (CaCO 3 ·6H 2 O), a rare metastable phase that has only been observed in freezing marine and lacustrine environments, and struvite (NH 4 MgPO 4 ·6H 2 O), a mineral that is often associated with bacterial activity. These crystals are important to cheesemakers because they affect cheese texture and sensory characteristics. The potential importance of the bacterial smear in the nucleation of these phases is discussed, and the possibility of using cheese as a model system to investigate geological biomineralization phenomena is explored.

Li3Co1.06(1)TeO6: synthesis, single-crystal structure and physical properties of a new tellurate compound with CoII/CoIII mixed valence and orthogonally oriented Li-ion channels.

A tellurate compound with CoII/CoIII mixed valence states and lithium ions within orthogonally oriented channels was realized in Li3Co1.06(1)TeO6. The single-crystal structure determination revealed two independent and interpenetrating Li/O and (Co,Te)/O substructures with octahedral oxygen coordination of the metal atoms. In contrast to other mixed oxides, a honeycomb-like ordering of CoO6 and TeO6 octahedra was not observed. Li3Co1.06(1)TeO6 crystallizes orthorhombically with the following unit cell parameters and refinement results: Fddd, a = 588.6(2), b = 856.7(2), c = 1781.5(4) pm, R1 = 0.0174, wR2 = 0.0462, 608 F2 values, and 33 variables. Additional electron density in tetrahedral voids in combination with neighboring face-linked and under-occupied octahedral lithium sites offers an excellent possible diffusion pathway for lithium ions. According to the symmetry of the crystal structure the diffusion pathways in Li3Co1.06(1)TeO6 were found in two orthogonal orientations. The CoII/CoIII mixed valence was investigated via X-ray photoelectron spectroscopy (XPS), revealing a composition comparable to that derived from single-crystal X-ray diffractometry. Magnetic susceptibility measurements underlined the coexistence of CoII and CoIII, the title compound, however, showed no magnetic ordering down to low temperatures. The ionic conductivity of Li3Co1.06(1)TeO6 was determined via alternating current (AC) electrochemical impedance spectroscopy and was found to be in the range of 1.6 × 10-6 S cm-1 at 573 K.

Synthesis, Characterization and DFT-Based Investigation of a Novel Trinuclear Singly-Chloro-Bridged Copper(II)-1-Vinylimidazole Complex.

A novel trinuclear copper(II) complex [Cu3(μ-Cl)2Cl4(1-Vim)6] with monodentate 1-vinylimidazole (1-Vim) and chloro ligands has been prepared and experimentally characterized by elemental analysis, thermogravimetry (TGA, DTG, DTA), X-ray single crystal diffractometry, TOF-MS and FT-IR spectroscopies. The electronic and structural properties of the complex were further investigated by DFT/TD-DFT methods. Density functional hybrid method (B3LYP) was applied throughout the calculations. The calculated UV-Vis results based on TD-DFT approach were simulated and compared with experimental spectrum. Based on the data obtained, DFT calculations have been found in reasonable accordance with experimental data.

Direct observation of the ferroelectric polarization in the layered perovskite Bi4Ti3O12

We investigated the crystal structure and ferroelectric domains of Bi4Ti3O12 (BTO) by means of transmission electron microscopy (TEM) and single-crystal X-ray diffractometry. From the extinction rule, we determined that the space group in the ferroelectric phase of BTO is P1a1 rather than B2cb and B1a1 which have been proposed previously. We successfully refined the crystal structure based on the space group P1a1. The 180° and 90° ferroelectric domain structures were observed by the [001]-zone dark-field TEM imaging. In the 180° domain structure, we determined that one component of the polarization vector is parallel to the a-axis. An annular bright-field scanning transmission electron microscopy (ABF-STEM) was performed for the direct observation of the crystal structures. The ABF-STEM images displayed the contrasts with respect to every atomic position in spite of the highly distorted structure of BTO. We could evaluate the tilting and distortion of the [TiO6] octahedra relatively. Therefore, we directly observed the ferroelectric displacements of Bi and Ti ions.

Alkylation of 2- and 3-alkoxycarbonyl-4-quinolinones. DFT study on the regioselectivity

The reaction of 2-alkoxycarbonyl-4-quinolinones (1) with a variety of alkylating reagents under different conditions, lead to the corresponding O-alkylated products. The behavior in basic medium of compounds 1 differs from the 3-alkoxycarbonyl-4-quinolinones (4) isomers suggesting that the position of the carboxylate group determines the regioselectivity of the reaction. DFT calculations allow us to conclude that for 3-alkoxycarbonyl-4-quinolinones, the N-alkylation would be thermodynamically and kinetically favored. But for 2-alkoxycarbonyl-4-quinolinones the side chain in the 2-position of the ring prevents the planar approximation to the contiguous heteroatom leading to a more favorable O-alkylation transition state. Crystal structure of an O-alkylated product is determined by single crystal X-ray diffractometry.

Structural, Spectroscopic, and Photochemical Investigation of an Octahedral NO-Releasing {RuNO}(7) Species.

[Ru(Me3[9]aneN3)(bpy)(NO)](BF4)2 ([1](BF4)2) was explored by single-crystal X-ray diffractometry, leading to the first crystal structure of an octahedral {RuNO}(7) complex. The metal resides on the center of a distorted octahedron, with dN-O and ∠Ru-N-O at 1.177(3) Å and 141.6(2)°, respectively. [1](BF4)2 can be stored indefinitely under argon. Solutions of [1](2+) show no signs of decomposition when protected from air and light. The electron paramagnetic resonance X-band spectrum at 85 K in vitrified acetonitrile (MeCN) shows signals consistent with an S = (1)/2 spin state, better described as Ru(II)NO(•) (g = [2.030, 1.993, 1.880] and A = [11.0, 30.4, 3.9]/10(-4) cm(-1)). In water, the {RuNO}(7) species reacts with O2 in a 1:4 stoichiometry. The reaction is first-order in both reactants with k = (1.9 ± 0.2) M(-1) s(-1) at 25 °C (ΔH(⧧) = 11.5 ± 0.3 kJ mol(-1); ΔS(⧧) = -189 ± 1 J K(-1) mol(-1)). Solutions of [1](2+) evolve NO when irradiated a 365 nm with ϕNO = 0.024 and 0.090 mol einstein(-1) in H2O and MeCN, respectively.

Oxide-Ion Conductivity Enhancement of Polycrystalline Lanthanum Silicate Oxyapatite Induced by BaO Doping and Grain Alignment

We prepared the c-axis-oriented polycrystal of BaO-doped lanthanum silicate oxyapatite (LSO) by a reactive diffusion technique. The sandwich-type ternary diffusion couple, which was made up of La2SiO5/[BaO-doped La2Si2O7 + BaO-doped LSO]/La2SiO5, was heated at 1873 K for 100 h. The thin-plate polycrystalline electrolyte was mechanically extracted from the inner part of the annealed couple and characterized by optical microscopy, transmission electron microscopy, electron probe microanalysis (EPMA), X-ray diffractometry (XRD), Raman spectroscopy, and impedance spectroscopy. On the basis of the numbers of cations determined by EPMA and structural data refined by single-crystal XRD, the chemical formula of the constituent crystallites was determined to be (La9.32Ba0.28)(Si5.87□0.13)O26, where □ denotes a vacancy in the Si site. The combined use of BaO-doping and grain-alignment techniques effectively improved the oxide-ion conductivity, which steadily increased from 2.17 × 10–2 to 1.42 × 10–1 S cm–1 as the t...

Solubilities and Glass Formation in Aqueous Solutions of the Sodium Salts of Malonic Acid With and Without Ammonium Sulfate.

The solubility of sodium hydrogen malonate and sodium malonate in water both with and without ammonium sulfate present has been studied using differential scanning calorimetry and infrared spectroscopy. The crystals that form from sodium hydrogen malonate/water solutions were determined to be sodium hydrogen malonate monohydrate by single-crystal X-ray diffractometry. The crystals formed in sodium malonate/water solutions were determined to be sodium malonate monohydrate, a compound whose structure had not been previously known. When ammonium sulfate is added to these respective aqueous systems, the precipitation solids contain sodium sulfate decahydrate under low to moderate ammonium concentrations and lecontite (NaNH4SO4·2H2O) under high ammonium concentrations, which can be found under dry atmospheric conditions. Thus, it appears the presence of malonate and hydrogen malonate ions does not significantly affect the precipitation of inorganic salts in these systems. The glass transition temperatures of all solutions were also determined, and it was observed that the addition of ammonium sulfate slightly lowers the glass transition temperature in these solutions.

Studies on an L-leucine hydriodide semiorganic crystal for frequency conversion applications

An L-leucine hydriodide semiorganic crystal has been synthesized and grown by a slow evaporation technique. The lattice parameters of the grown crystal have been confirmed using single-crystal x-ray diffractometry. Various functional groups present in the crystal were identified by Fourier transform infrared (FTIR spectral) assessment. The optical transmission percentage of the crystal was ascertained by UV–vis-near-infrared (NIR) studies. The thermal stability of the crystal was determined by thermogravimetric and differential thermal analysis curves. The mechanical behavior of the crystal was studied using the Vicker’s microhardness analysis. The dielectric properties of the crystal have been investigated for varying temperatures. The second-harmonic generation efficiency was measured by the Kurtz and Perry powder technique and the efficiency is comparable to that of potassium dihydrogen orthophosphate.

A mixed valence zinc dithiolene system with spectator metal and reactor ligands

Neutral complexes of zinc with N,N′-diisopropylpiperazine-2,3-dithione (iPr2Dt0) and N,N′-dimethylpiperazine-2,3-dithione (Me2Dt0) with chloride or maleonitriledithiolate (mnt2−) as coligands have been synthesized and characterized. The molecular structures of these zinc complexes have been determined using single crystal X-ray diffractometry. Complexes recrystallize in monoclinic P type systems with zinc adopting a distorted tetrahedral geometry. Two zinc complexes with mixed-valence dithiolene ligands exhibit ligand-to-ligand charge transfer bands. Optimized geometries, molecular vibrations and electronic structures of charge-transfer complexes were calculated using density functional theory (B3LYP/6-311G+(d,p) level). Redox orbitals are shown to be almost exclusively ligand in nature, with a HOMO based heavily on the electron-rich maleonitriledithiolate ligand, and a LUMO comprised mostly of the electron-deficient dithione ligand. Charge transfer is thus believed to proceed from dithiolate HOMO to dithione LUMO, showing ligand-to-ligand redox interplay across a d10 metal.

Synthesis and characterization of ruthenium compounds incorporating keto-amine ligands. The applications of catalytic transfer hydrogenation and cancer cell inhibition

A series of keto-amine bidentate precursors 1–5, OCCH3CHCCH3NHR (where 1, R = C6H3-2,6-iPr2; 2, R = C6H2-2,4,6-Me3; 3, R = C6H4-2-tBu; 4, R = C6H4-2-OMe; 5, R = C6H4-2-OMe-5-Me) were synthesized and combined with [Ru(ɳ6-p-cymene)Cl2]2 to generate the monomeric arene-Ru derivatives, [Ru(ɳ6-p-cymene)(OCCH3CHCCH3NR)Cl] (where 6, R = C6H3-2,6-iPr2; 7, R = C6H2-2,4,6-Me3; 8, R = C6H4-2-tBu; 9, R = C6H4-2-OMe; 10, R = C6H4-2-OMe-5-Me) in moderate yield. The ruthenium derivatives effectively catalyzed the conversion rate in transfer hydrogenation of substituted acetophenone. The molecular structures of 2, 6–10 were determined by single crystal X-ray diffractometry in the solid state, revealing a four-coordination environment around the Ru atom. The potential anti-cancer activity of ruthenium derivatives against human hormone-refractory metastatic prostate cancer (HRMPC) cell lines was also studied.

Approximation-based integral versus differential isoconversional approaches to the evaluation of kinetic parameters from thermogravimetry

The relative accuracies of approximation-based integral versus differential isoconversional approaches for ‘actual’ E determination were investigated on experimental dehydration data of roxithromycin monohydrate from thermogravimetric (TG) analysis. The dehydration kinetic parameters and the relationship to the structural characteristics of the monohydrate and anhydrate forms from differential scanning calorimetry (DSC) and single-crystal X-ray diffractometry (SC-XRD) are also reported. Integral methods versus the differential Friedman isoconversional method evaluated E correspondences in both iso- and non-isothermal TG methods. The reliability in E from Friedman approached that of estimates from current most accepted integral isoconversional methods and was even superior to methods (for non-isothermal studies) that employ an approximation to the temperature integral (modified Kissinger–Akahira–Sunose, Senum–Yang fourth degree). Structural characterization (DSC, SC-XRD) and kinetic analysis from generalized kinetic master plots concluded that coordinated water occupied interlinked voids in crystal structure which may have facilitated the multidimensional diffusional loss of water upon heating without disruption of the crystal structure.

Neodymium(III) Complexes of Dialkylphosphoric and Dialkylphosphonic Acids Relevant to Liquid–Liquid Extraction Systems

The complexes formed during the extraction of neodymium(III) into hydrophobic solvents containing acidic organophosphorus extractants were probed by single-crystal X-ray diffractometry, visible spectrophotometry, and Fourier-transform infrared spectroscopy. The crystal structure of the compound Nd(DMP)3 (1, DMP = dimethyl phosphate) revealed a polymeric arrangement in which each Nd(III) center is surrounded by six DMP oxygen atoms in a pseudo-octahedral environment. Adjacent Nd(III) ions are bridged by (MeO)2POO(-) anions, forming the polymeric network. The diffuse reflectance visible spectrum of 1 is nearly identical to that of the solid that is formed when an n-dodecane solution of di(2-ethylhexyl)phosphoric acid (HA) is saturated with Nd(III), indicating a similar coordination environment around the Nd center in the NdA3 solid. The visible spectrum of the HA solution fully loaded with Nd(III) is very similar to that of the NdA3 material, both displaying hypersensitive bands characteristic of an pseudo-octahedral coordination environment around Nd. These spectral characteristics persisted across a wide range of organic Nd concentrations, suggesting that the pseudo-octahedral coordination environment is maintained from dilute to saturated conditions.

Complexation of Lanthanides with Glutaroimide-dioxime: Binding Strength and Coordination Modes.

The complexation of lanthanides (Nd(3+) and Eu(3+)) with glutaroimide-dioxime (H2L), a cyclic imide dioxime ligand that has been found to form stable complexes with actinides (UO2(2+) and NpO2(+)) and transition metal ions (Fe(3+), Cu(2+), etc.), was studied by potentiometry, absorption spectrophotometry, luminescence spectroscopy, and microcalorimetry. Lanthanides form three successive complexes, M(HL)(2+), M(HL)L, and M(HL)2(+) (where M stands for Nd(3+)/Eu(3+) and HL(-) stands for the singly deprotonated ligand). The enthalpies of complexation, determined by microcalorimetry, show that the formation of these complexes is exothermic. The stability constants of Ln(3+)/H2L complexes are several orders of magnitude lower than that of the corresponding Fe(3+)/H2L complexes but are comparable with that of UO2(2+)/H2L complexes. A structure of Eu(3+)/H2L complex, identified by single-crystal X-ray diffractometry, shows that the ligand coordinates to Eu(3+) in a tridentate mode, via the two oxygen atoms of the oxime group and the nitrogen atom of the imide group. The relocation of protons of the oxime groups (-CH═N-OH) from the oxygen to the nitrogen atom, and the deprotonation of the imide group (-CH-NH-CH-) result in a conjugated system with delocalized electron density on the ligand (-O-N-C-N-C-N-O-) that forms strong complexes with the lanthanide ions.