Synthesis, structure, and photovoltaic property of a nanocrystalline 2H perovskite-type novel sensitizer (CH3CH2NH3)PbI3

A new nanocrystalline sensitizer with the chemical formula (CH₃CH₂NH₃)PbI₃ is synthesized by reacting ethylammonium iodide with lead iodide, and its crystal structure and photovoltaic property are investigated. X-ray diffraction analysis confirms orthorhombic crystal phase with a = 8.7419(2) Å, b = 8.14745(10) Å, and c = 30.3096(6) Å, which can be described as 2 H perovskite structure. Ultraviolet photoelectron spectroscopy and UV-visible spectroscopy determine the valence band position at 5.6 eV versus vacuum and the optical bandgap of ca. 2.2 eV. A spin coating of the CH₃CH₂NH₃I and PbI₂ mixed solution on a TiO₂ film yields ca. 1.8-nm-diameter (CH₃CH₂NH₃)PbI₃ dots on the TiO₂ surface. The (CH₃CH₂NH₃)PbI₃-sensitized solar cell with iodide-based redox electrolyte demonstrates the conversion efficiency of 2.4% under AM 1.5 G one sun (100 mW/cm²) illumination.     

Improving Protein Crystal Quality by the Without-Oil Microbatch Method: Crystallization and Preliminary X-ray Diffraction Analysis of Glutathione Synthetase from Pseudoalteromonas haloplanktis

Glutathione synthetases catalyze the ATP-dependent synthesis of glutathione from l-γ-glutamyl- l-cysteine and glycine. Although these enzymes have been sequenced and characterized from a variety of biological sources, their exact catalytic mechanism is not fully understood and nothing is known about their adaptation at extremophilic environments. Glutathione synthetase from the Antarctic eubacterium Pseudoalteromonas haloplanktis (PhGshB) has been expressed, purified and successfully crystallized. An overall improvement of the crystal quality has been obtained by adapting the crystal growth conditions found with vapor diffusion experiments to the without-oil microbatch method. The best crystals of PhGshB diffract to 2.34 Å resolution and belong to space group P2₁2₁2₁, with unit-cell parameters a = 83.28 Å, b = 119.88 Å, c = 159.82 Å. Refinement of the model, obtained using phases derived from the structure of the same enzyme from Escherichia coli by molecular replacement, is in progress. The structural determination will provide the first structural characterization of a psychrophilic glutathione synthetase reported to date.     

Purification, Crystallization and Preliminary X-ray Crystallographic Studies of RAIDD Death-Domain (DD)

Caspase-2 activation by formation of PIDDosome is critical for genotoxic stress induced apoptosis. PIDDosome is composed of three proteins, RAIDD, PIDD, and Caspase-2. RAIDD is an adaptor protein containing an N-terminal Caspase-Recruiting-Domain (CARD) and a C-terminal Death-Domain (DD). Its interactions with Caspase-2 and PIDD through CARD and DD respectively and formation of PIDDosome are important for the activation of Caspase-2. RAIDD DD cloned into pET26b vector was expressed in E. coli cells and purified by nickel affinity chromatography and gel filtration. Although it has been known that the most DDs are not soluble in physiological condition, RAIDD DD was soluble and interacts tightly with PIDD DD in physiological condition. The purified RAIDD DD alone has been crystallized. Crystals are trigonal and belong to space group P3₁21 (or its enantiomorph P3₂21) with unit-cell parameters a = 56.3, b = 56.3, c = 64.9 Å and γ = 120°. The crystals were obtained at room temperature and diffracted to 2.0 Å resolution.     

Improvement of Thermal Stability via Outer-Loop Ion Pair Interaction of Mutated T1 Lipase from Geobacillus zalihae Strain T1

Mutant D311E and K344R were constructed using site-directed mutagenesis to introduce an additional ion pair at the inter-loop and the intra-loop, respectively, to determine the effect of ion pairs on the stability of T1 lipase isolated from Geobacillus zalihae. A series of purification steps was applied, and the pure lipases of T1, D311E and K344R were obtained. The wild-type and mutant lipases were analyzed using circular dichroism. The T_m for T1 lipase, D311E lipase and K344R lipase were approximately 68.52 °C, 70.59 °C and 68.54 °C, respectively. Mutation at D311 increases the stability of T1 lipase and exhibited higher T_m as compared to the wild-type and K344R. Based on the above, D311E lipase was chosen for further study. D311E lipase was successfully crystallized using the sitting drop vapor diffusion method. The crystal was diffracted at 2.1 Å using an in-house X-ray beam and belonged to the monoclinic space group C2 with the unit cell parameters a = 117.32 Å, b = 81.16 Å and c = 100.14 Å. Structural analysis showed the existence of an additional ion pair around E311 in the structure of D311E. The additional ion pair in D311E may regulate the stability of this mutant lipase at high temperatures as predicted in silico and spectroscopically.     

A multifunctional strontium/silver-co-substituted hydroxyapatite derived from biogenic source as antibacterial biomaterial

The bioactive properties of hydroxyapatite (HAp) facilitate bone regeneration, however, its physico-chemical and bioactive properties can be further enhanced by ionic substitutions within the crystalline lattice. In this work, substitution with Sr²⁺ and Ag⁺ ions was investigated for the improvement of osseointegration and antibacterial activity in potential treatment of traumatic bone injuries. A series of single substituted HAp with Sr²⁺ or Ag⁺ ions and Ag/Sr-co-substituted HAp with different degrees of substitution (0, 1, 2.5, and 5 mol%) were obtained by wet precipitation from cuttlefish bone. Rietveld refinement indicated successful Ca²⁺ substitution by increasing cell parameters due to the larger ionic radii of Sr²⁺ and Ag⁺ compared to Ca²⁺, which was confirmed by elemental mapping showing uniform distribution of substituent cations. Characterization of the zeta-potential of Ag/Sr-co-substituted HAp showed negatively charged populations, at potentials not lower than ?15 mV. Increasing the degree of substitution resulted in decreasing zeta-potential. The higher absorption capacity of bovine serum albumin was determined on Ag/Sr-co-substituted HAp powders as compared to non-substituted HAp. All Ag-substituted HAps have shown an antibacterial activity towards Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, as determined by inhibition zone, viability analysis and scanning electron microscopy. In addition, non-cytotoxicity towards human cells was confirmed by in vitro tests with embryonic kidney 293 and mesenchymal stem cells.     

One-Dimensional Hydrogen-Bonded Infinite Chain from Nickel(II) Tetraaza Macrocyclic Complex and 1,2-Cyclopentanedicarboxylate Ligand

The reaction of [Ni(L)]Cl₂·2H₂O (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo [14,4,0^1.18,0^7.12]docosane) with trans-1,2-cyclopentanedicarboxylic acid (H₂-cpdc) yields a 1D hydrogen-bonded infinite chain with formula [Ni(L)(H-cpdc⁻)₂] (1). This complex has been characterized by X-ray crystallography, spectroscopy and cyclic voltammetry. The crystal structure of 1 exhibits a distorted octahedral geometry about Ni atom with four nitrogen atoms of the macrocycle and two oxygen atoms of the H-cpdc⁻ ligand at the axial position. Compound 1 crystallizes in the monoclinic system P2₁/c with a = 8.7429(17), b = 10.488(2), c = 18.929(4) Å, β = 91.82(2), V = 1734.8(6) ų, Z = 2. Electronic spectrum of 1 reveals a high-spin octahedral environment. Cyclic voltammetry of 1 undergoes two waves of a one-electron transfer corresponding to Ni^II/Ni^III and Ni^II/Ni^I processes.     

Increasing the X-ray Diffraction Power of Protein Crystals by Dehydration: The Case of Bovine Serum Albumin and a Survey of Literature Data

Serum albumin is one of the most widely studied proteins. It is the most abundant protein in plasma with a typical concentration of 5 g/100 mL and the principal transporter of fatty acids in plasma. While the crystal structures of human serum albumin (HSA) free and in complex with fatty acids, hemin, and local anesthetics have been characterized, no crystallographic models are available on bovine serum albumin (BSA), presumably because of the poor diffraction power of existing hexagonal BSA crystals. Here, the crystallization and diffraction data of a new BSA crystal form, obtained by the hanging drop method using MPEG 5K as precipitating agent, are presented. The crystals belong to space group C2, with unit-cell parameters a = 216.45 Å, b = 44.72 Å, c = 140.18 Å, β = 114.5°. Dehydration was found to increase the diffraction limit of BSA crystals from ~8 Å to 3.2 Å, probably by improving the packing of protein molecules in the crystal lattice. These results, together with a survey of more than 60 successful cases of protein crystal dehydration, confirm that it can be a useful procedure to be used in initial screening as a method of improving the diffraction limits of existing crystals.     

Ferroelectric and magnetic properties of Nd-doped Bi4 ? xFeTi3O12 nanoparticles prepared through the egg-white method

Multiferroic behavior of Bi_{4 − x}Nd_xFeTi₃O₁₂ (0.0 ≤ × ≤ 0.25, × = 0.05) ceramic nanoparticles prepared through the egg-white method was investigated. The dielectric properties of the samples show normal behavior and are explained in the light of space charge polarization. Room temperature polarization-electric field (P-E) curves show that the samples are not saturated with maximum remanence polarization, P_r = 0.110 μC/cm², and a relatively low coercive field, E_c = of 7.918 kV/cm, at an applied field of 1 kV/cm was observed for 5% Nd doping. The room temperature M-H hysteresis curve shows that the samples exhibit intrinsic antiferromagnetism with a weak ferromagnetism. These properties entitle the grown nanoparticles of BNFT as one of the few multiferroic materials that exhibit decent magnetization and electric polarization.     

Preferential occupancy of metal ions in the hydroxyapatite solid solutions synthesized by hydrothermal method

The solid solutions in the systems of Ca-Cd HAp [Ca_10−xCd_xHAp (x = 0–10)], Ca-Sr HAp [Ca_10−xSr_xHAp (x = 0–10)] and Ca-Pb HAp [Ca_10−xPb_xHAp (x = 0–10)], were successfully synthesized at 200 °C for 12 h under hydrothermal conditions. The site of the metal ions in the solid solutions was analyzed by the Rietveld method. The results of the Rietveld analysis indicated that the metal ions of Pb²⁺, Sr²⁺, and Cd²⁺ all preferentially occupied M (2) sites in the apatite structure. The preferential occupancy of the metal ions in M (2) sites were explained mainly by their ionic radius and electronegativity.     

Structural study of detonation nanodiamonds

The structure of spherical hollow detonation nanodiamonds (DND) previously ground in a planetary mill for 10 min has been studied by synchrotron radiation diffraction. The interference contribution of the diffraction pattern from DND calculated using different structural parameters has been compared with the experimental pattern of DND after mechanical treatment. It was shown that after mechanical treatment of spherical hollow DND (r_inner=19.94 A, r_outer=25.47 A), two kinds of particles were observed: one was non-hollow spheres of r=13.9 A size at the same lattice parameters a=b=3.85 A, c=3.45 A and the others, of the size 5a×13b×5c at the parameters a=c=3.567 A, b=3.85 A, were particles of non-spherical shape.     

Fabrication of silver-doped apatite powders from silver-substituted octacalcium phosphate powders via solid–solid phase-conversion process

The excellent biocompatibility of apatite (hydroxyapatite, HAp; carbonate apatite, CO₃Ap) materials makes them suitable candidates as bone substitutes. However, they have no antibacterial ability. Meanwhile, silver (Ag) exhibits excellent antibacterial properties across a wide antibacterial spectrum. However, soluble Ag salts exhibit cytotoxicity and poor aesthetic properties. We dope Ag into an apatite unit lattice in order for the composite material to exhibit antibacterial contact abilities while simultaneously limiting the release of Ag⁺, which is the primary cause of the unwanted color changes and cytotoxicity. When a crystal structure in which silver ions are substituted for Ca in octacalcium phosphate (OCP) (Ag-OCP) is immersed in water and/or (NH₄)₂CO₃-containing solutions, Ag-OCP is converted into an apatite containing Ag via a solid–solid phase-transformation process. The Ag contents of the apatite and precursor Ag-OCP are the same. The CO₃ content of apatite samples depends on the (NH₄)₂CO₃ concentration of the treated solutions. A single-pot, single-step treatment enables the synthesis of both Ag-containing HAp and CO₃Ap. Further, these Ag-containing HAp and CO₃Ap samples show little color change from that of the precursor Ag-OCP.     

Synthesis, Structure of Nitrogen-Containing Phosphinogold(I) Ferrocenes. In vitro Activity against Bladder and Colon Carcinoma Cell Lines

The gold salt [(tht)AuCl] was reacted with [1-N,N-dimethylaminométhyl-2-diphenylphosphino]ferrocene (1) forming the bimetallic derivative 4. The reaction of methyl iodide and tetramethylammonium bromide on the chloride 4 produced the ammonium salt 5 and the bromide 6 respectively. New aminophosphines 2 and 3, which represent two of the rare phosphorylated metallocenes containing P(III)-N bond have also been coordinated to gold(I) to form 7 and 8. The presence of the ethoxy group in 7 provides evidence for the lability of one nitrogen-phosphorus bond. The X-ray structure of compounds 4 and 7 have been established. Both crystallize in space group P2₁/c, monoclinic, with a = 11.095(2) Å, b = 12.030(3) Å, c = 17.763(4) Å, β= 94.02(2)∘, Z = 4 for 4 and a = 14.863(3) Å, b = 8.036(5)Å, c = 18.062(5)Å, β =101.64(1)°, Z = 4 for 7. ¹⁹⁷Au Mössbauer data are in good agreement with those for other linear P-Au-Cl containing complexes. The compounds were evaluated for in vitro anti-tumour activity against two human tumours. Differential cytotoxicity was observed with activity comparable to cisplatin, with the exception of one compound which was significantly more cytotoxic.     

A solvothermal synthesis of a novel 1D ladder-like (NH3CH2CH2NH3)AgAsS4 containing N–H⋯S hydrogen bonding

A one-dimensional compound (NH₃CH₂CH₂NH₃)AgAsS₄ with ladder-like chains was synthesized solvothermally. This compound crystallizes in the monoclinic system, space group C2/c, with a=13.5805(8) Å, b=6.5331(3) Å, c=22.7711(9) Å, α=90°, β=106.42(3)°, γ=90°, Z=8. The rare type hydrogen bonding of N–H⋯S and electrostatic force hold the anionic chains together.     

A Preliminary X-ray Study of Murine Tnfaip8/Oxi-α

Tnfaip8/oxidative stress regulated gene-α (Oxi-α) is a novel protein expressed specifically in brain dopaminergic neurons and its over-expression has been reported to protect dopaminergic cells against OS-induced cell death. In this study, murine C165S mutant Tnfaip8/Oxi-α has been crystallized and X-ray data have been collected to 1.8 Å using synchrotron radiation. The crystal belonged to the primitive orthorhombic space group P2₁2₁2, with unit-cell parameters a = 66.9, b = 72.3, c = 93.5 Å. A full structural determination is under way in order to provide insights into the structure-function relationships of this protein.     

Solubility of ammonium oxalate in water–acetone mixtures and metastable zone width of their solutions

Experimental results on the solubility c of ammonium oxalate in mixed water–acetone solvents containing acetone content x < 0.55 by weight at different saturation temperature T are presented and discussed using the theory of regular solutions. It was found that: (1) the dependence of the solubility c of ammonium oxalate in solutions of different mixed water–acetone solvents on temperature T follows an Arrhenius-type relation, (2) the dependence of c on acetone content x at different temperature T follows the relation: ln(c + δ) = a − bx, where the parameters a and b are measures of deviation of a solution from ideality and the correction factor δ is related to the activity coefficient f_a of the solution, which decreases with an increase in c, and (3) the dependence of the solubility c of ammonium oxalate in solutions of different compositions x of water–acetone mixtures is related to the dielectric constant ?* of the solvent mixture, following the relation ln c = C + C₁?*, where C and C₁ are related to the parameters a and b, respectively. Study of the metastable zone width, defined as maximum undercooling ΔT_max a solution saturated at a particular temperature T can withstand, of some selected solutions of mixed water–acetone solvents at different T revealed that ΔT_max decreases with an increase in antisolvent content x. The results are discussed using the self-consistent Nývlt-like approach.     

X-ray structure and spectroscopic properties of some lanthanides(III) complexes derived from 2,6-diacetylpyridine-bis(benzoylhydrazone)

A series of trivalent lanthanide complexes of type [Ln(L) NO₃)(S)_n](NO₃)_m(S^′)_n, have been synthesized by the reaction of 2,6-diacetylpyridine-bis-(benzoylhydrazone) (H₂L) with lanthanide(III) nitrates in ethanol. These complexes have been characterized by analysis, molar conductance, magnetic measurements, infrared spectral studies and X-ray diffraction. The analytical data revealed the formation of 1:1 (metal:ligand) stoichiometry. Molar conductance in dmf gives 2:1 electrolytes in all the complexes. Magnetic moment values are close proximity of the Van Vleck values. IR study suggests the coordination of the ligand through the azomethine and the oxygen of the hydrazonic moiety. The nitrate ion is also found to be bidentate in all the complexes. The crystal structures were determined. 6, C₂₇H₃₁N₆O₇S₂Gd: a=b=8.6821(4) Å, c=84.363(5) Å, tetragonal P4₁2₁2 and Z=8. bf 7, C₂₅H₂₅N₆O₆SDy: a=11.750(3) Å, b=13.250(3) Å, c=36.000(6) Å, β=98.50(2), monoclinic, C2/c, Z=8. 9, C₂₄H₂₅N₆O₇Yb: a=10.750(2) Å, b=17.750(3) Å, c=14.250(4) Å, β=99.00(2), monoclinic, P2₁/n, Z=4. In these complexes the lanthanide ion assumes a nine coordinated geometry for Gd and an eight coordinated geometry for Dy and Yb.     

Crystalline structures of intercalate molecular complexes of syndiotactic polystyrene with two fluorescent guests: 1,3,5-Trimethyl-benzene and 1,4-dimethyl-naphthalene

The crystal structures of two molecular complex phases of syndiotactic polystyrene (s-PS) with 1,3,5-trimethyl-benzene (TMB) and 1,4-dimethyl-naphthalene (DMN) have been described. These structures present a monoclinic unit cell in which the s(2/1)2 polymer helices and guest molecules are packed according the space group P2₁/a and unit cell constants: a=17.3 Å, b=15.4 Å, c=7.8 Å and γ=95.7° for s-PS/TMB and a=17.4 Å, b=17.2 Å, c=7.8 Å and γ=116.4° for s-PS/DMN. Both structures can be described as intercalates, since they present ac layers of polymer helices alternated to layers of contiguous guest molecules and a guest/monomeric-unit molar ratio of 1/2, as recently observed only for s-PS/norbornadiene molecular complex. On the basis of a comparison between crystalline structures and X-ray diffraction data of several s-PS molecular complexes, a simple criterion to anticipate their clathrate or intercalate nature has been suggested.     

Capillary-Seeding Crystallization and Preliminary Crystallographic Analysis of a Solvent-Tolerant Elastase from Pseudomonas aeruginosa Strain K

Seeding is a versatile method for optimizing crystal growth. Coupling this technique with capillary counter diffusion crystallization enhances the size and diffraction quality of the crystals. In this article, crystals for organic solvent-tolerant recombinant elastase strain K were successfully produced through microseeding with capillary counter-diffusion crystallization. This technique improved the nucleation success rate with a low protein concentration (3.00 mg/mL). The crystal was grown in 1 M ammonium phosphate monobasic and 0.1 M sodium citrate tribasic dihydrate pH 5.6. The optimized crystal size was 1 × 0.1 × 0.05 mm³. Elastase strain K successfully diffracted up to 1.39 Å at SPring-8, Japan, using synchrotron radiation for preliminary data diffraction analysis. The space group was determined to be monoclinic space group P12₁1 with unit cell parameters of a = 38.99 Ǻ, b = 90.173 Å and c = 40.60 Å.     

Effect of Ag/Al co-doping method on optically p-type ZnO nanowires synthesized by hot-walled pulsed laser deposition

Silver and aluminum-co-doped zinc oxide (SAZO) nanowires (NWs) of 1, 3, and 5 at.% were grown on sapphire substrates. Low-temperature photoluminescence (PL) was studied experimentally to investigate the p-type behavior observed by the exciton bound to a neutral acceptor (A⁰X). The A⁰X was not observed in the 1 at.% SAZO NWs by low-temperature PL because 1 at.% SAZO NWs do not have a Ag-O chemical bonding as confirmed by XPS measurement. The activation energies (E_a) of the A⁰X were calculated to be about 18.14 and 19.77 meV for 3 and 5 at.% SAZO NWs, respectively, which are lower than the activation energy of single Ag-doped NW which is about 25 meV. These results indicate that Ag/Al co-doping method is a good candidate to make optically p-type ZnO NWs.     

Lithium insertion in ultra-thin nanobelts of Ag2V4O11/Ag

In this study, ultra-thin nanobelts of Ag₂V₄O₁₁/Ag were successfully synthesized. The synthesized ultra-thin nanobelts of Ag₂V₄O₁₁/Ag are highly crystalline and the thickness is found to be about 5 nm. A lithium battery using ultra-thin nanobelts of Ag₂V₄O₁₁/Ag as the active materials of the positive electrode exhibits a high initial discharge capacity of 276 mAh g⁻¹, corresponding to the formation of Li_xAg₂V₄O₁₁ (x = 6). With increased cycling, the electrode made of ultra-thin nanobelts of Ag₂V₄O₁₁/Ag tends to loose electrochemical activity due to Ag⁺ ions in the ultra-thin nanobelts of Ag₂V₄O₁₁ were reduced and new phase was formed.