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.     

Decomposition and oxidation of CH3 13CH2OH on A12O3, Pd/Al2O3, and PdO/Al2O3 catalysts

Temperature-programmed desorption (TPD) and oxidation (TPO) were used to investigate the decomposition and oxidation of ethanol on Al₂O₃, Pd/Al₂O₃, and PdO/Al₂O₃. Ethyl--¹³C alcohol (CH₃ ¹³CH₂OH) was adsorbed on the catalysts so that reaction pathways of the two carbons could be distinguished. Alumina was mainly a dehydration catalyst, but dehydrogenation was also observed and some carbon remained on the surface. In the presence of O₂, A1₂O₃ oxidized the decomposition products and the-carbon was oxidized faster. Ethanol, which was adsorbed on A1₂O₃, decomposed much faster on Pd/A1₂O₃ by diffusing to Pd and undergoing CO elimination to form CH₄,¹³CO, H₂, and surface carbon. On PdO/A1₂O₃, the decomposition was slower than on Pd/A1₂O₃ until lattice oxygen was extracted above 450 K; the decomposition products were oxidized by lattice oxygen. In the presence of gas phase O₂, Pd/Al₂O₃ was an active oxidation catalyst at low temperature, but lattice oxygen had to be extracted from PdO/A1₂O₃ before it had significant oxidation activity.     

Regioselective synthesis and pharmacological activities of spirodibenzo[a,d]cycloheptene-5,2′-[1,3,4]thiadiazole derivatives

Some new 3^′,5^′-substituted-5H,3^′ H-spirodibenzo[a, d]cycloheptene-5,2^′-[1,3,4]thiadiazole and 10,11-dihydro-5H,3^′ H-spirodibenzo[a, d]cycloheptene-5,2^′-[1,3,4]thiadiazole derivatives 3a–n were regioselectively synthesized under 1,3-dipolar cycloaddition of 5-thiooxo-5H-dibenzo[a, d]cyclo-heptene and 5-thiooxo-10,11-dihydro-5H-dibenzo[a, d]cycloheptene with a variety of nitrilimines (generated in situ via dehydrohalogenation of the corresponding hydrazonoyl chlorides in the presence of triethylamine). The new products were tested for antiinflammatory, analgesic, and ulcerogenic score activities comparable to Indomethacin. Compounds 3i–l showed significant activity compared to Indomethacin.     

NO reduction by CH4over La2O3: temperature‐programmed reaction and in situ DRIFTS studies

The chemistry between NO _x species adsorbed on La₂O₃ and CH₄ was probed by temperature‐programmed reaction (TPR) as well as in situ DRIFTS. During NO reduction by CH₄ in the presence of O₂, NO ₃ ^- does not appear to activate CH₄, thus either an adsorbed O species or an NO ₂ ^- species is more likely to activate CH₄. In the absence of O₂, a different reaction pathway occurs and NO^- or (N₂O₂)^2- species adsorbed on oxygen vacancy sites seem to be active intermediates, and during NO reduction with CH₄ unidentate NO ₃ ^- , which desorbs at high temperature, behaves as a spectator species and is not directly involved in the catalytic sequence. Because reaction products such as CO₂ or H₂O as well as adsorbed oxygen cannot be effectively removed from the surface at lower temperatures, steady‐state catalytic reactions can only be achieved at temperatures above 800 K, even though formation of N₂ and N₂O from NO was observed at much lower temperature during the TPR experiments. This revised version was published online in July 2006 with corrections to the Cover Date.     

Titanium complexes with β-ketoiminate chelate ligands for ethylene polymerization: The significant influence of substituents on structures and catalytic activities

Four titanium complexes having β-ketoiminate chelate ligands with fluorine or alkyl groups [(Ar)NC(CH₃)C(H)C(CH₃)O]₂TiCl₂ (3a: Ar = 2.6-F₂C₆H₃; 3b: Ar = C₆F₅; 3c: Ar = 2.6-Me₂C₆H₃; 3d: Ar = 2.6-ⁱPr₂C₆H₃) have been synthesized and characterized by ¹H NMR and EA. Complexes 3a, 3c and 3d were further characterized by X-ray diffraction analysis and demonstrated distorted octahedral coordination structure around the titanium center. The substituents in ligands greatly affect the coordination mode, resulting in three different isomeric structures. These complexes are active catalysts for polymerization of ethylene with MMAO as cocatalyst. The substituents in ligands have also great influences on catalytic activity. The complexes with alkyl groups have lower activity, while the complexes with fluorine atoms have middle or high catalytic activity.     

Preparation of deuterated methyl 6,9,12-octadecatrienoates and methyl 6,9,12,15-octadecatetraenoates

Methyl 6,9,12-octadecatrienoate-15,15,16,16-d ₄ was obtained by Wittig coupling between 6,6,7,7-tetradeutero-3-nonenyltriphenylphosphonium iodide, 8, and the aldehyde ester, methyl 9-oxo-6-nonenoate. Methyl 6-oxohexanoate, obtained by ozonolysis of cyclohexene, was coupled in a Wittig reaction with [2-(1,3-dioxan-2-yl)ethyl]triphenylphosphonium bromide to give methyl 8-dioxanyl-6-octenoate. This compound was transacetalized to methyl 9,9-dimethoxy-6-nonenoate, which was then hydrolyzed to the aldehyde ester. For the preparation of compound 8, the tetrahydropyranyl ether of 2-pentynol was deuterated with deuterium gas and tris-(triphenylphosphine)chlororhodium. The tetradeuterated tetrahydropyranyl ether was converted to the bromide with triphenylphosphine dibromide, and the bromide was coupled with 3-butynol by means of lithium amide in liquid ammonia to give 3-nonynol-6,6,7,7-d ₄. Hydrogenation over Lindlar's catalyst converted the deuterated alkynol to 3-nonenol-6,6,7,7-d ₄. This deuterated alkenol was converted to the bromide with triphenylphosphine dibromide, then to the iodide with sodium iodide in acetone, and finally to 8 with triphenylphosphine in acetonitrile. Methyl 6,9,12,15-octadecatetraenoate-12,13,15,16-d ₄ was obtained by Wittig coupling between methyl 9-oxo-6-nonenoate and 3,4,6,7-tetradeutero-3,6-nonadienyltriphenylphosphonium iodide, 15. For the preparation of compound 15, the bromide obtained from the reaction of 2-pentynol with triphenylphosphine dibromide was coupled with 3-butynol with lithium amide in liquid ammonia. The resulting 3,6-nonadiynol was deuterated with deuterium gas in the presence of P-2 nickel, and the resultant deuterated nonadienol was converted to 15 through the bromide and iodide. The final products were separated from isomers formed during the synthetic sequences by silver resin chromatography.     

Effects of rice cultivars on methane fluxes in a paddy soil

CH₄ emission and its relevant processes involved (i.e. CH₄ production, rhizospheric CH₄ oxidation and plant-mediated CH₄ transport) were studied simultaneously to comprehensively understand how rice cultivars (Yanxuan, 72031, and 9516) at growth stages (early and late tillering, panicle initiation, ripening, and harvest stage) affect CH₄ emission in a paddy soil. Over the entire rice-growing season, Yanxuan had the highest CH₄ emission flux with 5.98 g CH₄ m^–2 h^–1 followed by 72031 (4.48 g CH₄ m^–2 h^–1) and 9516 (3.41 g CH₄ m^–2 h^–1). The highest CH₄ production rate of paddy soils planted to Yanxuan was observed with 18.0 g CH₄ kg_{{ (d.w.soil)}} h^–1 followed by the soil planted to 9516 (17.5 g CH₄ kg_{{ (d.w.soil)}} h^–1). For each cultivar, both rhizospheric CH₄ oxidation ability and plant-mediated CH₄ transport efficiency varied widely with a range of 9.81–76.8% and 15.5–80.5% over the duration of crop growth, respectively. Multiple regression analyses showed that CH₄ emission flux was positively related with CH₄ production rate and rice plant-mediated CH₄ transport efficiency, but negatively with rhizospheric CH₄ oxidation (R ²=0.425 for Yanxuan, P<0.01; R ²=0.426 for 72031, P<0.01; R ²=0.564 for 9516, P<0.01). The contribution of rice plants to CH₄ production seems to be more important than to rhizospheric CH₄ oxidation and plant-mediated transport in impact of rice plants on CH₄ emission.     

Trapping of CH3O formed from CO + H2

Methoxy formed on Al₂O₃ from¹³CO and H₂ coadsorption on Ni/Al₂O₃ was trapped by C₂H₅OH adsorption and temperature-programmed reaction (TPR). The presence of excess C₂H₅OH significantly increases the rate of¹³CH₃OH and (¹³CH₃)₂O formation. The¹³CH₃OH forms by the reaction of C₂H₅OH with¹³CH₃O on Al₂O₃. In the absence of C₂H₅OH,TPR following¹³CO and H₂ coadsorption did not produce significant amounts of¹³CH₃OHor(¹³CH₃)₂O.     

Mechanistic Study of Selective Oxidation of Dimethyl Ether to Formaldehyde over Alumina-supported Molybdenum Oxide Catalyst

XPS and IR spectroscopies were used to investigate the surface intermediates of dimethyl ether (DME) oxidation to formaldehyde over MoOx/Al₂O₃ catalyst. The reaction performances were tested by employing three typical reaction conditions, depending on the O₂/DME ratio and the reaction temperature. When there was sufficient oxygen present in the reaction media, a terminal or bridged CH₃O* species formed by DME dissociation was highly active and rapidly reacted with lattice oxygen to produce formaldehyde, leading to higher selectivity of HCHO. When oxygen was consumed completely or only DME was present in the reaction media, CH₃O species bonded to more than two Mo atoms (μ-OCH₃) and CH_x (x=1–3) species attached to the Mo atoms were observed and the relative ratio of (μ-OCH₃) /Mo–CH_x was significantly dependent on the reduction degree of MoO_x domains. The (μCH₃O) species was related to the formation of CH₃OH or CO_x, and the Mo–CH_x species led to the formation of CH₄.     

Facile Rh-C Bond Cleavage of Rhodium(III) Benzyl Porphyrin Complex in DMSO with Strong Bases

Rhodium-carbon bond cleavage represents an essential step for small molecule activation and transformation by rhodium porphyrin complexes. This article reports on a new method for the cleavage of porphyrin rhodium(III)-carbon bonds in DMSO solvent with strong bases. UV-Vis, in situ ¹H NMR spectrum and GC-MS analysis confirmed generation of rhodium(I) species and monodeuterated toluene. Mechanistic studies revealed that strongly reducing CD₃SOCD₂⁻, formed in situ from DMSO-d₆ and strong bases, promoted Rh-C bond cleavage.     

An efficient method for synthesis of some heterocyclic compounds containing 3-iminoisatin and 1,2,4-triazole using Fe3O4 magnetic nanoparticles

1,2,4-triazole derivatives were prepared by reaction of thiocarbohydrazide and some esters in 60% ethanol. Condensation of 1,2,4-triazole derivatives with isatin gave Schiff bases of 3-iminoisatin derivatives. Reaction of malonic or succinic acid dihydrazide with isatin lead to formation of N,N'-bis-(3-imino-1,3-dihydro-indolyl-2-one)-malonamide 8a and N,N'-bis-(3-imino-1,3-dihydro-indolyl-2-one)succinamide 8b in good yields under mild reaction conditions. These reactions are catalyzed by Fe₃O₄ MNPs. The chemical structures were confirmed by Fourier transform-infrared, ¹H-NMR, ¹³C-NMR, gas chromatography-mass spectrometry spectroscopy, and elemental analysis.     

Spectroscopic evidence for the formation of CHx species in the hydrogenation of carbidic carbon on Ni(100)

The CH _x species formed on Ni(100) by hydrogenation of carbidic carbon have been detected using high resolution electron energy-loss spectroscopy (HREELS). Exposures of carbidic carbon to 1×10^–7 Torr H₂ and D₂ at 313 K for 20 min produce CH _x and CD _x species, respectively. These species are identified by two energy-loss peaks for CH _x at 2970 and 1380 cm^–1 and only one peak for CD _x at 1980 cm^–1. Because of the existence of the intense peak at 1380 cm^–1, in the range of a scissors mode for CH₂ and a symmetric deformation mode for CH₃, the CH _x species are tentatively ascribed to CH₂ and/or CH₃. The CD _x species undergo decomposition at 330–370 K in UHV as well as in hydrogen below 10^–7 Torr. No stable CH _x species are observed above 400 K, which is lower than the normal reaction temperature of the methanation reaction (500 K).     

Preparation and characterization of multicomponent porous materials prepared by the sol-gel process

An experimental strategy was developed to obtain transparent Si-Al-Ti-Ni-Mo and Si-Zr-Ti-Ni-Mo sols via the sol-gel process. The sol was prepared from Si(OEt)₄ (TEOS), Al(OBu^s)₃ (OBu^s: C₂H₅CH(CH₃)O), Ti(OEt)₄ (OEt: OCH₂CH₃), Zr(OPrⁿ)₄ (OPrⁿ: OCH₂CH₂CH₃). In both cases nickel nitrate hexahydrate (Ni(NO₃)₂ · 6H₂O) and ammonium heptamolybdate tetrahydrate ((NH₄)₆Mo₇O₂₄ · 4H₂O) were the Ni and Mo sources, respectively. The sols were characterized by Fourier Transform Infrared Spectroscopy (FTIR). Assignments of the simultaneous formation of the Si-O-Al, Si-O-Ti, Si-O-Ni, and Si-O-Zr bonds were done. The sols were polymerized at room temperature (293 K) to obtain gels, and these were dried at 423 K and calcined at 573, 853 and 893 K in air. The characterization techniques used were small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and ²⁹Si and ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR). The density of the solids was measured following ASTM method D-4892 and the porosity and surface area were determined by N₂ adsorption/desorption isotherms. The corresponding average pore diameters were evaluated using the BJH, HK, and DA methods.     

Synthesis and characterization of per-substituted spermine-bridged cyclophosphazene derivatives: the first example of syn/anti conformational polymorphism in a bridged cyclophosphazene

The synthesis and characterization of a series of per-substituted spermine-bridged cyclophosphazene derivatives are reported based on the known compound [N₃P₃X₄(NHCH₂CH₂CH₂N)CH₂CH₂]₂, (1a) (where X = Cl), to give a number of new compounds (1b–1h) in which X = OPh, [spiro-O(CH₂)₃O]_0.5, OCH₂CF₃, NHPh, NC₄H₈, Ph and NHBu^t, respectively. Two synthetic routes were utilized: (i) using the chloro-precursor 1a in nucleophilic substitution reactions with a variety of anionic and neutral nucleophiles to give compounds 1b–1f and (ii) reaction of spermine with the appropriate di-gem tetrasubstituted cyclophosphazene to give compounds 1g and 1h. Bridged compounds such as 1a–1h may exist as syn or anti conformers in the solid state and the first example of syn and anti conformational polymorphism is reported for a bridged cyclophosphazene, viz. for compound 1a.     

Electrolysis of mixed melt of (CH3)4NF·mHF+x wt.% CsF·2.0HF with nickel anode

A new process for electrolytic synthesis of a perfluorinated compound using mixed melts of (CH₃)₄NF·4.0HF+x wt.% CsF·2.0HF as electrolytes and Ni sheet anode at room temperature was developed. The addition of CsF·2.0HF reduced the overvoltage of the Ni anode. The surface film on the anode formed in the presence of CsF·2.0HF consisted of inorganic compounds of NiF₂, CsNi₂F₆, and an organic compound of (CH₃)₄NF. The presence of CsNi₂F₆, which is a highly oxidized nickel compound, gave a high electronic conductivity to the film and decreased the anode overvoltage. The gas evolved on the anode was composed of (CF₃)₃N and CF₄ as main products with small amounts of NF₃, C₂F₆, CHF₃, C₂HF₅, CF₃N(CF₂H)₂, and (CF₃)₂NCHF₂. The addition of 20 wt.% CsF·2.0HF gave the highest ratio of (CF₃)₃N of 40.5% when the electrolysis was carried out at 5 mA cm⁻² at room temperature.     

Effect of Coordination Modes of HL Ligand on the Molecular Architecture of Its Transition Metal Complexes (HL = 5-Methyl-2-Phenyl-4-[(2-<Emphasis Type="Italic">o</Emphasis>-Tolylamino)-Phenylmethylene]pyrazol-3(2H)-one)

Abstract  Two Ag⁺ complexes [Ag(HL)₂(PF₆)] (1) and [(AgL) _n  · n(CH₂Cl₂) · n(0.5H₂O)] (2) (HL = 5-methyl-2-phenyl-4-[(2-o-tolylamino)-phenylmethylene]pyrazol-3(2H)-one) were synthesized and structurally characterized by EA analysis, IR spectra and X-ray crystallography. The result shows that two expected coordination modes (Modes I and III in Scheme 1) of the HL ligand, can be observed in its Ag⁺ complexes, while not in other transition metal ions (Ni²⁺, Co²⁺ or Cu²⁺) complexes whether deprotonation or not for the HL ligand. Graphical Abstract  Three possible coordination modes (Modes I, II or III in Scheme 1) of the selected HL (HL = 5-methyl-2-phenyl-4-[(2-o-tolylamino)-phenylmethylene]pyrazol-3(2H)-one) ligand, can be adopted, in which Modes I and III can be observed in its two Ag⁺ complexes [Ag(HL)₂(PF₆)](1) and [(AgL) _n  · n(CH₂Cl₂) · n(0.5H₂O)] (2), while Mode II just observed in its transition metal ions (Cu²⁺, Ni²⁺, or Co²⁺) complexes, resulting from the deprotonatd form of the HL ligand and the coordination characters of transition metal ions.      

Synthesis and characterization of polyamides based on cubane-1,4-dicarboxylic acid

The direct polycondensations of cubane-1,4-dicarboxylic acid with 1,4-phenylenediamine (2 a), 4,4′-oxydianiline (2 b), 4,4′-sulfonyldianiline (2 c), and 9,9′-bis(4-aminophenyl)florene (2 d) were carried out in N-methyl-2-pyrrolidone/pyridine containing triphenylphosphite and lithium chloride at 110 °C for 9 h. Polyamide 3 a obtained from 2 a was scarcely soluble in organic solvent even during heating, and was soluble only in conc-H₂SO₄, whereas 3 c and 3 d derived from 2 c and 2 d, respectively, were readily soluble in N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethylsulfoxide. After treating polyamide 3 d with the rhodium complex catalyst in NMP, cubane units were quantitatively converted into cyclooctatetraenes. Received: 3 March 1997/Accepted: 1 April 1997     

SORPTION BEHAVIOR OF PERTECHNETATE ION ON REILLEXTM-HPQ ANION EXCHANGE RESIN FROM HANFORD AND MELTON VALLEY TANK WASTE SIMULANTS AND SODIUM HYDROXIDE/SODIUM NITRATE SOLUTIONS

ABSTRACT

The batch distribution coefficients (K_d, mL solution /g dry resin) for pertechnetate (TcO₄) between Reillex^TMHPQ anion exchange resin and various caustic solutions have been determined. The average K_d value in 1.5 M NaNO₃/l.0 M NaOH solution is (262.2 ± 12.6) mL7sol;g for TcO₄ ^? ranging from 1.0 × 10^TM M to 5.0 × 10^?4 M. Pertechnetate K_d values were measured in a series of NaOH7sol;NaNO₃ solutions. The series are: 1.00 M NaOH with 0.010 to 5.00 M NaNO₃; 0.100 M NaOH with 0,010 to 5.00 M NaNO₃; 0.100 MNaNO₃ with 0.10 to 5.00M NaOH; 1.00MNaNO₃ with 0.10 to 5.00 M NaOH; 1.50 M NaNO₃ with 0.10 to 5.00 M NaOH; 3.50 M NaNO₃ With 0.10 to 5.00 M NaOH. The K_d values are described by the following equation.

This equation was used to predict the K_d values for a series of tank waste simulants. The predicted K_d values are different from the measured values with an average absolute difference of (29 ± 10)%.

Pertechnetate k_dvalues for 101-SY, 103-SY, DSS, DSSF-2.33, DSSF-5, DSSF7, 101-AW, and Melton Valley simulants have been determined as a function of time. A first order approach to equilibrium is observed. The K_d values at two hours are (1066±45), (870± 102), (346± 18), (296± 15), (245 ±6), (209± II), (218±5), and (167 ± 5) mL/g, respectively.     

Catalytic deNO x properties of novel vanadium oxide based open-framework materials

The deNO _x catalytic properties of a new class of open-framework structure materials, Li₆[Mn₃(H₂O)₁₂V₁₈O₄₂(XO₄)] · 24H₂O (X = V, S) (1), [Fe₃(H₂O)₁₂ V₁₈O₄₂(XO₄)] · 24H₂O (X = V, S) (2), [Co₃(H₂O)₁₂V₁₈O₄₂(XO₄)] · 24H₂O (X = V, S) (3), and Li₆[Ni ₃ ^II (H₂O)₁₂V ₁₆ ^VI V ₂ ^V O₄₂(SO₄)] · 24H₂O (4), have been studied. The crystal structures of these novel systems consist of three-dimensional arrays of vanadium oxide clusters {V₁₈O₄₂(XO₄)} , as building block units, interlinked by {–O–M–O–} (M = Mn, 1; M = Fe, 2; M = Co, 3; M = Ni, 4) bridges. Their open-framework structures contain cavities, similar to those observed in conventional zeolites, which are occupied by exchangeable cations and/or readily removable water of hydration. The catalysts derived from these materials were tested for the selective catalytic reduction (SCR) of nitrogen oxides {NO _x } into N₂ using a hydrocarbon, propylene, as the reducing agent. The catalysts were ineffective under lean burn conditions. However, the new catalysts, especially the one derived from the cobalt derivative (3), showed intriguing deNO _x activity under rich conditions. They remove up to ~ 99% of the toxic NO _x emissions in 1.5% O₂ with 100% selectivity to N₂. The active phase of the catalysts exhibit good stability, can be readily regenerated, and are selective to the desired product-N₂. The catalytic reactions occur at moderately low temperatures (400–500 °C). The catalysts were characterized by FT-IR, temperature programmed reactions (TPR and TPO), SEM, BET surface area measurements, elemental analysis, and X-ray diffraction (XRD). Additional advanced techniques were used to further characterize the catalyst phases that showed most promising deNO _x activity and increased tolerance to oxygen.