A one-dimensional silver(I) coordination polymer with saccharin and pyrazine: synthesis,crystal structure,thermal analysis,FTIR spectra,and DFT studies

A silver(I) complex of saccharinate (sac) with pyrazine (pyz), [Ag(sac)(pyz)] _n , has been synthesized and characterized by elemental analysis, IR, thermal analysis, and single-crystal X-ray diffractometry. The complex crystallizes orthorhombic space group Pnma with unit cell parameters of a = 13.0073(9) Å, b = 6.4907(6) Å, c = 13.4007(9) Å, V = 1131.37(15) Å³, and Z = 4. [Ag(sac)(pyz)] _n is a one-dimensional coordination polymer, in which the sac ligand acts as a monodentate ligand through the N atom and the trigonal silver centers are linked by the bridging pyz ligands. The individual chains are connected into two-dimensional supramolemular network by aromatic π(sac)···π(pyz) stacking interactions. The FTIR spectrum of [Ag(sac)(pyz)] _n has been recorded in the region and 4,000–400 cm^?1. The optimized geometry, frequency, and intensity of the vibrational bands of [Ag(sac)(pyz)] _n were obtained by density functional theory (DFT) at the B3LYP level. The vibrational frequencies were calculated and the scaled values have been compared with the experimental FTIR data. The observed and calculated frequencies are found to be in good agreement.     

Dendrimer Templated Synthesis of Carbon Nanotube Supported PdAu Catalyst and its Application as Hydrogen Peroxide Sensor

At present, CNT supported catalysts were prepared by two different methods as NaBH₄ reduction and dendrimer templated NaBH₄ reduction method to observe the effect of preparation method on the sensitivity and activity of H₂O₂ reduction. Then, CNT supported Pd_xAu_y bimetallic nanocatalysts having various atomic ratio were synthesized via novel dendrimer templated NaBH₄ reduction method. The resulting materials were characterized employing XRD and TEM. Crystallite size of 10 %Pd_0.7Au_0.3/CNT_dendrimer was obtained from XRD 17.1 nm and mean particle size obtained from TEM is about 15 nm. Moreover, the electrochemical behavior of these catalysts was characterized by cyclic voltammetry (CV) and chronoamperometry (CA) techniques. Pd_xAu_y bimetallic nanocatalysts have excellent electrocatalytic properties and great potential for applications in electrochemical detection. The sensitivity and the limit of detection values for the prepared sensor with monometallic 10 % Pd/CNT_dendrimer catalysts are 219.78 μA mM^?1cm^?2 and 2.6 μM, respectively. However, the sensor constructed with 10 %Pd_0.7Au_0.3/CNT_dendrimer modified electrode has a very high sensitivity of 316.89 μA mM^?1 cm^?2 with a quick response time of 2 s and a wide linear range of 0.001–19.0 mM. In addition, the interference experiment indicated that the 10 % Pd_0.7Au_0.3/CNT_dendrimer nanoparticles have good selectivity toward H₂O₂.     

Synthesis, structural, spectroscopic characterization, and structural comparison of 3-hydroxybenzoate and nicotinamide/N,N-diethylnicotinamide mixed ligand complexes with Zn(II)

The mixed-ligand 3-hydroxybenzoic acid complex of Zn(II) with nicotinamide and N,N-diethylnicotinamide were synthesized and characterized (colorless single crystals, [Zn(3-hba)₂(H₂O)₂(na)₂] and [Zn(3-hba)₂(H₂O)₂(dena)₂]). The chemical, FT-IR, thermal, mass spectral analyses, and X-ray data results revealed that both of the compounds contain two water molecules, two 3-hydroxybenzoate (3-hba) and two nicotinamide (na) or two N,N-diethylnicotinamide (dena) ligands per formula unit. 3-hba and na or dena ligands bind to the Zn(II) ion monodentately through their acidic oxygen and pyridinic nitrogen atoms, respectively. The coordination of metal atoms are completed by two molecules of aqua ligands. The charge balance of complexes is accommodated by two molecules of 3-hba ions. The unit cell has two molecules coordination molecules and each of them was as settled to four surfaces of unit cell cage in na complex. There is one mole molecule that was occupied to center of unit cell cage in dena complex. The two dimensional network structure of the complex is like a hexagonal for na and square plane for dena complexes. The thermal decomposition takes place in three steps; first, dehydration of the two aqua ligands, second, elimination of the two nicotinamide ligands, finally, burning of the two benzoate ion ligands.     

Exergoeconomic analysis of a thermochemical copper–chlorine cycle for hydrogen production using specific exergy cost (SPECO) method

The manner is investigated in which exergy-related parameters can be used to minimize the cost of a copper–chlorine (Cu–Cl) thermochemical cycle for hydrogen production. The iterative optimization technique presented requires a minimum of available data and provides effective assistance in optimizing thermal systems, particularly in dealing with complex systems and/or cases where conventional optimization techniques cannot be applied. The principles of thermoeconomics, as embodied in the specific exergy cost (SPECO) method, are used here to determine changes in the design parameters of the cycle that improve the cost effectiveness of the overall system. The methodology provides a reasonable approach for improving the cost effectiveness of the Cu–Cl cycle, despite the fact that it is still in development. It is found that the cost rate of exergy destruction varies between $1 and $15 per kilogram of hydrogen and the exergoeconomic factor between 0.5 and 0.02 as the cost of hydrogen rises from $20 to $140 per GJ of hydrogen energy. The hydrogen cost is inversely related to the exergoeconomic factor, plant capacity and exergy efficiency. The results are expected to assist ongoing efforts to increase the economic viability and to reduce product costs of potential commercial versions of this process. The impact of the results are anticipated to be significant since thermochemical water splitting with a copper–chlorine cycle is a promising process that could be linked with nuclear reactors to produce hydrogen with no greenhouse gases emissions, and thereby help mitigate numerous energy and environment concerns.     

Isoflavonoid glycosides from the rhizomes of Iris germanica

Four isoflavone glycosides were isolated from the rhizomes of Iris germanica. Compounds 1 and 2 are new, while compounds 3 and 4 are known isoflavone glycosides. These compounds were identified as iriskashmirianin 4'-O-beta-D-glucoside (1), nigricin 4'-O-beta-D-glucoside (2), irilone 4'-O-beta-D-glucoside (3) and iridin (4). Their structures were determined with the help of spectroscopic methods.     

Excitation of the T> components of the giant dipole states in N > Z nuclei by muon capture

Muon capture on N > Z nuclei is proposed as a means of studying the T_> isospin component of giant dipole states. Calculations for nickel isotopes (except ⁵⁶Ni) indicate that these states are strongly excited by muon capture. Possible experiments to detect these states are discussed.     

Synthesis, crystal structure, EPR and electrochemical studies of copper(II) dipicolinate complex with 2,2′-dipyridylamine ligand

The (2,2′-dipyridylamine)(pyridine-2,6-dicarboxylato)copper(II) trihydrate complex was synthesized and characterized by spectroscopic (IR, UV-vis, EPR), X-ray diffraction technique and electrochemical methods. The copper(II) center is surrounded by one bidentate 2,2′-dipyridylamine (dpa) and one tridentate dipicolinate (dpc) ligand, and exhibits a distorted square-pyramidal geometry. The crystal packing involves both hydrogen-bonding and π-π interactions. The solvent water molecules link monomers to one another through hydrogen-bonding interactions, forming ladder-type chains in the ab plane. π-π interactions also occur between the dpa rings of neighboring molecules and are responsible for interchain packing. Based on EPR and optical absorption studies, spin-Hamiltonian and bonding parameters have been calculated. The g-values, calculated for title complex in polycrystalline state at 298 K and in frozen DMF (110 K), indicate the presence of the unpaired electron in the d_x²-y² orbital. The evaluated metal-ligand bonding parameters showed strong in-plane σ- and π-bonding. The cyclic voltammogram of the title complex investigated in DMF (dimethylformamide) solution exhibits only metal centered electroactivity in the potential range ±1.25 V versus Ag/AgCl reference electrode.     

Synthesis,crystal structure and catalytic activity for H2O2 disproportionation of the manganese(II) coordination polymer {[Mn(O2C(CF2)8CO2)(phen)2]H2O}n (phen = 1,10-phenanthroline)

The title polymeric complex {[Mn(O₂C(CF₂)₈CO₂)(phen)₂]H₂O}_n was synthesized through the reaction of 1,10-phenanthroline, perfluorosebacic acid and MnCO₃ · H₂O. The molecular structure was characterized by X-ray diffraction, elemental analysis, thermal gravimetry, IR and UV–Vis spectroscopy and its catalytic activity has been studied. X-ray structure analysis shows that each Mn(II) ion is octahedrally coordinated by two bidentate phenanthroline ligands and the carboxylate oxygen atoms from two symmetry related perfluorosebacate ligands, which are coordinated in cisoid positions. The structure consists of polymeric chains, with the perfluorosebacato ligand bridging the Mn(II) ions in a monodentate fashion. Crystallographic characterization shows a supramolecular structure involving hydrogen bonds, π–π and π-ring interactions. The catalytic results indicated that the complex has reasonably good activity towards the disproportionation of hydrogen peroxide into water and dioxygen in methanol and it does not exhibit saturation kinetics with the substrate. The initial reaction rates and their temperature and base dependencies were investigated by monitoring the dioxygen evolution. Kinetic studies revealed a first-order dependence on the catalyst concentration. Activation parameters have been calculated at 301 K.     

Efficient synthesis of some oxalacetic acid and pyruvic acid derivatives from the reactions of 2,3-furandiones with 2-phenylindole

Oxalacetic acid and pyruvic acid derivatives have been synthesized efficiently in high yields by the treatment of 4-ethoxycarbonyl-5-phenyl-2,3-furandione and 4-benzoyl-5-phenyl-2,3-furandione with 2-phenylindole at room temperature and converted to simple derivatives such as an ester or a hydrazone.     

Mass attenuation coefficients for n-type InSe, InSe:Gd, InSe:Ho and InSe:Er single crystals

Measurements have been made to determine the mass attenuation coefficients of undoped n-type InSe, and Gd, Ho, Er doped n-InSe single crystals using a Si(Li) detector in the energy region 15.746–40.930 keV X-ray energies with energy dispersive X-ray fluorescence systems. InSe, InSe:Gd, InSe:Ho and InSe:Er single crystals were grown by using the stockbarger method. The measured values are graphically compared with the theoretical ones obtained using WinXcom.