Building an Iron Chromophore Incorporating Prussian Blue Analogue for Photoelectrochemical Water Oxidation

The replacement of traditional ruthenium-based photosensitizers with low-cost and abundant iron analogs is a key step for the advancement of scalable and sustainable dye-sensitized water splitting cells. In this proof-of-concept study, a pyridinium ligand coordinated pentacyanoferrate(II) chromophore is used to construct a cyanide-based CoFe extended bulk framework, in which the iron photosensitizer units are connected to cobalt water oxidation catalytic sites through cyanide linkers. The iron-sensitized photoanode exhibits exceptional stability for at least 5 h at pH 7 and features its photosensitizing ability with an incident photon-to-current conversion capacity up to 500 nm with nanosecond scale excited state lifetime. Ultrafast transient absorption and computational studies reveal that iron and cobalt sites mutually support each other for charge separation via short bridging cyanide groups and for injection to the semiconductor in our proof-of-concept photoelectrochemical device. The reorganization of the excited states due to the mixing of electronic states of metal-based orbitals subsequently tailor the electron transfer cascade during the photoelectrochemical process. This breakthrough in chromophore-catalyst assemblies will spark interest in dye-sensitization with robust bulk systems for photoconversion applications.     

The properties of the new Mn(II)–Co(II)–Mn(II)-type hetero-trinuclear oxime metal complexes with N4 and N4O2 ligands

1,3- and 1,2-calix[4]crown-7 and calix[4]crown-9 cone conformers were synthesized in acceptable yields by sequential introduction of two distal or proximal polyethylene glycolic chains with terminal hydroxyls at the lower rim, monotosylation, and intramolecular ring closure reaction. According to the two-phase extraction experiment, the title compounds showed mediocre affinity for alkali and alkaline earth metal picrates. The 1,2-calix[4]crown-9 extracted Sr²⁺ selectively among other alkaline earth metal cations.     

Transition-metal-ethylene complexes as high-capacity hydrogen-storage media

From first-principles calculations, we predict that a single ethylene molecule can form a stable complex with two transition metals (TM) such as Ti. The resulting TM-ethylene complex then absorbs up to ten hydrogen molecules, reaching to gravimetric storage capacity of approximately 14 wt %. Dimerization, polymerizations, and incorporation of the TM-ethylene complexes in nanoporous carbon materials are also discussed. Our results are quite remarkable and open a new approach to high-capacity hydrogen-storage materials discovery.     

Modeling of Thermal Conductivity of Concrete with Vermiculite by Using Artificial Neural Networks Approaches

In this article, the thermal conductivity of concrete with vermiculite is determined and also predicted by using artificial neural networks approaches, namely the radial basis neural network and multi-layer perceptron. In these models, 20 datasets were used. For the training set, 12 datasets (60%) were randomly selected, and the residual datasets (8 datasets, 40%) were selected as the test set. The root mean square error, the mean absolute error, and determination coefficient statistics are used as evaluation criteria of the models, and the experimental results are compared with these models. It is found that the radial basis neural network model is superior to the other models.     

Novel vic-dioxime ligands and their poly-metal complexes bearing 1,8-diamino-3,6-dioxaoctane: synthesis, characterization, spectroscopy and electrochemistry

Three novel vic-dioxime ligands containing the 1,8-diamino-3,6-dioxaoctane group, N,N′-(1,8-diamino-3,6-dioxaoctane)-p-tolylglyoxime (L¹SL¹H₄), N,N′-(1,8-diamino-3,6-dioxaoctane)-phenylglyoxime (L²SL²H₄), and N,N′-(1,8-diamino-3,6-dioxaoctane)-glyoxime (L³SL³H₄) have been prepared from 1,8-diamino-3,6-dioxaoctane with anti-p-tolylchloroglyoxime, anti-phenylchloroglyoxime or anti-monochloroglyoxime. Polynuclear complexes [M(L ^x SL ^x )] _n or [M(L ^x SL ^x )(H₂O)] _n (x = 1, 2 and 3), where M = Cu^II, Co^II, and Ni^II, have been obtained with 1:1 metal/ligand ratio. The Cu^II and Ni^II poly-metal complexes of these ligands are proposed to be square planar, while also the prepared Co^II complexes are proposed to be octahedral with two water molecules as axial ligands. The detection of H-bonding in the [Ni(L¹SL¹)] _n , [Ni(L²SL²)] _n and [M(L³SL³)(H₂O)] _n metal complexes by FT i.r. spectra revealed the square planar or octahedral [MN₄·H₂O)] _n coordination of poly-nuclear metal complexes. [MN₄] _n coordination of the [Ni(L¹SL¹)] _n and [Ni(L²SL²)] _n complexes were also determined by ¹H-n.m.r. spectroscopy. The ligands and poly-metal complexes were characterized by elemental analyses, FT-i.r., u.v.-vis., ¹H and ¹³C-n.m.r. spectra, magnetic susceptibility measurements, molar conductivity, cyclic voltammetry, and differential pulse voltammetric (DPV) techniques.     

Hetero‐ and homo‐leptic Ru(II) catalyzed synthesis of cyclic carbonates from CO2; Synthesis,spectroscopic characterization and electrochemical properties

Based on the a ligand BDPPZ [(9a,13a‐dihydro‐4,5,9,14‐tetraaza‐benzo[b]triphenylene‐11‐yl)‐phenyl‐methanone] (1) and its polypyridyl hetero‐ and homoleptic Ru(II) metal complexes, [Ru(bpy)₂L](PF₆)₂ (2), [Ru(phen)₂L](PF₆)₂ (3), [Ru(dafo)₂L](PF₆)₂ (4), [Ru(dcbpy)₂L](PF₆)₂ (5) and [RuL₃](PF₆)₂ (6) (where, L = ligand, bpy = 2,2′‐bipyridine, phen = 1,10‐phenantroline, dafo = 4,5‐diazafluoren‐9‐one and dcbpy = 3,3′‐dicarboxy‐2,2′‐bipyridine), have been synthesized and characterized by elemental analysis, UV–vis, FT‐IR, ¹H and ¹³C‐NMR spectra (for ligand), molar conductivity measurements and X‐ray powder techniques. The electrochemical parameters of the substituted ligand and its polypyridyl hetero‐ and homoleptic Ru(II) metal complexes are reported by cyclic voltammetry. UV–vis spectroscopy is used to compare the differences between the conjugated π systems in this ligand and its Ru(II) metal complexes. The polypyridyl hetero‐ and homoleptic Ru(II) metal complexes also tested as catalysts for the formation of cyclic organic carbonates from carbon dioxide and liquid epoxides which served as both reactant and solvent. The results showed that the [Ru(L)₃](PF₆)₂ (6) complex is more efficient than the other Ru(II) complexes for the formation of cyclic organic carbonates from carbon dioxide. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis of new boron complexes: application to transfer hydrogenation of acetophenone derivatives

Two new boron complexes were synthesized from N‐[3‐(methylmercapto)aniline]‐3,5‐di‐tert‐butylsalicylaldimine ( LH ) with boron reagent BPh₃ or BF₃.Et₂O. These boron complexes are stable and easily soluble in protic solvents such as ethanol (C₂H₅OH) but hardly soluble in nonprotic solvents such as chloroform (CHCl₃), dichloromethane (CH₂Cl₂) and tetrahydrofuran (THF). All new boron complexes have been fully characterized by both analytical and spectroscopic methods. The catalytic activities of complexes [LBPh₂], 2 , and [LBF₂], 3 , in the transfer hydrogenation of acetophenone derivatives were tested. Stable boron complexes were found to be efficient catalysts in the transfer hydrogenation of aromatic ketones in good conversions up to 99% in the presence of iso‐PrOH/KOH. Copyright © 2011 John Wiley & Sons, Ltd.     

Determination of kinetic parameters of crystal growth rate of borax in aqueous solution by using the rotating disc technique

Growth rate of polycrystalline disc of borax compressed at different pressure and rotated at various speed has been measured in a rotating disc crystallizer under well-defined conditions of supersaturation. It was found that the mass transfer coefficient, K, increased while overall growth rate constant, K_g, and surface reaction constant, k_r, decreased with increasing smoothness of the disc. It was also determined that kinetic parameters (k_r,r,K,g) of crystal growth rate of borax decreased with increasing rotating speed of the polycrystalline disc. The effectiveness factor was calculated from the growth rate data to evaluate the relative magnitude of the steps in series bulk diffusion through the mass transfer boundary layer and the surface integration. At low rotating speed of disc, the crystal growth rate of borax is mainly controlled by integration. However, both diffusion and integration steps affect the growth rate of borax at higher rotating speed of polycrystalline disc.     

Half-metallic silicon nanowires: first-principles calculations

From first-principles calculations, we predict that specific transition metal (TM) atom-adsorbed silicon nanowires have a half-metallic ground state. They are insulators for one spin direction, but show metallic properties for the opposite spin direction. At high coverage of TM atoms, ferromagnetic silicon nanowires become metallic for both spin directions with high magnetic moment and may have also significant spin polarization at the Fermi level. The spin-dependent electronic properties can be engineered by changing the type of adsorbed TM atoms, as well as the diameter of the nanowire. Present results are not only of scientific interest, but also can initiate new research on spintronic applications of silicon nanowires.     

Measurement of ‘closeness’ and Distinguishability of the Quantum States in Yang-Baxter Systems

Under the actions of different Hamiltonians on the different two-qubit input states by using the quantum Yang-Baxterization approach, we investigate the behaviors of the fidelity and the trace distance as measures of ‘closeness’ and distinguishability of two quantum states. The results show that the fidelity that is the main figure of merit for any communication and computing process can be kept to high values depending on the choice of the initial states and the Hamiltonians constructed by the Yang-Baxter equation. On the other hand, by choosing the initial states and Yang-Baxter systems which are the various extensions of the Yang-Baxter equations for several matrices, these quantifiers can be adjusted as desired to achieve many quantum computing and computational tasks. Furthermore, to quantify the performance of quantum teleportation we examine the teleportation fidelity for the outputs that correspond to the different two-qubit X-type states under the actions of the different Hamiltonians. It is possible to obtain high fidelity to use the quantum teleportation process.