Tuning the Triplet Excited State of Bis(dipyrrin) Zinc(II) Complexes: Symmetry Breaking Charge Transfer Architecture with Exceptionally Long Lived Triplet State for Upconversion

Zinc(II) bis(dipyrrin) complexes, which feature intense visible absorption and efficient symmetry breaking charge transfer (SBCT) are outstanding candidates for photovoltaics but their short lived triplet states limit applications in several areas. Herein we demonstrate that triplet excited state dynamics of bis(dipyrrin) complexes can be efficiently tuned by attaching electron donating aryl moieties at the 5,5′-position of the complexes. For the first time, a long lived triplet excited state (τ_T=296 μs) along with efficient ISC ability (Φ_Δ=71 %) was observed for zinc(II) bis(dipyrrin) complexes, formed via SBCT. The results revealed that molecular geometry and energy gap between the charge transfer (CT) state and triplet energy levels strongly control the triplet excited state properties of the complexes. An efficient triplet–triplet annihilation upconversion system was devised for the first time using a SBCT architecture as triplet photosensitizer, reaching a high upconversion quantum yield of 6.2 %. Our findings provide a blueprint for the development of triplet photosensitizers based on earth abundant metal complexes with long lived triplet state for revolutionary photochemical applications.     

CH_4 reforming with CO_2 for syngas production over La_2O_3 promoted Ni catalysts supported on mesoporous nanostructured γ-Al_2O_3

Nanostructured γ-Al2O3 with high surface area and mesoporous structure was synthesized by sol-gel method and employed as catalyst support for nickel catalysts in methane reforming with carbon dioxide. The prepared samples were characterized by XRD, N2adsorption-desorption,TPR, TPO, TPH, NH3-TPD and SEM techniques. The BET analysis showed a high surface area of 204 m2 g-1and a narrow pore-size distribution centered at a diameter of 5.5 nm for catalyst support. The BET results revealed that addition of lanthanum oxide to aluminum oxide decreased the specific surface area. In addition, TPR results showed that addition of lanthanum oxide increased the reducibility of nickel catalyst. The catalytic evaluation results showed an increase in methane conversion with increasing lanthanum oxide to 3 mol% and further increase in lanthanum content decreased the catalytic activity. TPO analysis revealed that the coke deposition decreased with increasing lanthanum oxide to 3 mol%. SEM and TPH analyses confirmed the formation of whisker type carbon over the spent catalysts. Addition of steam and O2 to dry reforming feed increased the methane conversion and led to carbon free operation in combined processes.     

Hydrogen‐Bonded Films for Zero‐Order Release of Leuprolide

Leuprolide has been widely used in androgen deprivation therapy for the treatment of advanced prostate cancer, but its use is still limited due to its short half‐life. Herein, hydrogen‐bonded layer‐by‐layer films are fabricated from PEGylated leuprolide (PEG‐LEU) and tannic acid (TA). Because of its dynamic nature, the film disintegrates gradually in water and releases PEG‐LEU and TA. The in vitro release profile indicated perfect zero‐order kinetics, which is explained by the unique release mechanism. When implanted subcutaneously in male rats, the films maintain a constant serum drug level. For a 60‐bilayer film, the serum drug level is maintained constant for ≈24 days. No initial burst release is observed, suggesting that the in vivo release also follows zero‐order kinetics. Initially, an increase in the level of serum testosterone is induced by the released drug, followed by testosterone suppression to a constant level below the castrate level, which could be maintained as long as a constant serum drug level is maintained. Since the new drug carriers avoid an initial burst release of the drug and maintain a constant serum drug level and hence a constant serum testosterone level below the castrate level, these carriers are highly promising for androgen deprivation therapy.     

A New Emissive Chalcone-Based Chemosensor Armed by Coumarin and Naphthol with Fluorescence “Turn-on” Properties for Selective Detection of F<Superscript>−</Superscript> Ions

A new chalcone-based probe containing coumarin and naphthol at both ends has been synthesized via aldol condensation. The uniqueness of the newly derived probe can be ascribed to the presence of naphthol and coumarin units acting as binding site and signaling element, respectively. The fluorogenic behaviors toward various anions were investigated. The probe was characterized by various spectroscopic techniques and the in-depth study led to show excellent selectivity and sensitivity for fluoride ions. The hydrogen bonding thus formed with fluoride anion provides remarkable fluorometric responses. The interactions of the probe with fluoride ions were determined by fluorescence, FT-IR and NMR spectroscopic techniques. The exploratory studies by fluorescent spectral changes augur well for the naked-eye sensing applications.     

Solvent effects on oxygen atom transfer reaction between manganese(V)-oxo corrole and alkene

Pseudo-first order reaction rate constants of 5,10,15-tris（pentafluorophenyl）corrole Mn（V）-oxo (F₁₅CMn（V）-oxo),5,15-bis（pentafluorophenyl）-10-（phenyl）corrole Mn（V）-oxo(F₁₀CMn（V）-oxo),5,15- bis（phenyl）-10-（pentafluorophenyl）corrole Mn（V）-oxo（F₅CMn（V）-oxo） and 5,10,15-tris（phenyl）corrole Mn（V）-oxo（F₀CMn（V）-oxo） with a series of alkene substrates in different solvents were determined by UV-vis spectroscopy.The results indicated that the oxygen atom transfer pathway between Mn（V）-oxo corrole and alkene is solvent-dependent.     

Microwave‐assisted Aqueous Multicomponent Reaction: Facile Synthesis of Polyfunctionalized Indoline‐spiro Fused Pyran Derivatives

A green and highly efficient method for the synthesis of polyfunctionalized indoline‐spiro fused pyran derivatives has been established. This reaction was conducted by reacting readily available and inexpensive starting materials, such as isatins, cyclic‐1,3‐dicarbonyl compounds, and malononitrile in aqueous media without any catalysts under microwave irradiation. The present green synthesis shows fascinating properties such as the use of water as the reaction solution, concise one‐pot conditions, short reaction periods (8–14 min), and easy purifications. The synthesis could also set a good example to GAP (Group‐Assistant‐Purification) chemistry in which purification via chromatography can be avoided and the pure products can be easily acquired only by washing the crude products with 95% EtOH.     

Synthesis of Diaryl Ethers Through the Copper-Catalyzed Arylation of Phenols with Aryl Iodides Using KF/Al2O3

An efficient synthesis of diaryl ethers by the copper-catalyzed arylation of phenols with a variety of aryl iodide susing KF/Al₂O₃ as a suitable base and CuI and 1,3 diphenyl-1,3 propandione as the catalyst is described.     

CFD Simulation of Rheological Model Effect on Cuttings Transport

Foam, as a non-Newtonian fluid, plays an important role in the underbalanced drilling technique in oil field development. The rheological properties of drilling fluids, such as foam, have a direct effect on flow characteristics and hydraulic performance. Two rheological models—the Herschel–Bulkley model and power law—were fitted to two foam systems in this study. Computational fluid dynamics (CFD) was used to simulate the effect of the rheological models on solid–liquid (cuttings transport) hydraulics in concentric and eccentric annulus during the foam drilling operation. The simulation results are compared to the experimental data from previous studies. The results of CFD using the power law model are in good agreement with experimental results in horizontal annulus with respect to the Herschel–Bulkley model with relative error less than 8%. Thus, for CFD cuttings transport for simulations in inclined and horizontal annulus, it is best to use the power law's rheological model parameters.     

Sedimentation rate in the Sungai Linggi estuary using excess 210Pb and 137Cs

The purpose of this study was to estimate the sedimentation rate in the Sungai Linggi estuary using the constant initial concentration of unsupported or excess ²¹⁰Pb model and verified with ¹³⁷Cs method. Five sediment cores were collected on 25 January 2011 using gravity corer with the inner tube of 50 cm length and 7.5 cm diameter. The total ²¹⁰Pb activities in the sediment cores profile at all sampling stations were varied and upper than those obtained for supported ²¹⁰Pb i.e. ²²⁶Ra, indicated disequilibrium among ²¹⁰Pb and its grandparents in the ²³⁸U decay series. Meanwhile, the lower ¹³⁷Cs activities were observed at all sampling stations due to no significant sources of ¹³⁷Cs releases were transferred into Malaysian marine. The estimation of sedimentation rate indicated the agreement of ²¹⁰Pb and ¹³⁷Cs method with a general presence of deep mixing in the Sungai Linggi estuary. Therefore, the apparent sedimentation rates calculated from ²¹⁰Pb profiles generally reflect the true value with the range from 0.70 to 1.97 cmyr^?1. High sedimentation rate was observed at some sampling stations which are located in river channel, estuary and closer to mainland. This suggested that land-use development, agriculture activities, channelization etc. introduced a large amount of sediment loaded into those areas.