Photoinduced electron transfer reaction for synthesis of tetrahydroquinoline derivatives with conjugated structure using chlorophyll b‐modified magnetic titanium dioxide photocatalyst

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Photoinduced electron transfer reaction for synthesis of tetrahydroquinoline derivatives with conjugated structure using chlorophyll b-modified magnetic titanium dioxide photocatalyst

In this study, the chlorophyll b-modified magnetic titanium dioxide photocatalyst was designed to synthesize conjugated derivatives of tetrahydroquinoline through a photoinduced electron transfer (PET) reaction. The prepared photocatalyst was highly active under visible-light irradiation toward the cyclization of (E)-3-[4-(dimethylamino)phenyl)]-1-arylprop-2-en-1-one with 1-aryl-1H-pyrrole-2,5-dione to achieve new tetrahydroquinoline derivatives with conjugated structure in high yields at ambient temperature, in air. The magnetic property enabled easy recovery of the photocatalyst and improved its reusability up to three runs.


Photocatalytic conversion of organic compounds has recently emerged as a cost-effective, safe, and easy-to-operate procedure to synthesize value-added materials. In this study, the magnetic titanium dioxide-based (Fe3O4/SiO2/TiO2) photocatalyst was designed to synthesize conjugated derivatives of tetrahydroquinoline through a photoinduced electron transfer (PET) reaction. Chlorophyll b was immobilized on the surface of magnetic titanium dioxide, as a natural visible-light-sensitive compound using 3-aminopropyltriethoxysilane (APTES) as a coupling agent containing terminal amine (Fe3O4/SiO2/TiO2-NH2-Chb) to improve light harvesting ability. Fourier transform infrared (FT-IR), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), energy-dispersive X-ray spectrometer (EDS), and vibrating sample magnetometer (VSM) results confirmed the successful synthesis of Fe3O4/SiO2/TiO2-NH2-Chb. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images displayed the preserved spherical morphology of Fe3O4/SiO2/TiO2-NH2-Chb. Chlorophyll b-modified magnetic titanium dioxide was highly active under visible-light irradiation toward the cyclization of (E)-3-[4-(dimethylamino)phenyl)]-1-arylprop-2-en-1-one with 1-aryl-1H-pyrrole-2,5-dione to achieve new tetrahydroquinoline derivatives with conjugated structure in high yields at ambient temperature, in air. The incorporation of chlorophyll b in the photocatalyst plays an important role in the photocatalytic mechanism, facilitating photoinduced electron transfer to the conduction band of TiO2. Moreover, the magnetic property enabled easy recovery of the photocatalyst and improved its reusability up to three runs. The characteristics of tetrahydroquinoline derivatives were studied by FT-IR, CHN, 1H NMR, and 13C NMR analyses.

A first‐principles investigation into the rational design of Sn‐halide perovskite materials as an alternative to Pb‐based perovskites

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A first-principles investigation into the rational design of Sn-halide perovskite materials as an alternative to Pb-based perovskites

Mixed cation based hybrid halide perovskite (ABX3) semiconducting materials have been studied by employing density functional theory formalism. Tolerance and octahedral factors indicate the structural stability of the studied materials. Neagative values of formation energy indicates their thermodynamic stability. Observed band gap values and high optical absorption in the visible range of electromagnetic spectrum manifest their potential to become suitable materials for photovoltaic applications.


Abstract

The development of Pb-free alternatives for perovskite-based photovoltaics is extremely important due to the toxicity of Pb to the environment. Sn-based organic inorganic hybrid halide perovskites are considered to be the most suitable alternative to Pb-based ABX3$$ {}_3 $$ perovskites due to their similar optoelectronic properties. The selection of A site cation in ABX3$$ {}_3 $$ type perovskites is crucial for favorable structural and mechanical properties. Using first principle methods, we have designed and investigated Sn–I based hybrid halide perovskite materials with different organic cations mixed in equal proportions. Observed tolerance (TF) and octahedral factors (μ$$ \mu $$) indicate the formation of stable three-dimensional perovskite structure. Our studied materials also exhibit thermodynamic stability due to the negative value of their formation energies. Observed band gap values indicate the semiconducting nature of our studied perovskite materials. Calculated optical properties indicate that all of the compounds exhibit suitable dielectric functions and absorption coefficients in the visible range of the electromagnetic spectrum. The observed highest value of theoretical power conversion efficiency of MA-AMSnI3$$ {}_3 $$ (11.24%) indicates its potential to be used in photovoltaics. Our investigation will be beneficial for researchers to develop less toxic and efficient perovskite materials for the fabrication of optoelectronic devices.

Tuning ultrafast time‐evolution of photo‐induced charge‐transfer states: A real‐time electronic dynamics study in substituted indenotetracene derivatives

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Tuning ultrafast time-evolution of photo-induced charge-transfer states: A real-time electronic dynamics study in substituted indenotetracene derivatives

The electronic layout and Real Time-TD-DFT electron dynamics are investigated to unveil the charge migration time evolution in two asymmetrically substituted indenotetracene compounds for potential singlet fission-based applications in photoactive materials.


Abstract

Photo-induced charge transfer (CT) states are pivotal in many technological and biological processes. A deeper knowledge of such states is mandatory for modeling the charge migration dynamics. Real-time time-dependent density functional theory (RT-TD-DFT) electronic dynamics simulations are employed to explicitly observe the electronic density time-evolution upon photo-excitation. Asymmetrically substituted indenotetracene molecules, given their potential application as n-type semiconductors in organic photovoltaic materials, are here investigated. Effects of substituents with different electron-donating characters are analyzed in terms of the overall electronic energy spacing and resulting ultrafast CT dynamics through linear response (LR-)TD-DFT and RT-TD-DFT based approaches. The combination of the computational techniques here employed provided direct access to the electronic density reorganization in time and to its spatial and rational representation in terms of molecular orbital occupation time evolution. Such results can be exploited to design peculiar directional charge dynamics, crucial when photoactive materials are used for light-harvesting applications.

Machine Learning‐Aided Data Analysis in Single‐Protein Conductance Measurement with Electron Tunneling Probes

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Comprehensive Summary

The electrical tunneling sensors have excellent potential in the next generation of single-molecule measurement and sequencing technologies due to their high sensitivity and spatial resolution capabilities. Electrical tunneling signals that have been measured at a high sampling rate may provide detailed molecular information. Despite the extraordinarily large amount of data that has been gathered, it is still difficult to correlate signal transformations with molecular processes, which creates great obstacles for signal analysis. Machine learning is an effective tool for data analysis that is currently gaining more significance. It has demonstrated promising results when used to analyze data from single-molecule electrical measurements. In order to extract meaningful information from raw measurement data, we have combined intelligent machine learning with tunneling electrical signals. For the purpose of analyzing tunneling electrical signals, we investigated the clustering approach, which is a classic algorithm in machine learning. A clustering model was built that combines the advantages of hierarchical clustering and Gaussian mixture model clustering. Additionally, customized statistical algorithms were designed. It has been proved to efficiently gather molecular information and enhance the effectiveness of data analysis.

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Facile and Cost‐effective Synthesis of CoP@N‐doped Carbon with High Catalytic Performance for Electrochemical Hydrogen Evolution Reaction

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Facile and Cost-effective Synthesis of CoP@N-doped Carbon with High Catalytic Performance for Electrochemical Hydrogen Evolution Reaction

This work proposes a new facile, cost-effective, and safe preparation method for CoP loaded on N-doped carbon using inexpensive starting materials. The optimized ratio in the starting materials allowed CoP loaded on N-doped carbon to show high hydrogen evolution activity with 202 mV of overpotential at 10 mA/cm2 and stability.


Abstract

The manufacture of efficient and low-cost hydrogen evolution reaction (HER) catalysts is regarded as a critical solution to achieve carbon neutrality. Herein, we developed an economical method to synthesize a CoP-anchored N-doped carbon catalyst via one-step pyrolysis using inexpensive starting materials (cobalt ion salt, phytic acid, and glycine). The size of the CoP nanoparticles was controlled by adjusting the Co/P ratio of the catalysts. Nanoscale CoP particles with adequate exposure to active sites were uniformly anchored on the surface of the conductive nitrogen-doped carbon substrate, ensuring the rapid transfer of electrons and species. When Co/P=0.89, the as-made catalyst exhibited outstanding HER activity, with an extraordinarily low overpotential of 202 mV at 10 mA cm−2 and long-term stability.

Dichlorocarbene: From Jack Hine to Robert Moss

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Dichlorocarbene: From Jack Hine to Robert Moss

A select history of dichlorocarbene chemistry between 1950 and 2010 will be presented. This is not a comprehensive review; rather, it is a personal perspective on the contributions of two respected colleagues. Jack Hine discovered a new mechanism—alpha elimination—to form carbenes. Moss (and his preceptor Closs) discovered the concept of carbenoids. Dichlorocarbene is the reactive intermediate that spanned the research efforts of Hine and Moss and stimulated their important contributions to organic synthesis and mechanistic thinking.


Abstract

A select history of dichlorocarbene chemistry between 1950 and 2010 will be presented. This is not a comprehensive review; rather, it is a personal perspective on the contributions of two respected colleagues, the reactive intermediate that spanned their research efforts, and their important contributions to organic synthesis and mechanistic thinking.

Design and Simulation of a Low‐Temperature Thermal Desalination System

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Design and Simulation of a Low-Temperature Thermal Desalination System

A low-temperature thermal desalination system based on the spray-assisted vacuum flash operation was designed with the passive heating of saline water and effective condensation of water vapor. The flash drum was designed effectively by simulation of the droplet dynamics. A corrugated plate heat exchanger and a thermosyphon solar water heater were designed to optimize the system.


Abstract

The prototype of a low-temperature thermal desalination system treating 2500 L day−1 of saline water was designed thermally and geometrically, to be integrated with a vacuum spray flash drum and spray nozzles, a plate heat exchanger-type condenser, and a thermosyphon solar water heater to produce potable water for a small community. The design bases were the feed flow rate, the feed temperature from 45 to 65 °C, the salinity of 0.035 kg kg−1, and the vacuum drum pressure from 2 to 6 kPa absolute. The estimated yield of potable water based on the simulated droplet dynamics was in the range of 68.91–75.80 %. The plate heat exchanger and the thermosyphon solar water heater were designed for effective condensation and passive heating, respectively.

Efficient contact between H2O and N‐coordinate Ru nanoparticles in three‐dimensionally ordered macro/mesoporous carbon boosting alkaline HER

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Comprehensive Summary

In this study, a novel approach is proposed to achieve the uniformly dispersed Ru nanoparticles with N coordination loaded on three-dimensionally ordered macro/mesoporous carbon (3DOMMC) through simultaneous pyrolysis of Ru3+ and cyanamide on 3DOMMC.In an alkaline medium, the synthesized catalysts exhibit exceptional hydrogen evolution reaction (HER) performance. Specifically, Ru-N/3DOMMC demonstrates a significantly low overpotential of 13.8 mV to achieve a current density of 10 mA cm-2, and it exhibits a mass activity 17.5 times higher than that of commercial Pt/C. The outstanding performance could be attributed to the ultrahigh Ru dispersion and more efficient contact between active sites and reactant, which derived from the large specific surface area and inter-connective three-dimensionally macro/mesoporous of 3DOMMC.

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