Monthly Archives: September 2023

Diastereoselective Construction of α‐Fluoroalkyl Cycloalkanols via Radical Alkylation of α‐Fluoroalkyl Ketones

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Diastereoselective Construction of α-Fluoroalkyl Cycloalkanols via Radical Alkylation of α-Fluoroalkyl Ketones†

A visible-light-induced cascade radical cyclization of alkenyl fluoroalkyl ketones is developed, producing various α-Rf cycloalkanols in promising yields with up to >20 : 1 dr selectivity. DFT calculations suggest that the fluorine effect plays an important role in this reaction.


Comprehensive Summary

α-Fluoroalkyl (Rf) alcohols are privileged motifs in drugs and pharmaceutically active compounds. As such, it is highly desirable to develop efficient methods for assembling these scaffolds. Herein, a visible-light-induced cascade radical cyclization of alkenyl fluoroalkyl ketones is developed, producing a variety of decorate α-Rf cycloalkanols in promising yields with up to >20 : 1 dr selectivity. A radical chain mechanism involving an intramolecular radical addition to the α-Rf carbonyl group and a subsequent intermolecular hydrogen atom transfer (HAT) has been proposed. Density functional theory (DFT) calculations indicate that a fluorine effect contributes to the radical addition to carbonyls by lowering the π* (C=O) orbital energy of CORf and energy barrier of the HAT between alkoxy radicals and THF, which may be valuable for controllable transformations of fluorinated molecules.

Zwitterionic “Solutions” for Reversible CO2 Capture

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Zwitterionic “Solutions” for Reversible CO2 Capture

A new class of basic aqueous sorbents for CO2 based on zwitterions that present environmental and safety advantages that significantly reduce the risks of possible human and environmental contamination and they may be used in the nowadays employed amine scrubbing industrial plants with little or no modifications.


Abstract

The zwitterions resulting from the covalent attachment of 3- or 4-hydroxy benzene to the 1,3-dimethylimidazolium cation represent basic compounds (pKa of 8.68 and 8.99 in aqueous solutions, respectively) that chemisorb in aqueous solutions 0.58 mol/mol of carbon dioxide at 1.3 bar (absolute) and 40 °C. Equimolar amounts of chemisorbed CO2 in these solutions are obtained at 10 bar and 40 °C. Chemisorption takes place through the formation of bicarbonate in the aqueous solution using imidazolium-containing phenolate. CO2 is liberated by simple pressure relief and heating, regenerating the base. The enthalpy of absorption was estimated to be −38 kJ/mol, which is about 30 % lower than the enthalpy of industrially employed aqueous solutions of MDEA (estimated at −53 kJ/mol using the same experimental apparatus). The physisorption of CO2 becomes relevant at higher pressures (>10 bar) in these aqueous solutions. Combined physio- and chemisorption of up to 1.3 mol/mol at 40 bar and 40 °C can be attained with these aqueous zwitterionic solutions that are thermally stable and can be recycled at least 20 times.

Green Alternatives in Treatment of Liver Diseases: the Challenges of Traditional Medicine and Green Nanomedicine

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Green Alternatives in Treatment of Liver Diseases: the Challenges of Traditional Medicine and Green Nanomedicine


Abstract

Over the last decade, liver diseases have become a global problem, with approximately two million deaths per year. The high increase in the mortality rate of these diseases is mostly related to the limitations in the understanding of the evolutionary clinical cases of liver diseases, the low delivery of drugs in the liver, the non-specific administration of drugs, and the side effects generated at the systemic level by conventional therapeutic agents. Today it is common knowledge that phytochemicals have a high curative potential, even in the prevention and/or reversibility of liver disorders; however, even using these green molecules, researchers continue to deal with the same challenges implemented with conventional therapeutic agents, which limits the pharmacological potential of these friendly molecules. On the other hand, the latest advances in nanotechnology have proven that the use of nanocarriers as a delivery system for green active ingredients, as well as conventional ones, increases the pharmacological potential of these active ingredients due to their physicochemical characteristics (size, Zeta potential, etc.,) moldable depending on the therapeutic objective; in addition to the above, it should be noted that in recent years, nanoparticles have been developed for the specific delivery of drugs towards a specific target (stellar cells, hepatocytes, Kupffer cells), depending on the clinical state of the disease in the patient. The present review addresses the challenges of traditional medicine and green nanomedicine as alternatives in the treatment of liver diseases.

Investigation of Two Zr‐p‐NO2Bn‐DOTA Isomers via NMR and Quantum Chemical Studies

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Investigation of Two Zr-p-NO2Bn-DOTA Isomers via NMR and Quantum Chemical Studies

Two regioisomers of Zr-p-NO2Bn-DOTA were isolated and characterized by NMR studies and quantum chemical calculations. As opposed to the side regioisomer, the corner regioisomer exists exclusively as the SAP isomer.


Abstract

A combination of NMR studies and quantum chemical calculations were employed to investigate the structure and energetics of Zr4+ chelates of pNO2Bn-DOTA. We have demonstrated that two discrete regioisomeric chelates are generated during the complex formation. The nitrobenzyl substituent can adopt either an equatorial corner or side position on the macrocyclic ring. These regioisomers are incapable of interconversion and were isolated by HPLC. The corner isomer is more stable than the side, and the SAP conformer of both regioisomers is energetically more favorable than the corresponding TSAP conformer.

Click Chemistry and Targeted Degradation: A Winning Combination for Medicinal Chemists?

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Click Chemistry and Targeted Degradation: A Winning Combination for Medicinal Chemists?

“Click chemistry” and targeted protein degradation – two flourishing trends in medicinal chemistry. May they be a winning combination? In this review, we provide the reader with selected examples offered by the combination of these two approaches trying to find a response to this question.


Abstract

Click chemistry is universally recognized as a powerful strategy for the fast and precise assembly of diverse building blocks. Targeted Protein Degradation (TPD) is a new therapeutic modality based on heterobifunctional small-molecule degraders that provides new opportunities to medicinal chemists dealing with undruggable targets and incurable diseases. Here, we highlight how very recently the TPD field and that of click chemistry have merged, opening up the possibility for fine-tuning the properties of a degrader, chemically assembled through a “click” synthesis. By reviewing concrete examples, we want to provide the reader with the insight that the application of click and bioorthogonal chemistry in the TDP field may be a winning combination.

Green synthesis and theoretical study of new 1,3,4‐oxadiazoles: Application of Cu/Fe3O4@MWCNT magnetic nanocomposites

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Green synthesis and theoretical study of new 1,3,4-oxadiazoles: Application of Cu/Fe3O4@MWCNT magnetic nanocomposites

Cu/Fe3O4@MWCNT MNCs as an effective catalyst was synthesized by using water extract of Petasits hybridus leaves and promoted producing of novel derivatives of 1,3,4-oxadiazols in high yields. These new compounds were synthesized by using multicomponent reaction of ninhydrins, diamines or hydroxyamines, ester of acetylene with electron deficient, α-haloketones, hydrazoyl chloride and synthesized nanocatalyst in aqueous media. It should be mentioned that the high performance of nanocatalyat was synthesized by using water extract of Petasits hybridus leaves, which was utilized in these reactions for many times to confirm the reusability of nanocatalyst.


Cu/Fe3O4@MWCNT magnetic nanocomposites (MNCs) as an effective catalyst was promoted producing of novel derivatives of 1,3,4-oxadiazols in high yields. These new compounds were synthesized by using multicomponent reaction of ninhydrins, diamines or hydroxyamines, ester of acetylene with electron deficient, α-haloketones, hydrazoyl chloride, and synthesized nanocatalyst in aqueous media. It should be mentioned that the high performance of nanocatalyat was synthesized by using water extract of Petasits hybridus leaves, which was utilized in these reactions for many times to confirm the reusability of nanocatalyst. The antioxidant property of new synthesized 1,3,4-oxadiazols is owing to having NH group which was evaluated by two procedures named diphenyl-picrylhydrazine (DPPH) radical trapping and Ferric ions (Fe3+) reducing potential (FRAP) experiment. Also, the antimicrobial activity of new generated 1,3,4-oxadiazols was evaluated by disk distribution process utilizing two kinds of Gram-negative bacteria and Gram-positive bacteria, proving bacterial growth was stopped by using of these compounds. This employed procedure for preparation of 1,3,4-oxadiazols derivatives conveys benefits including reaction with low time, products with high yields, and possibility of separating catalyst and products using an easy procedure.

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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