Cu(II)/PTABS-Promoted, Chemoselective Amination of HaloPyrimidines.

Chemoselective amination is a highly desired synthetic methodology, given its importance as a possible strategy to synthesize various drug molecules and agrochemicals. We, herein, disclose a highly chemoselective Cu(II)-PTABS-promoted amination of pyrimidine structural feature containing different halogen atoms.

Phenothiazine-Based Cu(II)-Selective Fluorescent Sensor: GHK-Cu Sensing Applications.

Sensing important metals in different environments is an important area and involves the development of a wide variety of metal-sensing materials. The employment of fluorescent sensors in metal sensing has been one of the most widely applied methodologies, and the identification of selective metal sensors is important. We herein report a phenothiazine-based Cu(II) fluorescent sensor that is highly selective to Cu(II) ions compared with other transition metal salts. The Lewis acidity of the Cu(II) salt certainly was found to be a factor for obtaining an enhanced sensing response in MeOH as the solvent, while a ratio of 1:1 was calculated to be the most optimum for getting the desired response.

Cu(II)/PTABS-Promoted, Regioselective SNAr Amination of Polychlorinated Pyrimidines with Mechanistic Understanding.

Regioselective amination of polyhalogenated heteroarenes (especially pyrimidines) has extensive synthetic and commercial relevance for drug synthesis applications but is plagued by the lack of effective synthetic strategies. Herein, we report the Cu(II)/PTABS-promoted highly regioselective nucleophilic aromatic substitution (SNAr) of polychlorinated pyrimidines assisted by DFT predictions of the bond dissociation energies of different C-Cl bonds. The unique reactivity of Cu(II)-PTABS has been attributed to the coordination/activation mechanism that has been known to operate in these reactions, but further insights into the catalytic species have also been provided.

Computational Study on the Effect of Thienyl π-Donor on the Optical Response of Nonclassical Oligo-Pyrazinothienothiadiazole Biradicaloids.

Computational analyses were performed on nitrogen-rich oligothiadizolothiophenes TTn (n = 0-3) and their four π-donor-substituted derivatives Th-TTn (n = 0-3) to examine the optical response due to geometrical and electronic structural attributes in the longitudinal and transverse axes, respectively. Our results are understood in the context of greater conjugation in the longitudinal axis (via additional fused rings) and substitution of a thienyl π-donor in the transverse axis of the geometry of each derivative. On inspection of the frontier molecular orbitals, we found that the better electron-accepting ability with minimal sacrifice in the ionization potentials results from geometrical aspects in both longitudinal and transverse axes. Due to the narrowed highest occupied molecular orbital-lowest unoccupied molecular orbital gaps, all of the derivatives exhibit a biradicaloid character (BRC) and one-photon panchromatic absorption; however, the open-shell nature weakened the charge transfer characteristics of excitation. In both the series, the odd electron density distributions and electron localization plots amply demonstrate the weakening of ylide character in fused thiophene rings and clearly indicate to the emergence of a long-bond/single BRC in the sulfurdimithide moiety in both series. In addition, the estimated tensor components of the second hyperpolarizability as well as overall responses confirm the shift from the longitudinal to transverse axis following the substitution with the π-donor. Interestingly, the TPA cross sections show comparable behavior, but contrary to γ, π-donor thienyl substitution appears to be discouraging in getting higher TPA responses for higher homologous series. Therefore, this study opens a new conjecture on tuning better nonlinear optical properties of organic functional materials.

A computational probe granting insight into intra and inter-stacking interactions in squaraine dye derivatives.

In order to decipher structure function relationships regarding the optoelectronic properties of organic functional materials, two sets of anilinosquaraine dye derivatives were analysed computationally. 2,4-Bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl]squaraine exhibits orthorhombic and monoclinic polymorphs (motif-1 and motif-2) in bulk and spin coated films, respectively, and concomitant J- and H-aggregate spectral features. In the second set, in spite of variation in the n-alkyl chain of the anilinosquaraine derivatives (n-propyl vs. n-butyl; motif-3 and motif-4), both acquired triclinic morphology and intermolecular charge transfer had been identified as the origin of their panchromaticity. The differences between these motifs were closely inspected at the theoretical level including geometrical parameters, internal reorganization energies, charge transfer integrals, drift mobilities, interaction energies and lattice energies along with a comprehensive Hirshfeld surface analysis. A correlation was established between C⋯C type intra-stack interactions with the observed red-shifted absorption patterns in the order motif-1 > motif-3 > motif-4. Hydrophobic interactions, π-π interactions and hydrogen bonds were found to influence the crystal packing patterns and concomitantly the overall molecule planarity and thereby the extent of π-bond delocalization/resonance. Insights into intra-stack and inter-stack interactions based on crystal packing effects are provided, which support and potentially guide the experimentalists' key ideas for shaping and encompassing the applications of promising squaraine derivative materials.

Correction: A computational probe granting insight into intra and inter-stacking interactions in squaraine dye derivatives.

Correction for 'A computational probe granting insight into intra and inter-stacking interactions in squaraine dye derivatives' by Krishna Chaitanya Gunturu et al., Phys. Chem. Chem. Phys., 2021, DOI: .

Pd/PTABS: Low-Temperature Thioetherification of Chloro(hetero)arenes.

The thioetherification of heteroaryl chlorides is an essential synthetic methodology that provides access to bioactive drugs and agrochemicals. Due to their (actual or potential) industrial importance, the development of efficient and low-temperature protocols for accessing these compounds is a requirement for economic and ecologic reasons. A particular highly effective catalytic protocol using the Pd/PTABS system at only 50 °C was developed accordingly. The coupling between chloroheteroarenes and a variety of less reactive arylthiols and alkylthiols was carried out with a high efficiency. Heteroarenes of commercial relevance such as purines and pyrimidines were also found to be useful substrates for the reported transformation. The commercial drug Imuran (azathioprine) was synthesized as an example, and its preparation could be optimized. DFT studies were performed to understand the electronic effects of the tested ligands on the catalytic reaction.

Synthesis, DFT analysis and in-vitro anti-cancer study of novel fused bicyclic pyranone isoxazoline derivatives of Goniodiol-diacetate-a natural product derivative.

Natural products, natural product-inspired molecules and natural product derivatives have contributed around 79% to the new chemotherapies against the most complex, deadly disease, cancer. In this study, a series of novel isoxazoline derivatives of Goniodiol diacetate (fused bicyclic pyranone isoxazoline derivatives)- a natural product derivative, were synthesized with quantitative yield as a single regioisomer by 1,3 - dipolar cycloaddition reaction with different aldoximes. The regiospecific product formed was confirmed by NOESY study and single-crystal X-ray diffraction. The regiospecificity of the product formation was further explained by coefficients of selected atomic orbitals in frontier molecular orbitals and natural population analysis (NPA in eV) of dipolarophile and dipole by density functional theory studies. All the derivatives have demonstrated anti-cancer activity selectively in human breast cancer (MDA-MB-231), ovarian cancer (SKOV3), prostate cancer (PC-3) and colon cancer (HCT-15) cell lines with EC50 < 10 µM. Additionally, Annexin V/PI assay and cell cycle analysis on selected potent compound 3 f exhibited tuned apoptotic response & necrosis compared to standard Vincristine and showed cell growth arrest at the S phase.

Recasting Ni-foam into NiF2 nanorod arrays via a hydrothermal process for hydrogen evolution reaction application.

A promising electrode for hydrogen evolution reaction (HER) has been prepared via a reduction process to form NiF2 nanorod arrays directly grown on a 3D nickel foam. We reveal NiF2@Ni nanorod arrays for a stable hydrogen evolution reaction (HER) application. The computational analysis for H2O, OH and H and experimentally in aqueous KOH endow considerable shift in Fermi levels for Ni (111) unlike for NiF2 (110) on account of an effective coalition of p-orbitals of fluorine and d-orbitals of Ni in NiF2, NiF2 under pinning the reduced overpotential of 172 mV at 10 mA cm-2 compared to Ni (242 mV) in same electrolyte. The electrocatalytic mechanism has been proposed using density functional theory (DFT) and is found in well accordance with the experimental findings of the present study. The preparation of self-grown porous nanostructured electrodes on the 3D nickel foam via a displacement reaction is possibly valuable for other metal halides for energy storage and conversion applications as these materials have inherently smaller overpotentials.

NiF2 Nanorod Arrays for Supercapattery Applications.

A electrode for energy storage cells is possible directly on Ni foam, using a simple reduction process to form NiF2 nanorod arrays (NA). We demonstrate NiF2@Ni NA for a symmetric electrochemical supercapattery electrode. With an areal specific capacitance of 51 F cm-2 at 0.25 mA cm-2 current density and 94% cycling stability, a NiF2@Ni electrode can exhibit supercapattery behavior, a combination of supercapacitor and battery-like redox. The symmetric electrochemical supercapattery delivers 31 W h m-2 energy density and 797 W m-2 power density with 83% retention in a 1 M KOH electrolyte, constituting a step toward manufacturing a laboratory-scale energy storage device based on metal halides. Producing self-grown hierarchically porous nanostructured electrodes on three-dimensional metal foams by displacement reactions may be useful for other metal halides as electrodes for supercapacitors, supercapatteries, and lithium-ion batteries.

Metal-free heterogeneous and mesoporous biogenic graphene-oxide nanoparticle-catalyzed synthesis of bioactive benzylpyrazolyl coumarin derivatives.

We report the preparation of graphene oxide nanoparticles (GONPs), a metal-free, heterogeneous, non-toxic, reusable and mesoporous green-(acid)-catalyst obtained by sugar carbonization through a micro-wave chemical synthesis method for the synthesis of bio-active benzylpyrazolyl coumarin derivatives (BCDs) under thermal conditions (50 °C) in ethanol solvent. The obtained products were purified by re-crystallization from ethanol, assuring usability of GONPs in multicomponent reactions (MCRs) that could find wide application in the synthesis of a variety of biologically potent molecules of therapeutic significance.

Palladacycle-Catalyzed Triple Suzuki Coupling Strategy for the Synthesis of Anthracene-Based OLED Emitters.

The development of the site-selective Suzuki-Miyaura cross-coupling of dibromoanthracene as an efficient strategy toward organic light emitting diodes (OLEDs) is disclosed in this article. An unprecedented step-economic palladacycle-promoted triple Suzuki coupling protocol allowed the synthesis of three new OLED emitters and could prove to be a useful general strategy for researchers working in this field. Characterization of the synthesized molecules by UV-vis spectroscopy and thermogravimetric analysis-differential scanning calorimetry followed by density functional theory studies of the different properties strongly confirms the derivatives possess more significant hole mobility character than electron transfer capability.

Natural Carbonized Sugar as a Low-Temperature Ammonia Sensor Material: Experimental, Theoretical, and Computational Studies.

Carbonized sugar (CS) has been synthesized via microwave-assisted carbonization of market-quality tabletop sugar bearing in mind the advantages of this synthesis method, such as being useful, cost-effective, and eco-friendly. The as-prepared CS has been characterized for its morphology, phase purity, type of porosity, pore-size distribution, and so on. The gas-sensing properties of CS for various oxidizing and reducing gases are demonstrated at ambient temperature, where we observe good selectivity toward liquid ammonia among other gases. The highest ammonia response (50%) of a CS-based sensor was noted at 80 °C for 100 ppm concentration. The response and recovery times of the CS sensor are 180 and 216 s, respectively. This unveiling ammonia-sensing study is explored through a plausible theoretical mechanism, which is further well-supported by computational modeling performed using density function theory. The effect of relative humidity on the CS sensor has also been studied at ambient temperature, which demonstrated that the minimum and maximum (20-100%) relative humidity values revealed 16 and 62% response, respectively.