Electron-withdrawing Functionality Research Articles

Intramolecular Quaternary Carbon Nitride Homojunction for Enhanced Visible Light Hydrogen Production.

In this work, an intramolecular carbon nitride (CN)-based quaternary homojunction functionalized with pyridine rings is prepared via an in situ alkali-assisted copolymerization strategy of bulk CN and 2-aminopyridine for efficient visible light hydrogen generation. In the obtained structure, triazine-based CN (TCN), heptazine-based CN (HCN), pyridine unit incorporated TCN, and pyridine ring inserted HCN constitute a special multicomponent system and form a built-in electric field between the crystalline semiconductors by the arrangement of energy band levels. The electron-withdrawing function of the conjugated heterocycle can trigger the skeleton delocalization and edge induction effect. Highly accelerated photoelectron-hole transfer rates via multi-stepwise charge migration pathways are achieved by the synergistic effect of the functional group modification and molecular quaternary homojunction. Under the addition of 5mg 2-aminopyridine, the resulting homojunction framework exhibits a significantly improved hydrogen evolution rate of 6.64mmol g-1 h-1 with an apparent quantum efficiency of 12.27% at 420nm. Further, the catalyst verifies its potential commercial value since it can produce hydrogen from various real water environments. This study provides a reliable way for the rational design and fabrication of intramolecular multi-homojunction to obtain high-efficient photocatalytic reactions.

Synthesis of Stereodefined Polysubstituted Bicyclo[1.1.0]butanes.

We report a highly diastereoselective synthesis of polysubstituted bicyclobutanes possessing up to three stereodefined quaternary centers and five substituents. Our strategy involves a diastereoselective carbometalation of cyclopropenes followed by a cyclization to furnish the bicyclobutane ring system. This straightforward approach allows for the incorporation of a diverse range of substituents and functional groups, notably without the need for electron-withdrawing functionalities.

The Synthesis, In Vitro Bio-Evaluation, and In Silico Molecular Docking Studies of Pyrazoline-Thiazole Hybrid Analogues as Promising Anti-α-Glucosidase and Anti-Urease Agents.

In the present work, a concise library of benzothiazole-derived pyrazoline-based thiazole (1-17) was designed and synthesized by employing a multistep reaction strategy. The newly synthesized compounds were screened for their α-glucosidase and urease inhibitory activities. The scaffolds (1-17) were characterized using a combination of several spectroscopic techniques, including FT-IR, 1H-NMR, 13C-NMR, and EI-MS. The majority of the synthesized compounds demonstrated a notable potency against α-glucosidase and urease enzymes. These analogues disclosed varying degrees of α-glucosidase and urease inhibitory activities, with their IC50 values ranging from 2.50 to 17.50 μM (α-glucosidase) and 14.30 to 41.50 (urease). Compounds 6, 7, 14, and 12, with IC50 values of 2.50, 3.20, 3.40, and 3.50 μM as compared to standard acarbose (IC50 = 5.30 µM), while the same compounds showed 14.30, 19.20, 21.80, and 22.30 comparable with thiourea (IC50 = 31.40 μM), respectively, showed excellent inhibitory activity. The structure-activity relationship revealed that the size and electron-donating or electron-withdrawing effects of substituents influenced the enzymatic activities such as α-glucosidase and urease. Compound 6 was a dual potent inhibitor against α-glucosidase and urease due to the presence of -CF3 electron-withdrawing functionality on the phenyl ring. To the best of our knowledge, these synthetic compounds were found to be the most potent dual inhibitors of α-glucosidase and urease with minimum IC50 values. Moreover, in silico studies on most active compounds, i.e., 6, 7, 14, and 12, were also performed to understand the binding interaction of most active compounds with active sites of α-glucosidase and urease enzymes.

Exploring the Co-Crystallization Landscape of One-Dimensional Coordination Polymers Using a Molecular Electrostatic Potential-Driven Approach.

The ability of coordination polymers (CPs) to form multicomponent heteromeric materials, where the key structural features of the parent CP are retained, has been explored via molecular electrostatic potential-driven co-crystallization technologies. Thirteen co-formers presenting hydrogen-bond donors activated through a variety of electron-withdrawing functionalities were employed, and the extent of activation was evaluated using molecular electrostatic potential values. Attempted co-crystallizations of the seven most promising co-formers with a family of nine CPs ([CdX'2(X-pz)2]n; X' = I, Br, and Cl; X = I, Br, and Cl) resulted in six successful outcomes; all four of the structurally characterized compounds displayed the intended hydrogen bond. The rationalization of the main structural features revealed that strict structural and electrostatic requirements were imposed on effective co-formers; only co-formers with highly activated hydrogen-bond donors, and with a 1,4-orientation of electron-withdrawing moieties bearing effective acceptor sites, were successfully implemented into the three-dimensional architectures composed of one-dimensional building units of CPs.

Exceptionally stable CePO4 and RuO2 contributing to catalytic oxidation of 1,2-dichloroethane on Co3O4 catalysts: Complete inhibition of chlorinated byproducts

Highly toxic, reactive and refractory chlorinated VOCs (Cl-VOCs) is urgent for purification by the most favoured catalytic oxidation technique, however, the formation of polychlorinated byproducts is huge obstacle for most catalysts. Here, nanorods assembled monoclinic CePO4 microspheres were synthesized and used as the support of highly active but low-selective Co3O4 for catalytic oxidation of Cl-VOCs. The prepared Co3O4/CePO4 using ascorbic acid (AA) as a chelating agent presented a high activity and low selectivity of vinyl chloride (VC) for catalytic oxidation of 1,2-dichloroethane (DCE) due to the high dispersion of Co3O4, compared with bulk Co3O4 and Co3O4/SiO2, possible polychlorinated byproducts were completely inhibited in the presence of CePO4 support. The co-introduction of RuO2 further suppressed the formation of VC as a representative dechlorinated byproduct owing to the enhanced redox ability and migration of surface lattice oxygen, below 0.5% VC selectivity was detected on the optimized RuCoOx/CePO4 and completely disappeared above 275 °C. Moreover, RuCoOx/CePO4 also revealed the superior versatility, durability and thermal stability as well as the outstanding resistance to CO2, H2O and sulfur. The restraint of polychlorinated byproducts also can be achieved by other phosphates besides CePO4 and attributed to the strong coordination effect and electron-withdrawing function of PO43-. This work was contributed to further understand the inhibition of chlorinated byproducts for catalytic oxidation of Cl-VOCs and rationally design full-featured catalysts.

Nucleophilic Aromatic Substitution of Pentafluorophenyl-Substituted Quinoline with a Functional Perylene: A Route to the Modification of Semiconducting Polymers.

A systematic study of the influence of the chemical substitution pattern of semiconducting polymers carrying side chain perylene diimide (PDI) groups is presented. Semiconducting polymers based on perflurophenyl quinoline (5FQ) were modified via a readily accessible nucleophilic substitution reaction. The perfluorophenyl group was studied as an electron-withdrawing reactive functionality on semiconducting polymers that can undergo fast nucleophilic aromatic substitution. A PDI molecule, functionalized with one phenol group on the bay area, was used for the substitution of the fluorine atom at the para position in 6-vinylphenyl-(2-perfluorophenyl)-4-phenyl quinoline. The final product was polymerized under free radical polymerization providing polymers of 5FQ incorporated with PDI side groups. Alternatively, the post-polymerization modification of the fluorine atoms at the para position of the 5FQ homopolymer with the PhOH-di-EH-PDI was also successfully tested. In this case, the PDI units were partially introduced to the perflurophenyl quinoline moieties of the homopolymer. The para-fluoro aromatic nucleophilic substitution reaction was confirmed and estimated via 1H and 19F NMR spectroscopies. The two different polymer architectures, namely, fully or partially modified with PDI units, were studied in terms of their optical and electrochemical properties, while their morphology was evaluated using TEM analysis, revealing polymers of tailor-made optoelectronic and morphological properties. This work provides a novel molecule-designing method for semiconducting materials of controlled properties.

Design, Synthesis, and Anticancer Activity of Novel 3,6-Diunsaturated 2,5-Diketopiperazines.

Based on the marine natural products piperafizine B, XR334, and our previously reported compound 4m, fourteen novel 3,6-diunsaturated 2,5-diketopiperazine (2,5-DKP) derivatives (1, 2, 4-6, 8-16), together with two known ones (3 and 7), were designed and synthesized as anticancer agents against the A549 and Hela cell lines. The MTT assay results showed that the derivatives 6, 8-12, and 14 had moderate to good anticancer capacities, with IC50 values ranging from 0.7 to 8.9 μM. Among them, compound 11, with naphthalen-1-ylmethylene and 2-methoxybenzylidene functions at the 3 and 6 positions of 2,5-DKP ring, respectively, displayed good inhibitory activities toward both A549 (IC50 = 1.2 μM) and Hela (IC50 = 0.7 μM) cancer cells. It could also induce apoptosis and obviously block cell cycle progression in the G2/M phases in both cells at 1.0 μM. The electron-withdrawing functions might not be favorable for the derivatives with high anticancer activities. Additionally, compared to piperafizine B and XR334, these semi-N-alkylated derivatives have high liposolubilities (>1.0 mg mL-1). Compound 11 can be further developed, aiming at the discovery of a novel anticancer candidate.

Martin Silicates as Partners in Photoredox/Ni Dual Catalysis for the Installation of CH3, CH2D, CD2H, CD3and13CH3Groups onto (Hetero)Arenes

Martin Silicates as Partners in Photoredox/Ni Dual Catalysis for the Installation of CH₃, CH₂D, CD₂H, CD₃and¹³CH₃Groups onto (Hetero)Arenes

Solvent-induced MultiStimuli-Responsive properties of cyano-substituted Oligo(p-phenylene vinylene) derivatives

Stimuli-responsive luminescent materials with controllable photophysical properties have attracted much attention because of their potential applications in smart materials and devices. Through the incorporation of electron-donating (NPh3) and electron-withdrawing (CN) functionalities, two donor-acceptor luminophores C4OPV-TPA and C8OPV-TPA bearing two different alkyl chain lengths were prepared and fully characterized. Although both C4OPV-TPA and C8OPV-TPA exhibited similar luminescence and AIEE effects in solution with intramolecular charge-transfer (ICT) transition, remarkable differences were observed in the self-assemble state. Specifically, precipitation of C4OPV-TPA into toluene and CH2Cl2, respectively, afforded two distinctly crystallines, with one in orange color (O-state) and the other in red color (R-state). Notably, C4OPV-TPA in O-state exhibited stimuli-responsive behaviors in solid state, which were ascribed to the formation of an inclusion complex with toluene molecules. Under thermal heating and mechanical grinding, toluene was released from crystal lattice of luminophore accompanied with red-shifted emission spectra. The molecular packing of C4OPV-TPA in R-state, on the other hand, adopted stronger H-aggregates without inclusion of CH2Cl2 molecules, which was further investigated by X-ray diffraction. These excellent optical properties enabled C4OPV-TPA serve as a fluorescent ink for thermal-responsive data storage device.

Modular preparation of cationic bipyridines and azaarenes via C-H activation.

Bipyridines are ubiquitous in organic and inorganic chemistry because of their redox and photochemical properties and their utility as ligands to transition metals. Cationic substituents on bipyridines and azaarenes are valuable as powerful electron-withdrawing functionalities that also enhance solubility in polar solvents, but there are no general methods for direct functionalization. A versatile method for the preparation of trimethylammonium- and triarylphosphonium-substituted bipyridines and azaheterocycles is disclosed. This methodology showcases a C-H activation of pyridine N-oxides that enables a highly modular and scalable synthesis of a diverse array of cationically charged azaarenes. The addition of trimethylammonium functionalities on bipyridine derivatives resulted in more anodic reduction potentials (up to 700 mV) and increased electrochemical reversibility compared to the neutral unfunctionalized bipyridine. Additonally, metallation of 4-triphenylphosphinated biquinoline to make the corresponding Re(CO)3Cl complex resulted in reduction potentials 400 mV more anodic than the neutral derivative.

Synergistic effect triggered by skeleton delocalization and edge induction of carbon nitride expedites photocatalytic hydrogen evolution

The multi-part functionalization of the carbon nitride (CN) molecular skeleton usually induces synergies to boost the photocatalytic activity, but it is a challenging undertaking owing to the uncontrollability in preparation process. Herein, the dual embellished CN is achieved by substituting bridged N with C atoms and grafting conjugated heterocycle on the skeleton edge through facile one-step thermal polymerization. The synergistic effect of skeleton delocalization and edge induction is triggered by the delocalized π bonds from incorporated C atoms and electron-withdrawing function of conjugated heterocycle, which importantly promotes the charge mobility and electron directional migration from center to edge of CN skeleton. The resulted photocatalytic hydrogen evolution (PHE) performance is propelled dramatically and the apparent quantum efficiency (AQE) reaches up to 22.4% at 420 nm. This work launches a typical exemplification for the high-efficiency photocatalytic application of conjugated polymer photocatalysts by triggering synergistic effect of multi-part functionalization.

PO4 3- Coordinated Robust Single-Atom Platinum Catalyst for Selective Polyol Oxidation.

Achieving efficient catalytic conversion over a heterogeneous catalyst with excellent resistance against leaching is still a grand challenge for sustainable chemical synthesis in aqueous solution. Herein, we devised a single-atom Pt1 /hydroxyapatite (HAP) catalyst via a simple hydrothermal strategy. Gratifyingly, this robust Pt1 /HAP catalyst exhibits remarkable catalytic selectivity and catalyst stability for the selective oxidation of C2 -C4 polyols to corresponding primary hydroxy acids. It is found that the Pt-(O-P) linkages with strong electron-withdrawing function of PO4 3- (Pt1 -OPO4 3- pair active site) not only realize the activation of the C-H bond, but also destabilize the transition state from adsorbed hydroxy acids toward the C-C cleavage, resulting in the sharply increased selectivity of hydroxy acids. Moreover, the strong PO4 3- -coordination effect provides electrostatic stabilization for single-atom Pt, ensuring the highly efficient catalysis of Pt1 /HAP for over 160 hours with superior leaching resistance.

Synthesis and Evaluation of 1,3,5-Triaryl-2-Pyrazoline Derivatives as Potent Dual Inhibitors of Urease and α-Glucosidase Together with Their Cytotoxic, Molecular Modeling and Drug-Likeness Studies.

In the present work, a concise library of 1,3,5-triaryl-2-pyrazolines (2a–2q) was designed and synthesized by employing a multistep strategy, and the newly synthesized compounds were screened for their urease and α-glucosidase inhibitory activities. The compounds (2a–2q) were characterized using a combination of several spectroscopic techniques including FT-IR, 1H NMR, 13C NMR, and EI-MS. All the synthesized compounds, except compound 2i, were potent against urease as compared to the standard inhibitor thiourea (IC50 = 21.37 ± 0.26 μM). These analogs disclosed varying degrees of urease inhibitory activities ranging from 9.13 ± 0.25 to 18.42 ± 0.42 μM. Compounds 2b, 2g, 2m, and 2q having IC50 values of 9.36 ± 0.27, 9.13 ± 0.25, 9.18 ± 0.35, and 9.35 ± 0.35 μM, respectively, showed excellent inhibitory activity as compared to standard thiourea (IC50 = 21.37 ± 0.26 μM). A kinetic study of compound 2g revealed that compound 2g inhibited urease in a competitive mode. Among the synthesized pyrazolines, the compounds 2c, 2k, 2m, and 2o exhibited excellent α-glucosidase inhibitory activity with the lowest IC50 values of 212.52 ± 1.31, 237.26 ± 1.28, 138.35 ± 1.32, and 114.57 ± 1.35 μM, respectively, as compared to the standard acarbose (IC50 = 375.82 ± 1.76 μM). The compounds (2a–2q) showed α-glucosidase IC50 values in the range of 114.57 ± 1.35 to 462.94 ± 1.23 μM. Structure–activity relationship revealed that the size and electron-donating or -withdrawing effects of substituents influenced the activities, which led to the urease and α-glucosidase inhibiting properties. Compound 2m was a dual potent inhibitor against urease and α-glucosidase due to the presence of 2-CF3 electron-withdrawing functionality on the phenyl ring. To the best of our knowledge, these synthetic compounds were found to be the most potent dual inhibitors of urease and α-glucosidase with minimum IC50 values. The cytotoxicity of the compounds (2a–2q) was also investigated against human cell lines MCF-7 and HeLa. Compound 2l showed moderate cytotoxic activity against MCF-7 and HeLa cell lines. Moreover, in silico studies on most active compounds were also performed to understand the binding interaction of most active compounds with active sites of urease and α-glucosidase enzymes. Some compounds exhibited drug-like characteristics due to their lower cytotoxic and good ADME profiles.

Design and Antioxidant Properties of Bifunctional 2H-Imidazole-Derived Phenolic Compounds-A New Family of Effective Inhibitors for Oxidative Stress-Associated Destructive Processes.

The synthesis of inhibitors for oxidative stress-associated destructive processes based on 2H-imidazole-derived phenolic compounds affording the bifunctional 2H-imidazole-derived phenolic compounds in good-to-excellent yields was reported. In particular, a series of bifunctional organic molecules of the 5-aryl-2H-imidazole family of various architectures bearing both electron-donating and electron-withdrawing substituents in the aryl fragment along with the different arrangements of the hydroxy groups in the polyphenol moiety, namely derivatives of phloroglucinol, pyrogallol, hydroxyquinol, including previously unknown water-soluble molecules, were studied. The structural and antioxidant properties of these bifunctional 5-aryl-2H-imidazoles were comprehensively studied. The redox transformations of the synthesized compounds were carried out. The integrated approach based on single and mixed mechanisms of antioxidant action, namely the AOC, ARC, Folin, and DPPH assays, were applied to estimate antioxidant activities. The relationship “structure-antioxidant properties” was established for each of the antioxidant action mechanisms. The conjugation effect was shown to result in a decrease in the mobility of the hydrogen atom, thus complicating the process of electron transfer in nearly all cases. On the contrary, the conjugation in imidazolyl substituted phloroglucinols was found to enhance their activity through the hydrogen transfer mechanism. Imidazole-derived polyphenolic compounds bearing the most electron-withdrawing functionality, namely the nitro group, were established to possess the higher values for both antioxidant and antiradical capacities. It was demonstrated that in the case of phloroglucinol derivatives, the conjugation effect resulted in a significant increase in the antiradical capacity (ARC) for a whole family of the considered 2H-imidazole-derived phenolic compounds in comparison with the corresponding unsubstituted phenols. Particularly, conjugation of the polyphenolic subunit with 2,2-dimethyl-5-(4-nitrophenyl)-2H-imidazol-4-yl fragment was shown to increase ARC from 2.26 to 5.16 (104 mol-eq/L). This means that the considered family of compounds is capable of exhibiting an antioxidant activity via transferring a hydrogen atom, exceeding the activity of known natural polyphenolic compounds.

Sulfonic Acid Functionalized Magnetic Starch as an Efficient Catalyst for the Synthesis of Chromeno[4,3‐b]quinoline‐6,8(9H)‐dione Derivatives

AbstractIn this paper, sulfonic acid functionalize magnetic starch (denoted Starch/SPION@SO3H) is fabricated by the polymerization of 4‐styrenesulfonic acid on the surface of magnetic starch. Magnetic starch (Starch/SPION) is synthesized by covalent modification of starch by silica capsulate superparamagnetic iron oxide nanoparticles (SPION). For this purpose, Starch/SPION is modified by allyltrimethoxysilane, follows by the polymerization of 4‐styrenesulfonic acid onto this material. The catalyst is characterized by various characterization techniques, including transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), vibrating‐sample magnetometer (VSM), X‐ray photoelectron spectroscopy (XPS), and acid/base titration. The characterizations prove the structure of Starch/SPION@SO3H catalyst. The catalytic activity of Starch/SPION@SO3H is evaluated in the multicomponent reaction of 4‐hydroxycoumarin, benzaldehydes, dimedone, and ammonium acetate for the synthesis of chromeno[4,3‐b]quinoline‐6,8(9H)‐dione derivatives. The catalyst shows very good activity in the synthesis of chromeno[4,3‐b]quinoline‐6,8(9H)‐dione derivatives. Several benzaldehydes with electron donating or electron withdrawing functionalities are used as starting material and all the substrates give the desired products in high isolated yields. In addition, the catalyst is extremely reusable during 10 sequential runs. Characterization of Starch/SPION@SO3H catalyst by TEM, VSM, and acid/base titration after recovery from the reaction proves the stability of the catalyst in the reaction conditions.

A Concise Synthesis of a Methyl Ester 2-Resorcinarene: A Chair-Conformation Macrocycle

Anions are important hydrogen bond acceptors in a range of biological, chemical, environmental and medical molecular recognition processes. These interactions have been exploited for the design and synthesis of ditopic resorcinarenes as the hydrogen bond strength can be tuned through the modification of the substituent at the 2-position. However, many potentially useful compounds, especially those incorporating electron-withdrawing functionalities, have not been prepared due to the challenge of their synthesis: their incorporation slows resorcinarene formation that is accessed by electrophilic aromatic substitution. As part of our broader campaign to employ resorcinarenes as selective recognition elements, we need access to these specialized materials. In this article, we report a straightforward synthetic pathway for obtaining a 2-(carboxymethyl)-resorcinarene, and resorcinarene esters in general. We discuss the unusual conformation it adopts and propose that this arises from the electron-withdrawing nature of the ester substituents that renders them better hydrogen bond acceptors than the phenols, ensuring that each of them acts as a donor only. Density Functional Theory (DFT) calculations show that this conformation arises as a consequence of the unusual configurational isomerism of this compound and interruption of the archetypal hydrogen bonding by the ester functionality.

Radical Chain Breaking Bis(ortho-organoselenium) Substituted Phenolic Antioxidants.

The presence of a chalcogen atom at the ortho-position of phenols enhances their radical chain-breaking activity. Here, a copper(I)-catalyzed reaction of 2,6-dibromo- and 2,6-diiodophenols with diorganodiselenides has been studied for the introduction of two organoselenium substituents at both ortho-positions of the phenolic radical chain-breaking antioxidants, which afforded 2,6-diorganoseleno-substituted phenols in 80-92% yields having electron-donating CH3 , and electron-withdrawing CN and CHO functionalities. Additionally, 2,6-diiodophenols with electron-withdrawing CHO and CN groups also afforded novel 5,5'-selenobis(4-hydroxy-3-(phenylselanyl)benzaldehyde) and 5,5'-selenobis(4-hydroxy-3-(phenylselanyl)benzonitrile) consisting of three selenium and two phenolic moieties along with 2,6-diorganoseleno-substituted phenols has been synthesized. The electron-withdrawing CHO group has been reduced by sodium borohydride to the electron-donating alcohol CH2 OH group, which is desirable for efficient radical quenching activity of phenols. The developed copper-catalyzed reaction conditions enable the installation of two-arylselenium group ortho to phenolic radical chain-breaking antioxidants, which may not be possible by conventional organolithium-bromine exchange methods due to the sluggish reactivity of trianions (dicarba and phenoxide anion), which are generated by the reaction of organolithium with 2,6-dibromophenols, with diorganodiselenides. The antioxidant activities of the synthesized bis and tris selenophenols have been accessed by DPPH, thiol peroxides, and singlet oxygen quenching assay. The radical quenching antioxidant activity has been studied for the synthesized compounds by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The bis-selenophenols show comparable radical deactivating activity, while tris seleno-bisphenols show higher radical deactivating activity than α-tocopherol. Furthermore, the tris seleno-bisphenol shows comparable peroxide decomposing activity with ebselen molecules.

Isatin-derived non-fullerene acceptors for efficient organic solar cells

Geometries optimization, electronic structure, electronic absorption spectra, charge transport rate, morphology, and photovoltaic properties of indacenodithiophene as donor core unit tie with isatin derive different end-capped electron acceptor groups have been performed using Density Functional Theory (DFT) and time dependent density functional theory (TD-DFT). Isatin unit connected with 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile in M1, 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile in M2, 2-thioxothiazolidin-4-one in M3, 2-(4-fluorothiophen-2-yl)acetonitrile in M4 and geometries, opto-electronic properties have been computed at TD-DFT MPW1PW91/6-31G level of theory and compared with reference molecule R. Among all novel structures, M2 has lowest value of energy band gap (1.99 eV) and has maximum absorption (λmax = 824.0 nm) in chloroform by TD-MPW1PW91/6-31G (d,p) using IEFPCM model. The red shift in M2 was due presence of strong electron withdrawing acceptor moiety and more extended conjugation as compared to other structures. Indeed, electron withdrawing functionality i.e fluorine and cyno moieties in M2 structure stabilized its LUMO orbital and hence improved its opto-electronic properties. Transition density matrix (TDM) maps results revealed obvious influence of end-capped acceptor group on the exciton. M2 has lower probability of coupling of electron and hole owing easy exciton dissociation as compared to other designed molecules. Theoretically calculated reorganization energy indicates that M1 has the highest hole transfer rate due to the lowest value of λh (0.0068 eV). Similarly, M4 has the highest electron mobility due to lowest value of λe (0.0053 eV). In short, choice of appropriate electron withdrawing end capped acceptor groups is very important for improving the performance of organic solar cells.

Strategies to Mitigate the Bioactivation of Aryl Amines.

The bioactivation of xenobiotics to yield reactive metabolites can lead to tolerability and toxicity concerns within a drug discovery program. Development of strategies for mitigating the metabolic liability of commonly encountered toxicophores, such as anilines, relies on an understanding of the relative tendency of these functionalities to undergo bioactivation. In this report, we present the first systematic study of the structure-activity relationships of the bioactivation of aryl amine fragments (molecular weight < 250 Da) using a glutathione (GSH) trapping assay in the presence of human liver microsomes and the reduced form of nicotinamide adenine dinucleotide phosphate. This study demonstrates that conversion of anilines to nitrogen-containing heteroarylamines results in a lower abundance of GSH conjugates in the order phenyl > pyrimidine ≈ pyridine > pyridazine. Introduction of electron-withdrawing functionality on the aromatic ring had a less pronounced effect on the extent of GSH conjugation. Examination of more drug-like compounds sourced from in-house drug discovery programs revealed similar trends in bioactivation between matched pairs containing (hetero)aryl amines. This study provides medicinal chemists with insights and qualitative guidance for the minimization of risks related to aryl amine metabolism.

Catalytic Hydrocyanation of Activated Terminal Alkynes.

A universal, practical and scalable organocatalytic hydrocyanation manifold to provide β-substituted acrylonitriles bearing an electron-withdrawing functionality has been implemented. The catalytic manifold operates under the reactivity generation principle "a good nucleophile generates a strong base", and it uses 1,4-diazabicyclo[2.2.2]octane (DABCO) as the catalyst, activated terminal alkynes as substrates and acetone cyanohydrin as the cyanide source. The acrylonitriles obtained as E,Z mixtures are straightforwardly resolved by simple flash chromatography delivering the pure isomers in preparative amounts.