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Employing naturally extracted dyes and their derivatives as photosensitizers towards the construction of dye-sensitized solar cells (DSSCs) has been recently emerging for establishing sustainable energy conversion devices. In this present work, Rhodobacter Sphaeroides Photobacteria (Rh. Sphaeroides) was used as a natural source from which Bacteriopheophytine-a (Bhcl) dye was extracted. Further, two cationic derivatives of Bhcl, viz., Guanidino-bacteriopheophorbide-a (Gua-Bhcl) and (2-aminoethyl)triphenylphosphono-bacteriopheophorbide-a (2AETPPh-Bhcl) were synthesized. The thus obtained Bhcl, Gua-Bhcl and 2AETPPh-Bhcl were characterized using liquid chromatography–mass spectrometry (LC–MS) and their photophysical properties were investigated using excitation and emission studies. All three near-infrared (NIR) responsive dyes were employed as natural sensitizers towards the construction of DSSC devices, using platinum as a photocathode, dye-sensitized P25-TiO2 as a photoanode and I−/I3− as an electrolyte. DSSCs fabricated using all three dyes have shown reasonably good photovoltaic performance, among which 2AETPPh-Bhcl dye has shown a relatively higher power conversion efficiency (η) of 0.38% with a short circuit photocurrent density (JSC) of 1.03 mA cm−2. This could be attributed to the dye's natural optimal light absorption in the visible and NIR region and uniform dispersion through the electrostatic interaction of the cationic derivatives on the TiO2 photoanode. Furthermore, the atomic force microscopy studies and electrochemical investigations using cyclic voltammetry, electrochemical impedance spectroscopy and Bode's plot also supported the enhancement in performance attained with 2AETPPh-Bhcl dye. [ABSTRACT FROM AUTHOR]

• Novel biologically active N -tosylated benzimidazole was prepared in good yield. • Structural elucidation was done by NMR and single crystal X-ray diffraction analysis. • Compound was determined by computational study. • Compound displayed significant antioxidant and TB activities. • A docking simulation was performed for the synthesized compound. Synthesis of 2-(diethoxymethyl)-1-tosyl-1H-benzo[ d ]imidazole 5 in excellent yield was achieved from 2-(1-ethoxypropyl)-1H-benzo[ d ]imidazole by ionic liquid supported eco-friendly green protocol. The precursor, 2-(diethoxymethyl)-1H-benzo[ d ]imidazole was prepared from o -phenylenediamine in good yield. The compound 5 was characterized by 1H, 13C and mass spectroscopic analyses. Also, its structure was further confirmed by X-ray single crystal analysis. From Hirshfeld calculations, it was clear that the H...H (51.1 %), H...C (21.6 %), O...H (18.9 %) and N...H (6.3 %) interactions were the most dominant in the solid-state structure of compound 5. The crystal stability was controlled by the short distance of O3...H7 (2.556 Å), N2...H6 (2.555 Å) and H11C...H11C (1.964 Å). Natural bond orbital (NBO) calculations were used to calculate the different intramolecular charge transfer interactions in the synthesized benzimidazole molecule 5. In addition, the DFT calculations were used to predict its electronic and reactivity descriptors. Furthermore, the synthesized compound was examined for its antioxidant properties and it was found that the compound 5 exhibited potent antioxidant activity (IC 50 value of 42.32 µM) when compared to the standard drug butylated hydroxyanisole (BHA) (IC 50 value of 58.6 µM). In addition, the compound 5 showed significant tuberculosis activity (3.12 µg/mL) against Mycobacterium tuberculosis H37Rv when compared to the standard drug, ethambutol (1.56 µg/mL). The docking simulation was also performed for compound 5 which correlated well with the in vitro findings. [ABSTRACT FROM AUTHOR]

• Synthesis of new class of dispiropyrrolidine grafted indole heterocycle. • Compound was achieved in excellent yield employing cycloaddition strategy. • Compound unambiguously assigned by spectroscopic and XRD analysis. • Structural determination of the compound was explored by theoretical study. • Compound displayed potent antibacterial and antioxidant activities. Synthesis of dispirooxindolopyrrolidine embedded indole hybrid heterocycle was achieved in excellent yield employing intermolecular 1,3-dipolar cycloaddition cascade reaction sequence. The non-stabilized 1,3-dipole component was derived from isatin and l -tryptophan under decarboxylative condensation methodology, was reacts with 3-(4-fluorobenzylidene)indolin-2-one to form 5-benzyl-spiro[2.3′]oxindolo-spiro[3.3′′]-oxindolo-4-[4-fluorophenyl-pyrrolidinewith four stereogenic center via two C C and one C N bonds in single synthetic operation. The structure of compound was undoubtably determined by 1D and 2D NMR spectroscopic analysis. The stereo and regiochemistry of cycloadduct was confirmed through single crystal X-ray diffraction studies. The packing aspects of compound 4 were analyzed using Hirshfeld calculations. It is found that the O...H, N...H, C...H and H...H interactions have major role in the crystal stability. Their percentages are estimated to be 10.1, 3.4, 25.0 and 51.0%, respectively indicating that the H...H contacts are the most dominant. Different electronic parameters such as charge population, dipole moment, molecular electrostatic potential map and frontier molecular orbitals as well as their derived reactivity descriptors were presented. Compound 4 showed potent antibacterial efficacy against E. coli with MIC value of >7.8 µg/mL, besides, compound 4 displayed significant antioxidant activity (84.05%) at the concentration of 500 µg/mL. [ABSTRACT FROM AUTHOR]

A three‐component, [3 + 2]‐cycloaddition/annulation domino protocol is described for the synthesis in excellent yield of a polycyclic cage‐like heterocyclic hybrid (PCHH) that comprises various advantaged structural units viz., α,β‐unsaturated ketone moiety, 4‐pyridinone and pyrroloisoquinoline in a cage‐like framework. The antitumor activity of PCHH on human breast (MCF7), colon (HCT116), cervical (JURKAT) and lung (NCI‐H460) malignant cell lines inhibited the propagation of all cell lines. This hybrid molecule displayed increased broad‐spectrum anticancer activity with higher doses of PCHH. Furthermore, the compound induced 45.21% of early apoptosis and 46.32% of late apoptosis in the Jurkat cancer cell line. Cell cycle analysis showed that this cage‐like compound caused cell cycle arrest of Jurkat cells at the S phase and sub G0/G1 phase. Additionally, it led to increased DNA fragmentation and mitochondrial membrane permeabilization through activation of caspase‐3 enzyme. Present investigation demonstrates the specific cytotoxic activity of the cage‐like compound and the induction of apoptosis through the intrinsic pathway of Jurkat cells. [ABSTRACT FROM AUTHOR]

The stereoselective syntheses of novel trans-5-aroyl-2,4-diaryl-4,5-dihydrofuran-3-carbonitriles have been achieved via a one-pot, three-component tandem protocol involving aroyl acetonitriles, aromatic aldehydes, and imidazolium ylide in the presence of Et3N. [ABSTRACT FROM AUTHOR]

• A new class of spirooxindolopyrrolidines was synthesized in excellent yields. • Compound was well characterized through spectroscopic studies. • Regio and stereochemistry of compounds clearly assigned by X-ray analysis. • Compound was determined through computational studies. • Compound displayed good antibacterial and antioxidant properties. An excellent yield of spiropyrrolidine grafted with two units of oxindole moieties was obtained employing a one-pot three component 1,3-dipolar cycloaddition cascade reaction strategy. In this cascade reaction, the key intermediate 1,3-dipole compound is formed in situ from isatin and l-phenylalanine, which was further reacted with highly functionalized 3-benzylideneindolin-2-one to form structurally complex heterocycles viz. 5-benzyl-2-spiro[2.3′]-3-spiro[3.3′′]-4-chlorophenylpyrrolidine with broad substrate diversity. The formation of a stereoselective spirocycloadduct with four contiguous stereogenic centers, two of which are spirocarbons. The structure of compound 4 was assigned through one-, two-dimensional NMR and mass spectroscopic analyses. The structure of the spiroadduct was undoubtable determined through single crystal analysis. The supramolecular structure aspects of 4 was found to depend on the O...H, N...H, C...O, and H...H interactions. Their percentages are 49.4, 24.4, 1.0 and 11.1%, respectively based on Hirshfeld analysis. The DFT/B3LYP optimized structure is found to agree well with the experimental one. Compound 4 has significant polarity where the calculated dipole moment is 4.2147 Debye. The antibacterial efficacy of the compound 4 showed more sensitive results against Shigella sp. (19.00±0.30 mm) followed by Acinetobacter sp. (17.00±0.15 mm), besides, the compound 4 showed notable antioxidant properties. [ABSTRACT FROM AUTHOR]

A- and D-ring-modified luotonin-inspired heterocycles have been synthesized and were evaluated for their activity against the viability of four cancer cell lines in vitro, namely, MCF7, HCT116, JURKAT, and NCI-H460. The analysis of results indicated that two of the synthesized derivatives displayed good inhibition against the growth of the human colon cancer HCT116 cell line, with potencies lower than but in the same order of magnitude as camptothecin (CPT). These two luotonin analogues also showed an activity similar to that of the highly potent alkaloid CPT as inhibitors of topoisomerase I and also inhibited topoisomerase II. These results show that complete planarity is not a strict requirement for topoisomerase inhibition by luotonin-related compounds, paving the way to the design of analogues with improved solubility. [ABSTRACT FROM AUTHOR]

An efficient palladium‐catalyzed annulation of 3‐arylquinazolinones with mono and double alkyne insertion was developed for the synthesis of fused quinazolinone derivatives in 43–80 % yields. A notable effect was observed in product yield, when bases/additives were modulated. The reaction mechanism is believed to proceed through C−X cleavage/alkyne insertion/1,4‐Pd migration and C−H annulation in a one‐pot manner. [ABSTRACT FROM AUTHOR]

A small library of new class of dispiropyrrolidinyl-piperidone tethered indono[1,2- b ]quinoxaline heterocyclic hybrids 7 a – j were synthesized employing multicomponent 1,3-dipolar cycloaddition strategy in [bmim]Br. The azomethine ylide employed is first of its kind and generated in situ from indenoquinoxalinone and l -tryptophan, a combination that has not been employed previously for the in situ generation of azomethine ylides. The synthesized heterocyclic hybrids 7a – j were evaluated for their in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities, therein compounds 7h and 7j displayed more potent AChE and BChE enzyme inhibition than the standard drug with IC 50 values of 3.22, 2.01, 12.40 and 10.45 mM, respectively. Molecular docking studies have also been investigated for most active compounds that disclosed interesting binding templates to the active site channel of cholinesterase enzyme. [ABSTRACT FROM AUTHOR]

A small library of spirooxindole-pyrrolidine hybrids have been synthesized for the first time in an ionic liquid, [bmim]Br in good to excellent yields employing a new class of non-stabilized azomethine ylides derived from isatin and tyrosine, a combination that has been rarely employed for the in situ generation of azomethine ylides using [3+2] cycloaddition strategy. Following the synthesis and characterization of the spirooxindole-pyrrolidine heterocyclic hybrids, they were tested for their anticancer activity as against the changes in the concentrations and time periods with different in vitro cell cultures containing cancer and non-cancer cells, where the results revealed for a potential therapeutic activity. Further analysis for the mechanism of cell death by the cancer cells indicated for the caspase-dependent apoptotic pathway, specifically mediated by caspase-3. Based on these results, it can be demonstrated that the synthesized spirooxindole-pyrrolidine hybrids may serve as one of the better therapeutic agents used for the treatment of malignant tumors. [ABSTRACT FROM AUTHOR]

A- and d -ring modified luotonin-inspired heterocyclic systems have been synthesized starting from phenylalanine following a six-step route that includes the final key stage an intramolecular Povarov reaction. • A- and D-ring modified luotonin-inspired heterocyclic systems have been synthesized. • The six-step route that starts from phenylalanine has the final key stage an intramolecular Povarov reaction. • The synthesized analogues with reduced planarity were characterized by spectroscopic studies. A small library of A- and D-ring modified luotonin-inspired heterocyclic systems have been synthesised in moderate to good yields following a six-step route that starts from phenylalanine and has the final key stage an intramolecular Povarov reaction of imines obtained from a tetrahydroquinoline-derived alkynyl aldehyde and various arylamines. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A series of structurally intriguing pyrrolo[3,2- c ]quinolinones were synthesized in excellent yields. • These heterocyclic hybrids were achieved employing multicomponent domino protocol. • The reaction provided five new bonds, three new rings and four contiguous stereocenters. Abstract A series of structurally intriguing novel pyrrolo[3,2- c ]quinolinone heterocyclic hybrids have been synthesized for the first time via a one-pot multicomponent domino reaction sequence that involves a 1,3-dipolar cycloaddition and two subsequent annulation steps. Baylis-Hillman adducts derived from various substituted benzaldehyde and methyl acrylate in presence of DABCO were used as a dipolarophiles, while the 1,3-dipole components were azomethine ylides, formed in situ from isatin derivatives and l -phenylalanine. The reaction generated five new bonds, three new rings and four contiguous stereocenters, which were created with full diastereomeric control. [ABSTRACT FROM AUTHOR]

Graphical abstract Highly functionalized 2-amino-4 H -pyrans were achieved in excellent yields and assessed for their potential as inhibitors of AD. Compound bearing nitro groups on both the aryl rings showed the highest activity and this is also supported by its inhibition mechanisms on AChE and BChE receptors. Highlights • Novel highly functionalized 2-amino-4 H -pyrans were achieved in excellent yields. • The structure of 4 H -pyrans were confirmed by FT-IR and NMR spectroscopic studies. • The compounds were evaluated as potential agents for Alzheimer's disease. • Molecular docking simulation was performed to disclose the mechanism of inhibition. Abstract Novel highly functionalized 2-amino-4 H -pyrans were achieved in excellent yields under simple grinding at ambient temperature and were assessed for their potential for treating Alzheimer's disease (AD). The 2-amino-4 H -pyran bearing nitro groups on both the aryl rings showed the highest activity, with an IC 50 of 1.98 ± 0.09 µM against acetylcholinesterase (AChE) and 10.62 ± 0.21 µM against butyrylcholinesterase (BChE), the inhibition mechanisms on AChE and BChE receptors were revealed by means of molecular docking simulations. [ABSTRACT FROM AUTHOR]

Abstract A small library of novel hybrid spiroheterocycles containing spirooxindole, pyrrolidine and indole/imidazole moieties were synthesized with complete regio- and diastereoselectively in good to excellent yields from a three-component process starting from a series of variously substituted ( E )-(2-nitrovinyl)benzenes, indoline-2,3-dione derivatives and l -tryptophan or l -histidine in an ionic liquid. The key step of this transformation is a 1,3-dipolar cycloaddition reaction involving a rare class of in situ -generated azomethine ylides derived from aromatic amino acids. The compounds thus synthesized were evaluated for their anticancer activity and were shown to inhibit the proliferation of FaDu cells, a human epithelial cell line isolated from a squamous cell carcinoma of the hypopharynx, via apoptotic cell death. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

A regio and stereo- selective synthesis of hitherto unexplored hybrid heterocyclic system comprising spiropyrrolidine, indolizino[6,7- b ]indole units in good to excellent yields, has been developed via three component 1,3-dipolar cycloaddition and concomitant trifluoroacetic acid catalyzed Pictet-Spengler cyclization with paraformaldehyde. The newly synthesized compounds were evaluated for their in vitro acetylcholinesterase (AChE) and butylcholinesterase (BChE) enzyme inhibitory activities. Most of the synthesized compounds showed good inhibitory activity, among them, compounds 4d and 4g displayed highest potency against AChE (IC 50 1.88 and 1.98 μM), and BChE (IC 50 18.32 and 10.21 μM) enzyme, respectively than the standard drug, galanthamine. Molecular modeling simulation was investigated for the most active compounds 4d and 4g on AChE and BChE enzymes to disclose the binding and orientation of these molecules into active site of respective receptors. [ABSTRACT FROM AUTHOR]

The stereoselective syntheses of novel dispiro acenaphthylene–indolizine–pyridinone hybrid heterocycles have been achieved through one-pot four-component domino 1,3-dipolar cycloaddition–Michael addition–air oxidation sequence of reactions. [ABSTRACT FROM AUTHOR]

A small library of novel spiropyrrolidine heterocyclic hybrids has been prepared regioselectively in 1-butyl-3-methylimidazoliumbromide ([bmim]Br) with good to excellent yields using a [3+2] cycloaddition reaction. These synthesized compounds were evaluated as potential agents for treating Alzheimer’s disease. Compound 4b showed the most potent activity, with an IC 50 of 7.9 ± 0.25 µM against acetylcholinesterase (AChE). The inhibition mechanisms for the most active compounds on AChE and butyrylcholinesterase (BChE) receptors were elucidated using molecular docking simulations. [ABSTRACT FROM AUTHOR]

Highly functionalized spirooxindole-pyrrolidine hybrids have been synthesized stereoselectively through a [3 + 2] cycloaddition strategy in an ionic liquid, 1-butyl-3-methylimidazolium bromide ([bmim]Br). The structure of these spiro heterocyclic hybrids was elucidated using one and two dimensional NMR spectroscopy, single crystal X-ray crystallographic studies and Density Functional Theory (DFT) calculations. The calculated geometric parameters are in good agreement with the experimental data obtained from the X-ray structures. The Natural Bond Orbital (NBO) calculations on these molecules confirm the electron rich carbonyl oxygen and electron deficient NH groups. The 1 H and 13 C NMR chemical shifts calculated using GIAO method are in good agreement with the experimental data. The DFT computed polarizability values also suggest the possible NLO activity of these molecules. [ABSTRACT FROM AUTHOR]

( Z/E )-3-(1,8-Dichloro-9,10-dihydro-9,10-ethanoanthracen-11-yl)acrylaldehyde 2 has been investigated experimentally and theoretically. The Wittig reaction of 1,8-dichloro-9,10-dihydro-9,10-ethanoanthracene-11-carbaldehyde 1 and (triphenylphosphoranylidene) acetaldehyde in toluene under reflux conditions resulted in compound 2 . Spectroscopic characterization of compound 2 was performed by the Fourier-transform infrared spectroscopy, nuclear magnetic resonance, and high-resolution mass spectroscopy techniques. Density functional theory (DFT) calculations were conducted to study various global and local reactive properties. The spectra were also obtained by DFT calculations and corresponding comparisons were performed to validate the level of theory. Using DFT calculations, reactivity has been studied based on frontier molecular orbitals, charge distribution, average local ionization energies, Fukui functions, and bond dissociation energies for hydrogen abstraction. Molecular dynamics simulations have been used to investigate the influence of water as a solvent for compound 2 . Finally, compound 2 was docked into the central and allosteric binding sites of the serotonin transporter enzyme and was found to be a good candidate as an antidepressant-like compound. [ABSTRACT FROM AUTHOR]

A small library of benzimidazole-fused pyrrolo[3,4- b ]quinoline has been synthesized from readily available benzimidazole 2-carbaldehyde and various substituted arylamines in good to excellent yields utilizing an intramolecular Povarov reaction catalyzed by boron trifluoride diethyl etharate as the key final step. The compounds thus synthesized can be considered as decarbonyl analogues of the anticancer alkaloid luotonin A and were evaluated in a DNA relaxation assay for their ability to inhibit human topoisomerase I. Interestingly, two of the compounds showed a remarkable activity that is comparable to that of the standard drug camptothecin. The compounds were also evaluated for their cytotoxic effect in four highly aggressive human cancer cell lines, namely KB, MDA-MB231 (breast), LNCap (prostate), and HT1080 (fibrosarcoma). Some of the compounds obtained showed promising cytotoxicities for these four cell lines. [ABSTRACT FROM AUTHOR]

The synthesis of highly functionalized dispiro oxindole–pyrrolo[1,2- c ]thiazole–piperidone hybrid has been achieved regioselectively employing microwave-assisted three-component 1,3-dipolar cycloaddition. Structural elucidation of the compound has been accomplished using NMR spectroscopy and further confirmed by single crystal X-ray crystallographic studies. The molecular structure of the compound crystallized in monoclinic, P 2 1 / c , a = 11.6182 (2) Å, b = 12.2466 (2) Å, c = 21.7061 (3) Å, β = 103.018 (1)°, V = 3009.04 (8) Å 3 , Z = 4. The cycloaddition was found to proceed by normal electronic demand (NED) character with a significant high charge transfer (0.1247 eV) from the 1,3-dipole to the dipolarophile. The regiochemistry has been explained using the local reactivity descriptors obtained from the DFT calculations. The DFT optimized molecular structure agreed well with the X-ray results. [ABSTRACT FROM AUTHOR]

The one-pot, four-component reactions of cyclooctanone, malononitrile, aromatic aldehydes and alkyl amines led to the unprecedented formation of novel 1- N -alkyl-2-imino-4-aryl-cycloocta[ b ]pyridines via a six-step domino sequence in a single transformation. In contrast, the lower ring-size cycloalkanones viz . cycloheptanone, cyclohexanone and cyclopentanone afforded the commonly observed product, 2-benzylamino-4-aryl-cycloalkano[ b ]pyridines. [ABSTRACT FROM AUTHOR]

series of benzimidazole-tethered oxazepine heterocyclic hybrids has been synthesized in good to excellent yields from an N-alkylated benzimidazole 2-carboxaldehyde, which in turn was accomplished from o-phenylenediamine in three good yielding steps. The calculated molecular structure of compounds 2-methyl-4-(2-((phenylimino)methyl)-1H-benzo-[d]imidazol-1-yl)-butan-2-ol 9 and 10 3,3-dimethyl-N-phenyl-1,2,3,5-tetrahydrobenzo-[4,5]imidazo[2,1-c][1,4]oxazepin-5-amine using the B3LYP/6-31 G(d, p) method were found to agree well with their X-ray structures. The charge distributions at the different atomic sites were computed using the natural bond orbital (NBO) method. The regions of electrophilic and nucleophilic reactivity were shown using a molecular electrostatic potential (MEP) map. In addition, the frontier molecular orbitals of these compounds were discussed at the same level of theory. Nonlinear optical (NLO) properties have also been investigated by computational hyperpolarizability studies, and it was found that Compound 9 is the best candidate for NLO applications. [ABSTRACT FROM AUTHOR]

The microwave-assisted three-component reactions of 3,5-bis(E)-arylmethylidene] tetrahydro-4(1H)-pyridinones, acenaphthenequinone and cyclic α-amino acids in an ionic liquid, 1-butyl-3-methylimidazolium bromide, occurred through a domino sequence affording structurally intriguing diazaheptacyclic cage-like compounds in excellent yields. [ABSTRACT FROM AUTHOR]

In this account our own research results on the methods of annulation and hetero-annulation across alkynes are summarized, especially emphasizing the annulation and hetero-annulation through C-H and X-Y activation. A wide range of quinolines, isoquinolines, indoles, benzofurans, indenes, and benzothiophenes can be synthesized via mono-annulation of ortho-alkynylaryl derivatives using transition metal catalysts and/or iodine reagents. Benzocarbazoles, benzonaphthothiophenes, and indenochromenes can be synthesized via cascade annulation of 1,2-dialkynyl substituted benzene derivatives. Palladium-catalyzed crossover annulation of compounds bearing two vicinal CC triple bonds attached to an unsaturated ring gives dibenzopentalenes through C-H activation, and intramolecular cross annulation of bis-biarylalkynes affords 9,9-bifluorenylidenes via dual C-H activation. [ABSTRACT FROM AUTHOR]

A series of novel pyrrolo[3,4- b ]quinolines have been synthesized from N -alkynyl aldehydes and various substituted arylamines in good to excellent yields utilizing an intramolecular Povarov reaction catalyzed by boron trifluoride diethyl etherate as the key final step. [ABSTRACT FROM AUTHOR]

A set of nicotinic acid derived tetrazines were synthesized and evaluated for activity in inverse-electron-demand Diels-Alder (IEDDA) reactions with various dienophiles. It was found that the performance of these tetrazines is governed by two factors. Theoretical and experimental investigations showed that steric effects may override the energetically predicted order of reactivity. Making a compromise between reactivity and stability, a selected tetrazine was incorporated into a deoxynucleotide to afford a bioorthogonalized building block enabling IEDDA-based tagging schemes of nucleic acids. [ABSTRACT FROM AUTHOR]

A series of hitherto unreported anthracene-embedded dispirooxindoles has been synthesized via a one-pot three-component 1,3-dipolar cycloaddition reaction of an azomethine ylide, generated in situ from the reaction of isatin and sarcosine to 10-benzylideneanthracen-9(10H)-one as a dipolarophile in 1-butyl-3-methylimidazolium bromide([bmim]Br), an ionic liquid. This reaction proceeded regio- and diastereoselectively, in good to excellent yields. [ABSTRACT FROM AUTHOR]

Excessive emission of CO2 has caused a critical greenhouse effect that is emerging as a major threat to the environment. Electrocatalytic reduction of CO2 is an advanced technology where chemically inert CO2 is reduced and can be used to produce value-added fuels or chemicals. In this work, the electrocatalytic performance of a single Cu atom embedded in a MoS2 monolayer with a sulfur vacancy for the electroreduction of CO2 is studied using density functional theory (DFT) with dispersion correction. The single Cu atom is stably located in the sulfur vacancy of the MoS2 monolayer. The multiple pathways explored here involve proton–electron pair transfer in the CO2 reduction reaction (CO2RR) to yield a variety of C1 products, such as HCOOH, CO, CH3OH and CH4. These pathways were examined using the corresponding free energy profiles and overpotentials. Among the different C1 products, CH4 formation is more favored via the following optimized pathway: *CO2 → *OCHO → *OCHOH → *OCH2OH → *OCH2 → *OCH3 → *OHCH3 → *OH + CH4 → H2O. The MoS2 monolayer with embedded Cu has enhanced CO2RR activity with an appreciably low overpotential compared to pristine MoS2. This study provides a deep understanding of the structure–reaction relationships and various mechanistic pathways of the CO2RR, and could aid in the design of high-performance single-atom electrocatalysts. [ABSTRACT FROM AUTHOR]

A library of novel, highly functionalized spiropyrrolidines has been synthesized stereoselectively for the first time in ionic liquid medium employing [3+2] cycloaddition of a series of 2-arylmethylidene-5,6-dimethoxy-2,3-dihydro-1H-inden-1-ones with an unexplored azomethine ylide derived from acenaphthenequinone or isatin and tryptophan. These compounds were evaluated in vitro for their acetylcholinesterase and butyrylcholinesterase inhibitory activities. Molecular modelling simulation was performed to determine the binding interaction and orientation of these molecules in the active site gorge of the respective receptors. [ABSTRACT FROM AUTHOR]

A series of novel dimethoxyindanone embedded spiropyrrolidines were synthesized in ionic liquid, [bmim]Br and were evaluated for their inhibitory activities towards cholinesterases. Among the spiropyrrolidines, compound 4f exhibited the most potent activity with an IC50 value of 1.57 μM against acethylcholinesterase (AChE). Molecular docking simulation for the most active compound was employed with the aim of disclosing its binding mechanism to the active site of AChE receptor. [ABSTRACT FROM AUTHOR]

A series of hexahydro-1,6-naphthyridines were synthesized in good yields by the reaction of 3,5-bis[(E)-arylmethylidene]tetrahydro-4(1H)-pyridinones with cyanoacetamide in the presence of sodium ethoxide under simple mixing at ambient temperature for 6–10 minutes and were assayed for their acetylcholinesterase (AChE) inhibitory activity using colorimetric Ellman’s method. Compound 4e with methoxy substituent at ortho-position of the phenyl rings displayed the maximum inhibitory activity with IC50 value of 2.12 μM. Molecular modeling simulation of 4e was performed using three-dimensional structure of Torpedo californica AChE (TcAChE) enzyme to disclose binding interaction and orientation of this molecule into the active site gorge of the receptor. [ABSTRACT FROM AUTHOR]

A facile synthesis of dispirooxindolopyrrolidines has been accomplished via a one-pot three component 1,3-dipolar cycloaddition reaction. The reaction of azomethine ylides generated in situ from L-phenylalanine and substituted isatins with a series of unusual (E)-2-oxoindolino-3-ylidene acetophenone dipolarophiles in the ionic liquid 1-butyl-3-methylimidazolium bromide [bmim]BF4, furnished the cycloadducts in good yields, with the regioisomers 5a-f being obtained with high selectivity. Furthermore, the recyclability of [bmim]BF4, up to five times, was also investigated. [ABSTRACT FROM AUTHOR]

A number of novel spiro-pyrrolidines/pyrrolizines derivatives were synthesized through [3+2]-cycloaddition of azomethine ylides with 3,5-bis[(E)- arylmethylidene]tetrahydro-4(1H)-pyridinones 2a–n. Azomethine ylides were generated in situ from the reaction of 1H-indole-2,3-dione (isatin, 3) with N-methylglycine (sarcosine), phenylglycine, or proline. All compounds (50 μM) were evaluated for their antiproliferative activity against human breast carcinoma (MDA-MB-231), leukemia lymphoblastic (CCRF-CEM), and ovarian carcinoma (SK-OV-3) cells. N-α-Phenyl substituted spiro-pyrrolidine derivatives (5a–n) showed higher antiproliferative activity in MDA-MB-231 than other cancer cell lines. Among spiro-pyrrolizines 6a–n, a number of derivatives including 6a–c and 6i–m showed a comparable activity with doxorubicin in all three cell lines. Among all compounds in three classes, 6a, 6b, and 6m, were found to be the most potent derivatives showing 64%, 87%, and 74% antiproliferative activity in MDA-MB-231, SK-OV-3, and CCRF-CEM cells, respectively. Compound 6b showed an IC50 value of 3.6 μM in CCRF-CEM cells. These data suggest the potential antiproliferative activity of spiro-pyrrolidines/pyrrolizines. [ABSTRACT FROM AUTHOR]

• Synthesis of a structurally unexplored novel class of ferrocene fused spiropyrrolidine hybrid. • Spiro compound was achieved in excellent yield via a one-pot multicomponent cascade protocol. • The synthesized compound was elucidated by spectroscopic, X-ray diffraction and computational studies. • Spirocompound displayed significant activity against tested MDR S. aureus strains. Our synthetic approach for the assembly of highly diversified spiropyrrolidine grafted ferrocene was based on a one-pot four component cascade reaction protocol involving 1,3-dipolar cycloaddition reaction of (E)-3-ferrocene-1-(4-bromophenyl)prop‑2-en-1-one and azomethine ylide generated in situ from quinoxalinone and l -tryptophan. The structure of the compound was assigned by one- and two-dimensional NMR spectroscopic studies. The regio- and stereochemistry of the spirocompound was confirmed by single crystal X-ray diffraction analysis. The nature of three-dimensional orientation of the synthesized compound has been investigated through single crystal X-ray diffraction study. Crystal structure of the synthesized compound was analyzed using Hirshfeld calculations. In spirocompound, the packing of molecules is controlled by significant O...H (3.3%), N...H (4.1%) and C H...π (24.8%) interactions. The different π-donation and π-back donation interactions was analysed using NBO calculations. The compound 6 exhibited potent inhibitory activity against tested MDR S. aureus strains ranging from 8.00 to 256.00 µg/mL with respect to MIC and MBC determination. [ABSTRACT FROM AUTHOR]

• Structurally diverse azetidinone integrated spirooxindolopyrrolidine has been accomplished. • Spirocompound has been synthesized through green synthetic protocol using ionic liquids. • Structure of spirocompound elucidated through spectroscopic, X-ray and DFT studies. • Antibacterial potential of the synsthesized compound has also been investigated. Synthesis of structurally diverse novel class of azetidinone integrated spirooxindolopyrrolidine heterocyclic hybrid was achieved in excellent yield employing a single-pot intermolecular 1,3-dipolar cycloaddition cascade protocol. The highly functionalized dipolarophile, azetidinone Baylis-Hillman adduct, was prepared from 4-formyl azetidinone whereas the non-stabilized 1,3-dipole component was derived from trifluoromethoxyisatin and l -phenylalanine via decarboxylative condensation. The structure of the product was determined by X-ray diffraction on single crystal method. Further, the crystal structure was analyzed using Hirshfeld calculations. The packing of molecules is controlled by the O...H (19.2%), F...H (17.3%), C...C (3.2%) and N...H (14.8%) which are the most significant in cycloadduct. The electronic and reactivity descriptors of the cycloadduct were calculated on the basis of DFT calculations. The synthesized heterocyclic hybrid displayed significant activity against selected ESBL producing E. coli strains and the minimal MIC values was observed against E. coli WTP005. [Display omitted] [ABSTRACT FROM AUTHOR]

Quinoline Schiff bases display potential applications in optoelectronics and laser fields because of their unique optical properties that arise from extensive delocalization of the electron cloud, and a high order of non-linearity. In this context, a new class of conjugated quinoline-derivative viz. N-(quinolin-3-ylmethylene)anilines were synthesized from 2-hydroxyquinoline-3-carbaldehyde in two good yielding steps. The ability of these imines to accept an electron from a donor is denoted by their electron acceptor number and sites, which is calculated using density functional theory (DFT). The optical properties such as FT-IR, Raman, UV-VIS, and EDS spectra were calculated using TD-DFT, which also provided the energy gap, HOMO-LUMO structure. The optical properties of the synthesized imino quinolines were experimentally studied using photoluminescence and absorption spectroscopy. The properties such as Stokes shift and quantum yield were calculated using experimental data. Furthermore, the compound bearing a methyl group on the aryl ring and ZnO nanoparticles (hydrothermally synthesized) were dissolved in toluene, and optically excited with a 355 nm nanosecond laser, which produced a random laser. [ABSTRACT FROM AUTHOR]

Highlights: [•] Synthesis of hitherto unreported morpholine fused unusual spiroheterocyle. [•] Product achieved in good yield via one-pot cascade reaction sequence. [•] The structure determined by spectral and single crystal X-ray diffraction studies. [•] Formation of spiroheterocyle has been investigated through DFT calculation. [ABSTRACT FROM AUTHOR]

Abstract: An expedient regio-, stereo- and product-selective synthesis of novel hybrid heterocyclic systems comprising [1,2-c]oxazolidine, pyrrolidine and piperidine units, in good to excellent yields, has been developed via three-component 1,3-dipolar cycloaddition/annulation domino reactions and concomitant trifluoroacetic acid mediated condensative annulation with paraformaldehyde. These novel structurally complex heterocyclic hybrids, accessed by a two-step protocol, possess seven rings and seven contiguous stereocentres. [Copyright &y& Elsevier]

Abstract: A series of dispiropyrrolothiazoles compounds were synthesized using 1,3-dipolar cycloaddition and were screened for antimycobacterial activity against Mycobacterium tuberculosis H37Rv and INH resistant M. tuberculosis strains. Two of them were showing good activity with MIC of less than 1μM. Compound (5f) was found to be the most active with MIC of 0.210 and 8.312μM respectively. [Copyright &y& Elsevier]

Abstract: Four-component reactions of (R)-1-(1-phenylethyl)tetrahydro-4(1H)-pyridinone, aromatic aldehydes and malononitrile in a 1:2:1 molar ratio in the presence of solid sodium ethoxide under solvent free conditions afforded an inseparable mixture of two diastereomeric 4(H)-pyrans in near quantitative yields. These compounds upon 1,3-dipolar cycloaddition with nitrile oxides furnished two enantiomerically pure 1,2,4-oxadiazoles in moderate yields, which were screened for in vitro activity against Mycobacterium tuberculosis H37Rv (MTB) and multi-drug resistant M. tuberculosis (MDR-TB). Among the compounds screened, compound 10h was found to be the most active in vitro with a MIC value of 0.07 and 0.14μM against MTB and MDR-TB respectively. [Copyright &y& Elsevier]

• Structurally diverse spirooxindole-pyrrolidine molecular scaffolds achieved. • Their molecular structures were elucidated from NMR, X-ray and DFT studies. • Hirshfeld analysis was performed to determine different intermolecular contacts. • DFT computed parameters are in good agreement with experimental findings. Structurally diverse highly functionalized flouro- and nitro - substituted spirooxindole-pyrrolidine heterocyclic hybrids have been achieved in good yields. The molecular structure of these diverse spiroheterocyclic hybrids was elucidated by spectroscopic analysis and further confirmed by single crystal X-ray crystallographic studies and density functional theory (DFT) calculations. Analysis of molecular packing for these hybrids was performed using Hirshfeld analysis. Geometric parameters calculated by DFT are in good agreement with the experimental data obtained from X-ray crystallography. Structurally diverse highly functionalized flouro- and nitro - substituted spirooxindole-pyrrolidine molecular scaffolds have been achieved and their molecular structures were elucidated by NMR spectroscopy and X-ray crystallographic studies. Geometric parameters calculated by DFT are in good agreement with the experimental data obtained from the X-ray crystallography. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel spirooxindolopyrrolidine tethered indandiones have been synthesized in excellent yields. • A one-pot eco-friendly three component cycloaddition strategy have been employed. • Compounds were assessed for their antimycobacterium activity against Mtb H37Rv. • Compound with chloro substituent displayed two fold activity than that of standard drug, ethambutol. Novel spirooxindolopyrrolidine embedded indandione heterocyclic hybrids were obtained in excellent yields via a regio- and stereoselective one-pot three component reaction between Baylis-Hillman adduct and non-stabilized azomethine ylides. The structure of newly synthesized compounds was elucidated through 1D and 2D spectroscopic data and the stereochemistry was determined by single crystal X-ray diffraction analysis. In vitro tubercular activity against Mycobacterium tuberculosis H37Rv using MABA assay reveals that the compound bearing chlorine substituted on the oxindole ring displayed the most potent activity with MIC 0.78 μg/mL and is two-fold active than the standard drug, ethambutol (MIC 1.56 μg/mL). [ABSTRACT FROM AUTHOR]

Protein engineering by directed evolution is time-consuming. Hence, in silico techniques like FoldX-Yasara for ∆∆G calculation, and SNPeffect for predicting propensity for aggregation, amyloid formation, and chaperone binding are employed to design proteins. Here, we used in silico techniques to engineer BDNF-NTF3 interaction and validated it using mutations with known functional implications for NGF dimer. The structures of three mutants representing a positive, negative, or neutral ∆∆G involving two interface residues in BDNF and two mutations representing a neutral and positive ∆∆G in NGF, which is aligned with BDNF, were selected for molecular dynamics (MD) simulation. Our MD results conclude that the secondary structure of individual protomers of the positive and negative mutants displayed a similar or different conformation from the NTF3 monomer, respectively. The positive mutants showed fewer hydrophobic interactions and higher hydrogen bonds compared to the wild-type, negative, and neutral mutants with similar SASA, suggesting solvent-mediated disruption of hydrogen-bonded interactions. Similar results were obtained for mutations with known functional implications for NGF and BDNF. The results suggest that mutations with known effects in homologous proteins could help in validation, and in silico directed evolution experiments could be a viable alternative to the experimental technique used for protein engineering. [ABSTRACT FROM AUTHOR]

The contemporary food industry's uses of nanoemulsions (NEs) include food processing, effective nutraceutical delivery, the development of functional chemicals, and the synthesis of natural preservatives, such as phytocompounds. Although cinnamon essential oil (CEO) is widely used in the cosmetic, pharmaceutical, and food industries, it is difficult to add to aqueous‐based food formulations due to its weak stability and poor water solubility. This study describes the formulation of a CEO nanoemulsion (CEONE) by spontaneous emulsification and evaluates its antibacterial and antibiofilm properties against biofilm‐forming Serratia rubidaea BFMO8 isolated from spoiled emperor fish (Lethrinus miniatus). Bacteria causing spoilage in emperor fish were isolated and identified as S. rubidaea using common morphological, cultural, and 16S RNA sequencing methods, and their ability to form biofilms and their susceptibility to CEONE were assessed using biofilm‐specific methods. The spontaneous emulsification formulation of CEONE was accomplished using water and Tween 20 surfactant by manipulating organic and aqueous phase interface properties and controlling particle growth by capping surfactant increases. The best emulsification, with highly stable nano‐size droplets, was accomplished at 750 rpm and a 1:3 ratio concentration. The stable CEONE droplet size, polydispersity index, and zeta potential values were 204.8 nm, 0.115, and −6.05 mV, respectively. FTIR and high‐resolution liquid chromatography‐mass spectrometry (HR‐LCMS) analyses have revealed carboxyl, carbonyl, and phenol‐like primary phytochemical functional groups in CEO and CEONE, which contribute to their antibacterial and antibiofilm properties. [ABSTRACT FROM AUTHOR]

In this framework, the authors have intended to examine the phase‐transition probability of ammonium sulfate (NH4)2SO4 under dynamic shock loaded conditions, whereby it is authenticated from the observations that the title crystal undergoes the process of reversible phase transition of crystallographic nature. The observed phase‐transition sequence is Pnam (crystalline) → Pnam (crystalline) → distorted Pnam (semicrystalline) → Pnam (crystalline) → Pnam (crystalline) under the exposure of 0, 1, 2, 3, and 4 shocks, respectively, such that the order of the transition is evaluated by diffraction and spectroscopic techniques. The obtained differential scanning calorimetry and thermogravimetric analysis results provide the crystalline‐state ammonium sulfate which has higher thermal stability than that of the disordered‐state ammonium sulfate. Analyzing the acquired results of the analytical experiments, the authentication can be arrived at such that the phase transition of reversible nature is enforced by the molecular distortions followed by the occurrence of rotational disorder involving ammonium and sulfate groups of ions influenced by the impulsion of shock waves thereby the title crystal can be a potential material for molecular switching applications. [ABSTRACT FROM AUTHOR]

Over the years, metal oxides have been leveraged to create several intriguing novel antibacterial active materials such that while finding the ways and means to increase efficiency, rare earth elements are found to have often served as potential optical dopants such that an optimistic en route to achieve the same, branched Sm‐doped CuO nano‐lanceolates were synthesized employing a wet chemical approach. The samples were then annealed at three distinct temperatures, which were fixed to 300 °C, 400 °C, and 500 °C. The nano‐lanceolates have crystallized in the monoclinic phase, according to the XRD analysis. The SEM image of Sm‐doped CuO captured at a magnification of 2 μm reveals a branched morphology, with multiple nano‐lanceolates stacked in a stem. TEM image reveals that the width of a typical nano‐lanceolate attached to a stem and its tip are found to be 87 nm and 212 nm, respectively and the obtained EDS data validate that elements including Cu, Sm, and O are present in the doped sample. The UV‐visible spectra of the annealed samples indicate that the sample annealed at 300 °C (1.43 eV) has a larger band gap than the other samples. The sample that was annealed at 400 °C has endured defect emissions that are more intense than those of other samples, according to the obtained PL spectra. In addition to these fascinating findings, the samples annealed at 300 °C, 400 °C and 500 °C exhibit a zone of inhibition of 23 mm & 24 mm, 11 mm & 12 mm and 12 mm & 11 mm, respectively for the two tested bacterial strains which authenticate that the 300 °C annealed Sm‐doped CuO nano‐lanceolate deactivates the two pathogenic bacteria more effectively compared to the other samples. As a consequence, the Sm‐doped CuO nano‐lanceolates at 300 °C could potentially be an effective alternative for antibacterial materials, particularly in biomedical applications [ABSTRACT FROM AUTHOR]

• Structurally intriguing novel spiroheterocyclic hybrid has been synthesized in excellent yield. • Spiroheterocycle has been achieved via one-pot [bmim]Br accelerated multicomponent green protocol. • The structure and stereochemistry of the compound elucidated by spectroscopic and X-ray analysis. • Molecular packing and interaction has been investigated by Hirshfeld and DFT calculations. • Food borne bacterial inhibitory activity observed. Synthesis of a hybrid heterocycle comprising ferrocene, spiropyrrolidine and quinoxaline structural moieties have been achieved in good yield via ionic liquid expedited multicomponent 1,3-dipolar cycloaddition reaction. Structural properties of the synthesized compound were exploited using single crystal X-ray crystallographic studies. Hirshfeld analysis revealed the importance of H...H (59.6%), C H...π (22.4%) and N...H (3.5%) contacts within the molecular packing. The Fe-C interactions around ferrocenyl moiety were investigated using Natural Bond Orbital (NBO) and Atoms In Molecules (AIM) calculations. A predominant covalent character of interactions between Fe-C were been accessed from AIM calculation. A weaker extend of π-back donation appeared in cyclopentadienyl moiety carrying the substituent instead of unsubstituted one. Further, the in vitro antimicrobial potential of the synthesized compound against five food borne bacterial pathogens reveals its significant activity against E. coli and S. enterica with MIC values 6.00 µg/mL and 8.00 µg/mL, respectively. The antioxidant activity of compound 5 was found to be 84.37±0.55 at 250 µg/mL concentration with an IC 50 value = 33.80 µg/mL. [ABSTRACT FROM AUTHOR]

• A novel spiropyrrolidine heterocyclic hybrid was achieved in good yield. • Structural aspects were done using spectroscopic and X-ray diffraction analysis. • Regioselectivity and possible transition states were investigated by DFT studies. • AChE and BChE inhibitory activity observed. A facile eco-friendly approach for the regio- and stereoselective synthesis of structurally intriguing novel spiropyrrolidinoquinoxaline tethered indole hybrid heterocycle has been accomplished via a cascade reaction sequence involving 1,3-dipolar cycloaddition as the key step. Structural elucidation of the synthesized spiroheterocycle was performed by NMR spectroscopy, mass spectrometric analysis and the stereochemistry of asymmetric carbons have been confirmed by single crystal X-ray diffraction analysis. The mechanistic rationalization for the formation of spiroheterocyclic hybrid was investigated through density functional theory (DFT) calculations. In addition, the synthesized spiroheterocyclic hybrid was tested for its cholinesterase inhibitory activity against ChEs and displayed good activity when compared to the standard drug galantamine. [ABSTRACT FROM AUTHOR]

The continuous development of antimicrobial resistance and appearance of new diseases necessitate use of novel and effective antimicrobial molecules. This research work was planned to determine the antimicrobial and metabolite profiling of Streptomyces filamentosus strain KS17 from unexplored regions of Devbag beach, India. The Streptomyce s filamentosus strain KS17 was screened and was subjected to various characterization techniques. Antagonistic activity of ethyl acetate extract was carried out and finally spectral and Gas Chromatography-Mass Spectrometry (GC-MS) analysis was done. The Streptomyces filamentosus strain KS17 displayed a strong antimicrobial activity on cross streak method. The organism produced greyish and light yellow mycelia and optimal growth was observed at 30–35 ℃ and expressed an evolutionary relationship with Streptomyces filamentosus strain Act74 (KT996121). The UV spectrum exhibited active peak at 213 nm. The ethyl acetate extract exhibited significant antimicrobial activity against bacteria and yeasts, such as S. flexneri , E. coli , K. pneumoniae , B. cereus , S. aureus , E. faecalis , B. subtilis , C. albicans and C. glabrata. The gram negative bacteria P. aeruginosa was unsusceptible. The metabolite profiling through GC-MS acquainted the presence of 30 bioactive compounds having antibacterial, anticancer properties. Pentane, 2,4-dimethyl- (40.75%), Stigmast-5-en-3-ol, oleate (17.09%), 2-methylhexacosane (4.52%), 9-Octadecenoic acid, 1,2,3-propanetriyl ester, (E , E , E)- (3.85%) and Phthalic acid, di(2-propylpentyl) ester (2.82%) were the leading compounds available in extract. These compounds are known to have strong antibacterial and antifungal activity. In conclusion, the results clearly suggest the possibility of Streptomyces filamentosus strain KS17 as optimistic candidate for the development of potential antimicrobial drugs after structure elucidation and detail characterizations of bioactive metabolite. [Display omitted] • Streptomyces filamentosus strain KS17 was isolated from marine sediment samples. • The organism was identified as Streptomyces filamentosus through gene sequencing. • Streptomyces filamentosus strain KS17 showed smooth & rectiflexibiles spore chains. • The organism exhibited significant antimicrobial activity against pathogens. • The GC-MS analysis reported 30 compounds having several biological activities. [ABSTRACT FROM AUTHOR]