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Our prior studies have illustrated that the uracil ruthenium(II) diimino complex, [Ru(H 3 ucp)Cl(PPh 3 )] (1) (H 4 ucp = 2,6-bis-((6-amino-1,3-dimethyluracilimino)methylene)pyridine) displayed high hypoglycemic effects in diet-induced diabetic rats. To rationalize the anti-diabetic effects of 1, three new derivatives have been prepared, cis-[Ru(bpy) 2 (urdp)]Cl 2 (2) (urdp = 2,6-bis-((uracilimino)methylene)pyridine), trans-[RuCl 2 (PPh 3 )(urdp)] (3), and cis-[Ru(bpy) 2 (H 4 ucp)](PF 6 ) 2 (4). Various physicochemical techniques were utilized to characterize the structures of the novel ruthenium compounds. Prior to biomolecular interactions or in vitro studies, the stabilities of 1-4 were monitored in anhydrous DMSO, aqueous phosphate buffer containing 2% DMSO, and dichloromethane (DCM) via UV-Vis spectrophotometry. Time-dependent stability studies showed ligand exchange between DMSO nucleophiles and chloride co-ligands of 1 and 3, which was suppressed in the presence of an excess amount of chloride ions. In addition, the metal complexes 1 and 3 are stable in both DCM and an aqueous phosphate buffer containing 2% DMSO. In the case of compounds 2 and 4 with no chloride co-ligands within their coordination spheres, high stability in aqueous phosphate buffer containing 2% DMSO was observed. Fluorescence emission titrations of the individual ruthenium compounds with bovine serum albumin (BSA) showed that the metal compounds interact non-discriminately within the protein's hydrophobic cavities as moderate to strong binders. The metal complexes were capable of disintegrating mature amylin amyloid fibrils. In vivo glucose metabolism studies in liver (Chang) cell lines confirmed enhanced glucose metabolism as evidenced by the increased glucose utilization and glycogen synthesis in liver cell lines in the presence of complexes 2-4., Competing Interests: Declaration of competing interest The authors reported no potential conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

We present the results of the analysis of 2,2,6,6-tetramethyl-4-oxo-piperidinium nitrate isolated from the stem bark of Vitex doniana, a tree growing in Nigeria. The low-temperature molecular structure comprises one 2,2,6,6-tetramethyl-4-oxopiperidinium cation and one nitrate anion as one molecule in the asymmetric unit. The compound crystallizes in the monoclinic space group P 2 1 / n . A portion of the nitrate anion exhibits positional disorder with the main disorder component present 66.253(2) % of the time and the minor disorder component present 33.279(2) % of the time. In comparison with the previously reported room-temperature structure of C 9 H 18 N 2 O 4 . The low-temperature structure shows similarity with the piperidinium ring adopting a slightly deformed chair conformation while the nitrate anion is disordered. DFT method was used to complement the experimental study.

The new compound 4-hydroxy-1-[(4-nitrophenyl)sulfonyl]pyrrolidine-2-carboxyllic acid was obtained by the reaction of 4-hydroxyproline with 4-nitrobenzenesulfonyl chloride. The compound was characterized using single crystal X-ray diffraction studies. Spectroscopic methods including NMR, FTIR, ES-MS, and UV were employed for further structural analysis of the synthesized compound. The title compound was found to have crystallized in an orthorhombic crystal system with space group P2 1 2 1 2 1 . The S1-N1 bond length of 1.628 (2) Å was a strong indication of the formation of the title compound. The absence of characteristic downfield 1 H NMR peak of pyrrolidine ring and the presence of S-N stretching vibration at 857.82 cm -1 on the FTIR are strong indications for the formation of the sulfonamide. The experimental study was complemented with computations at the B3LYP/6-311G +  + (d,p) level of theory to gain more understanding of interactions in the compound at the molecular level. Noncovalent interaction, Hirsfeld surface analysis and interaction energy calculations were employed in the analysis of the supramolecular architecture of the compound. Predicted ADMET parameters, awarded suitable bioavailability credentials, while the molecular docking study indicated that the compound enchants promising inhibition prospects against dihydropteroate synthase, DNA topoisomerase, and SARS-CoV-2 spike., Graphical Abstract: Herein we present the solid state structure, noncovalent interaction and spectroscopic analysis of a prospective bioactive compound 4-hydroxy-1-[(4-nitrophenyl)sulphonyl]pyrrolidine-2-carboxyllic acid., Supplementary Information: The online version contains supplementary material available at 10.1007/s10870-023-00978-0., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2023, Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

The thermodynamics and mechanisms of the atmospherically relevant reaction dimethyl sulphide (DMS) + atomic chlorine (Cl) were investigated in the absence and presence of a single water molecule, using electronic structure methods. Stationary points on each reaction surface were located using density functional theory (DFT) with the M06-2X functional with aug-cc-pVDZ (aVDZ) and aug-cc-pVTZ (aVTZ) basis sets. Then fixed point calculations were carried out using the UM06-2X/aVTZ optimised stationary point geometries, with aug-cc-pVnZ basis sets (n = T and Q), using the coupled cluster method [CCSD(T)], as well as the domain-based local pair natural orbitals coupled cluster [DLPNO-UCCSD(T)] approach. Four reaction channels are possible, formation of (A) CH 3 SCH 2 + HCl, (B) CH 3 S + CH 3 Cl, (C) CH 3 SCl + CH 3 , and (C') CH 3 S(Cl)CH 3 . The results show that, in the absence of water, channels A and C' are the dominant channels. In the presence of water, the calculations show that the reaction mechanisms for A and C formation change significantly. Channel A occurs via submerged TSs and is expected to be rapid. Channel B occurs via TSs which present significant energy barriers indicating that this channel is not significant in the presence of water relative to CH 3 SCH 2 + HCl and DMS·Cl adduct formation, as is the case in the absence of water. Channel C was not considered as it is endothermic in the absence of water. In the presence of water, pathways which proceed via (a) DMS·H 2 O + Cl, (b) Cl·H 2 O + DMS and (c) DMS·Cl + H 2 O were considered. It was found that under tropospheric conditions, reactions via pathway (b) are of minor importance relative to those that proceed via pathways (a) and (c). This study has shown that water changes the mechanisms of the DMS + Cl reactions significantly but the presence of water is not expected to affect the overall reaction rate coefficient under atmospheric conditions as the DMS + Cl reaction has a rate coefficient at room temperature close to the collisional limit.

In this study, we used computational methods to investigate the interaction of amphetamine (AMP) with 1,2-indanedione (IND) and 1,8-diazafluoren-9-one (DFO) so as to understand whether AMP can be detected in latent fingerprints using either of these reagents. The results show that the binding energies of AMP with IND and DFO were enhanced by the presence of amino acid from -9.29 to -12.35 kcal mol -1 and -7.98 to -10.65 kcal mol -1 , respectively. The physical origins of these interactions could be better understood by symmetry-adapted perturbation theory. The excited state properties of the binding structures with IND demonstrate distinguishable absorption peaks in the UV-vis spectra but zero fluorescence. Furthermore, the UV-vis spectra of the possible reaction products between AMP and the reagents reveal absorption peaks in the visible spectrum. Therefore, we could predict that reaction of AMP with IND would be observable by a reddish colour while with DFO, a colour change to violet is expected. To conclude, the reagents IND and DFO may be used to detect AMP by UV-vis spectroscopy and if their reactions are allowed, the reagents may then act as a potentially rapid, affordable and easy colorimetric test for AMP in latent fingerprints without destruction of the fingerprint sample., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Synthesis of sulfonamide through an indirect method that avoids contamination of the product with no need for purification has been carried out using the indirect process. Here, we report the synthesis of a novel sulfonamide compound, ({4-nitrophenyl}sulfonyl)tryptophan (DNSPA) from 4-nitrobenzenesulphonylchloride and L-tryptophan precursors. The slow evaporation method was used to form single crystals of the named compound from methanolic solution. The compound was characterized by X-ray crystallographic analysis and spectroscopic methods (NMR, IR, mass spectrometry, and UV-vis). The sulfonamide N-H NMR signal at 8.07-8.09 ppm and S-N stretching vibration at 931 cm -1 indicate the formation of the target compound. The compound crystallized in the monoclinic crystal system and P2 1 space group with four molecules of the compound in the asymmetric unit. Molecular aggregation in the crystal structure revealed a 12-molecule aggregate synthon sustained by O-H⋯O hydrogen bonds and stabilised by N-H⋯O intermolecular contacts. Experimental studies were complemented by DFT calculations at the B3LYP/6-311++G(d,p) level of theory. The computed structural and spectroscopic data are in good agreement with those obtained experimentally. The energies of interactions between the units making up the molecule were calculated. Molecular docking studies showed that DNSPA has a binding energy of -6.37 kcal/mol for E. coli DNA gyrase (5MMN) and -6.35 kcal/mol for COVID-19 main protease (6LU7).

The role of cyclopropane substitution on the ethylene in zw-type [3+2] cycloaddition (32CA) reactions of cyclic nitrones has been studied within Molecular Electron Density Theory (MEDT) at the ω B97X-D/6-311G(d,p) computational level. Electron Localization Function (ELF) analysis of the ethylenes shows that the presence the cyclopropane only slightly increases the electron density in the C-C bonding region. Analysis of the Conceptual DFT reactivity indices indicates that the presence of the cyclopropane does not produce any remarkable change in the reactivity of these strained ethylenes. The marginal electrophilic character of ethylene makes the zw-type 32CA reactions of non-polar character. The presence of the cyclopropane in the ethylene decreases the activation enthalpy of the 32CA reactions by only 1.7 and 2.6 kcal mol -1 , and also decreases the ortho regioselectivity. The loss of the strain present in the cyclopropane is responsible for the reduction of the activation enthalpy and the increase of the reaction enthalpy in these non-polar 32CA reactions. The presence of the cyclopropane does not cause any change, neither in the transition state structure (TS) geometries nor in their electronic structure. The very low global electron density transfer (GEDT) computed at the TSs confirms the non-polar character of these 32CA reactions. The ortho regioselectivity experimentally observed in these non-polar 32CA reactions is determined by the most favorable two-center interaction between the less electronegative C1 carbon of nitrone and the non-substituted methylene C5 carbon of the ethylenes., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The coating industry is one of the most important consumers of water and chemicals and consequently is a major water polluter in Mauritius. The focus of this study was to characterise wastewater generated by a coating industry in Mauritius. The objectives were to develop a wastewater sampling strategy and to analyse the pollutant parameters as per Mauritian regulations. The wastewater samples were analysed for physicochemical properties and metal abundances over a period of 6 months. The physicochemical parameters analysed were pH, electrical conductivity (EC), true colour, total suspended solids (TSS), biological oxygen demand (BOD 5 ), chemical oxygen demand (COD), nitrate, phosphate, sulphate and free chlorine. The wastewater samples were also analysed for metal ions such as sodium, potassium, arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, molybdenum, nickel and zinc. The results of the physicochemical parameters indicated the presence of biologically resistant organic matters in all the wastewater samples with elevated values of BOD 5 and COD, and low biodegradability index, respectively. The coating industry wastewater samples were acidic and saline in nature. Moreover, they presented high concentrations of TSS, free chlorine and sodium ions compared to standard limits promulgated by the Mauritian Government. Spearman's rank correlation matrix with non-linear regression analysis showed significant associations among the measured parameters which were found to have a common origin in the coating industry wastewater. This research will be useful for regular monitoring and setting up an adequate coating industry wastewater treatment for the potential reuse in production processes in Mauritius., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The current research used a virtual screening method to study 57 isolated phytochemicals (alkaloids, phytosterols, and flavonoids) against the SARS-CoV-2 main protease (M pro ). The absorption, distribution, metabolism, excretion, and toxicity (ADMET) of the selected compounds were analysed using admetSAR tool while SwissADME and Molinspiration chemoinformatics tools were used to examine the oral bioavailability and drug-likeness properties. Parameters such as physicochemical properties, activity spectra for substances (PASS) prediction, bioactivity, binding mode, and molecular interactions were also analysed. Our results favoured Lupeol (-8.6 kcal/mol), Lupenone (-7.7 kcal/mol), Hesperetin (-7.4 kcal/mol), Apigenin (-7.3 kcal/mol) and Castasterone (-7.3 kcal/mol) as probable inhibitors of SARS-CoV-2. This is because of their good binding affinities, bioactivities, drug-likeness, ADMET properties, PASS properties, oral bioavailability, binding mode and their interactions with the active site of the target receptor compared to Remdesivir and Azithromycin. Therefore, these compounds could be explored towards the development of new therapeutic agents against SARS-CoV-2.

We investigated the flow of electron density along the cyclocondensation reaction between ethyl acetate 2-oxo-2-(4-oxo-4H-pyrido[1.2-a]pyrimidin-3-yl) polyazaheterocycle (1) and ethylenediamine (2) at the ωB97XD/6-311++G(d,p)computational method within of bond evolution theory (BET). The exploration of potential energy surface shows that this reaction has three channels (1-3) with the formation of product 3 via channel-2 (the most favorable one) as the main product and this is in good agreement with experimental observations. The BET analysis allows identifying unambiguously the main chemical events happening along channel-2. The mechanism along first step (TS2-a) is described by a series of four structural stability domains (SSDs), while five SSDs for the last two steps (TS2-b and TS2-c). The first and third steps can be summarized as follows, the formation of N1-C6 bond (SSD-II), then, the restoration of the nitrogen N1 lone pair (SSD-III), and finally, the formation of the last O1-H1 bond (SSD-IV). For the second step, the formation of hydroxide ion is noted, as a result of the disappearance of V(C6,O7) basin and the transformation of C6-N1 single bond into double one (SSD-IV). Finally, the appearance of V(O7,H2) basin lead to the elimination of water molecule within the last domain is observed., (© 2022 Wiley Periodicals LLC.)

The proposed S N 2 reactions of a hindered organophosphorus reactant with aliphatic and aromatic nucleophiles [Ye et al. , Org. Lett. , 2017, 19 , 5384-5387] were studied theoretically in order to explain the observed stereochemistry of the products. Our computations (using B3LYP as the functional) indicate that the reaction with the aliphatic nucleophile occurs through a backside S N 2@P pathway while the reaction with the aromatic nucleophile proceeds through a novel S N 2@Cl mechanism, followed by a frontside S N 2@C mechanism., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Hydroxychloroquine (HCQ) and favipiravir (FPV) are known to be effective antivirals, and there are reports about their use to fight the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) despite that these are not conclusive. The use of combined drugs is common in drug discovery, and thus, we investigated HCQ and FPV as a combined drug. The density functional theory method was used for the optimization of geometries, spectroscopic analysis and calculation of reactivity parameters. The quantum theory of atoms in molecules was applied to explain the nature of the hydrogen bonds and confirm the higher stability of the combined drug. We also evaluated the absorption, distribution, metabolism and excretion (ADME) parameters to assess their drug actions jointly using SwissADME. The preliminary findings of our theoretical study are promising for further investigations of more potent and selective antiviral drugs., Supplementary Information: The online version contains supplementary material available at 10.1007/s11696-021-01946-8., Competing Interests: Conflict of interestsOn behalf of all authors, the corresponding author states that there is no conflict of interest., (© Institute of Chemistry, Slovak Academy of Sciences 2021.)

The proverb "Old is gold" is applicable in drug discovery and the proverb "All that Glitters is not Gold" is also appropriate. In the COVID-19 era, there has been a race for drugs to be effective against SARS-CoV-2. There are reports about the uses of Remdesivir and Favipiravir as existing antivirals against virus but none have been conclusive so far. In the attempts for innovations, the combination of drugs is also under trials. Therefore, we used the density functional theory method and quantum theory of atoms in molecules to investigate drug-drug interactions involving Remdesivir and Favipiravir. The computed parameters were related to the antiviral actions of both drugs together. The results indicate enhanced antiviral activity and it will be worthy to consider additional investigations with the combination of these two drugs., Competing Interests: The authors declare that no conflicts of interest exist., (Thieme. All rights reserved.)

Purpose: Diabetes mellitus is a common condition in the clinically obese. Bariatric surgery is one of the ways to put type 2 diabetes in remission. Recent findings propose the appetite-regulator peptide tyrosine tyrosine (PYY) as a therapeutic option for patients with type 2 diabetes. This novel gut hormone restores impaired insulin and glucagon secretion in pancreatic islets and is implicated in type 2 diabetes reversal after bariatric surgery. The current study elucidates the interactions between PYY and the NPY1R and NPY4R receptors using computational methods., Methods: Protein structure prediction, molecular docking simulation, and molecular dynamics (MD) simulation were performed to elucidate the interactions of PYY with NPY1R and NPY4R., Results: The predicted binding models of PYY-NPY receptors are in agreement with those described in the literature, although different interaction partners are presented for the C-terminal tail of PYY. Non-polar interactions are predicted to drive the formation of the protein complex. The calculated binding energies show that PYY has higher affinity for NPY4R (ΔG GBSA = -65.08 and ΔG PBSA = -87.62 kcal/mol) than for NPY1R (ΔG GBSA = -23.11 and ΔG PBSA = -50.56 kcal/mol)., Conclusions: Based on the constructed models, the binding conformations obtained from docking and MD simulation for both the PYY-NPY1R and PYY-NPY4R complexes provide a detailed map of possible interactions. The calculated binding energies show a higher affinity of PYY for NPY4R. These findings may help to understand the mechanisms behind the improvement of diabetes following bariatric surgery., (© 2021. Hellenic Endocrine Society.)

A-234, [EtO-P([double bond, length as m-dash]O)(F)-N[double bond, length as m-dash]C(Me)-N(Et) 2 ], is the suspected A-type nerve agent used in the Skripal attack on the 4th of March 2018. Studies related to the structure and reactivity of this compound are limited. We, therefore, aimed at understanding the underlying hydrolysis mechanism of A-234 within the DFT framework. The attack of the water molecule can occur at the phosphinate and acetoamidine reactive centres. Our theoretical findings indicate that the hydrolysis at the acetoamidine centre is thermodynamically favoured compared to the hydrolysis at the phosphinate centre. The hydrolysis at the acetoamidine moiety may proceed via two pathways, depending on the nitrogen atom participating in the hydrolysis. The main pathway consists of four distinct channels to reach the final product, with the concerted 1,3-proton shift favoured kinetically and thermodynamically in the gas phase and water as solvent. The results are in good agreement with the literature, although some differences in the reaction mechanism were observed., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

A new photoredox-catalyzed decarboxylative radical addition approach to functionalized cyclobutanes is described. The reaction involves an unprecedented formal Giese-type addition of C(sp 3 )-centered radicals to highly strained bicyclo[1.1.0]butanes. The mild photoredox conditions, which make use of a readily available and bench stable phenyl sulfonyl bicyclo[1.1.0]butane, proved to be amenable to a diverse range of α-amino and α-oxy carboxylic acids, providing a concise route to 1,3-disubstituted cyclobutanes. Furthermore, kinetic studies and DFT calculations unveiled mechanistic details on bicyclo[1.1.0]butane reactivity relative to the corresponding olefin system., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We have computationally studied the bimolecular nucleophilic substitution (S N 2) reactions of M n NH 2 (n-1) + CH 3 Cl (M +  = Li + , Na + , K + , and MgCl + ; n = 0, 1) in the gas phase and in tetrahydrofuran solution at OLYP/6-31++G(d,p) using polarizable continuum model implicit solvation. We wish to explore and understand the effect of the metal counterion M + and of solvation on the reaction profile and the stereochemical preference, that is, backside (S N 2-b) versus frontside attack (S N 2-f). The results were compared to the corresponding ion-pair S N 2 reactions involving F - and OH - nucleophiles. Our analyses with an extended activation strain model of chemical reactivity uncover and explain various trends in S N 2 reactivity along the nucleophiles F - , OH - , and NH 2 - , including solvent and counterion effects. © 2019 Wiley Periodicals, Inc., (© 2019 Wiley Periodicals, Inc.)

A microhydration study of sulfur mustard (SM) was carried out using M06-2X, B3LYP, B3LYP-D3, and MP2 levels of theory with the 6-311++G(2d,2p) basis set. The changes in energetics, structural parameters and vibrational wavenumbers following the addition of up to three discrete water molecules to SM were analyzed. We observed slight changes in the geometry of SM upon microhydration. The stability of hydrated clusters is due to weak C-H···O-H hydrogen bonds. The free energy change for the formation of the clusters is positive at room temperature and becomes exergonic when the temperature decreases. The infrared stretchings of C-Cl of SM and O-H of water are redshifted upon the addition of water molecules. The findings from this work add to the literature of hydrated SM and can be useful in its detection and subsequent destruction., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Correction for 'A colorimetric probe for the real-time naked eye detection of cyanide and hydroxide ions in tap water: experimental and theoretical studies' by Veikko Uahengo et al., Analyst, 2019, 144, 6422-6431.

Herein, a colorimetric sensor (L) based on a naphthyl derivative bearing hydrazone receptors was synthesized via a one-step reaction process, and its recognition properties towards biologically important anions in an acetonitrile-water mixture were investigated by naked-eye observation and UV-Vis and 1 H NMR spectroscopy. The molar addition of anions, such as TBAF - , TBAOH - , TBACN - and TBAAcO - , induced a significant red shift in the charge transfer band (Δλ = 73 nm, from 337 nm to 410 nm), in agreement with visible "naked eye" detectable colorimetric activities; in addition, soaked-in-L paper strips were prepared, which could significantly discriminate cyanide (KCN) and hydroxide (NaOH) ions dissolved in tap water via the litmus test method. This study was complemented by density functional theory computations to gain more insight into the interaction between L and anions.

Antimicrobial agents containing symmetrical triiodides complexes with halogen bonding may release free iodine molecules in a controlled manner. This happens due to interactions with the plasma membrane of microorganisms which lead to changes in the structure of the triiodide anion. To verify this hypothesis, the triiodide complex [Na(12-crown-4) 2 ]I 3 was prepared by an optimized one-pot synthesis and tested against 18 clinical isolates, 10 reference strains of pathogens and five antibiotics. The antimicrobial activities of this symmetrical triiodide complex were determined by zone of inhibition plate studies through disc- and agar-well-diffusion methods. The triiodide complex proved to be a broad spectrum microbicidal agent. The biological activities were related to the calculated partition coefficient (octanol/water). The microstructural analysis of SEM and EDS undermined the purity of the triiodide complex. The anionic structure consists of isolated, symmetrical triiodide anions [I-I-I] - with halogen bonding. Computational methods were used to calculate the energy required to release iodine from [I-I-I] - and [I-I···I] - . The halogen bonding in the triiodide ion reduces the antibacterial activities in comparison to the inhibitory actions of pure iodine but increases the long term stability of [Na(12-crown-4) 2 ]I 3 .

Novichoks are the suspected nerve agents in the March 2018 Skripal poisoning. In this context, the novichok agent A234 (chemical structure proposed by Mirzayanov) was studied using computational methods to shed light on its molecular, electronic, spectroscopic, thermodynamic and toxicity parameters as well as on potential thermal and hydrolysis degradation pathways. The poisoning action and antidote of A234 were also investigated. Some of these parameters were compared to three common G- and V-series nerve agents, namely GB, VR and VX. The research findings should be useful towards the detection, development of antidotes and destruction of A234., Competing Interests: The authors declare no competing financial interest.

The distortion/interaction-activation strain model (D/I-ASM), a fragment analysis method, is applied to study the structure-reactivity relationship in reactions. The application of D/I-ASM involves the generation of input files for points along a reaction profile, submission of input files to a quantum software package, processing of parameters from the resulting output files and generation of graphical plots. The ExcelAutomat tool (Laloo et al., J. Comput. Aided Mol. Des. 2017, 31, 667) provides a framework and library in Visual Basic for Application programming language to process such files. New routines were written in ExcelAutomat 1.3 to facilitate processing of files for D/I-ASM. The worksheet "ASM" was included where initial parameters needed can be defined. The routines for D/I-ASM were tested successfully on bimolecular nucleophilic substitution, cycloaddition, and barrierless reactions. The automation of fragment analysis by ExcelAutomat 1.3 is compatible with Microsoft Excel and LibreOffice Calc. The extensible tool processes files from Gaussian and GAMESS-US packages. © 2018 Wiley Periodicals, Inc., (© 2018 Wiley Periodicals, Inc.)

Comparative study of nonlinear optical properties of red fluorescent coumarins was carried out with density functional theory based ab initio method using the popular global hybrid (GH) and range separated hybrid (RSH) functionals and correlated with the spectroscopic values. The GHs - M06 L, PBE1PBE, M06, BHHLYP, M062X and M06HF and RSHs - HISSbPBE, wB97, wB97X, HSEH1PBE, CAM-B3LYP and wB97XD in combination with the double zeta basis function 6-311 + G(d,p) were used. The computed polarizability (α 0 ), hyperpolarizability of the first order (β 0 ) and second order (γ) computed by the RSHs are closer to the spectroscopic values compared to GHs. Polarizabilities computed with the functionals BHHLYP and M06-2X are closer with the spectroscopic values. Incorporation of additional cyano group enhances the NLO response. An increase in electrophilic nature contributed from the reduced orbital band gap culminating an increase in α 0 , β 0 , and γ in all the cases. The NLO response was found to be highly solvent dependent that is the polarity of the micro environment created by the solvents. To understand the agreement and accuracy among the NLO parameters obtained from the selected DFT functionals and the spectroscopic values, the mean absolute error (MAE) and vibrational contribution parameters are presented. Two photon absorption (TPA) cross section depends upon the molecular structure where π-framework is an important factor rather than number of acceptors.

A Molecular Electron Density Theory (MEDT) study of the regio- and stereoselectivity of the [3 + 2] cycloaddition (32CA) reaction of 1 H -phosphorinium-3-olate and 1-methylphosphorinium-3-olate with methyl methacrylate was carried out using the B3LYP/6-31G(d) method. In order to test the method dependence for the most favorable reaction path leading to the 1 H -substituted 6- exo cycloadduct (CA) various functionals using higher basis sets were taken into consideration in the gas phase. An analysis of the energetic parameters indicates that the reaction path leading to 6- exo CA are kinetically as well as thermodynamically favored in the gas phase, THF and ethanol. The calculated energetic parameters of the 32CA reaction of these phosphorus derivatives were compared with those of methyl acrylate and their nitrogen analogues. Investigation of the global electron density transfer at the TSs indicates that these 32CA reactions have non-polar character, while electron localisation function topological analysis of the C-C bond formation along the most favorable reaction path indicates that these 32CA reactions take place through a non-concerted two-stage one-step mechanism, via highly asynchronous TSs., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We have theoretically studied the non-identity S N 2 reactions of M n OH (n-1) +CH 3 Cl (M + =Li + , Na + , K + , and MgCl + ; n=0, 1) in the gas phase and in THF solution at the OLYP/6-31++G(d,p) level using polarizable continuum model (PCM) implicit solvation. We want to explore and understand the effect of the metal counterion M + and solvation on the reaction profile and the stereoselectivity of these processes. To this end, we have explored the potential energy surfaces of the backside (S N 2-b) and frontside (S N 2-f) pathways. To explain the computed trends, we have carried out analyses with an extended activation strain model (ASM) of chemical reactivity that includes the treatment of solvation effects., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel Pd-ZnO-expanded graphite (EG) photoelectrode was constructed from a Pd-ZnO-EG nanocomposite synthesised by a hydrothermal method and characterised using various techniques such as X-ray diffractometry (XRD), Raman spectroscopy, UV-Vis diffuse reflectance spectroscopy, nitrogen adsorption-desorption analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Cyclic voltammetry and photocurrent response measurements were also carried out on the electrode. The Pd-ZnO-EG electrode was employed in the photoelectrocatalytic removal of 4-nitrophenol as a target water pollutant at a neutral pH and with a current density of 7 mA cm -2 . Optical studies revealed that the Pd-ZnO-EG absorbed strongly in the visible light region. The Pd-ZnO-EG electrode showed improved photoelectrocatalytic activity in relation to ZnO-EG and EG electrodes for the removal of the 4-nitrophenol. The photocurrent responses showed that the Pd-ZnO-EG nanocomposite electrode could be employed as a good photoelectrode for photoelectrocatalytic processes and environmental remediation such as treatment of industrial waste waters. Density functional theory method was used to model the oxidative degradation of 4-nitrophenol by the hydroxyl radical which generates hydroquinone, benzoquinone, 4-nitrocatechol, 4-nitroresorcinol and the opening of the 4-nitrophenol ring. Furthermore, the hydroxyl radical is regenerated and can further oxidise the ring structure and initiate a new degradation process., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

Density functional theory and time-dependent density functional theory computations were used to understand the electronic and photophysical parameters of NIR β-thiophene-fused BF 2 -azadipyrromethene dyes. The computed data are in good agreement with those obtained experimentally and they provide insights into the origin of red shifted optical spectra compared to the parent aza-BODIPY, low Stokes shift, non-linear optical responses and quantitative description of the singlet-triplet energy gap. The resultant decrease in the HOMO - LUMO energy gap is responsible for the red shift. The possible use as non-linear optical materials is supported by large enhancement in the non-linear optical properties. On the basis of vertical triplet energies, their possible potential therapeutic use as a photosensitizer in photodynamic therapy is proposed. The singlet-triplet energetic gaps suggest that the β-thiophene-fused BF 2 -azadipyrromethene dyes can act as a sensitizer to produce an efficient generation of singlet oxygen. Their optimal use as an efficient singlet fission materials has been proposed on the basis of excitation energies in the ground, lowest singlet and triplet excited states.

Metal-cyclen complexes have a number of important applications. However, the coordination chemistry between metal ions and cyclen-based macrocycles is much less well studied compared to their metal ion-crown ether analogues. This work, which makes a contribution to address this imbalance by studying complex ions of the type [M(Me 4 cyclen)(L)] + , was initiated by results of an experimental study which prepared some Group 1 metal cyclen complexes, namely [Li(Me 4 cyclen)(H 2 O)][BAr F ] and [Na(Me 4 cyclen)(THF)][BAr F ] and obtained their X-ray crystal structures [J. M. Dyke, W. Levason, M. E. Light, D. Pugh, G. Reid, H. Bhakhoa, P. Ramasami, and L. Rhyman, Dalton Trans., 2015, 44, 13853]. The lowest [M(Me 4 cyclen)(L)] + minimum energy structures (M = Li, Na, K, and L = H 2 O, THF, DEE, MeOH, DCM) are studied using density functional theory (DFT) calculations. The geometry of each [M(Me 4 cyclen)(L)] + structure and, in particular, the conformation of L are found to be mainly governed by steric hindrance which decreases as the size of the ionic radius increases from Li + → Na + → K + . Good agreement of computed geometrical parameters of [Li(Me 4 cyclen)(H 2 O)] + and [Na(Me 4 cyclen)(THF)] + with the corresponding geometrical parameters derived from the crystal structures [Li(Me 4 cyclen)(H 2 O)] + [BAr F ] - and [Na(Me 4 cyclen)(THF)] + [BAr F ] - is obtained. Bonding analysis indicates that the stability of the [M(Me 4 cyclen)(L)] + structures originates mainly from ionic interaction between the Me 4 cyclen/L ligands and the M + centres. The experimental observation that [M(Me 4 cyclen)(L)] + [BAr F ] - complexes could be prepared in crystalline form for M + = Li + and Na + , but that experiments aimed at synthesising the corresponding K + , Rb + , and Cs + complexes failed resulting in formation of [Me 4 cyclenH][BAr F ] is investigated using DFT and explicitly correlated calculations, and explained by considering production of [Me 4 cyclenH] + by a hydrolysis reaction, involving traces of water, which competes with [M(Me 4 cyclen)(L)] + formation. [Me 4 cyclenH] + formation dominates for M + = K + , Rb + , and Cs + whereas formation of [M(Me 4 cyclen)(L)] + is energetically favoured for M + = Li + and Na + . The results indicate that the number and type of ligands, play a key role in stabilising the [M(Me 4 cyclen)] + complexes and it is hoped that this work will encourage experimentalists to prepare and characterise other [M(Me 4 cyclen)(L)] + complexes.

This study reports the synthesis and comparative investigation of the substituent effects of a new series of highly luminescent homoleptic tris-cyclometalated iridium(III) complexes of the type [Ir(N ˄ C)₃]. These are based on two ligand type derivatives comprising of 4-fluorophenylvinylquinolines and 4-methoxyphenylvinylquinolines with electron-donating and/or electron-withdrawing groups as aryl substituents at 2-position. The structures of the ligands and their complexes were characterized by means of FT-IR, UV-Vis and NMR spectrometry complemented with photoluminescence and cyclic voltammetry. The photophysical properties of 2-aryl-4-(4-fluorophenylvinyl)quinoline and its corresponding complex were also studied using the density functional theory method. The photoluminescent properties of the ligands and the corresponding complexes showed high fluorescent intensities and quantum yields in solvents of different polarities. The photoluminescence spectra of the complexes in solid film, showed common transmission curves at longer wavelengths maximum (λ em = 697 nm) possibly originating from the interference of scattered light of higher-order transmission of monochromators., Competing Interests: The authors declare no conflict of interest.

The processing of the input and output files of quantum chemical calculations often necessitates a spreadsheet as a key component of the workflow. Spreadsheet packages with a built-in programming language editor can automate the steps involved and thus provide a direct link between processing files and the spreadsheet. This helps to reduce user-interventions as well as the need to switch between different programs to carry out each step. The ExcelAutomat tool is the implementation of this method in Microsoft Excel (MS Excel) using the default Visual Basic for Application (VBA) programming language. The code in ExcelAutomat was adapted to work with the platform-independent open-source LibreOffice Calc, which also supports VBA. ExcelAutomat provides an interface through the spreadsheet to automate repetitive tasks such as merging input files, splitting, parsing and compiling data from output files, and generation of unique filenames. Selected extracted parameters can be retrieved as variables which can be included in custom codes for a tailored approach. ExcelAutomat works with Gaussian files and is adapted for use with other computational packages including the non-commercial GAMESS. ExcelAutomat is available as a downloadable MS Excel workbook or as a LibreOffice workbook.

2,4-Ditellurouracil exhibits keto-enol tautomerism via different pathways resulting in seven tautomers. These pathways were studied in the gas phase using density functional theory method. The functionals used were BLYP, B3LYP and BHLYP and the basis sets were 6-311++G(d,p) for all atoms except that LanL2DZ ECP was used for tellurium atom only. The results indicate that the diketo form is more stable as observed for uracil and its sulfur and selenium analogues. The effect of introducing fluorine at position 5 was also investigated and the energy difference between the diketo and dienol forms is reduced. 2,4-Ditellurouracil and its 5-fluoro analogue are expected to exist exclusively as the diketo form due to the high interconversion energy barrier. We extended the investigation to predict ADME parameters of the most stable diketo and dienol tautomers in view of understanding their biological properties. This research enlightens keto-enol tautomerism of 2,4-ditellurouracil and its 5-fluoro derivative with additional insights to biological functions., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The electronic structures and spectroscopic properties of triphenylamine-based monostyryl and bis(styryl) dyes were studied using quantum chemical methods. The ground-state geometries of these dyes were optimized using the density functional theory (DFT) method. The lowest singlet excited state was optimized using time-dependent density functional theory (TD-DFT). The absorption was also calculated using the ground-state geometries. All the calculations were carried out in the gas phase and in solvent. The results indicate that the absorption maxima calculated using the TD-DFT are in good agreement with those obtained experimentally. These dyes possess a large second-order non-linear property and this is mainly due to the strong donor-π-acceptor conjugation which is attributed to the excited state intramolecular charge transfer (ICT). There is a relationship between the hardness and first hyperpolarizability and second hyperpolarizability of mono- and bis(styryl) dyes. The efficiency of the intersystem crossing process can be improved by reducing the energy gap between the singlet and triplet excited states.

The structures of the mono- and the dihalogenated N -unsubstituted 2-aminobenzamides were characterized by means of the spectroscopic (¹H-NMR, UV-Vis, FT-IR, and FT-Raman) and X-ray crystallographic techniques complemented with a density functional theory (DFT) method. The hindered rotation of the C(O)-NH₂ single bond resulted in non-equivalence of the amide protons and therefore two distinct resonances of different chemical shift values in the ¹H-NMR spectra of these compounds were observed. 2-Amino-5-bromobenzamide ( ABB ) as a model confirmed the presence of strong intramolecular hydrogen bonds between oxygen and the amine hydrogen. However, intramolecular hydrogen bonding between the carbonyl oxygen and the amine protons was not observed in the solution phase due to a rapid exchange of these two protons with the solvent and fast rotation of the Ar-NH₂ single bond. XRD also revealed the ability of the amide unit of these compounds to function as a hydrogen bond donor and acceptor simultaneously to form strong intermolecular hydrogen bonding between oxygen of one molecule and the NH moiety of the amine or amide group of the other molecule and between the amine nitrogen and the amide hydrogen of different molecules. DFT calculations using the B3LYP/6-311++G(d,p) basis set revealed that the conformer ( A ) with oxygen and 2-amine on the same side predominates possibly due to the formation of a six-membered intramolecular ring, which is assisted by hydrogen bonding as observed in the single crystal XRD structure.

The 2,2'-dinaphtholazobenzene molecular framework (P) was designed, synthesized and characterized. Its absorption and fluorescence properties revealed that P is a dual sensor for copper ions (Cu 2+ ) and fluoride ions (F - ) in DMSO. The colorimetric activities were clearly visible by naked eye upon the addition of the two ions. Fluorescence quenching and enhancement were observed when Cu 2+ and F - ions were added respectively. Density Functional Theory (DFT) calculations were carried out to provide an insight into the interaction of guest ions (Cu 2+ and F - ) with P, and to explain how the molecular orbitals were affected. Graphical Abstract ᅟ.

Hanson et al. [Org. Lett., 2011] reported the absorption and emission spectrum of 5,6-dichloro-1,3-bis(2-pyridylimino)-4,7-dihydroxyisoindole but the excited-state intramolecular proton transfer (ESIPT) process was not investigated. The photo-physical behaviour of 5,6-dichloro-1,3-bis(2-pyridylimino)-4,7-dihydroxyisoindole was studied using the density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The functional used was B3LYP and 6-31G(d) was the basis set for all the atoms. All the ten tautomers were studied for the absorption and emission properties. It is found that the tautomer where hydroxyl groups are syn to nitrogen of isoindoline ring is most stable and thus, responsible for the ESIPT process. The computed absorption and emission values of tautomers using TD-DFT are in good agreement with those obtained experimentally.