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Abstract Extensively conjugated donor-π-acceptor-donor (D-π-A-π-D) type fluorescent styryl dyes bearing imidazo[1,2-a]pyridine units have been investigated for their nonlinear optical properties (NLO). Enhanced Stokes shift (2486–2843 cm−1) brought about by replacing methoxy group by diethyl, dimethyl, cyclohexylamino substituents at C-2 and C-7 positions of imidazo[1,2-a]pyridine core in styryl dyes have been understood in elucidating the electronic structures. The position of methoxy group acting as auxiliary donor largely influences the nonlinear optical (NLO) properties of imidazo[1,2-a]pyridine derivatives. Polarizabilities and hyperpolarizabilies were estimated by solvatochromic and DFT method using BHandHLYP and CAM-B3LYP functionals with the 6-311 + G(d,p) basis set. Imidazo[1,2-a]pyridine derivatives showed minimum ten-fold higher NLO parameters compared to reminiscent of charge transfer contribution of donor groups. The dyes have two-photon cross-section values 66–189 GM and comparable with commercial two photon absorbing styryl dyes. Graphical abstract Image 1 Highlights • Effect of auxiliary methoxy donor group on imidazo[1,2-a]pyridine studied. • Nonlinear Optical properties evaluation by Solvatochromic and DFT method. • Charge transfer explained by NBO analysis, FMO, McRea polarity function & GM equation. • TPA values 66–189 100 GM of studied dyes and comparable with commercial TPA dyes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) and time dependent density functional theory (TD-DFT) calculations of two excited state intramolecular proton transfer (ESIPT) molecules [2,5-bis(2-benzothiazolyl)hydroquinone and 2,5-bis(benzo[d]thiazol-2-yl)-4-methoxyphenol] were performed to study their structural and photo-physical behavior upon excitation. The most stable structure was established by optimizing all possible rotamers. The vertical excitation and emission wavelengths obtained by using TD-DFT show very good correlation with the experimental values. A correlation has been established based on the absorption values to determine the contribution of stable rotamers. [ABSTRACT FROM AUTHOR]

Houk and co-workers clarified several aspects of the mechanism of the Fischer indole synthesis, showing that the SCS-MP2/6-31G(d)//MP2/6-31G(d) method is suitable for studying the mechanism in water. Fluorine substitution can affect the kinetic and thermodynamic parameters of a reaction, hence the work reported here considers the impact of fluorine substituents located on the ketone component of the starting phenylhydrazone in a Fischer indole synthesis. When one of the nitrogens is protonated, the presence of one fluorine decreases the activation energy of the key [3,3]-sigmatropic rearrangement and increases the thermodynamic stability of the resulting non-aromatic imine; the presence of two fluorines also reduces the activation energy versus the unsubstituted situation, but by a smaller amount. For a non-protonated sequence, although the presence of one fluorine again decreases the activation energy of the key [3,3]-sigmatropic rearrangement, inclusion of two fluorines actually increases the activation energy slightly. [ABSTRACT FROM AUTHOR]

As part of our search for new compounds having antiviral effects, the prepared 2-aminonaphthalimide series was examined for its activity against the herpes simplex viruses HSV-1 and HSV-2. This represents the first study of the antiviral effects of this class of compounds. The new series of 2-amino-1H-benzo[de]isoquinoline-1,3-diones was examined against HSV-1 and HSV-2 using a cytopathic effect inhibition assay. In terms of effective concentration (EC50), furaldehyde, thiophene aldehyde and allyl isothiocyanide derivatives 14‒16 showed potent activity against HSV-1 (EC50 = 19.6, 16.2 and 17.8 μg/mL), compared to acyclovir as a reference drug (EC50 = 1.8 μg/mL). Moreover, 14 and 15 were found to exhibit valuable activity against HSV-2. Many of the tested compounds demonstrated weak to moderate EC50 values relative to their inactive parent compound (2-amino-1H-benzo[de]isoquinoline-1,3-dione), while compounds 7, 9, 13, 14, 15, 16, 21 and 22 were the most active set of antiviral compounds throughout this study. The cytotoxicity (CC50), EC50, and the selectivity index (SI) values were determined. In a molecular docking study, the ligand-receptor interactions of compounds 1–24 and their parent with the HSV-1 thymidine kinase active site were investigated using the Molegro Virtual Docker (MVD) software. Based on the potent anti-HSV properties of the previous naphthalimide condensate products, further exploration of this series of 2-amino-1H-benzo[ de]isoquinoline-1,3-diones is warranted. [ABSTRACT FROM AUTHOR]

A new series of 2-amino-benzo[de]isoquinoline-1,3-diones was synthesized and fully characterized in our previous paper. Here, their cytotoxic effects have been evaluated in vitro in relation to colon HCT-116, hepatocellular Hep-G2 and breast MCF-7 cancer cell lines, using a crystal violet viability assay. The IC50-values of the target compounds are reported in μg/mL, using doxorubicin as a reference drug. The findings revealed that compounds 14, 15, 16, 21 and 22 had significant cytotoxic effects against HCT-116, MCF-7 and Hep-G2 cell lines. Their IC50 values ranged between 1.3 and 8.3 μg/mL in relation to doxorubicin (IC50 ≈ 0.45-0.89 μg/mL). Therefore, these compounds could be used as templates for furthering the development and design of more potent antitumor agents through structural modification. [ABSTRACT FROM AUTHOR]

The structural and spectroscopic parameters of the fluorine doped carbon isomers, C n F 2 + (n = 1–5) cations, were calculated using frozen core second order Møller-Plesset perturbation theory (MP2(fc)) at the complete basis set (CBS) limit with the aug-cc-pVXZ (X = D, T, Q) basis sets. The optimised geometries, rotational constants, dipole moments, and vibrational frequencies of the cations were computed to the CBS limit. The even-odd alternation effect was observed in the geometrical parameters, the dipole moments and the stabilities of the isomers. The carbon clusters containing even numbers of carbon atoms are linear with D ∞h symmetry, while those containing an odd number of carbon atoms adopt a bent structure with bond angle in the range 120–130°. Some of the calculated parameters show good agreement to those available in the literature. Therefore, the reported data of the isomers should be accurate and it is hoped that the data on the isomers will be useful in helping to detect these cations in the interstellar medium. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A series of some newly methylsulfanyl-triazoloquinazoline derivatives ( 1- 21) have been tested against Coxsackievirus B4 and Adenovirus type 7. The antiviral activity of the titled compounds against Coxsackie B4 and Adeno type 7 was evaluated in BGM and Hep-2 cell lines. Compounds 4, 5, and 6 represent the most populated set of compounds obtained during this study, and 4 and 6 in particular were found to display the highest activities against Coxsackie B4 and exhibited good effect against Adeno type 7. The % of reduction in the case of Coxsackie B4 titer was 63.3 % ( 4, 6) and 83.3 % ( 5), while in Adeno type 7 titer was 63.3, 50, and 66.6 % for 4, 5, and 6, respectively. [ABSTRACT FROM AUTHOR]

Background Several quinazoline and triazole derivatives are reported to possess a wide-range of interesting pharmacological effects. Although various triazoloquinazoline subclasses having been synthesized and studied, the preparation of 1,2,4-triazolo[1,5-a]quinazolines as antihypertensive agent is still relatively unexplored. In continuation of our earlier research, we aimed at the synthesis and development of various potent antihypertensive 1,2,4- triazoloquinazoline derivatives. Results A new series of 1,2,4-triazolo[1,5-a]quinazoline derivatives have been synthesized. Their structures were mainly established by spectroscopic methods of analysis (IR, MS, 1H and 13C NMR). Their in vivo antihypertensive activity was evaluated by tail cuff method using Muromachi Blood Pressure Monitor (Model MK 2000) for rats and mice. Some of the tested compounds were found to exhibit valuable effects in terms of heart rate and blood pressure. According to the biological results, some of tested derivatives have abolished completely the tachycardia of the parent compounds and may be studied and modified as potential adrenoblockers and cardiac stimulant. Conclusion New series of fifteen 1,2,4-triazolo[1,5-a]quinazolines were synthesized by convenient methodology from four key molecules, whereby their structures were established by advanced spectroscopic analyses. Some lead compounds have abolished completely the tachycardia of the parent compounds, that may be examined as potent adrenoblockers and some other compounds seem to be a cardiac stimulant or may be modified to enhance their hypotensive activity. [ABSTRACT FROM AUTHOR]

The [3 + 2] cycloaddition (32CA) reactions between the unsubstituted, P1 and C-methyl substituted 1,4-diphosphorinium-3-olates (DPOs) with methyl acrylate (MA) and methyl methacrylate (MMA) were studied within the molecular electron density theory using the B3LYP/6-31G(d) method in the gas phase, THF and MeCN. An analysis of the kinetic and thermodynamic parameters associated to these 32CA reactions indicates that the formation of the 6-exo cycloadducts (CAs) is preferred. The theoretical findings of the 32CA reactions of DPOs with MA and MMA were compared with those of phosphorinium-3-olate and the nitrogen analogs. These zw-type 32CA reactions have very low polar character as a consequence of the low electrophilic character of MA and MMA. The electron localization function topological analysis of the bonding changes along the most favorable reaction path associated with the unsubstituted and highly substituted 32CA reactions indicates that these reactions take place through a non-concerted two-stage one-step mechanism. These reactions may be used to examine 32CA reactions involving complex phosphorus moieties. The major outcome of these investigations is promising for the study of phosphorus containing heterocycles due to their rising applications and limited research. [ABSTRACT FROM AUTHOR]

A new organic-inorganic hybrid compound (1) based on 4-(dimethylamino)pyridine and manganese(II), MnCl4(C7H11N2)2, has been synthesized and its structure determined by single-crystal X-ray diffraction, infrared and Raman spectroscopy, Hirshfeld and thermal analysis. At room temperature, 1 crystallizes in the centrosymmetric space group P-1. The structure is built up on isolated [MnCl4]2- anions and 4-(dimethylamino)pyridinium (C7H11N2)+ cations connected by a network of N–H···Cl, C–H···Cl, and π-π supramolecular interactions. The 3 D Hirshfeld surface calculations were performed to investigate the quantitatively relative contribution of these interactions in the crystal packing. The thermal behavior of 1 was characterized by TGA/DTA analysis and Density Functional Theory (DFT); there is a good comparison between the experimental and computed results. [ABSTRACT FROM AUTHOR]

Abstract A new pyrazole based 'NNO' tridentate ligand, 5-methylpyrazole-3yl-N-(2́-hydroxyphenylamine)methyleneimine, (MP z OAP) was synthesized and characterized by elemental analyses, mass, IR, 1H NMR spectral parameters. The versatile coordination mode of the ligand was established by the synthesis of Co(III), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) metal ion complexes. These complexes were characterized by elemental analyses, conductance and magnetic susceptibility measurements, UV–Vis, IR, 1H NMR spectroscopy, PXRD and thermal analysis. The structures of the ligand and complexes were also investigated using the DFT method. The ligand structure contains the coordination function of the tertiary nitrogen atom of pyrazole ring, the azomethine nitrogen and the phenolic oxygen atom, suitably spaced for chelation with a metal ion and acting as a 'NNO' tridentate donor ligand. In vitro antimicrobial activity of the reported ligand and the metal ion complexes were screened and the mode of action was also studied by scanning electron microscopy (SEM) against some pathogenic bacteria. Graphical abstract A new pyrazole containing Schiff base ligand and its Co(III), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) complexes have been synthesized & characterized. The reported NNO tridentate ligand (MP z OAP) binds with the metal ion via the tertiary nitrogen atom of pyrazole ring, the azomethine nitrogen and the phenolic oxygen atom. The structural conformation of the ligand has been established by X-ray study. The structures of the ligand and the metal ion complexes are also investigated using the DFT method. The In vitro antimicrobial activities of the ligand and the complexes have been reported and the mode of action against some pathogenic bacteria, studied by scanning electron microscopy (SEM), is shown. Image 1 Highlights • Syntheses and characterizations of a Schiff base ligand and its metal ion complexes have been reported. • X-ray study confirmed the structure of ligand molecule. The structures of complexes and ligand have also been confirmed by DFT study. • Antimicrobial screening of the compounds and the mode of cell killing activity through SEM study have been reported. [ABSTRACT FROM AUTHOR]

Melanoidins are composite biopolymers which consist of amino carbonyl compounds which are the major coloring and polluting elements of distillery effluent. In this study, a synthetic melanoidin was used as a model for natural melanoidins, the chief colorant of the effluent. Deportations of melanoidins were investigated using both natural adsorbents and constructed microbial consortia based adsorbents and denoting it using the adsorption isotherms and SEM analysis. A review enabled us to assess about the valuation of the prepared low cost adsorbent and microbial coated adsorbents and for the treatment of the synthetic melanoidin solution. Based on the performances, both Microbial Coated Commercially Activated Carbon (MCCAC) and Commercially Activated Carbon (CAC) were better when compared with the other adsorbents at lower melanoidin concentrations; however, at higher melanoidin concentration, MCCAC performed better. The utilization of CAC for the removal of melanoidins may be cost competitive; hence Microbial Coated Procured Prosopsis Activated Carbon (MCPPAC) can be used as a substitute for the removal systems. Therefore, the microbial coated adsorbents can be a remedy for the removal of color through expatriation of melanoidin from the distillery effluents. [ABSTRACT FROM AUTHOR]

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 (α0), hyperpolarizability of the first order (β0) 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 α0, β0, 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. [ABSTRACT FROM AUTHOR]

The static first and second hyperpolarizability and their related properties were calculated for triphenylamine-based “push-pull” dyes using the B3LYP, CAM-B3LYP and BHHLYP functionals in conjunction with the 6-311+G(d,p) basis set. The electronic coupling for the electron transfer reaction of the dyes were calculated with the generalized Mulliken-Hush method. The results obtained were correlated with the polarizability parameter α C T , first hyperpolarizability parameter β CT , and the solvatochromic descriptor of 〈 γ 〉 SD obtained by the solvatochromic method. The dyes studied show a high total first order hyperpolarizability (70–238 times) and second order hyperpolarizability (412–778 times) compared to urea. Among the three functionals, the CAM-B3LYP and BHHLYP functionals show hyperpolarizability values closer to experimental values. Experimental absorption and emission wavelengths measured for all the synthesized dyes are in good agreement with those predicted using the time-dependent density functional theory. The theoretical examination on non-linear optical properties was performed on the key parameters of polarizability and hyperpolarizability. A remarkable increase in non-linear optical response is observed on insertion of benzothiazole unit compared to benzimidazole unit. [ABSTRACT FROM AUTHOR]

Abstract: The intramolecular Diels‐Alder (IMDA) reactions of N‐allyl‐furfurylamine (1a) and N‐trityl‐allyl‐furfurylamine (1b), were studied within the molecular electron density theory (MEDT) using density functional theory method [B3LYP/6‐31G(d)]. In spite of the high activation enthalpies, the low unfavourable activation entropies associated to these intramolecular processes permit these IMDA reactions to take place. The IMDA reaction of 1a is thermodynamically unfavourable. The presence of the bulky −CPh3 group in the amine nitrogen atom that destabilises the extended conformation of 1b turns the process into an exergonic one. This behaviour does not only affect the thermochemistry of the reaction, but also the kinetic parameters, thus accelerating the reaction. Electron localisation function topological analysis of the C−C single bond formation along the IMDA reaction of 1a shows a bonding pattern similar to non‐polar intermolecular Diels‐Alder reactions. The present MEDT study explains the experimental results; although the steric buttress is able to change the direction of these reversible IMDA reactions, this change is only possible due to the aromatic nature of the furanyl diene system. [ABSTRACT FROM AUTHOR]

This research investigates molecular parameters such as equilibrium structure, dipole moment, rotational constant, harmonic frequency, adiabatic electron affinity, atomisation energy, and ionisation potential of some identified diatomic molecules in interstellar/circumstellar medium. A theoretical understanding of the molecular properties of the investigated molecules is obtained using the popular B3LYP hybrid density functional with four basis sets: 6-311++G(2df,2pd), 6-311++G(3df,3pd), cc-pVTZ, and aug-cc-pVTZ. The computed data conform very well with available experimental and theoretical results. The accuracy of the B3LYP functional on the studied molecular systems are ±0.006 Å for the bond length, ±0.044 D for the dipole moment, ±0.854 GHz for the rotational constant, ±59 cm-1 for the harmonic frequency, ±2.03 kcal/mol for the electron affinity, ±4.74 kcal/mol for atomisation energy, and ±3.19 kcal/mol for ionisation potential. [ABSTRACT FROM AUTHOR]

Formation of pyrazolo[5,1- c ]-1,2,4-triazoles by means of Cu(I)-catalysed [3+2] cycloaddition (32CA) reactions of C,N -cyclic azomethine imines with phenylacetylene, experimentally reported by Katritzky et al. (JOC 2012, 77, 5813), was studied using the density functional theory (DFT) method. Comparison with the uncatalysed 32CA reaction indicates that the Cu(I) catalyst provides new reaction pathways with lower electronic energy barriers in dichloromethane as solvent. The mechanism proposed by Katritzky for the Cu(I) catalysed reaction is compared with that proposed by Sharpless et al. (JACS 127, 2005, 210). The major difference between these two mechanisms lies in the coordination of the Cu(I) acetylide to the C,N -cyclic azomethine imine moiety. DFT calculations suggest that the mechanism proposed by Katritzky is kinetically favoured over that of CuAAC-type. ELF topological analysis of the electron density of the stationary points involved in the most favourable reaction pathway associated with the Cu(I)-catalysed 32CA reactions explains the bond formation. This study also reveals the requirement of C,N -cyclic azomethine imines rather than acyclic azomethine imines to favour the mechanism proposed by Katritzky. [ABSTRACT FROM AUTHOR]

The structure of 1-formyl-3-phenyl-5-(4-isopropylphenyl)-2-pyrazoline synthesized as single crystal was investigated by FTIR, NMR, XRD. Experimental data were complemented by quantum mechanical calculations. XRD data show that the compound crystallizes in the triclinic system (P−1) via trans isomer (a = 6.4267(4) Å, b = 10.9259(12) Å, c = 12.4628(9) Å and α = 102.894(8)°, β = 102.535(6)°, γ = 101.633(7)°). Anti-microbial screening results indicate that the compound shows promising activity. The theoretically predicted and experimentally obtained parameters reveal further insight into pyrazoline systems. [ABSTRACT FROM AUTHOR]

The Schiff base, 4-[3-(4-methoxy-phenyl)-allylideneamino]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one (TPMC/AAP) was synthesized by the condensation of 4-aminoantipyrine (4-amino-1,5-dimethyl-2-phenylpyrazole-3-one) and trans-para-methoxycinnamaldehyde (trans-3,4-methoxyphenyl-2-propenal) in dry methanol at 75 °C. The compound was characterized using elemental microanalysis, IR, NMR, UV spectroscopies and single-crystal X-ray crystallography. The X-ray structure determination shows that the Schiff base, (TPMC/AAP) is orthorhombic with the Pbca space group. The anti-microbial screening of the compound was carried out with Escherichia coli, Bacillus subtillis, Staphylococcus aureus, Pseudemonas aeruginosa, Candida albicans and Aspergillus niger using agar well diffusion method. The Schiff base possesses significant antimicrobial activity. The minimum inhibitory concentration (MIC) of the compound was also determined and the activity was compared with that of conventional drugs ciprofloxacin and ketoconazole. The compound (TPMC/AAP) showed varying activity against the cultured bacteria and fungi used. To complement the experimental data, density functional theory (DFT) was used to have deeper understanding into the molecular parameters and infrared spectra of the compound. [ABSTRACT FROM AUTHOR]

A correction to the article "Structural, spectroscopic and energetic parameters of P-bearing species having astrophysical importance" that was published in the previous issue is presented.

Molecular parameters such as equilibrium structure, dipole moment, rotational constant, harmonic frequency, IR intensity, adiabatic electron affinity, atomisation energy and ionisation potential of some P-bearing molecules PS, PO and HC3P in their neutral, cationic and anionic forms were investigated using the popular B3LYP hybrid density functional with four basis sets 6-311++G(2df,2pd), 6-311++G(3df,3pd), cc-pVTZ and aug-cc-pVTZ. The computed data conform well to those existing in the literature. Therefore, the predicted data for those molecules or ions which are not available in the literature should be reliable. [ABSTRACT FROM AUTHOR]