Adsorption of Tunable aryl alkyl ionic liquids (TILs) on the graphene and Defective graphene nanosheets: A DFT Study.

Optical and electronic characteristics of the graphene nanosheets (GNS) could be altered by some structural defects such as double-vacancy and Stone-Wales ones. The physisorption manner of [MPI][BF4], [MPT1][BF4], [MPT2][BF4], and [MPTT][BF4] ionic liquids on intact and defective GNS surfaces were investigated using M06-2X/cc-pVDZ computational method. Capability for adsorption on the DV and SW graphene surfaces by TILs is increased by about 1.0-4.3 and 0.4-2.0 kcal/mol respectively. The electrostatic potential of the GNS-DV surface is more negative than the GNS-SW one which enables it to interact with cation parts of the adsorbed TILs so extensively. The highest adsorption energy belongs to the [MPI][BF4]/GNS-DV system. Adsorption of the TILs on the GNS surfaces leads to a decrease in the energy of the LUMO molecular orbital as well as their energy gap of them. Results revealed that the electrical conductivity, as well as absorption spectra of the GNS surfaces, are affected by TILs adsorption and defect nature.

New task-specific ionic liquids based on phenyl diazenyl methyl pyridinium cation: Energetic, electronic and optical properties exploration based on DFT calculations.

Physicochemical properties of the three series of task-specific ILs formed from methyl pyridinium [MPy]+, phenyl diazenyl methyl pyridinium [DMPy]+ and functionalized diazenyl methyl pyridinium [X-DMPy]+ (X: NH2, OH, OCH3, CH3, C2H5, H, F, CHO, CN and NO2) cations and benzoate ([Y1]-), benzenesulfonate ([Y2]-), nitrate ([Y3]-) and tetra fluoroborate ([Y4]-) anions were investigated using density functional theory (DFT) calculations at M06-2X/AUG-cc-pVDZ level of theory. For the introduced task-specific ILs the structural parameters, energetic, electronic and topological characteristics were calculated and discussed using electrostatic maps and indexes of NBO, QTAIM, ECW and NCI. The effect of the type of anions, functional group, variation of the substituents on the functional group at cationic part on the interaction energy as well as some of their physical, chemical and optical properties are taking into account.

A highly selective silver ion optical chemosensor based on isoxazolyl-azo pyrimidine: synthesis, spectroscopy, DFT calculations and applications.

In this work, an isoxazolyl-azo pyrimidine optical chemosensor (PICS) was efficiently synthesized and applied for naked-eye detection of Ag+ ions in solution. The chemical formula of the PICS was recognized by UV-vis, FTIR and NMR analyses. The detection ability of PICS toward various ions was assessed. The results revealed the excellent selectivity and sensitivity of the chemosensor PICS to Ag+ ions in aqueous DMSO solutions. The PICS displayed an obvious color change from yellow to dark red in the presence of silver ions. The PICS could efficiently detect Ag+ ions over a wide pH range of 6-11, which makes it suitable for detection of Ag+ under physiological conditions. PICS also binds Ag+ ions to form a 1 : 1 stoichiometry complex (PICS-Ag+), resulting in a bathochromic shift in the absorption maximum from 372 to 410 nm. The detection limit of the probe PICS towards Ag+ was calculated to be 1.78 µM. Furthermore, the probe PICS shows excellent detection performance in the solid state, and PICS-based test strips were fabricated and applied as efficient Ag+ test kits for detection of silver ions in water samples. In addition, the sensing mechanism of PICS-Ag+ was completely evaluated using the density functional theory (DFT) calculations. Results indicated that the calculated energy gap between the HOMO and LUMO (3.41 eV) of PICS-Ag is lower than that of the free PICS (3.57 eV). This suggests that a red shift occurred upon addition of the Ag+ ion to PICS.

Novel edaravone-based azo dyes: efficient synthesis, characterization, antibacterial activity, DFT calculations and comprehensive investigation of the solvent effect on the absorption spectra.

The present study deals with designing and synthesizing novel dyes using the drug combination of edaravone and azo compounds which can be used as an indicator for anions and cations. The desired product synthesis was accomplished via a two-step process involving diazotizing the aromatic amines followed by the resultant salts coupling with edaravone. The resulting dyes were obtained with high yields under mild conditions. The structures of the dyes were identified with UV-vis, FT-IR, 1H NMR and 13C NMR spectra and CHN analysis. To investigate the solvatochromism effect, the interaction of different solvents with the selected dyes was evaluated using several parameters including the dielectric constant, refractive index, hydrogen bond donating ability, hydrogen bond accepting ability and dipolarity/polarizability scale. To achieve deep understanding about the stability and geometrical characteristics of the azo-hydrazo tautomers of the synthesized dyes and their UV-visible spectra prediction, some DFT calculations were also carried out on the synthesized dyes. The antibacterial activities of some synthesized compounds were also evaluated using the disk diffusion method. The results revealed different activity of the selected synthesized dyes for antibacterial tests against selected Gram positive and Gram negative bacteria.

A novel chromone based colorimetric sensor for highly selective detection of copper ions: Synthesis, optical properties and DFT calculations.

In this work, a new chromone based colorimetric sensor (ChrCS) was developed for highly selective detection of copper ions in semi-aqueous media. Evaluation of color and spectral changes displayed by the developed sensor shows that the sensor can be applied to detect copper ions in the presence of other competing metal ions and anions. The developed sensor, which contains biologically active chromone ring, shows excellent selectivity at microlevel for Cu2+ with a color change from colorless to yellow. Job's plot based on spectroscopic data showed the complex formation between ChrCS and Cu2+ ions has the stoichiometric ratio of 1:1 (ChrCS-Cu2+ complex). In addition, the binding constant of the ChrCS to Cu2+ was determined using the Benesi-Hildebrand equation. Furthermore, the test papers of the developed ChrCS were successfully prepared and employed to detect different concentration Cu2+ (10-3 M to 10-7 M) in aqueous solution. Importantly, sensor ChrCS was applied to detect Cu2+ ions in real water samples. To better understand the optical character of ChrCS and the effect of metal ion titration, density functional theory (DFT) calculations at the B3LYP/6-31 + G(d,p) level were performed for ChrCS and its complex ChrCS-Cu2+. Furthermore, on the basis of the Job's plot analysis DFT calculations, and reversible nature of the developed sensor, the sensing mechanism was demonstrated.

An insight into the interaction of L-proline with the transition metal cations Fe(2+), Co(2+), Ni(2+): a gas phase theoretical study.

The interaction of Fe(2+), Co(2+), and Ni(2+) with L-proline has been studied. Three modes of interaction have been considered: salt bridged (SB), involving binding in a bi-dentate manner through the carboxylate group of L-proline, charge solvated 1 (CS1) involving carbonyl and hydroxyl oxygen, and charge solvated 2 (CS2) involving carbonyl oxygen and the lone pair of the nitrogen atom. All calculations including geometry optimization, metal ion affinities (MIAs), and frequency calculations of the binding structures of Fe(2+), Co(2+), and Ni(2+) to L-proline were calculated using the hybrid density functional theory (DFT-B3LYP) method. All three cations were found to bind preferentially in a zwitterionic (SB) coordination pattern with the metal ion affinity in the order Ni(2+) ˃ Co(2+) ˃ Fe(2+) in all binding forms. The nature of the binding interaction between metal cations and L-proline was found to be mainly electrostatic. Comparison of the infrared vibrations of the C=O, the N-H and the O-H groups of free L-proline with L-proline-M(2+) in both CS1 and CS2 complex structures indicated a considerable shift to lower frequency during complexation. In order to gain more insight into the nature of the interaction of L-proline with group VIIIB metal ions, comparison of the interaction of L-proline with other cations such as (Li(+), Na(+), K(+), Be(2+), Mg(2+), and Ca(2+)) was made. Graphical Abstract L-proline with the transition metal cations Fe(2+), Co(2+), Ni(2.)

Novel push-pull heterocyclic azo disperse dyes containing piperazine moiety: Synthesis, spectral properties, antioxidant activity and dyeing performance on polyester fibers.

Six novel push-pull azo disperse dyes were synthesized via classical azo coupling reaction using 2-amino-thiazolyl derivatives as the diazo components and 1-(4-bromobenzyl)-4-phenylpiperazine as a key coupling intermediate. The structures of the dyes and synthesized intermediate were confirmed by FT-IR, (1)H NMR, (13)C NMR and UV-vis analyses. The solvatochromic behavior of the dyes was studied in a set of 10 solvents of different polarity and considerable results were obtained. The prepared heterocyclic azo dyes were applied for dyeing polyester fibers and their dyeing properties were studied. The fastness properties of the dyed fabrics such as wash, light and rubbing fastness degrees were measured by standard methods. Investigation of antioxidant activity of compounds was carried out by ferric reducing antioxidant power (FRAP) method. The synthesized dyes exhibited significant antioxidant activities.

Novel one-pot, three-component synthesis of new 2-alkyl-5-aryl-(1H)-pyrrole-4-ol in water.

New 2-alkyl-5-aryl-(1H)-pyrrole-4-ol derivatives were synthesized via three-component reaction of beta-dicarbonyl compounds with arylglyoxals in the presence of ammonium acetate in water at room temperature.