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• Selective colorimetric recognition of cyanide ion in both solution and solid states. • Fast response to CN– (< 5 s). • Water percentage has a key role in the cyanide's recognition mechanism. • Recognition mechanism was investigated by IR soectroscopy. A novel chemosensor based on Nifuroxazide Cr(III) complex was developed for recognizing CN– over other tested anions e.g., F–, Cl–, Br–, I–, CH 3 COO–, NO 2 –, PO 4 3–, and SCN– in DMSO–H 2 O (9:1, v/v) and THF. Without any interference from the tested anions, UV–vis spectroscopy was used to investigate the recognition of CN–. The deprotonated species that resulted from the ionization of the phenolic group may be the cause of the color shift that occurred after adding CN– to the solution of the Cr(III) complex. The charge transfer interaction between the electron-donor unit and the electron-deficient nitro-furan moiety was improved as a result of the ionization of the phenolic group. The fact that the developed color vanishes in protic polar solvents e.g., H 2 O, CH 3 OH, and C 2 H 5 OH may lend credence to this assumption. The Lambert–Beer's law was obeyed in the concentration ranges of 3.4 × 10−3–3.4 × 10−5 M and 1.0 × 10−4–5.0 × 10−6 M in DMSO–H 2 O (9:1, v/v) and THF, respectively, reflecting the significant role of the solvent in controlling the sensitivity of the developed probe. The electronic transitions were investigated by executing time-dependent density functional theory calculations. [Display omitted] [ABSTRACT FROM AUTHOR]

[Co(FBZ) 2 (H 2 O)]·2NO 3 ·0.5H 2 O ( 1 ), [Ni(FBZ) 2 X 2 ]·zH 2 O (X = Cl ​− , z = 0.5 ( 2 ) and X = CH 3 COO − , z = 1 ( 3 )) and [Cu(FBZ) 2 (H 2 O) (NO 3 )]·NO 3 ·1.5H 2 O ( 4 ) (FBZ = methyl-5-(Phenylthio) benzimidazole-2-carbamate; Fenbendazole) complexes were synthesized and characterized by elemental analysis, thermal, IR, EPR, UV–Vis, magnetic and conductance measurements. Geometry optimization, molecular electrostatic potential maps and natural bond orbital analysis were carried out at DFT/B3LYP/6-31G ∗ level of theory. FBZ behaves as a neutral bidentate ligand via the pyridine-type nitrogen of the benzimidazole moiety and the carbamate group. Three-step ionization with pK a values of 3.38, 4.06 and 10.07 were reported for FBZ. The coordination of FBZ to the metal ions led to an increase in the antibacterial activity against the tested Staphylococcus aureus and Escherichia coli bacteria. [ABSTRACT FROM AUTHOR]

A simple, sensitive and rapid method was developed for the quantitative analysis of sparfloxacin in its pharmaceutical formulations through the formation of charge transfer complexes with π-acceptor systems. The Lambert–Beer’s law was obeyed in the concentration ranges of 7–70 and 10–50 μg/mL sparfloxacin for 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and tetracyanoquinodimethane. Structural characterization of the isolated solid CT complexes was carried out by IR, 1 H NMR, UV–Vis. and MS. The experimental studies were complemented by quantum chemical calculations at DFT level of theory. The electronic structures were investigated by TD-DFT calculations. Natural bond orbital analysis and molecular electrostatic potential maps were helpful in assigning the CT route. The formation constant, molar extinction coefficient, oscillator strength, dipole moment, standard free energy and ionization potential were calculated. [ABSTRACT FROM AUTHOR]

Abstract: Two new charge transfer complexes (L1,2 →DDQ; L1 =(1H-benzimidazol-2-ylmethyl)-N-phenyl amine, L2 =(1H-benzimidazol-2-ylmethyl)-(4-nitro-phenyl)-amine, and DDQ=2,3-dichloro-5,6-dicyano-1,4-benzoquinone) have been synthesized and characterized by a variety of physico-chemical techniques. The experimental studies were complemented by quantum chemical calculations at DFT/B3LYP level of theory. Electronic structures were investigated by TD-DFT method and the descriptions of frontier molecular orbitals and the relocation of the electron density were determined. Stability of the molecule arises from hyperconjugative interactions, charge delocalization and hydrogen bonding has been analyzed using natural bond orbital (NBO) analysis. 1H NMR chemical shifts were computed at B3LYP/6-311+G(2d,p) level of theory by Gauge-invariant atomic orbital (GIAO) in DMSO as a solvent using the polarizable continuum model (PCM). Photometric titration was carried out to shed more light about the stoichiometry of the formed complexes in the solution. Spectral data were analyzed in terms of formation constant, molar extinction coefficient, oscillator strength, dipole moment, standard free energy, and ionization potential. [Copyright &y& Elsevier]

Highlights: [•] The unit-cell of PQC is built by two molecules of different conformations. [•] DFT/B3LYP gives better agreement than HF method. [•] MCF7 cell line is more sensitive to PQC than HCT and HEPG2. [•] PQC has several sites for electrophilic attack. [•] The inclusion of solvation to NMR calculations is essential for acidic protons. [ABSTRACT FROM AUTHOR]

• Square-pyramidal Zn(II) azide complexes. • Based on TDDFT calculations, the lowest E transition is assigned to LLCT (N 3 →Terpy). • NBO analysis supported charge transfer from coordination sites toward Zn(II). • MEP maps showed that azido ligands have roles in the cycloaddition reaction. Square-pyramidal Zn(II) azide complexes with the formula of [Zn n (N 3) 2n L] (n = 1; L = 4′-(2-pyridyl)-2,2′:6′,2′'-terpyridine (LPy), 4′-(4-phenylmorpholine)-2,2′:6′,2′'-terpyridine (LMorph), and n = 2; L = 1,4- bis (2,2′:6′,2′'-terpyridin-4′-yl)benzene (LBPY)) were synthesized, and structurally characterized using different spectroscopic and analytical tools. Ground-state geometry optimization and harmonic vibrational analysis were carried out at two different levels of theory (B3LYP/LANL2DZ and CAM-B3LYP/def2-SVP) to gather insights into the local minimum structures. Natural bond orbital (NBO) analyses revealed that the electronic population of the 3d orbitals of Zn(II) ion is corresponding to the oxidation state of Zn(I), not Zn(II), in agreement with the ligand to metal charge transfer. Molecular electrostatic potential energy maps showed that the azido ligand may act as a nucleophile in the cycloaddition coupling with electron poor dipolar molecules. The electronic structure and transitions were investigated by executing time dependent density functional theory (TDDFT) calculations. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Comprehensive theoretical and experimental structural studies on N-(4,6-dimethyl-pyrimidin-2-yl)-4-[(2-hydroxy-benzylidene)-amino]benzenesulfonamide (SMS) have been carried out by elemental analysis, FT IR, 1H NMR, UV–Vis. and MS. Optimized molecular structure and harmonic vibrational frequencies have been investigated by DFT/B3LYP and HF methods combined with 6-31G(d) basis set. Stability of the molecule arises from hyperconjugative interactions, charge delocalization and intramolecular hydrogen bond has been analyzed using natural bond orbital (NBO) analysis. Electronic structures were discussed by TD-DFT method and the descriptions of frontier molecular orbitals and the relocation of the electron density were determined. 1H NMR chemical shifts were computed by Gauge-invariant atomic orbital (GIAO) method in both gas and DMSO media, using the polarizable continuum model (PCM). Structure–activity relationship has been used to correlate biological activity with some appropriate quantum descriptors such as E HOMO, E LUMO, energy gap, dipole moment (μ), global hardness (η), softness (S), electrophilicity index (ω), molecular polarizability (α), Mulliken electronegativity (χ), Mulliken charge (Qi ) and molecular electrostatic potential (MEP). [Copyright &y& Elsevier]

[MnLCl(H2O)3]·H2O complex (HL=4-amino-N-(4,6-dimethyl-2-pyrimidinyl)benzenesulfonamide, sulfamethazine) has been synthesized and characterized by elemental analysis, TG/DTA, MS, FT-IR, UV–Vis, magnetic, electrochemical, and X-ray powder diffraction. The experimental studies were complemented by quantum chemical calculations at DFT/B3LYP level of theory. Sulfamethazine behaves as a mono-negatively bidentate ligand and interacts with Mn(II) ion through sulfonamidic (N15) and pyrimidic (N23) nitrogen atoms. Electronic structures were investigated using TD-DFT method and the descriptions of frontier molecular orbitals and the relocation of the electron density were determined. The voltammogram of NaL shows one irreversible one-electron process due to oxidation of p-amino group, and one anodic peak characteristic of reduction of - SO2 group. The synthesized complex, in comparison to the parent drug, was screened for its antibacterial activity. [ABSTRACT FROM AUTHOR]

Abstract: (1H-benzimidazol-2-ylmethyl)-(4-methoxyl-phenyl)-amine (L1), (1H-benzimidazol-2-ylmethyl)-(4-methyl-phenyl)-amine (L2) and their Pd(II) and Pt(II) complexes have been synthesized as potential anticancer compounds and their structures were elucidated using a variety of physico-chemical techniques. Theoretical calculations invoking geometry optimization, vibrational assignments, 1H NMR, charge distribution and molecular orbital description HOMO and LUMO were done using density functional theory. Natural bond orbital analysis (NBO) method was performed to provide details about the type of hybridization and the nature of bonding in the studied complexes. Strong coordination bonds (LP(1)N11→σ*(Md (LP(1)N21→σ*(M=Pd or Pt) result from donation of electron density from a lone pair orbital on the nitrogen atoms to the acceptor metal molecular orbitals. The experimental results and the calculated molecular parameters revealed square-planar geometries around the metallic centre through the pyridine-type nitrogen of the benzimidazole ring and secondary amino group and two chlorine atoms. The activation thermodynamic parameters were calculated using non-isothermal methods. The synthesized ligands, in comparison to their metal complexes were screened for their antibacterial activity. In addition, the studied complexes showed activity against three cell lines of different origin, breast cancer (MCF-7), Colon Carcinoma (HCT) and human heptacellular carcinoma (Hep-G2) comparable to cis-platin. [Copyright &y& Elsevier]

• Acid dissociation constants fit well with Hammett constant. • Introduction of a substituent reduces the toxicity compared to the unsubstituted one. • Solvatochromism behaviour is mainly attributed to solvent dipolarity/polarizability. • Structural activity relationship is recognized by correlating toxicity to total energy. A series of (1H-benzimidazol-2-ylmethyl)-N-(4-phenyl)amine derivatives incorporating different electron-donating and withdrawing groups (X = 4 OCH 3 (1), 4 CH 3 (2), H (3), 4 Cl (4), and 4 Br (5)) on the para -position of the phenyl substituent was prepared, characterized and screened for their potential antimicrobial activity against some microbes. The substituent effect on the spectroscopic data (vibrational modes and NMR resonances) is well established by fitting with the Hammett constant. The unsubstituted derivative 4 exhibited comparable activity (MIC = 0.26 μM) to the standard tetracycline (MIC = 0.18 μM) against Staphylococcus aureus. Introduction of a substituent to the phenyl ring led to diminishing of the antibacterial activity. The substituent effect on the electron structure of 1–5 was investigated by TDDFT calculations. The acid dissociation constants of the ionizable NH group correlate well with Kubota's σ− parameter (R2 = 0.9196). The solvatochromism behavior of 1–5 , in solvents of different polarity and hydrogen-bond tendency, was investigated by linear solvation–energy relationship equation analysis. Correlation between various quantum chemical descriptors, and antibacterial activity was carried out to verify a structural activity relation for this series of benzimidazole derivatives. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• Sixteen compounds of novel benzylidene-quinazolinone hybrids derivatives were designed and synthesized. • The target compounds were tested in vivo for their anti-hyperglycemic effects against STZ-induced hyperglycemic rats. • In vitro α-glucosidase inhibitory activity was evaluated. • A homology model of α-glucosidase was built. • Molecular docking studies were carried out. A novel series of benzylidene-quinazolinone hybrids 8 a,b and 10 a-n were designed, synthesized, and evaluated for their in vitro α -glucosidase inhibitory effect aiming to discover efficient anti-diabetic agents. The synthesized compounds were assessed for their in vivo anti-hyperglycemic activities against STZ-induced hyperglycemic rats. Five compounds (10 m , 10 f , 10 c , 10 d and 8 b) demonstrated potent activities with percent reduction in blood glucose levels of 43.07, 40.14, 39.83, 37.04 and 36.16, respectively. The most active members were further evaluated in vitro for their α -glucosidase inhibitory binding affinities. Among them, Compound 10 m containing 4-hydroxybenzylidene moiety and compound 10 f with 4-chlorobenzylidene moiety connected to the acetohydrazide demonstrated the most potent inhibitory activities towards α -glucosidase with IC 50 values of 561 and 610 µM, respectively. Molecular docking study was performed in order to understand the molecular interactions between the molecule and enzyme. [ABSTRACT FROM AUTHOR]