Mass Spectral Studies Research Articles

2,2′-Bipyridine based biologically active mixed ligand metal(II) complexes: Synthesis, characterization, DFT and antioxidant studies

Mixed ligand [CoL(bpy)], [NiL(bpy)], [CuL(bpy)] and [ZnL(bpy)] complexes were synthesized from Schiff base ligand L, metal(II) acetates of Co, Ni, Cu and Zn with 2,2′-bipyridine (bpy). The synthesized compounds were characterized using molar conductance, elemental analyses, 1H-NMR, FTIR and mass spectral studies. The geometry of metal complexes has been assigned by magnetic moment analysis and UV-vis spectral techniques. The X-band ESR spectra of [CuL(bpy)] complex in DMSO were recorded at room temperature and liquid nitrogen temperature. Grain size of metal complexes was predicted using Powder XRD. Computational DFT studies were performed using Gaussian 6.0 program package. HOMO-LUMO of L, optimized geometry, bond angle and bond length calculations were preceded at B3LYP/GENECP level with 6-31G (d,p) basis sets. Antimicrobial and antioxidant activities of complexes were evaluated.

Synthesis and characterization of novel silane derivatives of phenothiazinium photosensitisers

Phenothiazine based dyes are widely explored dyes for their antibacterial and photosensitising applications. Despite their amazing optical and photosensitising (theranostic) properties, their usage in nanomedicine is very low compared to other organic dyes. This is due to the lack of reactive functional groups for encapsulating them into metal oxide nanoparticles. This work describes the synthesis of three different phenothiazinium alkoxysilane derivatives by oxidative amination of 10H-phenothiazine using amino alkoxysilanes. The new derivatives were characterized using NMR, FT-IR, DSC/TGA, and mass spectral studies. Optical and photosensitising properties (absorption spectrum, photostability, and singlet oxygen quantum yield) of the silane derivatives were investigated using UV–Visible spectroscopy. These compounds are suitable for conjugation with silica in the sol-gel synthesis of silica nanoparticles and silica surface coaters, which will reduce dye leakage and improve the dye efficacy in the treatment of cancer and light activated antimicrobial surfaces.

A NEW MICROWAVE-ASSISTED METHOD FOR THE SYNTHESIS OF 2-SUBSTITUTED-THIAZOL-4(5H)-ONE VIA HANTZSCH CONDENSATION

A new microwave-assisted method is developed for the synthesis of 2-substituted-thiazol-4(5H)-ones via Hantzsch condensation by a simple experimental protocol without using any catalyst. The products were isolated in excellent yield without any purification. Synthesized compounds were characterized by applying FTIR, 1H NMR, 13C NMR, and mass spectral studies and a plausible mechanism is proposed for the formation of the product. The method is versatile for the preparation of a new class of 2-substituted-thiazol-4(5H)-ones.

SYNTHESIS, SPECTRAL CHARACTERIZATION, BIOLOGICAL ACTIVITY OF MACROCYCLIC LIGANDS AND METAL COMPLEXES DERIVED FROM 3,4- DIAMINOBENZOPHENONE AND DIKETONES

A mononuclear macrocyclic ligand and its Co(II), Ni(II), Cu(II) and Zn(II) complexes were made from3,4- Diaminobenzophenone with Diketones such as Dibenzoylmetthane, 5-Chloroisatin and Metal Chloride salts. They were analyzed by Infrared Spectroscopy, Electronic Spectroscopy, NMR Spectroscopy (1H&13CNMR), CHN analysis, magnetic moment conductivity, Mass spectral studies and SEM analysis. An octahedral and distorted octahedral structure is suggested for the complexes, where two coordination sites are occupied by chloride ions and the other four by tertiary amines. The complexes show higher antimicrobial activity in comparison with the ligand.

Synthesis and Structural Characterization of Process Related Impurities of Mirabegron: A Beta-3 Adrenergic Agonist Drug

In the synthesis of active pharmaceutical ingredient and the development of pharmaceutical products, the impurities profiling plays a significant role. The control of impurities is essential for producing the quality, safe and efficient drug products for therapeutic use. Few works reported for the synthesis of potential impurities and further characterized to support the synthesis route and purity of the synthesized compound. Hence in present study, five impurities of mirabegron such as impurity 3, 4, 6, 8 and 9 were synthesized and structural characterization was carried using NMR, IR and mass spectral studies. Based on the results, it was confirmed that the route of synthesis established in the study was simple, convenient and economical and can be useful for the products of potential impurities of mirabegron. By characterizing each of these impurities, the regulatory need has been met. Additionally, the analytical method development and validation studies have utilized the generated impurity standards. This effort helped with the process development’s optimization stage and made it possible to identify the crucial parts of the process. The production method for mirabegron was carefully adjusted to eliminate or reduce the formation of impurities, which is helpful for the creation of safe pharmaceutical goods.

Mononuclear Manganese(IV) Complexes Derived from Polyfunctional Fumaryldihydrazone

A series of mononuclear manganese(IV) complexes of disalicylaldehyde fumaroyldihydrazone (slfhH4) were synthesized by reacting manganese acetate tetrahydrate with dihydrazone in absence and presence of various pyridine bases in methanol medium. Pyridine (py) and its derivatives like 2-picoline (2-pic), 3-picoline (3-pic), 4-picoline (4-pic), 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) were added to the reaction mixture of metal salt and dihydrazone to explore the binding possibilities of these molecules to manganese center. The elemental analysis, mass spectral and thermal studies were used to derive their composition. Study of magnetic moment, molar conductances, electronic, EPR and infrared spectroscopy have led to interpretation of their tentative structures. Magnetic moment and EPR studies correspond to their Mn(IV) oxidation state. The dihydrazone functions as tetradentate ligand chelating the manganese(IV) ion present in octahedral geometry with anti-cis configuration in enol form. Electrochemical and antimicrobial studies were also performed.

Phytochemical Analysis, Tuberculosis Effect, Purification and Characterization of Aerial Parts of Avicennia alba

The present study deals with phytochemical, pharmacological (In vitro antioxidant), purification and characterization studies of aerial parts of Avicennia alba. The phytochemical analysis for qualitative and quantitative investigation revealed the presence of more bioactive compounds in methanolic extract than hexane and chloroform extracts of Avicennia alba. The methanolic extract showed better activity on 2,2-diphenyl-1-picrylhydrazyl free radical than remaining free radical tests i.e hydrogen peroxide and hydroxyl radical. The methanolic extract was potent in inhibiting the free radicals upon comparison with standard ascorbic acid. The tuberculosis effect of the plant was not up to the mark when compared with standard control. The methanolic plant extract was subjected to column chromatography and three compounds were isolated. The isolated compounds were characterized by ultraviolet, fourier transform infrared spectroscopy, proton nuclear magnetic resonance, carbon nuclear magnetic resonance and mass spectral data studies and were identified as stigmasterol, beta-sitosterol and lupeol. The work carried out was distinctive as the source of plant was taken from coringa mangrove, Kakinada, first of its kind and the tuberculosis effect was also reported for the first time, though it was not up to the mark the work reported inspires the researcher to enlighten and save their time. The natural compounds selected were reported previously but an in depth characterization was reported for a thorough look.

Synthesis, characterization and molecular docking studies of acetamide derivatives of 2-aminothiazole and 2-dihydropyridinone derivative of benzimidazole

An efficient and easy synthesis of highly functionalized thiazole and pyridinone-substituted benzimidazole derivatives has been developed. The imino carbon of the benzimidazole derivative is coupled with the nitrogen atom of 1,4-dihydropyridinone and the aminothiazole-substituted acetic acid is condensed with two differently functionalized aniline, in two different reactions to form the amide linkages. These two amides and pyridinone-coupled benzimidazole are characterized by IR, 1H & 13C NMR and mass spectral studies. They are further evaluated for their antibacterial activity against the gram-positive bacterium Staphylococcus epidermidis and the fungus Saccharomyces cerevisiae by molecular docking method. All the three synthesized compounds had relatively lesser binding energy than what the standard drugs chloramphenicol and fluconazole have and may be considered as better inhibitors.

SYNTHESIS, POLAROGRAPHIC AND ANTIMICROBIAL STUDIES OF BENZISOXAZOLYLN- GLUCOSIDES

The desired compounds 7-amino-3-methyl-5-(3′-aryl prop-2′-enoyl)-1,2-benzisoxazoles 2a-j were prepared by the reaction of appropriate 5-acetyl-7-amino-3-methyl-1,2-benzisoxazole 1 with different aromatic aldehydes. The reaction of (2a-j) with hydroxylamine hydrochloride was done to form 7-amino-3-methyl-5-(3′-aryl isoxazol-5′-yl)-1,2- benzisoxazoles (3a-j). Condensation of tetra-O-acetyl-α-D-glucopyranosyl bromide (TAGBr) with 7-amino-3-methyl-5- (3′-aryl isoxazol-5′-yl)-1,2-benzisoxazoles furnishes 7-amino-(β-D-2,3,4,6-tetra-O-acetyl glucopyranosyl)-3-methyl-5- (3′-aryl isoxazol-5′-yl)-1,2-benzisoxazoles (4a-j) which on deprotection yielded 7-amino-(β-D-glucopyranosyl)-3- methyl-5-(3′-aryl isoxazol-5′-yl)-1,2-benzisoxazoles (5a-j). The identities of newly synthesized compounds were established on the basis of IR, 1HNMR, 13CNMR, Mass spectral, Elemental analysis, TLC, and Polarographic studies. All compounds have been evaluated for antimicrobial activities and some compounds show potent activities.

Spectral, antimicrobial and anticancer activity of E-4-{[(5-bromothiophen-2-yl)methylidene]amino}-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one

A Schiff base E-4-{[(5-bromothiophen-2-yl)methylidene]amino}-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4ATP) has been synthesized by condensation 5-bromothiophene-2-carboxaldehyde with 4-amino antipyrine by condensation. The compound crystallized in the monoclinic system (P2 1 /n) with E-configuration at azomethine C = N bond. The Hirshfeld surface analysis and crystal structure data confirm the intramolecular hydrogen bonding interaction (C-H…O: 2.963 Å) in a conjugated six-membered cyclic structure. The IR, Raman, 1H NMR, 13C NMR and mass spectral studies have been interpreted based on the crystal structure data. The compound is more effective in its cytotoxic activity for the A549 cell line than that of Vero cells.

DEVELOPMENT OF FORCED DEGRADATION STUDIES OF FAVIPIRAVIR BY RP-HPLC

Forced degradation studies and stability indicating method were developed for the estimation of Favipiravir by reverse phase High performance liquid chromatography in active Pharmaceutical ingredient and its tablet dosage form. The method was achieved by using C18 column (250 X 4.6mm X 4µm) with mobile phase mixture ortho phosphoric acid and acetonitrile in the ratio 60:40. The mobile phase was allowed to pump with the flow rate 1ml/min by maintaining detection wavelength at 324nm using ultra-violet detector. Favipiravir drug was subjected to various stress conditions according to International Conference of Harmonization Q1A(R2) guidelines to establish stability indicating method. Favipiravir drug was found to be sensitive at peroxide degradation. The impurity peak was characterized by mass spectral studies. The method was validated for analytical standards such as linearity, accuracy, Precision, sensitivity and robustness. A rapid and sensitive method was developed for the estimation of favipiravir which indicates its stability indicating behavior.

Synthesis, characterization of novel coumarin dyes as corrosion inhibitors for mild steel in acidic environment: Experimental, theoretical, and biological studies

The new azo acetyl coumarin derivatives were synthesized and characterized using Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR) and mass spectral studies. The ability for these three dyes to act as corrosion inhibitors for mild steel in 1.0 M HCl was confirmed by potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). The state of mixed adsorption with the PP effect is shown. The azo acetyl coumarin derivatives showed the strongest corrosion inhibition of 85.29–93.01% at a corrosion of 7.5 × 10−4 M. Adsorption of the inhibitory molecules on the mild steel surface followed Langmuir adsorption isotherm. The adsorption phenomenon was verified using UV–Vis, scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) technique, whereas FTIR confirmed the presence of several functional groups containing heteroatoms. Also, quantum chemical parameters, inductively coupled plasma atomic emission spectroscopy, and the anti-bacterial effect of these new derivatives against sulfate reducing bacteria (SRB) were studied. All obtained results ensure that these derivatives can form an effective blocking layer and control the corrosion process.

Spectroscopic profiling and molecular docking of novel chalcone derivative (2E)-1-(3,4-dimethoxyphenyl)-3-(4-n-propyloxyphenyl)-2-propen-1-one- A prospective respiratory drug

The present study explores the wide potent applications of an organic pharmacophore (2E)-1-(3,4-dimethoxyphenyl)-3-(4-n-propyloxyphenyl)-2propen-1-one(DMPP)using experimental and theoretical analysis for the design of prospective respiratory drugs using docking simulations for virtual screening with different strategies. The theoretical analysis was done using Gaussian 09Wsoftware. Optimized geometry, vibrational frequencies were deduced from B3LYP/6–311++G(d,p) basis set. To understand the structure and functional groups of DMPP, UV–Vis, FT-Raman, FT-IR and NMR, ESI-HR mass spectral analysis spectral studies was compared in solid phase and gas phase and found to be in good accord with each other. Fukui functions, Electron Localization Function (ELF) and Localized Orbital Locator (LOL) were studied to diagnose the most active reactive sites of DMPP. Natural Bond Orbital (NBO) and AIM (Atoms Inside Molecule) analysis revealed the inner stability of the compound under investigation. The in vitro and virtual screening of DMPP discloses worthy cytotoxic behavior against normal (VERO) cell lines and anticancer activity with A549-Human Lung cancer cell line, and also proclaims good response against COVID-19 virus. In comparison with the standard clinical trials, the obtained results unveil that the crystalline organic compound is a new material with promising results via molecular docking studies. Thus the diverse methods used in the present study proves the effectiveness of DMPP to be suitable for a respiratory drug where extended in vitro and in vivo research has to be extended towards clinical trials.

Development of an ‘OFF-ON-OFF’ colorimetric and fluorometric pH sensor for the study of physiological pH and its bioimaging application

2-hydroxyl-1-naphthaldehyde based probe 1,1′((1E,1′E)((4hydroxy1,3phenylene) bis(azanylylidene)bis(methanylylidene)bis(naphthalen-2-ol) (NAP) has been synthesized and thoroughly characterized by IR, 13C & 1H NMR, fluorescence, UV-Vis, and mass spectral studies. The detection of pH is a necessary feature of the intracellular atmosphere and probably affects all cellular systems. NAP acts as a highly sensitive pH sensor in ethanol/HEPES (7:3, v/v) medium. Upon increasing the pH of NAP solution from acidic-neutral-basic medium, a distinct color change occurs from colorless-yellow-brown followed by a subsequent bathochromic shift in UV-Vis spectra and fluorescence response from ‘OFF-ON-OFF’. Photo-induced electron transfer (PET) mechanism has been proposed for the fluorescence change on the basis of theoretical studies on protonated, neutral and deprotonated NAP. Bioimaging investigations display a pH dependent fluorescence behavior of NAP in gut tissue of drosophila 3rd instar larvae. Additionally, NAP paper strips have been successfully developed for solid state pH sensing based on colorimetric and fluorescence responses.

SYNTHESIS, BIOLOGICAL STUDY, DNA INTERACTION OF MANNICH BASE METAL COMPLEXES DERIVED FROM BENZAMIDE

Objective: Coordination compounds occur widely in nature and they comprise a large share of current inorganic research. The Mannich reaction is a classic method for the preparation of Mannich bases, namely, β amino compounds, which are heterocyclic.
 Methods: A novel Mannich base of N-((3,4-dimethoxyphenyl)(2,5-dioxopyrrolidin-1-yl) methyl)benzamide and its coordination complexes with transition metals Mn and Co have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, UV-Visible, IR, NMR, and Mass spectral studies.
 Results: Based on the magnetic moment and UV-Visible spectral data, octahedral geometries were assigned for the metal complexes. The metal complexes were screened for antifungal activity.
 Conclusion: the metal complexes have shown good activity than the ligand. The binding of selected metal complexes with calf thymus DNA was investigated. It is found that the cobalt (II) metal complex of the ligand showed efficient DNA binding ability.

STRUCTURE-BASED MULTITARGETED MOLECULAR DOCKING ANALYSIS OF PYRAZOLE-CONDENSED HETEROCYCLICS AGAINST LUNG CANCER

Objective: The significant drawbacks of chemotherapy are that it destroys healthy cells, resulting in adverse effects. Hence, there is a need to adopt new techniques to develop cancer-specific chemicals that target the molecular pathways in a non-toxic fashion. This study aims to screen pyrazole-condensed heterocyclics for their anticancer activities and analyse their enzyme inhibitory potentials EGFR, ALK, VEGFR and TNKS receptors. Methods: The structures of the compounds were confirmed by IR, NMR and Mass spectral studies. The in silico techniques applied in this study were molecular docking and pharmacophore modeling to analyse the protein-ligand interactions, as they have a significant role in drug discovery. Drug-likeness properties were assessed by the Lipinski rule of five and ADMET properties. Anticancer activity was performed by in vitro MTT assay on lung cancer cell lines. Results: The results confirm that all the synthesised pyrazole derivatives interacted well with the selected targets showing docking scores above-5 kcal/mol. Pyrazole 2e interacted well with all the four lung cancer targets with its stable binding mode and was found to be potent as per the in vitro reports, followed by compounds 3d and 2d. Pharmacophore modeling exposed the responsible features responsible for the anticancer action. ADMET properties reported that all the compounds were found to have properties within the standard limit. The activity spectra of the pyrazoles predicted that pyrazolopyridines (2a-2e) are more effective against specific receptors such as EGFR, ALK and Tankyrase. Conclusion: Thus, this study suggests that the synthesised pyrazole derivatives can be further investigated to validate their enzyme inhibitory potentials by in vivo studies.

Synthesis, Crystal Structure, Biological Evaluation, DFT Calculations and Third Order Nonlinear Optical Studies of Pyrazolines

• Synthesis of a novel series of pyrazolines. • Chemical structures were confirmed by crystal study and spectral techniques. • In-silico and anticancer properties of compounds were tested against MCF-7 and HCT116 cell lines. • DFT computational studies were carried out to understand structural, absorption, and first static hyperpolarizability properties. • NLO properties were studied using open/closed aperture z-scan techniques. Novel pyrazoline derivatives were synthesized and characterized by FTIR, NMR, UV-visible, and mass spectral studies. All the synthesized compounds 6a-f were screened for anticancer activity against MCF-7 and HCT 116 cell lines via SRB assay. Among the synthesized pyrazolines 6b and 6f showed appreciable anticancer activity. The molecular docking study was done with two proteins (PDB No: 1M17 and 5ZTO) to study the binding interactions of the compounds with proteins. ADME study showed that the compounds exhibited drug-likeness properties, following Lipinski's rule of five. The molecular structure of compound 6b was studied using the single-crystal X-ray diffraction method. The structural, absorption and first static hyperpolarizability properties of the compound 6b were studied using density functional theory (DFT) calculations. The experimental data and calculated FTIR and UV-visible spectral data are in good agreement. The third order nonlinear optical properties were studied using open and closed aperture z-scan techniques. The compound 6b showed nonlinear absorption ( β ) of 1.94 × 10 − 11 m/W at intensity ( I 0 ) is 4.49 GW / c m 2 . Third order nonlinear susceptibility is of the order of 10 −12 esu and this indicates the molecule has the potential to be used in nonlinear optical device applications.

SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY OF MIXED LIGAND COMPLEXES OF INNER TRANSITION METAL WITH L-ASCORBIC ACID, ITS DERIVATIVE AND ADENINE BASE

Complexes of La(III), Ce(III), Nd(III) and Gd(III) with mixed Ligand of 2-aminopurene and L-ascorbic acid derivative were prepared in aqueous ethanol. The two types of mixed ligand complexes [M(AA)(ADE)(H2O)2]+and [M(IPAA) (ADE)(H2O)2]+ have been synthesized. All complexes were characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility measurements, IR, UV-VISSIBLE, NMR, ESR and Mass spectral studies. IR spectra of the complexes reveal that the complex formation occurred through both nitrogen and oxygen atoms. On the basis of electronic spectral data and magnetic susceptibility measurement octahedral geometry has been proposed for the complexes. The ESR spectral data of the M (III) complexes showed that the metal-ligand bonds have considerable covalent character. The electrochemical behaviour of mixed Ligand M(III) complexes was studied which showed that complexes of IPAA appear at more positive potential as compared to those for corresponding AA complexes. In addition, biological activity of the synthesised metal complexes against Salmonella typhi, Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae bacteria and Aspergillus niger, Aspergillus flavus, Fusarium oxisporium and Trichoderma viride fungi respectively were examined in-vitro. Some of the metal complex displayed pounced biological activity.

Synthesis, biological–pharmacological evaluation and molecular docking studies of Schiff base analogues of transition metal (II) complexes of 4-amino-1,5-dimethyl-2-phenylpyrazol-3-one

Novel tridentate Schiff base [CuL2], [NiL2], [CoL2], [MnL2] and [ZnL2] complexes have been prepared with Schiff base resulting from acetophenylidene-4-iminoantipyrine and tyrosine. Microanalytical data, IR, UV–vis, 1H, 13C-NMR, powder XRD, SEM, cyclic voltammetry, ESR, and mass spectral techniques confirmed the structural features of the chelates. The general formula of the complexes [ML2] was confirmed from elemental analysis, mass and 1H-NMR spectral studies. Octahedral geometry of the chelates is confirmed by electronic absorption spectra and FT-IR spectra. The magnetic susceptibility and low conductance values reveal that the complexes are monomeric and non-electrolytic nature, respectively. Powder XRD and SEM images confirm the crystalline structure of the complexes. At 300 and 77 K, the X-band ESR spectra of [CuL2] complex in DMSO solution were recorded and their salient features have been reported. The binding of [CuL2] with CT-DNA study reveals that interactions occur through intercalation. Analgesic, anti-inflammatory and CNS activities and antimicrobial activities of Schiff base and its complexes reveal that the chelates have higher potent than free ligand. The molecular docking studies have been performed with DNA and 6COX enzyme using Hex 8.0 software which recognizes the biological activities and nature of binding of the complexes. Communicated by Ramaswamy H. Sarma

Synthesis of Novel Substituted Piperazin-1-yl-7H-Pyrrolo[2,3-d] Pyrimidines for C-N Bond Formation via Buchwald Hartwig Coupling Reaction

The formation of C-N bonds is an essential step in the synthesis of many pharmaceutical drugs. In the present study, diversified novel substituted Piperazin-1-yl-7H-pyrrolo[2,3-d] pyrimidines are synthesized via Buchwald Hartwig coupling reaction using Tetrakis(triphenylphosphine)palladium(0) as a catalyst and cesium carbonate as a base. All the synthesized compounds were purified by a simple workup procedure and without column chromatography. All these compounds demonstrated a good to excellent yield and were characterized by 1H NMR, 13C NMR, DEFT-135 NMR, FT-IR, Elemental analysis (CHNS) and Mass spectral studies.