C. S. Chidan Kumar

Structural Correlation of Some Heterocyclic Chalcone Analogues and Evaluation of Their Antioxidant Potential

A series of six novel heterocyclic chalcone analogues 4(a–f) has been synthesized by condensing 2-acetyl-5-chlorothiophene with benzaldehyde derivatives in methanol at room temperature using a catalytic amount of sodium hydroxide. The newly synthesized compounds are characterized by IR, mass spectra, elemental analysis and melting point. Subsequently; the structures of these compounds were determined using single crystal X-ray diffraction. All the synthesized compounds were screened for their antioxidant potential by employing various in vitro models such as DPPH free radical scavenging assay, ABTS radical scavenging assay, ferric reducing antioxidant power and cupric ion reducing antioxidant capacity. Results reflect the structural impact on the antioxidant ability of the compounds. The IC50 values illustrate the mild to good antioxidant activities of the reported compounds. Among them, 4f with a p-methoxy substituent was found to be more potent as antioxidant agent.

Heteroaryl Chalcones: Design, Synthesis, X-ray Crystal Structures and Biological Evaluation

Chalcone derivatives have attracted increasing attention due to their numerous pharmacological activities. Changes in their structures have displayed high degree of diversity that has proven to result in a broad spectrum of biological activities. The present study highlights the synthesis of some halogen substituted chalcones 3(a–i) containing the 5-chlorothiophene moiety, their X-ray crystal structures and the evaluation of possible biological activities such as antibacterial, antifungal and reducing power abilities. The results indicate the tested compounds show a varied range of inhibition values against all the tested microbial strains. Compound 3c with a p-fluoro substituent on the phenyl ring exhibits elevated antimicrobial activity, whereas the compounds 3e and 3f displayed the least antimicrobial activities. The compounds 3d, 3e, 3f and 3i showed good ferric and cupric reducing abilities, and the compounds 3b and 3c showed the weakest reducing power in the series.

FT-IR, molecular structure, first order hyperpolarizability, HOMO and LUMO analysis, MEP and NBO analysis of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate

2-(4-Chlorophenyl)-2-oxoethyl 3-nitrobenzoate is synthesized by reacting 4-chlorophenacyl bromide with 3-nitrobenzoic acid using a slight excess of potassium or sodium carbonate in DMF medium at room temperature. The structure of the compound was confirmed by IR and single-crystal X-ray diffraction studies. FT-IR spectrum of 2-(4-chlorophenyl)-2-oxoethyl 3-nitrobenzoate was recorded and analyzed. The crystal structure is also described. The vibrational wavenumbers were computed using HF and DFT methods and are assigned with the help of potential energy distribution method. The first hyperpolarizability and infrared intensities are also reported. The geometrical parameters of the title compound obtained from XRD studies are in agreement with the calculated (DFT) values. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. MEP was performed by the DFT method.

Molecular structure, FT-IR, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 2-(4-chlorophenyl)-2-oxoethyl 3-methylbenzoate by HF and density functional methods.

2-(4-Chlorophenyl)-2-oxoethyl 3-methylbenzoate is synthesized by reacting 4-chlorophenacyl bromide with 2-methylbenzoic acid using a slight excess of potassium or sodium carbonate in DMF medium at room temperature. The structure of the compound was confirmed by IR and single-crystal X-ray diffraction studies. FT-IR spectrum of 2-(4-chlorophenyl)-2-oxoethyl-3-nitrobenzoate was recorded and analyzed. The crystal structure is also described. The vibrational wavenumbers were computed using HF and DFT methods and are assigned with the help of potential energy distribution method. The first hyperpolarizability and infrared intensities are also reported. The geometrical parameters of the title compound obtained from XRD studies are in agreement with the calculated (DFT) values. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. MEP was performed by the DFT method.

Synthesis and Crystal Structure Studies of Novel 4-Tosyloxychalcone Derivative

4-Tosyloxychalcone derivative, C23H20O4S, was synthesized and characterized by infrared and 1H NMR spectral studies. Grown crystal was further characterized by single crystal X-ray diffraction studies. The compound crystallizes in monoclinic space group C2/c with unit cell parameters a = 33.431 (6) Å, b = 5.8451 (10) Å, c = 21.439 (4) Å, Z = 8, and V = 3848.2 (12) Å3. The crystal packing is mainly stabilized by C—H…π interaction. There are no significant intermolecular interactions beyond van der Waals forces observed in the solid state structure of the compound.

Synthesis, molecular structure, FT-IR and XRD investigations of 2-(4-chlorophenyl)-2-oxoethyl 2-chlorobenzoate: a comparative DFT study

2-(4-Chlorophenyl)-2-oxoethyl 2-chlorobenzoate has been synthesized, its structural and vibrational properties have been reported using FT-IR and single-crystal X-ray diffraction (XRD) studies. The conformational analysis, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the synthesized compound (C15H10Cl2O3) have been examined by means of Becke-3-Lee-Yang-Parr (B3LYP) density functional theory (DFT) method together with 6-31++G(d,p) basis set. Furthermore, reliable conformational investigation and vibrational assignments have been made by the potential energy surface (PES) and potential energy distribution (PED) analyses, respectively. Calculations are performed with two possible conformations. The title compound crystallizes in orthorhombic space group Pbca with the unit cell dimensions a=12.312(5) Å, b=8.103(3) Å, c=27.565(11) Å, V=2750.0(19) Å(3). B3LYP method provides satisfactory evidence for the prediction of vibrational wavenumbers and structural parameters.

Benzofuranyl Esters: Synthesis, Crystal Structure Determination, Antimicrobial and Antioxidant Activities

A series of five new 2‐(1‐benzofuran‐2‐yl)‐2‐oxoethyl 4-(un/substituted)benzoates 4(a–e), with the general formula of C8H5O(C=O)CH2O(C=O)C6H4X, X = H, Cl, CH3, OCH3 or NO2, was synthesized in high purity and good yield under mild conditions. The synthesized products 4(a–e) were characterized by FTIR, 1H-, 13C- and 1H-13C HMQC NMR spectroscopic analysis and their 3D structures were confirmed by single-crystal X-ray diffraction studies. These compounds were screened for their antimicrobial and antioxidant activities. The tested compounds showed antimicrobial ability in the order of 4b < 4a < 4c < 4d < 4e and the highest potency with minimum inhibition concentration (MIC) value of 125 µg/mL was observed for 4e. The results of antioxidant activities revealed the highest activity for compound 4e (32.62% ± 1.34%) in diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 4d (31.01% ± 4.35%) in ferric reducing antioxidant power (FRAP) assay and 4a (27.11% ± 1.06%) in metal chelating (MC) activity.

Synthesis, spectroscopic characterization, electronic and optical studies of (2Z)‐5,6‐dimethyl‐2‐[(4‐nitrophenyl)methylidene]‐2,3‐dihydro‐1‐benzofuran‐3‐one

The title compound, (2Z)‐5,6‐dimethyl‐2‐[(4‐nitrophenyl) methylidene]‐2,3‐dihydro‐1‐benzo furan‐3‐one, has been synthesized and characterized using experimental (XRD) and theoretical methods (FTIR, NMR, electronic and optical studies). The compound crystallizes in monoclinic space group P21/c with a = 7.527 (7) A, b = 15.9397(15) A, c = 13.5106 (10) A, β = 117.649 (4)° and Z = 4. The initial coordinate geometry obtained by XRD is further used to obtain the optimized ground state geometry of the title compound using DFT/B3LYP/6-311++G (2d,2p) level of theory. Geometrical parameters, vibration frequencies, Gauge invariant atomic orbital (GIAO) 1H and 13C NMR chemical shifts of the title compound have been calculated theoretically using the optimized ground state geometry. Apart from this, density of states of different atoms, band gap studies and optical properties have also been studied successfully using theoretical models.

(2E)-1-(3-Bromo­phen­yl)-3-(4,5-dimeth­oxy-2-nitro­phen­yl)prop-2-en-1-one

In the title compound, C17H14BrNO5, the dihedral angle between the 3-bromo-substituted benzene ring and the 4,5-dimethoxy-2-nitro-phenyl ring is 15.2 (1)°. The dihedral angles between the mean plane of the propenone group and the mean planes of the 3-bromo-substituted benzene and 4,5-dimethoxy-2-nitrophenyl rings are 6.9 (6) and 20.5 (5)°, respectively. Weak intermolecular C—H⋯O interactions contribute to crystal stability and π–π interactions [centroid–centroid distances = 3.7072 (18) and 3.6326 (18) Å] are also observed.

Spectroscopic (FT-IR, 1H, 13C NMR and UV–vis) characterization and DFT studies of novel 8-((4-(methylthio)-2,5-diphenylfuran-3-yl)methoxy)quinoline

In this study, computational calculations of a new quinoline derivative: 8-((4-(methylthio)-2,5-diphenylfuran-3-yl)methoxy)quinoline is carried out using ab initio methods. The geometry optimization as well as fundamental frequencies of the most stable configuration of the title compound is reported. A detailed study of Infrared spectrum, chemical shifts and electronic spectrum of the title compound is also presented. The Gauge-Invariant Atomic Orbital approach is used to calculate the proton and carbon chemical shifts of the title compound. The natural bond orbital analysis of the title compound is also reported in order to understand the stability of the molecule which arises from hyper conjugative interactions and charge delocalization. The theoretical electronic absorption spectrum is also reported using the time dependent density functional approach. The molecular structure along with vibrational frequencies as simulated for binding of iron with the title compound is also reported using ab initio methods.