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Background: Small molecule compounds are docked into receptor binding sites and the binding affinity of the complex is calculated using the structure-based drug design technique. Precise and quick docking processes, as well as the capacity to examine binding geometries and interactions, are required for a full knowledge of the structural principles that influence the strength of a protein/ligand complex. The present work deals with in-silico molecular docking studies of some heterocyclic compounds such as benzoxazole, benzimidazole, imidazole and tetrazole against the EGFR tyrosine kinase receptor. Methodology: Molecular docking studies of some heterocyclic compounds such as benzoxazole, benzimidazole, imidazole and tetrazole against the EGFR tyrosine kinase receptor using Schrodinger LLC (Maestro 9.2) software. Results: Our in silico observations reveal that, all the selected heterocyclic compounds (1-8) show good binding interaction and good docking score against selected target enzyme. Out of eight compounds selected for the study two compounds compound 3 and 7 shows higher glide score. Compound 3 binded to ASP855 with a docking score of −11.20 kcal/mol. Compound 7 binded to ASP855 with a docking score of −11.56kcal/mol. Conclusion: Docking results revealed that compounds (1-8) interact with EGFR kinase receptor active site. Among the compounds, compound 7 has shown the highest glide score of -11.56 kcal/mol.

Benzoxazole compounds have an important and broad range of biological activities. The benzoxazole and its substituted derivatives possess antimicrobial, antitumor, anti-inflammatory, antihistaminic, anti-parasitic, herbicidal, anti-allergic, anti-helmintic, anti-tubercular, anticonvulsant, hypoglycaemic, HIV-1 reverse transcriptase inhibitor and insecticidal activities. It has also been shown to have a binding affinity to Aβ42 fibrils. Such complex biological uses of benzoxazole compounds have inspired new efforts to find new derivatives with improved biological activity and different applications in the pharmaceutical industry. Due to outstanding relevance of this structure, the purpose of this analysis is to highlight aspects published in recent years (2000-2020) on the chemistry and biological activity of benzoxazoles.

2,4-Dimorpholino-4-yl-6-(4-nitrophenoxy)-[1,3,5]-triazine (DMNT) was synthesized and the molecular structure and vibrational frequencies were studied by density functional theory (DFT) method. The functional used was Becke’s three parameter exchange functional combined with the Lee-Yang-Parr correlation (B3LYP) and the standard basis set was 6-31G(d) for all atoms. The Fourier Transform-Infra Red (FT-IR) and FT-Raman spectra of DMNT were recorded and complete assignments of the observed vibrational frequencies are done. The assignments were confirmed by isotopic labelling. The structural parameters, harmonic vibrational frequencies, IR intensities and Raman intensities of DMNT in the ground-state were also computed. Non-linear optical behaviour of DMNT was analysed by examining the properties like electric dipole moment, polarizability and hyperpolarizability. Molecular properties such as ionization potential, electro-negativity, chemical potential and chemical hardness were obtained from molecular orbital analysis. Hyper conjugative interaction and charge delocalization taking place in DMNT was confirmed by Natural bond analysis studies. UV-Vis spectrum of DMNT was also recorded to understand the electronic properties. Graphical Abstract

Bismuth based nanoparticles (BBNs)exhibit immense potential due to unique physico chemical properties, therefore extensively applied in diverse technologies. On this account, a great deal of attention is being devoted to green synthesizing BBNs, which is an environmentally safe process, non-toxic, and stable, with a wide range of nanoscale production options. This review emphasizes the importance of green approaches for synthesizing BBNsusing bio extracts derived from plants and microorganisms. The selection of precursors, reducing agents, coating agents, solvents, quantity evaluation, and experimental conditions are all discussed in this review elaborately. Also,a consolidative account ona diverse range of applications of BBNsisbeing highlighted, along with recent breakthroughs of green synthetic technology based onthe knowledge of mechanism routes that have been available in the recent literature. Since review articles are often central points for beginners, this report leads readers to the articles that highlight the noteworthy advancement in the field of BBNs research. The goals of this study are to (i) outline advanced bismuth-based compounds that have been used to date, (ii) describe drawbacks in synthetic strategy and possible solutions, and (iii) make recommendations for future research.

The Fourier-transform infrared spectroscopy (FT-IR) spectrum of 2,4-dichloro-N-phenethylbenzenesulfonamide (DPBS) was obtained and the compound was studied theoretically. The optimized geometry, total electronic energy and vibrational wavenumbers of DPBS were examined using Hartree–Fock (HF) and density functional theory (DFT) method such as B3LYP, BP86 and M06 functionals with the basis set of 6-311++G(d,p) for all atoms. A complete vibrational assignment was studied for DPBS. The molecular orbital energies, polarizability and thermodynamic properties of DPBS were also computed. Analysis of molecular orbitals reveals the parameters such as chemical potential, chemical hardness and electrophilicity index. The molecular properties such as electric dipole moment µ, polarizability α, and hyperpolarizability β reveal the non-linear optical (NLO) property of DPBS. Natural bond analysis study reveals charge delocalization of the molecule. The experimental and computational results are found to have good agreement among themselves. The results of this work will pave the way for further insight in the study of the applications of DPBS.Graphical Abstract

In the title compound, C17H21NO4S, the phenyl and dimethoxyphenyl rings are almost perpendicular to each other, making a dihedral angle of 82.57 (5)°. The structure is stabilized by intermolecular C—H...O interactions and the packing is further enhanced by C—H ...π interactions.

Department of Physics, Panimalar Institute of Technology, Chennai 602 103, India, Department of Physics, SRM University, Kattankulathur Campus, Chennai 603 203, India, Department of Physics, Easwari Engineering College, Ramapuram, Chennai 600 089, India, Department of Chemistry, SRM University, Ramapuram Campus, Chennai 600 089, India, and Department of Research and Development, PRIST University, Vallam, Thanjavur 613 403, India Correspondence e-mail: jasprabhu1@yahoo.co.in

In the title compound, C15H12BrNO2S, the dihedral angle between the two aromatic rings is 87.81 (8)°. The five-membered thiazolidine ring has an envelope conformation, with the S atom displaced by 0.4545 (7) Å from the mean plane of the other four ring atoms. The crystal structure exhibits O—H...O, C—H...O, C—H...Br and C—H... π interactions.

The title compound, C13H20ClN5, crystallizes with two molecules in the asymmetric unit. The piperidine rings in both molecules adopt chair conformations. Weak π–π interactions [centroid–centroid distance = 3.9815 (8) Å] are observed in the crystal structure.

In the title compound, C16H13NO3S, the plane of the naphthalene ring system forms a dihedral angle of 64.66 (10)° with the benzene ring. The molecular structure is stabilized by weak intramolecular C—H...O interactions and the crystal packing is stabilized by weak intermolecular N—H...O and C—H...O interactions and by π–π stacking interactions of the inversion-related naphthalene units [centroid–centroid distance of 3.7373 (14) Å].

The title molecule, C14H9NO2, is nearly planar with a dihedral angle of 3.72 (4)° beteewn the plane of the phenyl ring and the 3,1-benzoxazin-4-one fragment. The molecules are arranged into stacks parallel to the b axis via π–π stacking interactions [centroid-centroid distance = 4.2789 (11) Å] and the crystal packing is additionally stabilized by weak intermolecular C—H...O interactions.

In the title compound, C22H15NO3S, the plane of the carbazole ring system forms a dihedral angle of 65.06 (4)° with the naphthalene ring system. In the crystal structure, a weak intramolecular C—H...O interaction is observed between the naphthalene ring system and the sulfonate group. Two weak intermolecular C—H...O interactions are also observed.

In the title compound, C21H23NO4S, the dihedral angle between the naphthalene residue and the benzene ring is 7.66 (3)°. In the molecule, there are some short C—H...O interactions. In the crystal, the structure is stabilized by weak intramolecular C—H...O hydrogen bonds and the crystal structure is stabilized by weak C—H...O, C—H...π and π–π [centroid–centroid distance = 3.710 (2) Å] interactions.

The title compound, C18H20N2O, crystallizes with two molecules in the asymmetric unit. The seven-membered ring in both molecules adopts a distorted chair conformation. The dihedral angles between the phenyl rings are 43.2 (1) and 54.7 (1)° in the two molecules. The crystal packing features N—H...O and weak N—H...π and C—H...π interactions.

In the title compound, C19H22BrNO6S·H2O, the dihedral angle between the planes of the two benzene rings is 3.1 (1)°. These rings are stacked over one another with their centroids separated by 3.769 (2) Å, indicating weak π–π interactions. In the crystal structure, molecules are linked by O—H...O and O—H...(O,O) hydrogen bonds involving the water molecule, forming a two-dimensional network parallel to (001).

In the title compound, C20H17BrClNO2S, the dihedral angle between the benzene ring and the naphthalene plane is 8.95 (8)°. The crystal packing is stabilized by weak intermolecular C—H...O, C—H...Cl and π–π [centroid–centroid distance = 3.8782 (16) Å] interactions.

In the title compound, C14H13Cl2NO2S, the dihedral angle between the phenyl ring and the benzene ring is 69.94 (9)°. Two short intramolecular C—H...O contacts occur and a weak intermolecular C—H...π interaction is seen in the crystal.

In the crystal structure of the title compound, C16H12O3S, the dihedral angle between the naphthalene ring system and the phenyl ring is 65.21 (3)°. The molecules are linked by intermolecular C—H...O hydrogen bonds, forming a chain along the a axis. The chains are connected through weak C—H...π interactions.

In the title compound, C(16)H(13)NO(3)S, the plane of the amino-benzene ring makes a dihedral angle of 61.04 (6)° with the naphthalene ring system. Both ring systems form weak intra-molecular C-H⋯O hydrogen bonds with the sulfonate group. In the crystal structure, weak inter-molecular N-H⋯O hydrogen bonds and a C-H⋯π inter-action are observed.