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Catalyst free new bioactive 2‐amino‐4‐(2‐oxo‐2H‐chromen‐4‐yl)‐6‐arylpyridine‐3‐carbonitrile molecular entities (2 a‐2 o) have been synthesized from 4‐formylcoumarins with malononitrile, different ketones and ammonium acetate via one‐pot four component coupling reaction under neat microwave method. Detailed characterization of all the compounds and anticancer properties for the synthesized compounds are reported. Compounds 2 f and 2 k exhibited promising anticancer activity at low concentration (10−5 M) against NCI‐60 cell lines. Further, IC50 values were calculated for most potent compounds against three cancer cell lines such as HT‐29, Hep‐G2 and KB. Among the eight compounds, 2 f and 2 k are exhibited most promising activity, the potent anticancer molecules 2 f and 2 k were screened for their CT‐DNA cleavage and fluorescence quenching study with transport protein BSA. Molecular docking study has been performed for the synthesized compounds with binding site of the tubulin using podophyllotoxin‐tubulin stathmin‐like domain complex (PDB 1SA1) and results obtained are quite good.

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A series of coumarin tetrahydro‐β‐carboline hybrids 3 have been synthesized by the Pictet‐Spengler reaction. Stoichiometrically controlled DDQ oxidation has led to dihydro 4 and β‐carboline 5. In vitro anticancer activity against 60 cell lines has revealed the potency of 3 f, 4 a and 5 c. In silico studies indicate the binding properties of 5 c with Kinesin spindle protein (KSP) and tubulin protein. Gel electrophoresis studies revealed that compound 3 f partially cleaved the CT‐DNA, whereas the ring C aromatized compound 5 c completely cleaved the CT‐DNA. Structures of the newly synthesized compounds are confirmed by spectroscopic and X‐ray studies.

Electronic absorption and emission spectra of 3-acetyl coumarin, 3-(bromoacetyl) coumarin and 3-(di bromoacetyl) coumarin have been recorded at room temperature in thirteen solvents with different polarities. Both ground and excited state dipole moments have been calculated for both locally excited and charge transfer transitions by using the solvatochromic method. Excited state dipole moments of all the three compounds are higher than their ground state values. DFT calculations have been profound to estimate their ground and excited state dipole moments. The estimated change in dipole moment by the application of microscopic solvent polarity parameter and bulk solvent polarity methods are in close agreement. Concentration dependent dual fluorescence has been observed in the emission spectra of all the three compounds. Graphical Abstract Dual fluorescence of 3-acetyl coumarin (I) in different solvents.

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