Vibrational and theoretical study of coumarin-3-carboxylic acid binding mode in Ce(III) and Nd(III) complexes

Density functional theory calculation and vibrational spectral analysis of 4‐hydroxy‐3‐(3‐oxo‐1‐phenylbutyl)‐2H‐1‐benzopyran‐2‐one

“…The Fourier transform infrared (FT-IR) and the Raman spectra and the ab initio studies of different coumarin derivatives are reported earlier. [17,18] Modern FT-IR and the near infrared (NIR) FT-Raman spectroscopies have proven to be an exceptionally powerful technique for solving many drug molecules, biological molecules, and the natural products. It has been extensively employed both in the study of chemical kinetics and chemical analysis.…”

An efficient and simple approach for the synthesis of pyranopyrazoles using imidazole (catalytic) in aqueous medium, and the vibrational spectroscopic studies on 6-amino-4-(4′-methoxyphenyl)-5-cyano-3-methyl-1-phenyl-1,4-dihydropyrano[2,3-c]pyrazole using density functional theory

“…Raman spectroscopy has recently been proved to be a valuable tool in the investigation of complex molecules of biological interest [15][16][17]. Recently, vibrational spectral studies and theoretical computations related to natural coumarin derivatives [18,19], ginkgolide [20], cresyl violet perchlorate [21], and molecules like 2,4-dichloro-6-nitrophenol [22] have appeared in the literature. Atalay et al [23,24] have reported the theoretical studies on molecular structure and vibrational spectra of 2-amino-5-phenyl-1,3,4-thiadiazole and 1-amino-5-benzoyl-4-phenylpyrimidin-2(1H).…”

Is the CO frequency shift a reliable indicator of coumarin binding to metal ions through the carbonyl oxygen?

“…The interpretation of the observed coumarin IR spectra is however a challenge because of (1) abundance of IR bands in the spectra, (2) presence of more than one donor atoms and possibility of various binding modes, and (3) coumarin donor groups are involved in a conjugated system and H-bondings. The modeling of coumarins and their metal complexes, including calculations of their vibrational spectra and comparison with the experimental ones, is a powerful approach for reliable interpretation of the available IR data and for prediction of the coumarin binding mode to metals [24,26,27]. With the help of geometry and frequency calculations of coumarin derivatives it has been shown that the downshifts of the carbonyl and carboxylic C@O stretching frequencies observed on going from the ligand IR spectrum to the metal complex spectrum is not a direct indication of a metal coordination to the corresponding groups [26,27].…”

“…The modeling of coumarins and their metal complexes, including calculations of their vibrational spectra and comparison with the experimental ones, is a powerful approach for reliable interpretation of the available IR data and for prediction of the coumarin binding mode to metals [24,26,27]. With the help of geometry and frequency calculations of coumarin derivatives it has been shown that the downshifts of the carbonyl and carboxylic C@O stretching frequencies observed on going from the ligand IR spectrum to the metal complex spectrum is not a direct indication of a metal coordination to the corresponding groups [26,27]. The active ligand form in the complexation reaction is the deprotonated one, which is experimentally inaccessible.…”

“…Our previous calculations revealed an interesting vibrational behaviour of some coumarin vibrational modes in the metal complex spectra. Due to the conjugated coumarin system, the coordination of the metal to one donor group (for example hydroxyl C-O) induces polarization in the lactone ring and hence a significant shift in the free carbonyl stretching frequency [23,24,26,27]. The aim of the present study is to elucidate the vibrational behaviour of the coumarin ligand, 4-hydroxy-3-nitro-2H-chromen-2-one in metal complexes and to derive a vibrational criteria capable to distinguish (1) the coumarin (hnc À ) binding modes in Cu(II) and Ag(I) complexes and (2) the H-bonded from metal-bonded carbonyl group.…”