Experimental and theoretical vibrational study of isatin, its 5-(NO2, F, Cl, Br, I, CH3) analogues and the isatinato anion

Synthesis of new spiroindolinones incorporating a benzothiazole moiety as antioxidant agents

“…1 H NMR spectra of 3a-c displayed the NH protons of the indole (d 10.01-11.07 ppm) and benzothiazole (d 7.22-7.33 ppm) rings as two separate signals, whereas, the benzothiazole NH (d 7.18-7.28 ppm) and the indole N-CH 3 (d 3.08-3.20 ppm) signal were observed in the spectra of 4a-e [23,24,[26][27][28]. The formation of spiroindolinones is evident by both the presence of a signal assigned to spiro C (d 74.10-74.80 ppm) and a signal attributed to the C]O function of indolinones (d 174.75-175.62 ppm) in the 13 C NMR spectra of 4a-e [28].…”

Theoretical and spectroscopic studies of 5-fluoro-isatin-3-(N-benzylthiosemicarbazone) and its zinc(II) complex

“…The anharmonicity of the fundamental frequencies is most often taken into account by scaling the calculated harmonic frequencies, and this procedure has been found to work well since the overestimation of vibrational frequencies is fairly uniform. The HF and B3LYP calculated vibrational frequencies have been scaled by a single factor of 0.88 and 0.96 for all molecules to correct the well-known systematic 10-12% frequency overestimation [15,21]. We used 0.85 for the HF predicted m(NH) stretching frequencies.…”

“…Naumov and Anastasova [15] reported the theoretical (ab initio) as well as experimental data on the FT-IR spectra of isatin and its derivatives.…”

Synthesis and chemotherapeutic activities of 5-chloro-1H-indole-2,3-dione-3-thiosemicarbazones

“…The IR spectra provided evidence for the confirmation of the thiosemicarbazone structure. Amidic and ketonic C=O stretching bands of 5-chloro-1H-indole-2,3-dione 2 absorbing as two separate bands absorbed as a single amidic C=O stretching band and a ketonic C=O stretching band disappeared in the IR spectra of 3a-g (19,20). 1 H NMR spectra of 3a-g displayed the NH protons of the thiosemicarbazone moiety (δ 9.33-11.10 and 12.36-12.79 ppm) and the indole NH proton (δ 11.26-11.38 ppm) as three separate signals.…”