Synthesis, Spectrometric Characterization (ESI-MS, NMR, IRTF), X-Ray Study and Quantum Chemical Calculations of 2-oxo-2H-chromen-7-yl Benzoate

• Published in: Journal of organic chemistry 2020, Vol.10 (1), p.1-16
• Main Authors: Abou, Akoun, Djandé, Abdoulaye, Ilagouma, Amadou Tidjani, Ouari, Olivier, Saba, Adama
• Format: Article
• Language: English
• Subjects: Chemical Sciences
• ISSN: 0022-3263; 1520-6904
• DOI: 10.5923/j.ajoc.20201001.01

The paper presents a combined experimental and computational study of 7-substituted coumarin derivative, the 2-oxo-2H-chromen-7-yl benzoate (I). The compound was prepared in the laboratory by linking the coumarin system (7-hydroxycoumarin) to benzoyl chloride and crystallized in the monoclinic space group P2 1 with = 3.86010(10), = 27.7876(9), = 5.7453(2) Å, = = 90, =91.063(3)° and = 2. The compound has been characterized structurally by spectroscopy and by single-crystal X-Ray diffraction. In the latter, the structure of (I) was solved by direct methods and refined to a final R value of 0.038 for 2260 independent reflections. Its structure is stabilized by intramolecular C-H•••O and intermolecular C-H•••O hydrogen bonds that extended as infinite 1D chain along [001]. Stabilization is also ensured by oxygen-π stacking interaction between the aromatic ring and oxygen of the benzoate moiety. The analysis of intermolecular interactions through the mapping of d norm and shape-index revel that the most significant contributions to the Hirshfeld surface 36.2 and 27.9% are from H•••H and O•••H contacts, respectively. Besides, the molecular geometry of (I) was also optimized using density functional theory (DFT/RB3LYP), the basic ab initio model i.e the restricted Hartree-Fock (RHF) methods with the 6-311 ++ G(d, p) basis set in ground state and frequency calculations with RB3LYP method using 6-31G(d,p) basis set. The theoretical data resulting from these quantum chemical calculations are generally in good agreement with the observed structure. The only significant observed difference is in the torsion angles between the coumarin ring system and the benzoate ring, where the observed CO -CC value (59.6 (4)°) is slightly lower than the DFT/RB3LYP calculated value (54.32°) and the frequency calculations (41.23°) value and larger than that of the RHF computed value (110.63°). The non-linear optical effects (NLO), molecular electrostatic potential (MEP), frontier molecular orbitals (FMO), and the Mulliken charge distribution were also investigated theoretically. The theoretical HOMO-LUMO energy gap values originating from these calculations are 4.465 eV (DFT/RB3LYP/6-311++G(d,p)) and 4.434 eV (FREQ/ RB3LYP/6-31G(d,p)).