Simulations ab initio et DFT des propriétés structurales et électroniques des molécules de l’heptacène et des limonoïdes Rubescin D et E

Abstract

Quantum chemical methods were used to study the electronic structure and some physicochemical properties of therapeutic (Rubescin D and E) and acenes (C30H18 and C30H9K9) molecules. For the Rubescin molecules D and E, good agreement with experimental results were found for 3JH-H coupling constant, IR and NMR (1H and 13C), and this led us to confirm the geometry and calculation model used. Larges values were obtained for dipole moment, polarizability, first molecular hyperpolarizability, refractive index and dielectric constant, suggesting that they have strong optical and photonic applications and they can be good candidates for nonlinear optics materials. The 3D molecular orbitals analysis shows that the electron can easily be transferred from furan to tetrahydrofuran. The global and local reactivity, along with parameters such as energy of solvation (∆𝐸𝑠), free energy of solvation (∆𝐺𝑠),partition coefficient (log P) and solubility (log S) of Rubescin D and E were evaluated in gas phase and in some solvents media using IEF-PCM model. We found that, these molecules are thermodynamically more stable in water than in other used solvents, can easily react in water, they are lipophilic, can be delivered orally and can cross brain barriers. C2 and C62, C57 and C32 are respectively the preferred sites for electrophilic and free radicals attack. For C30H18 and C30H9K9 molecules, the structural, electronic, optoelectronic, linear and nonlinear optical properties were evaluated and compared from first-principles calculation. We found that the gap values of C30H9K9 are smaller than those of C30H18, the difference being found from 2.71 and 3.84 eV. Because of electron correlation, Eg decreases from 0.14 to 0.57 eV for C30H18 and from 0.3 to 0.84 eV for C30H9K9. The values of ˂⍺˃, χ, η and βmol of C30H9K9 are larger than those of C30H18, these last being in excellent agreement with existing theoretical results. Results suggest that these molecules have potential applications as semi-conductor components, linear and nonlinear optical materials, photoactive materials in electronic, optoelectronic and photonic devices.