Exploring the role of quantum‐mechanical descriptors in the concentration‐dependent adsorption of aromatic organic compounds by multiwalled carbon nanotubes

Abstract

An accurate quantitative prediction for concentration‐dependent adsorption of organic compounds by carbon‐nanotubes (CNTs) is increasingly in demand to evaluate not only their applications but also risk associated using CNTs. This is often carried out using poly‐parameter linear‐solvation‐energy‐relationships (pp‐LSERs) based on adsorbate descriptors. This work examines the predictivity of existing pp‐LSERs in the prediction of adsorption of aromatic organic compounds by multi‐walled CNTs (MWCNTs) at five different adsorbate concentrations, and compares that with the predictivity of quantum‐mechanical models while revealing an essential role of electron‐correlation. Notably, the most influencing descriptor for the adsorption was found to be the mean polarizability but that arising from the quantum‐mechanical exchange interactions between electrons of the same spin. This work also proposes reliable predictive models based on a combination of the quantum‐mechanical descriptors and pp‐LSER's descriptors, which were applied to predict the adsorption of nucleobases and steroid hormones, with Progesterone found to be maximally adsorbed.

Modeling the Solubility of C70 Fullerenes in Diverse Solvents: Role of Quantum‐mechanical Descriptors

“…25] and refrences therein). The various quantum‐mechanical descriptors ( D s) employed in this work (as provided in Table and SI Table S1) are the total molecular energy ( E ) including the zero point vibrational energy ( ZPE ), energies of highest‐occupied molecular orbital ( E HOMO ), energy of lowest‐occupied molecular orbital ( E LUMO ), HOMO‐LUMO energy gap, dipole moment ( d ), mean polarizability ( α ), absolute electronegativity ( χ ), absolute hardness ( η ), electrophilicity index ( ω ), and quantum‐mechanically computed thermodynamical properties, namely, enthalpy ( H ), and Gibbs free energy ( G ) at 298.15 K. These descriptors were computed using an ab initio Hartree‐Fock (HF) and density functional theory (DFT) quantum‐mechanical methods . The HF method effectively takes care of the quantum‐mechanical exchange interactions between electrons of parallel spin but it significantly neglects the Coulombic interactions between electrons (irrespective of their spin) which are commonly referred to as electron correlation.…”

“…The HF method effectively takes care of the quantum‐mechanical exchange interactions between electrons of parallel spin but it significantly neglects the Coulombic interactions between electrons (irrespective of their spin) which are commonly referred to as electron correlation. Following this, the effect of electron correlation (CORR) on the solubility was also analyzed using the electron correlation based descriptors calculated using, …”

“…For this, the quantitative models based on the quantum‐mechanical descriptors are developed which are further validated using an external prediction set of compounds. In our recent works, the instantaneous interactions between electrons (the electron correlation) are found to play an essential role towards the quantitative prediction of physico‐chemical properties and biological activities of chemicals. Following this, the present work explores the role of quantum mechanical descriptors in the prediction of the solubility of fullerenes in diverse solvents, using the methodology described in the next section.…”