Molecular Reactivity and Absorption Properties of Melanoidin Blue-G1 through Conceptual DFT

Abstract

This computational study presents the assessment of eleven density functionals that include CAM-B3LYP, LC-wPBE, M11, M11L, MN12L, MN12SX, N12, N12SX, wB97, wB97X and wB97XD related to the Def2TZVP basis sets together with the Solvation Model Density (SMD) solvation model in calculating the molecular properties and structure of the Blue-G1 intermediate melanoidin pigment. The chemical reactivity descriptors for the system are calculated via the conceptual Density Functional Theory (DFT). The choice of the active sites related to the nucleophilic, electrophilic, as well as radical attacks is made by linking them with the Fukui function indices, the electrophilic Parr functions and the condensed dual descriptor Δffalse(boldrfalse). The prediction of the maximum absorption wavelength tends to be considerably accurate relative to its experimental value. The study found the MN12SX and N12SX density functionals to be the most appropriate density functionals in predicting the chemical reactivity of the studied molecule.

Local Molecular Reactivity of the Colored Dansylglycine in Water and Dioxane Studied through Conceptual DFT

“…In the same way, as in our recent works on melanoidins [6][7][8][9][10], it has been found that the model chemistry formed by the connection between the MN12SX density functional and the Def2TZVP basis set is the best for justifying the fulfilling of the KID procedure for the dansylglycine molecule, both in the presence of water and dioxane. is, instead of presenting the comparison of the values of the orbital energies with the ionization potential I and the electron affinity A for different density functionals, we are showing the results for the global descriptors calculated with the MN12SX density functional in Table 1 comparing the values that arise from both solvents.…”

“…Following the lines of our previous work [6][7][8][9][10], the computational studies were performed with the Gaussian 09 [34] series of programs with density functional methods as implemented in the computational package. e basis set used in this work was Def2SVP for geometry optimization and frequencies, while Def2TZVP was considered for the calculation of the electronic properties [35,36].…”

“…If we consider the KID (for Koopmans in DFT) procedure presented in our previous works [6][7][8][9][10] together with a finite difference approximation, then the global reactivity descriptors can be calculated starting from the orbital energies of the HOMO and LUMO: electronegativity χ [19,20], global hardness η [19,20], electrophilicty ω [21], electrodonating ω − [22], electroaccepting power ω + [22], and net electrophilicity Δω ± [23]. Applying the same ideas related to the KID procedure, the local reactivity descriptors can be expressed as follows: [24][25][26][27][28][29][30], nucleophilic Parr function: P − (r) � ρ rc s (r) [31,32], and electrophilic Parr function: P + (r) � ρ ra s (r) [31,32], where ρ N+1 (r), ρ N (r), and ρ N−1 (r) are the electronic densities at point r for the system with N + 1, N, and N − 1 electrons, respectively, and ρ rc s (r) and ρ ra s (r) are related to the atomic spin density (ASD) at the r atom of the radical cation or anion of a given molecule, respectively [33].…”

“…One of these isolated molecules is called dansylglycine (or 2-[[5-(dimethylamino)naphthalen-1-yl]sulfonylamino] acetic acid) which has interesting properties as a colored molecule and as a fluorescent dye in water and dioxane, and we believe that it could be of interest to study their molecular reactivity by using the ideas of conceptual DFT [1][2][3][4][5], in the same way of our previous works [6][7][8][9][10].…”

Conceptual Density Functional Theory Study of the Chemical Reactivity Properties and Bioactivity Scores of the Leu-Enkephalin Opioid Peptide Neurotransmitter

“…Then, rather than employing the usual methodology in Medicinal Chemistry research based on Molecular Docking and QSAR and QSPR approximations, we prefer to rely on that mentioned protocol for our research on peptides. Thus, the objective of this work is to study the chemical reactivity of the Leu-Enkephalin opioid peptide neurotransmitter using the techniques of the Conceptual DFT, determining its global properties (of the molecule as a whole) as well as the local properties that allow to understand and predict active reaction sites, both electrophilic and nucleophilic by considering the recent methodology proposed by us [5]- [12]. Likewise, the pKa value of the peptide will be predicted based on a methodology previously developed by us [13], the ability of this potentially therapeutic peptide to act as inhibitor of the formation of Advanced Glycation Endproducts (AGEs) will be established according to our previous ideas [14], and the descriptors of bioavailability and bioactivity (Bioactivity Scores) will be calculated through different procedures described in the literature.…”