Conformational analysis of tannic acid: Environment effects in electronic and reactivity properties

Author(s)

Petry, Romana ^{[1, 2]} ; Focassio, Bruno ^{[1, 2]} ; Schleder, Gabriel R. ^{[1, 2]} ; Martinez, Diego Stefani T. ^[1] ; Fazzio, Adalberto ^{[1, 2]}

Affiliation

^[1] Brazilian Ctr Res Energy & Mat CNPEM, Brazilian Nanotechnol Natl Lab LNNano, BR-13083100 Campinas, SP - Brazil

^[2] Fed Univ ABC UFABC, Ctr Nat & Human Sci, BR-09210580 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Journal of Chemical Physics; v. 154, n. 22 JUN 14 2021.
• Web of Science Citations: 0

Abstract

Polyphenols are natural molecules of crucial importance in many applications, of which tannic acid (TA) is one of the most abundant and established. Most high-value applications require precise control of TA interactions with the system of interest. However, the molecular structure of TA is still not comprehended at the atomic level, of which all electronic and reactivity properties depend. Here, we combine an enhanced sampling global optimization method with density functional theory (DFT)-based calculations to explore the conformational space of TA assisted by unsupervised machine learning visualization and then investigate its lowest energy conformers. We study the external environment's effect on the TA structure and properties. We find that vacuum favors compact structures by stabilizing peripheral atoms' weak interactions, while in water, the molecule adopts more open conformations. The frontier molecular orbitals of the conformers with the lowest harmonic vibrational free energy have a HOMO-LUMO energy gap of 2.21 (3.27) eV, increasing to 2.82 (3.88) eV in water, at the DFT generalized gradient approximation (and hybrid) level of theory. Structural differences also change the distribution of potential reactive sites. We establish the fundamental importance of accurate structural consideration in determining TA and related polyphenol interactions in relevant technological applications. Published under an exclusive license by AIP Publishing. (AU)

• FAPESP's process: 19/04527-0 - Interface between crystalline topological insulators and 2D-trivial materials: defect proximity study
• Grantee: Bruno Focassio
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 17/02317-2 - Interfaces in materials: electronic, magnetic, structural and transport properties
• Grantee: Adalberto Fazzio
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 17/18139-6 - Machine learning for Materials Science: 2D materials discovery and design
• Grantee: Gabriel Ravanhani Schleder
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 18/25103-0 - Interfaces - functionalized graphenes and organic pollutans: theoretical-experimental approach in environmental nanotechnology
• Grantee: Romana Petry
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)