Role of O Substitution in Expanded Porphyrins on Uranyl Complexation: Orbital- and Density-Based Analyses

• DOI: 10.1021/acs.inorgchem.1c01981
• Publication Date: 2021-09-29T22:05:11Z
• Authors: Saparya Chattaraj; Arunasis Bhattach...; Biswajit Sadhu
• Keywords: Uranyl; Natural bond orbital

Search for new U(VI) sequestering macrocyclic ligands is an important area of research due to manifold applications. Besides hard- or soft-donor-based ligands, mixed-donor are also gaining popularity in achieving optimized performances. However, how the combination hard-soft-donor centers alters bonding interactions with still not well-understood. Moreover, a consensus yet be reached on nature and role underlying covalent mixed N,O-donor ligands. In this work, using relativistic density functional theory (DFT), we attempted address these intriguing issues by investigating subtle change characteristics uranyl ion upon binding expanded porphyrin, viz. sapphyrin, subsequent O substitutions at cavity. The results obtained from range modern analysis tools suggest that O-substituted sapphyrin variants, UO22+ prefers bind N over O, increase number O-donor sites cavity prompts have better interaction rest N-donor-centers. Although donors involved more numbers molecular orbitals, variation amplitude overlap σ-donation ability favor stronger uranyl. Molecular orbital (MO) states (DOS) analyses show favorable participation U(d), involvement U(f) orbitals low extent but non-negligible. electrostatic dominates U-O/N bonds equatorial plane, quantum atoms molecules descriptors, MO analysis, overlap-integral calculations confirm presence near-degeneracy-driven interactions.