On the Interaction between Superatom Al12Be and DNA Nucleobases/Base Pairs: Bonding Nature and Potential Applications in O2 Activation and CO Oxidation

Transformation of Distinct Superatoms to Superalkalis by Successive Ligation of Thymine Nucleobases

The ligation strategy has been widely used in the chemical synthesis of atomically precise clusters. A series of thymine (T)-ligated Al12M-Tn (M = Be, Al, C; n = 1-5) complexes have been studied to reveal the effect of DNA nucleobase ligands on the electronic structures of different superatoms in the present work. In addition to its protective role, the successive attachment of thymine ligands significantly lowers the adiabatic ionization energies (AIEs) of the studied Al12M superatoms with filled and unfilled electronic shells. The continuous decrease in the AIEs of Al12M-Tn is derived from the gradually raised highest occupied molecular orbital (HOMO) levels upon the addition of ligands. Interestingly, the lowering degree of AIEs for such nucleobase-protected superatoms is independent of the distinct shell fillings of Al12M superatoms but is significantly related to the types of nucleobases. Moreover, the obtained Al12M-T5 superalkalis not only exhibit excellent performance in activating the stable CO2 and O2 molecules but also have considerable nonlinear optical (NLO) responses. We, therefore, hope that this study could provide a viable strategy for synthesizing novel nucleobase-ligated superatom clusters with excellent reducing capability to enrich the family of multifunctional nanoclusters.

Theoretical prediction of superatom WSi12-based catalysts for CO oxidation by N2O

Catalytic conversion of N2O and CO into nonharmful gases is of great significance to reduce their adverse impact on the environment. The potential of the WSi12 superatom to serve as a new cluster catalyst for CO oxidation by N2O is examined for the first time. It is found that WSi12 prefers to adsorb the N2O molecule rather than the CO molecule, and the charge transfer from WSi12 to N2O results in the full activation of N2O into a physically absorbed N2 molecule and an activated oxygen atom that is attached to an edge of the hexagonal prism structure of WSi12. After the release of N2, the remaining oxygen atom can oxidize one CO molecule via overcoming a rate-limiting barrier of 28.19 kcal mol-1. By replacing the central W atom with Cr and Mo, the resulting MSi12 (M = Cr and Mo) superatoms exhibit catalytic performance for CO oxidation comparable to the parent WSi12. In particular, the catalytic ability of WSi12 for CO oxidation is well maintained when it is extended into tube-like WnSi6(n+1) (n = 2, 4, and 6) clusters with energy barriers of 25.63-29.50 kcal mol-1. Moreover, all these studied MSi12 (M = Cr, Mo, and W) and WnSi6(n+1) (n = 2, 4, and 6) species have high structural stability and can absorb sunlight to drive the catalytic process. This study not only opens a new door for the atomically precise design of new silicon-based nanoscale catalysts for various chemical reactions but also provides useful atomic-scale insights into the size effect of such catalysts in heterogeneous catalysis.

DFT study on the adsorption of 5-fluorouracil on B40, B39M, and M@B40 (M = Mg, Al, Si, Mn, Cu, Zn)

Based on density functional theory, the adsorption behavior of 5-fluorouracil (5-Fu) on B40 and its derivatives has been explored. It was observed that 5-Fu prefers to combine with the corner boron atom of the B40 cage via one of its oxygen atoms, forming a strong polar covalent B-O bond. The adsorption energy of 5-Fu on B40 was calculated to be -11.15 kcal mol-1, and thus, it can be duly released from B40 by protonation in the slightly acidic environment of tumor tissue, which makes for reducing the toxic and side effects of this drug. Additionally, the substituent and embedding effect of Mg, Al, Si, Mn, Cu, and Zn atoms on the drug delivery performance of B40 have been also considered. We hope this work could offer some implications for the potential application of boron-based nanomaterials, such as B40 in drug delivery.