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Does gold cluster promote or scavenge radicals? A controversy at DFT
Author(s) -
Ahmadi Aliakbar,
Kassaee Mohammad Zaman,
Fattahi Alireza
Publication year - 2018
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.3776
Subject(s) - chemistry , radical , bond dissociation energy , dissociation (chemistry) , covalent bond , enthalpy , gold cluster , cluster (spacecraft) , natural bond orbital , photochemistry , medicinal chemistry , crystallography , stereochemistry , density functional theory , computational chemistry , organic chemistry , physics , computer science , programming language , quantum mechanics
Anticancer character of gold cluster has been indicated through its free radical scavenging properties. This is in contrast to its free radical promoting ability suggested by other workers. Here, we address this controversy by probing the stabilizing effects of Au 3 cluster on RO • vs its impacts on RO–H bond dissociation enthalpy, at B3LYP/ LACVP+* level (R═H, methyl, ethyl, n ‐propyl, i ‐propyl, n ‐butyl, t ‐butyl, and phenyl). In the presence of Au 3 cluster, bond dissociation enthalpy of O–H bond and the spin density at the RO • oxygen are reduced dramatically. These are clear evidences for both the Au 3 facilitation of the RO–H bond breakage and its scavenging of RO • radical. Since O–Au anchoring bond is responsible for the interaction of Au 3 cluster and ROH (or RO • ), its nature was interpreted by means of the quantum theory of atoms in molecules and the natural bond orbital. The results indicate that O–Au bond is stronger and has more covalent character in RO • –Au 3 than in ROH–Au 3 . The interaction of Au 3 cluster with RO • is 1.5 to 3 times more than that with ROH. As a result, gold cluster scavenging property appears more prominent than its free radical initiation activity.