Theoretical Study On The Mechanism Of Fragmentation Of 5-methoxylated Flavonoids

In this thesis,density functional theory was employed to investigate the dissociation mechanism of the molecular ion[L]+.(L = 5-methoxyflavone)into[L—(2H,0)]+,[L-(H,C,O)]+ and[L-(2H,C,20)]＋’.We constructed the dissociation potential energy profile using the computed Gibbs free energies of the optimized stationary points for investitate the preferred reaction pathways.Further,we used the B3LYP/6-311++G(d,p)-computed structures of stationary points and their thermodynamic and kinetic data to draw the detailed dissociation mechanism of[L]+’.Finally,the similarities and differences between the theoretical and available experimental results were discussed in detail.This study provides new insight into the dissociation of flavonoids and their analogues in mass spectrometry.