Intramolecular proton transfer of hypomycin A in the ground state S0 and singlet excited state S1 were calculated by high level quantum chemical method in this letter. It was found that the IPT barriers for I→TS1 ar...Intramolecular proton transfer of hypomycin A in the ground state S0 and singlet excited state S1 were calculated by high level quantum chemical method in this letter. It was found that the IPT barriers for I→TS1 are 38.56 kJ/mol in S0 and 8.19 kJ/mol in S1, while those for I→TS4 get approximately 17 kJ/mol higher in S0 and 28 kJ/mol higher in S1. The calculation of IPT rate constants suggests that the experiment observed process of PQD is in S1. The height of the IPT barriers correlate not only with the variance of charge for labile hydrogen, the change of H-bonds length, the change of O-H bonds length and the change of O-O distance, but also with the reactant molecular H-bonds length. Moreover, the correlations are the same for S0 and S1.展开更多
The sendempirical method AM1 was used to calculate AHOF values ofperylenequinone (PQ), and HOF was used as a theoretical parameter to predict the scavengingability of Po hydroxyls. Owing to strong intramolecular hydro...The sendempirical method AM1 was used to calculate AHOF values ofperylenequinone (PQ), and HOF was used as a theoretical parameter to predict the scavengingability of Po hydroxyls. Owing to strong intramolecular hydrogen bonds and the electronattracting property of the keto-function, hydroxyls of PQ were so weak in scavenging free radicalsthat the its effect was negligible in photodynandc therapy. However, when Po was substitilted withstrong electron-donating groups, its scavenging activity was enhanced markedly.展开更多
文摘Intramolecular proton transfer of hypomycin A in the ground state S0 and singlet excited state S1 were calculated by high level quantum chemical method in this letter. It was found that the IPT barriers for I→TS1 are 38.56 kJ/mol in S0 and 8.19 kJ/mol in S1, while those for I→TS4 get approximately 17 kJ/mol higher in S0 and 28 kJ/mol higher in S1. The calculation of IPT rate constants suggests that the experiment observed process of PQD is in S1. The height of the IPT barriers correlate not only with the variance of charge for labile hydrogen, the change of H-bonds length, the change of O-H bonds length and the change of O-O distance, but also with the reactant molecular H-bonds length. Moreover, the correlations are the same for S0 and S1.
文摘The sendempirical method AM1 was used to calculate AHOF values ofperylenequinone (PQ), and HOF was used as a theoretical parameter to predict the scavengingability of Po hydroxyls. Owing to strong intramolecular hydrogen bonds and the electronattracting property of the keto-function, hydroxyls of PQ were so weak in scavenging free radicalsthat the its effect was negligible in photodynandc therapy. However, when Po was substitilted withstrong electron-donating groups, its scavenging activity was enhanced markedly.
