Using molecular mechanics method,values of the heat of formation (HF) of different conformations,of perylenequinonoid photosensitizes hypocrellin A (HA) and hypocrellin B (HB) were calculated and the variance of HF af...Using molecular mechanics method,values of the heat of formation (HF) of different conformations,of perylenequinonoid photosensitizes hypocrellin A (HA) and hypocrellin B (HB) were calculated and the variance of HF after phenolic protons' dissociation were calculated as well The following was found:(i) The HF values of lour conformational isomers of HA and HB are similar to each other,so the four isomcrs can transform to each other room temperature,(ii) There exists the difference between the ability of dissociation of phenolic protons of HA and that of HB,the former is higher than the latter (iii) There exist two intramolecular hydrogen bonds in HA and HB The bond energy is approximately 8 kJ/mol and the energy of conformation Ⅰ is lower than that of conformationⅡ The bond energy of HA is lower than that of HB.(iv) There exists a low energy snot when phenolic hydroxyl bond twists 180° from the position where hydrogen bond is formed,which suggests that this kind of conformation probably exists,(v) The phenolic hydrogen of HBMC forms hydrogen bond with the neighbouring nitrogen,which is its striticture basis of possessing photosensitizing activity.展开更多
AM1 method is employed to calculate the barriers against intramolecular proton transfer (IPT) of perylenequinone (PQ). The results obtained are as follows: (i) Barriers against the IPT reaction of ground state, single...AM1 method is employed to calculate the barriers against intramolecular proton transfer (IPT) of perylenequinone (PQ). The results obtained are as follows: (i) Barriers against the IPT reaction of ground state, singlet excited state and triplet excited state of PQ are 89.75, 55.40 and 83.97 kJ/mol, respectively. (ii) Barriers a-gainst the IPT process of anion of PQ in ground state and singlet excited state are 80.12 and 79. 91 kJ/mol, respectively, (iii) Barriers against the IPT of cation and anion radical of PQ (PQ,+ and PC,-) are 65. 94 and 59.29 kJ/ mol. (iv) The barrier against double proton transfer of PQ is 172.13 kJ/mol. (v) Two barriers against IPT of a type of perylenequinonoid photosensitizer (PQP), hypocrellin A (HA), are 89. 24 and 88. 07 kJ/mol. From these data conclusions can be drawn as follows: (i) IPT processes in ground state and excited state of PQ exist, but the transfer rate of excited state is much higher than that of ground state. (ii) It is almost impossible for PQ to transfer two protons simultaneously. (iii) IPT processes in anion, anion radical and cation radical of PQ still exist. (iv) The seven-membered side ring of HA has no marked influence on its barrier against IPT.展开更多
基金Project supported by the National Natural Science Foundation of China
文摘Using molecular mechanics method,values of the heat of formation (HF) of different conformations,of perylenequinonoid photosensitizes hypocrellin A (HA) and hypocrellin B (HB) were calculated and the variance of HF after phenolic protons' dissociation were calculated as well The following was found:(i) The HF values of lour conformational isomers of HA and HB are similar to each other,so the four isomcrs can transform to each other room temperature,(ii) There exists the difference between the ability of dissociation of phenolic protons of HA and that of HB,the former is higher than the latter (iii) There exist two intramolecular hydrogen bonds in HA and HB The bond energy is approximately 8 kJ/mol and the energy of conformation Ⅰ is lower than that of conformationⅡ The bond energy of HA is lower than that of HB.(iv) There exists a low energy snot when phenolic hydroxyl bond twists 180° from the position where hydrogen bond is formed,which suggests that this kind of conformation probably exists,(v) The phenolic hydrogen of HBMC forms hydrogen bond with the neighbouring nitrogen,which is its striticture basis of possessing photosensitizing activity.
文摘AM1 method is employed to calculate the barriers against intramolecular proton transfer (IPT) of perylenequinone (PQ). The results obtained are as follows: (i) Barriers against the IPT reaction of ground state, singlet excited state and triplet excited state of PQ are 89.75, 55.40 and 83.97 kJ/mol, respectively. (ii) Barriers a-gainst the IPT process of anion of PQ in ground state and singlet excited state are 80.12 and 79. 91 kJ/mol, respectively, (iii) Barriers against the IPT of cation and anion radical of PQ (PQ,+ and PC,-) are 65. 94 and 59.29 kJ/ mol. (iv) The barrier against double proton transfer of PQ is 172.13 kJ/mol. (v) Two barriers against IPT of a type of perylenequinonoid photosensitizer (PQP), hypocrellin A (HA), are 89. 24 and 88. 07 kJ/mol. From these data conclusions can be drawn as follows: (i) IPT processes in ground state and excited state of PQ exist, but the transfer rate of excited state is much higher than that of ground state. (ii) It is almost impossible for PQ to transfer two protons simultaneously. (iii) IPT processes in anion, anion radical and cation radical of PQ still exist. (iv) The seven-membered side ring of HA has no marked influence on its barrier against IPT.
