Investigation On The Photosensitive Reaction Of Amino Acid With Photoinduced Excited Triplet States Of Aromatic Ketone

Two common aromatic ketones,2-Acetonaphthone?Ace?and Benzophenone?BP?,are both common industrial raw materials and typical photosensitizers.Benzophenone becomes the main component of sunscreen because of its absorption of ultraviolet light.However,the excited triplet molecules ³Ace^*and ³BP^*of 2-Acetonaphthone and Benzophenone can also react with proteins or amino acids in the organism to cause damage to the organism.In this paper,the photosensitivity reaction of ³Ace^*and ³BP^*with several amino acids in physiological environment have been investigateated by laser flash photolysis technology.Our main works as follows.?1?The photosensitivity reaction of ³Ace^*to Trp in aqueous solution and SDS,CTAB and TX-100 micelle solutions have been investigated.Photolysis Ace in aqueous solution and SDS,CTAB and TX-100 micelle solutions,the ground state Ace molecule will be excited by laser to generate excited triplet molecule ³Ace^*.When Trp is added to the system,there was hydrogen transfer between ³Ace*and Trp to generateAceH^·,Trp/N^·andT rp^·/NH.For SDS,CTAB and TX-100 micelles,Ace is dissolved in the hydrophobic region of the micelle core,and Trp is dissolved in the bulk water region outside SDS,CTAB micelles or in the polyoxyethylene hydrophilic chain of TX-100micelles.³Ace^*and Trp diffuse to the surface of micelles for hydrogen transfer reaction and the micelle molecules didn't react with ³Ace^*.The reaction rate constants of ³Ace^*and Trp in aqueous and three micelle solutions are?2.386±0.051??10⁸,?2.922±0.078??10⁸,?2.581±0.058??10⁸,?4.342±0.148??10⁷L×mol^-1×s^-1,respectively.The reaction rate constants of ³Ace^*and Trp are in the order of10⁷?10⁸L×mol^-1×s^-1,and the reaction is approximately controlled by diffusion.The reaction rate constant of ³Ace*with Trp is the smallest in TX-100 micelle solution,which is caused by the obstruction of Trp molecules in the process of diffusion to the micelle surface.?2?The photosensitivity reaction of ³BP^*to Trp and Tyr in aqueous solution and SDS,CTAB micelle solutions have been investigated.Photolysis BP in aqueous solution and SDS,CTAB micelle solutions,the ground state BP molecule will be excited by laser to generate excited triplet molecule ³BP^*.When Trp is added to the system,there was hydrogen transfer between ³BP^*and Trp to generateBPH^·andTrp/N^·in aqueous and SDS,CTAB micelle solutions.The reaction rate constants of ³BP^*and Trp in aqueous and SDS,CTAB micelle solutions are?0.857±0.027??10⁹,?1.480±0.086??10⁹and?1.779±0.106??10⁹L×mol^-1×s^-1,respectively.When Tyr is added to the system,there was hydrogen transfer between ³BP^*and Tyr to generateBPH^·andTyrO^·in aqueous and SDS,CTAB micelle solutions.The reaction rate constants of ³BP^*and Tyr in aqueous and SDS,CTAB micelle solutions are?.0903±0.018??10⁹,?1.083±0.038??10⁹and?1.911±0.019??10⁹L×mol^-1×s^-1,respectively.In SDS and CTAB micelles,the lipophilic BP is dissolved in the hydrophobic region of the micelle core,the water-soluble Trp and Tyr are dissolved in the bulk water region outside the micelle.They all diffuse to the micelle surface for hydrogen transfer reaction.There was no photochemical reaction between the micelle molecules and ³BP^*.The reaction rate constants of ³BP^*with Trp and Tyr in aqueous solution and two kinds of micelle solutions are in the order of10⁹L×mol^-1×s^-1,the reaction is controlled by diffusion.