title: Molecular interactions of monosulfonate tetraphenylporphyrin (TPPS1) and meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) with dimethyl methylphosphonate (DMMP).
abstract: The molecular interactions of monosulfonate tetraphenylporphyrin (TPPS(1)) and meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) with dimethyl methylphosphonate (DMMP) have been investigated by UV-vis and fluorescence spectroscopies. The association constants and interaction stoichiometries of the bindings were obtained through Benesi-Hildebrand (B-H) method. Particularly, both linear and nonlinear fitting procedures were performed to evaluate the possible 1:2 interactions. Experimental results showed that hydrogen-bonding interactions existed in both of the two systems, resulting in regular changes in the absorbance and fluorescence characteristics of the porphyrins. The association constants and stoichiometries determined from absorbance and fluorescence studies were in excellent agreement. Using a nonlinear fitting method, we demonstrated that the one-step 1:2 interaction took place in the TPPS(1)-DMMP system, and the association constants were determined to be 71.4 M(-1) by absorbance measurements and 70.92 M(-1) by fluorescence measurements. The interaction stoichiometry of the TPPS-DMMP system was 1:1, and the association constants were determined to be 16.06 M(-1) by absorbance measurements and 16.03 M(-1) by fluorescence measurements. It was concluded that the interaction between TPPS(1) and DMMP was stronger than that between TPPS and DMMP.
authors.affiliation: College of Bioengineering/Key Laboratory of Biorheology Science and Technology of Ministry of Education, Chongqing University, Chongqing 400030, PR China. huodq@cqu.edu.cn
authors.forename: Danqun
authors.initials: D
authors.lastname: Huo
authors.forename: Limin
authors.initials: L
authors.lastname: Yang
authors.forename: Changjun
authors.initials: C
authors.lastname: Hou
authors.forename: Huanbao
authors.initials: H
authors.lastname: Fa
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Luo
authors.forename: Yi
authors.initials: Y
authors.lastname: Lu
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Zheng
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.forename: Li
authors.initials: L
authors.lastname: Yang
mesh_terms: D009943:Organophosphorus Compounds / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D009943:Organophosphorus Compounds; D011166:Porphyrins; C509598:tetra(4-sulfonatophenyl)porphyrin; C031116:dimethyl methylphosphonate; C016136:tetraphenylporphine sulfonate