title: Hydrogen bond controlled adduct formation of meso-tetra(4-sulfonatophenyl)porphyrin with protic acids: a UV-vis spectroscopic study.
abstract: Interaction of meso-tetra(4-sulfonatophenyl)porphyrin (H2tppS4) with weak and strong protic acid have been studied by UV-vis spectroscopy in water, dichloromethane and methanol. Different shifts of the Soret and Q(0,0) bands in the three solvents, the aggregation of diprotonated species and the stability of porphyrin-acid adducts in the solution, may be explained by the inter- and intramolecular hydrogen bonds. Whilst, the addition of excess amounts of tetra-n-butylammonium chloride to H2tppS4(Cl)2 in dichloromethane has little to no effect on the UV-vis spectrum of the dication, gradual addition of tetra-n-butylammonium hydrogen sulfate to the dichloromethane solution of H2tppS4(H2SO4)2 leads to the degradation of adducts and the release of porphryin. The results of this study clearly show the crucial role played by hydrogen bonds between the porphyrin diprotonated species and the counter ion in the stability of porphyrin diacids in solution.
authors.affiliation: Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Gava Zang, Zanjan 45137-66731, Iran. zakavi@iasbs.ac.ir
authors.forename: Saeed
authors.initials: S
authors.lastname: Zakavi
authors.forename: Hajar
authors.initials: H
authors.lastname: Rahiminezhad
authors.forename: Robabeh
authors.initials: R
authors.lastname: Alizadeh
mesh_terms: D000143:Acids / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D006860:Hydrogen Bonding; D046911:Macromolecular Substances / Q000737:chemistry / Q000378:metabolism*; D008752:Methylene Chloride / Q000737:chemistry; D008954:Models, Biological; D008968:Molecular Conformation / Q000187:drug effects; D011166:Porphyrins / Q000737:chemistry*; D011522:Protons; D000644:Quaternary Ammonium Compounds / Q000737:chemistry / Q000494:pharmacology; D012492:Salts / Q000737:chemistry / Q000494:pharmacology; D012997:Solvents / Q000737:chemistry / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D014867:Water / Q000737:chemistry
chemical_list: D000143:Acids; D002412:Cations; D046911:Macromolecular Substances; D011166:Porphyrins; D011522:Protons; D000644:Quaternary Ammonium Compounds; D012492:Salts; D012997:Solvents; C515756:tetra-n-butylammonium chloride; D014867:Water; C016136:tetraphenylporphine sulfonate; D008752:Methylene Chloride