title: Distinct photoacidity of honokiol from magnolol.
abstract: Honokiol, 5,5'-diallyl-2,4'-dihydroxy- biphenyl, by comparison with its isomer magnolol, 5,5'-diallyl- 2,2'-dihydroxy- biphenyl, has been characterized by steady-state and time-resolved spectroscopy as well as (1)H NMR. Honokiol shows more complex pH dependence of absorption and fluorescence characteristics compared with magnolol. Honokiol possesses much weaker acidity than magnolol both in the ground and excited states. Its weak photoacidity is similar to that of 4-hydroxy- biphenyl or 4, 4'-dihydroxy- biphenyl rather than 2-hydroxy- biphenyl or 2, 2'-hydroxy- biphenyl. The electron effect and geometry configuration of substitution has been discussed.
authors.affiliation: School of Basic Science, China Pharmaceutical University, Nanjing, China. Lihongm2001@hotmail.com
authors.forename: Hongmei
authors.initials: H
authors.lastname: Li
authors.forename: Xianfeng
authors.initials: X
authors.lastname: Wang
authors.forename: Yuzhu
authors.initials: Y
authors.lastname: Hu
mesh_terms: D000143:Acids / Q000737:chemistry*; D001713:Biphenyl Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017705:Lignans / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010777:Photochemistry; D013050:Spectrometry, Fluorescence; D000498:Allyl Compounds; D010636:Phenols
chemical_list: D000143:Acids; D001713:Biphenyl Compounds; D017705:Lignans; C005498:magnolol; C005499:honokiol; D000498:Allyl Compounds; D010636:Phenols
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