title: Nitro-substituted 3,3'-bis(indolyl)methane derivatives as anion receptors: electron-withdrawing effect and tunability of anion binding properties.
abstract: A series of nitro-substituted 3,3'-bis-indolyl phenylmethane derivatives were synthesized and their anion binding properties were investigated in detail. The introduction of the electron-withdrawing nitro group into indole unit and/or meso-phenyl ring, which leads to the increased acidity of indole NH and meso-position CH proton, has a positive effect on anion binding. The nitro-substituted bis(indolyl)methane receptors exhibited selective colorimetric sensing of F- anion, as revealed by the notable color and spectral changes, rationally due to the deprotonation of the indole NH of the receptor. Meanwhile, the additive introduction of the nitro substituents on the meso-phenyl ring of bis(indolyl)methane can lead to the deprotonation of the meso-position CH and further induce an irreversible oxidation process obtaining bis(indolyl)methene product in the F- anion sensing system.
authors.affiliation: Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China.
authors.forename: Litao
authors.initials: L
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.forename: Yong
authors.initials: Y
authors.lastname: Guo
authors.forename: Jian
authors.initials: J
authors.lastname: Xu
authors.forename: Shijun
authors.initials: S
authors.lastname: Shao
mesh_terms: D000838:Anions; D004583:Electrons; D007211:Indoles / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D011522:Protons; D013056:Spectrophotometry, Ultraviolet; D017186:Titrimetry
chemical_list: C512018:1,1-bis(3'-indolyl)methane; D000838:Anions; D007211:Indoles; D011522:Protons