The meso-salicylaldehyde substituted BODIPY was synthesized over a sequence of steps and characterized by X-ray crystallography, mass, NMR, absorption, fluorescence and electrochemical techniques. The crystal structure showed the presence of strong intramolecular hydrogen bonding between hydroxyl and formyl groups, which induces rigidity in the BODIPY core and makes the BODIPY relatively more fluorescent than the meso-phenyl BODIPY. Our studies showed that the meso-salicylaldehyde BODIPY can be used as a specific chemidosimetric sensor for CN(-) ions. The presence of a hydroxyl group adjacent to a formyl group helps in activating the formyl group for a nucleophilic attack. Upon addition of the CN(-) ion to the meso-salicylaldehyde BODIPY, the CN(-) ion attacks the formyl group and converts it to the cyanohydrin group. This irreversible reaction was monitored by following the changes in absorption, fluorescence and electrochemical properties and the results support the view that the meso-salicylaldehyde substituted BODIPY can be used as a specific chemodosimetric sensor for CN(-) ions. To substantiate the role of the hydroxyl group, we also prepared the meso(m-formylphenyl) BODIPY which contains only the formyl group on meso-phenyl, and our studies indicated that the meso(m-formylphenyl) BODIPY cannot be used as a chemodosimetric sensor for CN(-) ions, as verified by absorption and emission studies.
A simple, one-step, supramolecular strategy was adopted to synthesize Sn(IV) -porphyrin-based axially bonded triads and higher oligomers by using meso-pyridyl Sn(IV) porphyrin, meso-hydroxyphenyl-21,23-dithiaporphyrin, and Ru(II) porphyrin as building blocks and employing complementary and non-interfering Sn(IV) O and Ru(II) ⋅⋅⋅N interactions. The multiporphyrin arrays are stable and robust and were purified by column chromatography. (1) H, (1) H-(1) H COSY and NOESY NMR spectroscopic studies were used to unequivocally deduce the molecular structures of Sn(IV) -porphyrin-based triads and higher oligomers. Absorption and electrochemical studies indicated weak interaction among the different porphyrin units in triads and higher oligomers, in support of the supramolecular nature of the arrays. Steady-state fluorescence studies on triads indicated the possibility of energy transfer in the singlet state from the basal Sn(IV) porphyrin to the axial 21,23-dithiaporphyrin. However, the higher oligomers were weakly fluorescent due to the presence of heavy Ru(II) porphyrin unit(s), which quench the fluorescence of the Sn(IV) porphyrin and 21,23-dithiaporphyrin units.
We report the synthesis of two E‐dicyanovinyl substituted 1,2‐ditolyl dipyrroethenes over a sequence of steps and characterized by mass, NMR, and X‐ray crystallography. The crystal structure reveals that the E‐dicyanovinyl substituted 1,2‐ditolyl dipyrroethene is significantly distorted and shows propeller shaped structure. The pyrrole protected E‐dicyanovinyl substituted 1,2‐ditolyl dipyrroethene is strongly fluorescent compared to unprotected one. The anion sensing studies indicated that the pyrrole protected E‐dicyanovinyl substituted 1,2‐ditolyl dipyrroethene is selective colorimetric, chemodosimetric turn‐off fluorescence sensor for CN− ion as confirmed by absorption, fluorescence and NMR studies.
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