Fluorescent behavior of 2‐(3,4,5,6‐tetrafluoro‐2‐hydroxyphenyl)imidazo‐[1,2‐a]pyridine in the presence of metal perchlorate

Metal cation-induced multifluorescence of azacrown-substituted (tetrafluorophenyl)imidazo[1,2-a]pyridine

“…Absorption spectra of 1 in an acetonitrile solution were slightly red-shifted and its absorbance was substantially strong, compared with those of 2-(pentafluorophenyl)imidazo[1,2-a]pyridine (12). Its fluorescence around 380 nm wavelength was considerably weak and the intensity was affected by the polarity of the solvent; the intensity in nonpolar solvents such as toluene and dioxane was stronger than that in a polar solvent such as acetonitrile ( Figure 1).…”

“…In a continuing research on the application of fluorinated 2-(2-hydroxyphenyl)benzazoles to fluorescent probes sensing metal cations, we reported that fluorescence of 2-(pentafluorophenyl)imidazo [1,2-a]pyridine is strongly enhanced by the protonation with acids (12,13). In this paper, we wish to describe that azacrownmodified (tetrafluorophenyl)imidazo[1,2-a]pyridine (1) emits three different fluorescent lights responding to Li þ , Zn 2þ or H þ cation, respectively; 388 nm light to Li þ cation, 433 nm light to Zn 2þ cation or 469 nm light to H þ cation.…”

“…Total concentration of 1 plus Zn(SCN) 2 is maintained at 1 £ 10 22 M. Pentafluorophenyl)imidazo[1,2-a]pyridine was prepared by the reaction of bromomethyl pentafluorophenyl ketone, according to the previously reported paper(12).…”

Syntheses and fluorescence of salicylaldimine schiff base derivatives of 1,1′‐di(aminoethylaminocarbonylalkyl)‐2,2′‐biimidazole

“…Fluorescence of salicylaldehyde [25] and 2-(2-hydroxyphenyl)imidazo-[1,2-a]pyridine analogues [23,24] exhibiting hydrogen bonding similar to that shown between the salicylaldimino nitrogen and phenolic proton in Scheme I, have been reported to involve excited state intramolecular proton transfer [23,24], in which the nitrogen atom (oxygen atom in the case of salicylaldehyde) serves as a proton acceptor during the fluorescing process. As neither of the amideamine precursors was noted to fluoresce, the fluorescence exhibited by the title compounds is likely due entirely to the salicylaldimine moiety.…”

Fluorescent property of 3-hydroxymethyl imidazo[1,2-a]pyridine and pyrimidine derivatives

“…In another study, it was reported that 2-(3,4,5,6-tetrafluoro-2-hydroxyphenyl)imidazo[1,2-a]pyridine emitted long wavelength light around 540 nm both in polar and in nonpolar solvents [16]. Based upon this information, it was hypothesized that introduction of a hydroxymethyl group at position 3 of the imidazo[1,2-a]azines should enhance fluorescence (probably through a spatial non-covalent interaction of the hydroxyl non-bonding electrons with the aryl rings) as compared to the parent fluorophore (the unsubstituted imidazo[1,2-a]azine).…”