title: Friedel-Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)methylphosphonic acid.
abstract: Friedel-Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates promoted by trifluoromethanosulfonic acid afforded diethyl 1-(pyrene-1-carbothioamido)alkylphosphonates in 83-94% yield. These compounds were transformed, in 87-94% yield, into the corresponding diethyl 1-(pyrene-1-carboxamido)alkylphosphonates by treatment with Oxone(®). 1-(Pyrene-1-carboxamido)methylphosphonic acid was obtained in a 87% yield by treating the corresponding diethyl phosphonate with Me3Si-Br in methanol. All of the synthesized amidophosphonates were emissive in solution and in the solid state. The presence of a phosphonato group brought about an approximately two-fold increase in solution fluorescence quantum yield in comparison with that of a model N-alkyl pyrene-1-carboxamide. This effect was tentatively explained by stiffening of the amidophosphonate lateral chain which was caused by the interaction (intramolecular hydrogen bond) of phosphonate and amide groups. The synthesized phosphonic acid was soluble in a biological aqueous buffer (PBS, 0.01 M, pH 7.35) and was strongly emissive under these conditions (λem = 383, 400 nm, τ = 18.7 ns, ΦF > 0.98). Solid-state emission of diethyl 1-(pyrene-1-carboxamido)methylphosphonate (λmax = 485 nm; ΦF = 0.25) was assigned to π-π aggregates, the presence of which was revealed by single-crystal X-ray diffraction analysis.
authors.affiliation: Department of Organic Chemistry, Faculty of Chemistry, University of Łódź, Tamka 12, 91-403 Łódź, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Wrona-Piotrowicz
authors.affiliation: Department of Organic Chemistry, Faculty of Chemistry, University of Łódź, Tamka 12, 91-403 Łódź, Poland.
authors.forename: Janusz
authors.initials: J
authors.lastname: Zakrzewski
authors.affiliation: Institute of Organic Chemistry, Faculty of Chemistry, Technical University of Łódź, Stefana Żeromskiego116, 90-924 Łódź, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Gajda
authors.affiliation: Institute of Organic Chemistry, Faculty of Chemistry, Technical University of Łódź, Stefana Żeromskiego116, 90-924 Łódź, Poland.
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Gajda
authors.affiliation: University of Warsaw, Biological and Chemical Research Center, Żwirki i Wigury 101, 02-089 Warszawa, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Makal
authors.affiliation: PPSM, ENS Cachan, CNRS, UniverSud, 61 av President Wilson, 94230 Cachan, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Brosseau
authors.affiliation: PPSM, ENS Cachan, CNRS, UniverSud, 61 av President Wilson, 94230 Cachan, France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Métivier
keywords: X-ray structure; amide; fluorescence; isothiocyanate; phosphonate; pyrene; thioamide