title: Preparation and characterization of thermochemiluminescent acridine-containing 1,2-dioxetanes as promising ultrasensitive labels in bioanalysis.
abstract: Thermochemiluminescence is the luminescence process in which a thermodynamically unstable molecule decomposes with light emission when heated above a threshold temperature. We recently reported the thermochemiluminescence properties of an acridine-containing 1,2-dioxetane, which emits at relatively low temperatures (i.e., below 100 °C). Herein, we explored the effect of the introduction of methyl substituents in the acridine system. The methyl group did not determine an excessive destabilization of 1,2-dioxetane ring nor significantly affect the general physical properties of the molecule. Monosubstituted methyl derivatives and a series of derivatives bearing several combinations of two, three, and four methyl groups were prepared. The rate of formation of 1,2-dioxetane derivatives 1b-k strongly depended on the methyl substitution pattern. All members of this library of mono-, di-, tri-, and tetramethyl-substituted derivatives were characterized in terms of photophysical and thermochemiluminescence properties. The introduction of methyl groups into the acridine ring caused a marked decrease in the activation energy of the thermochemiluminescent reaction. Tri- and tetramethyl-substituted acridones had the highest fluorescence quantum yields, in the range 0.48-0.52, and the corresponding 1,2-dioxetanes 1h and 1j showed in thermochemiluminescence imaging experiments limit of detection values more than ten times lower with respect to the unsubstituted derivative.
authors.affiliation: Advanced Applications in Mechanical Engineering and Materials Technology Interdepartmental Center for Industrial Research, Alma Mater Studiorum, University of Bologna , Bologna, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Di Fusco
authors.forename: Arianna
authors.initials: A
authors.lastname: Quintavalla
authors.forename: Claudio
authors.initials: C
authors.lastname: Trombini
authors.forename: Marco
authors.initials: M
authors.lastname: Lombardo
authors.forename: Aldo
authors.initials: A
authors.lastname: Roda
authors.forename: Massimo
authors.initials: M
authors.lastname: Guardigli
authors.forename: Mara
authors.initials: M
authors.lastname: Mirasoli
mesh_terms: D000166:Acridines / Q000737:chemistry*; D001681:Biological Assay; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D006573:Heterocyclic Compounds, 1-Ring; D049449:Luminescence; D015394:Molecular Structure; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
chemical_list: D000166:Acridines; D006571:Heterocyclic Compounds; D006573:Heterocyclic Compounds, 1-Ring; C079142:1,2-dioxetane