title: Magnesium azaphthalocyanines: an emerging family of excellent red-emitting fluorophores.
abstract: Magnesium(II), zinc(II), and metal-free phthalocyanines (Pcs) and azaphthalocyanines (AzaPcs) containing alkylsulfanyl, aryloxy, and dialkylamino peripheral substituents have been synthesized. The complexation of magnesium(II) by metal-free Pcs and AzaPcs has been studied in detail to determine the optimal reaction conditions necessary to ensure a complete conversion. Photophysical and photochemical measurements in tetrahydrofuran showed that magnesium(II) AzaPcs with aryloxy and alkylsulfanyl substituents have excellent fluorescent properties (Φ(F) up to 0.73) and that the corresponding zinc(II) Pcs are efficient singlet oxygen producers (Φ(Δ) up to 0.68). The presence of dialkylamino substituents causes intramolecular charge transfer within the molecule that competes with fluorescence and singlet oxygen formation. Alkylsulfanyl MgAzaPc and ZnAzaPc were the most photostable compounds among the series of studied derivatives. In addition, high molar absorption coefficients (ε ∼ 300,000 M(-1) cm(-1)), absorption (λ(max) ∼ 650 nm), and emission (λ(em) ∼ 660 nm, high Φ(F)) in the red region suggest that these molecules are potential fluorescent probes that are superior to the commercial red cyanine dye Cy5. MgAzaPc, when incorporated into lipidic bilayers of liposomes, maintains excellent fluorescence properties (Φ(F) = 0.64). Water-soluble MgAzaPc with quaternary ammonium peripheral substituents retained a high fluorescence quantum yield even in water (Φ(F) = 0.25). The described properties show that magnesium(II) AzaPcs are excellent red-emitting fluorophores with potential applications as fluorescent probes in sensing or in vitro imaging applications.
authors.affiliation: Department of Pharmaceutical Chemistry and Drug Control, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Heyrovskeho 1203, 50005, Hradec Kralove, Czech Republic. petr.zimcik@faf.cuni.cz
authors.forename: Petr
authors.initials: P
authors.lastname: Zimcik
authors.forename: Veronika
authors.initials: V
authors.lastname: Novakova
authors.forename: Kamil
authors.initials: K
authors.lastname: Kopecky
authors.forename: Miroslav
authors.initials: M
authors.lastname: Miletin
authors.forename: Rabia Zeynep
authors.initials: RZ
authors.lastname: Uslu Kobak
authors.forename: Eva
authors.initials: E
authors.lastname: Svandrlikova
authors.forename: Lenka
authors.initials: L
authors.lastname: Váchová
authors.forename: Kamil
authors.initials: K
authors.lastname: Lang
mesh_terms: D005453:Fluorescence; D005456:Fluorescent Dyes / Q000138:chemical synthesis*; D005663:Furans / Q000737:chemistry; D007211:Indoles / Q000138:chemical synthesis*; D054833:Isoindoles; D008274:Magnesium / Q000737:chemistry*; D015394:Molecular Structure; D011789:Quantum Theory; D026082:Singlet Oxygen; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry; D015032:Zinc / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D005663:Furans; D007211:Indoles; D054833:Isoindoles; D014867:Water; D026082:Singlet Oxygen; C018674:tetrahydrofuran; D008274:Magnesium; D015032:Zinc; C013647:phthalocyanine