Bichromophoric fluorescent photolabile protecting group for alcohols and carboxylic acids

Abstract

Novel bichromophoric fluorescent photolabile protecting group, (5-dansyloxy-3-hydroxynaphthalen-2-yl)methyl (DNS-NQMP), allows for the independent photochemical release and fluorescent imaging of caged substrates. Irradiation of DNS-NQMP-caged alcohols and carboxylic acids with 300 or 350 nm light results in fast (k_release ∼ 10⁵ s⁻¹), efficient (Φ = 0.2), and quantitative release of the substrates. This uncaging chemistry is compatible with aqueous media and DNS-NQMP-protected hydroxy compounds are hydrolytically stable at neutral pH. Upon excitation with 400 nm light, caged compounds show intense green emission (λ_max = 559 nm) with 21% fluorescence quantum yield. Fluorescent readout conducted using 400 nm or longer wavelengths does not cause substrate release. The DNS-NQMP chromophore retains its fluorescent properties after photo-uncaging reaction.