Nitric oxide (NO) is an endogenous signaling molecule used in multiple biochemical processes. The development of switchable NO donors that deliver an NO payload under spatiotemporal control harbors many medicinal benefits. Previously, 4-fluorofuroxans were found to function as a UV light-induced NO donor under physiological conditions based on the photoinduced isomerization mechanism; however, the isomerization of fluorofuroxans with longer wavelength light is desired for further application into living systems. Herein, we report the use of photosensitizers in the photochemical isomerization of fluorofuroxan, enabling the use of visible light to induce isomerization. Among the tried photosensitizers, anthraquinone derivatives showed a good sensitizing ability to isomerize 4-fluorofuroxan to 3-fluorofuroxan using visible light. This new phenomenon was applied to the synthesis of a water-soluble anthraquinone-fluorofuroxan all-in-one molecule, which demonstrated promising NO-releasing ability using 400-500 nm irradiation. A high level of control is displayed with "on" and "off" NO-release functionality suggesting that photosensitizer-furoxan hybrids would make valuable donors. Furthermore, unlike most furoxans, NO is released in the absence of thiol cofactor.

We describe the design and facile synthesis of a fluorescent alkoxyfuroxan naphthalenediimide (NDI) hybrid nitric oxide (NO) donor molecule which releases NO under spatiotemporal control when irradiated with visible light (420-600 nm). The hybrid also demonstrates cellular uptake made possible by its fluorescence capability. This research consolidates on our recent work into visible light absorbing photosensitised furoxan NO release by addressing the limitations of previous designs. Key points of photoinduced nitric oxide donors are highlighted such as water solubility, NO release, cellular uptake, fluorescence, and longer absorption wavelengths.