Abstract:Singlet O2 is a key reactive oxygen species responsible for photodynamic therapy and is generally recognized to be chemically reactive towards C=C double bonds. Herein, we report the hydroperoxidation/lactonization of α-ethereal C–H bonds by singlet O2 (1Δg) under exceptionally mild conditions, i.e., room temperature and ambient pressure, with modest to high yields (38~90%) and excellent site selectivity. Singlet O2 has been known for > 90 years, but was never reported to be able to react with weakly activated… Show more
“…The Flack parameters for compounds 5 and 6 were very precise, allowing assignment of the absolute configuration of the four stereogenic centers in each compound with high confidence. Notably, the absolute configurations of (3aR)-(+)-Sclareolide and drospirenone have not been established by X-ray diffraction (Supplementary Table 5) 38,39 .Fig. 4Illustrative crystal structures of GS inclusion compounds.…”
Single crystal X-ray diffraction is arguably the most definitive method for molecular structure determination, but the inability to grow suitable single crystals can frustrate conventional X-ray diffraction analysis. We report herein an approach to molecular structure determination that relies on a versatile toolkit of guanidinium organosulfonate hydrogen-bonded host frameworks that form crystalline inclusion compounds with target molecules in a single-step crystallization, complementing the crystalline sponge method that relies on diffusion of the target into the cages of a metal-organic framework. The peculiar properties of the host frameworks enable rapid stoichiometric inclusion of a wide range of target molecules with full occupancy, typically without disorder and accompanying solvent, affording well-refined structures. Moreover, anomalous scattering by the framework sulfur atoms enables reliable assignment of absolute configuration of stereogenic centers. An ever-expanding library of organosulfonates provides a toolkit of frameworks for capturing specific target molecules for their structure determination.
“…The Flack parameters for compounds 5 and 6 were very precise, allowing assignment of the absolute configuration of the four stereogenic centers in each compound with high confidence. Notably, the absolute configurations of (3aR)-(+)-Sclareolide and drospirenone have not been established by X-ray diffraction (Supplementary Table 5) 38,39 .Fig. 4Illustrative crystal structures of GS inclusion compounds.…”
Single crystal X-ray diffraction is arguably the most definitive method for molecular structure determination, but the inability to grow suitable single crystals can frustrate conventional X-ray diffraction analysis. We report herein an approach to molecular structure determination that relies on a versatile toolkit of guanidinium organosulfonate hydrogen-bonded host frameworks that form crystalline inclusion compounds with target molecules in a single-step crystallization, complementing the crystalline sponge method that relies on diffusion of the target into the cages of a metal-organic framework. The peculiar properties of the host frameworks enable rapid stoichiometric inclusion of a wide range of target molecules with full occupancy, typically without disorder and accompanying solvent, affording well-refined structures. Moreover, anomalous scattering by the framework sulfur atoms enables reliable assignment of absolute configuration of stereogenic centers. An ever-expanding library of organosulfonates provides a toolkit of frameworks for capturing specific target molecules for their structure determination.
“…9,10 However, SO has also been used in a constructive sense, it being a highly effective reagent in chemical syntheses. 11,12 Photosensitized generation of SO underpins photodynamic therapy (PDT) where SO is generated in order to kill cancer cells. A therapeutic chromophore is administered depending on the disease condition followed by local irradiation at the disease site with an appropriate wavelength resulting in a high local concentration of SO.…”
Singlet oxygen sensitization involving a class of hemiquinonoid-substituted resorcinarenes prepared from the corresponding 3,5-di-t-butyl-4-hydroxyphenyl-substituted resorcinarenes is reported.
“…To the best of our knowledge, the selectivity of probe 1 for 1 O 2 could be described by two-step reactions. First, an aliphatic carbon adjacent to the oxygen atom was attacked by 1 O 2 [34]. Then, water reacted with the 1 O 2 -derived activated group to form a hydroxyl end group in the dicyanostilbene moiety.…”
We report self-assembled novel triphenylphosphonium-conjugated dicyanostilbene-based as selective fluorescence turn-on probes for 1O2 and ClO−. Mono- or di-triphenylphosphonium-conjugated dicyanostilbene derivatives 1 and 2 formed spherical structures with diameters of ca. 27 and 56.5 nm, respectively, through π-π interaction between dicyanostilbene groups. Self-assembled 1 showed strong fluorescent emission upon the addition of 1O2 and ClO− compared to other ROS (O2−, •OH, NO, TBHP, H2O2, GSH), metal ions (K+, Na+), and amino acids (cysteine and histidine). Upon addition of 1O2 and ClO−, the spherical structure of 1 changed to a fiber structure (8-nm wide; 300-nm long). Upon addition of 1O2 and ClO−, the chemical structural conversion of 1 was determined by FAB-Mass, NMR, IR and Zeta potential analysis, and the strong emission of the self-assembled 1 was due to an aggregation-induced emission enhancement. This self-assembled material was the first for selective ROS as a fluorescence turn-on probe. Thus, a nanostructure change-derived turn-on sensing strategy for 1O2 or ClO− may offer a new approach to developing methods for specific guest molecules in biological and environmental subjects.
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