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Creators/Authors contains: "Da Silva, José P."

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  1. ; ; ; ; ; ; ; (, Photochemical & Photobiological Sciences)
    null (Ed.)
    Extending the applications of Photoremovable Protecting Groups (PPGs) to “cage” phenols has generally met with unusually complex PPG byproducts. In this study, we demonstrate that the p –hydroxyphenacyl (pHP) cage for both simple and complex phenolics, including tyrosine, dispenses free phenols. With the simpler unsubstituted phenols, the reaction is governed by their Brønsted Leaving Group ability. On the other hand, the byproducts of the cage vary with these phenols. For the more acidic phenols the cage byproduct follows the Favorskii rearrangement to form p -hydroxyphenylacetic acid whereas for the weaker phenols other reactions such as reduction and hydrolysis begin to emerge. When the photolysis is conducted in octa acid (OA) containers, non-Favorskii, unrearranged fragments of the cage and other byproducts arise. 
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  2. ; ; ; ; (, Photochemical & Photobiological Sciences)
    ortho -Nitrobenzyl ( o NB) triggers have been extensively used to release various molecules of interest. However, the toxicity and reactivity of the spent chromophore, o -nitrosobenzaldehyde, remains an unaddressed difficulty. In this study we have applied the well-established supramolecular photochemical concepts to retain the spent trigger o -nitrosobenzaldehyde within the organic capsule after release of water-soluble acids and alcohols. The sequestering power of organic capsules for spent chromophores during photorelease from ortho -nitrobenzyl esters, ethers and alcohols is demonstrated with several examples. 
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