Photo-oxidation of triarylmethanes sensitised by carbonium ions

Photo‐Oxidation of Some DI‐2‐Benzothiazolymethane Derivatives

“…As we have previously shown that compound 1 does not tautomerize to the corresponding NH form (2), it can be deduced from the above results that the CH forms can be substrates of that photo-oxidation reaction (13)(14)(15)(16), but the enamine substrates are oxidized at higher apparent rates. The existence of different reaction mechanisms, can be tentatively proposed for both types of structures.…”

Triarylmethane Mechanophores Enable Full-Visible Spectrum Mechanochromism

“…Finally, to acquire a persistent yellow color, we opted for a xanthone core in Tr-3 + instead of an unsubstituted Tr + , which is also yellow. , This choice was motivated by the fact that xanthone-based Tr + species have a p K R+ of 5.4, which is much higher than the p K R+ of unsubstituted Tr + (−6.6) . However, the introduction of electron-donating alkoxy substituents in the skeleton of Tr + increases the stability of the resulting carbocation and also causes an undesired bathochromic shift in its absorption spectrum. , We opted to introduce only a single dimethoxy group into the design of Tr-3 + to facilitate purification, handling, and storage. Our attempts at preparing symmetrical, dialkoxy-substituted, xanthone-based Tr + revealed that these carbocations have a higher tendency to degrade than their monosubstituted counterparts.…”

“…38 However, the introduction of electron-donating alkoxy substituents in the skeleton of Tr + increases the stability of the resulting carbocation and also causes an undesired bathochromic shift in its absorption spectrum. 39,40 We opted to introduce only a single dimethoxy group into the design of Tr-3 + to facilitate purification, handling, and storage. Our attempts at preparing symmetrical, dialkoxy-substituted, xanthone-based Tr + revealed that these carbocations have a higher tendency to degrade than their monosubstituted counterparts.…”