Abstract Methyl 20-substituted mesopyropheophorbides-a were prepared by the chemical modification of natural chlorophyll-a via palladium-catalyzed cross-coupling reactions. The 20-ethynylation and further 2-pyridylation showed bathochromic shifts in their visible absorption bands… Click to show full abstract
Abstract Methyl 20-substituted mesopyropheophorbides-a were prepared by the chemical modification of natural chlorophyll-a via palladium-catalyzed cross-coupling reactions. The 20-ethynylation and further 2-pyridylation showed bathochromic shifts in their visible absorption bands as well as hyperchromic effects of the Qx bands in a diluted chloroform solution. The protonation and methylation at the nitrogen atom of the 202-pyridyl group induced much larger shifts and effects, especially giving red-shifted and intensified Qx bands.
               
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