Surfactant-Like Porphyrins in Homogeneous Solution and Organized Media: Studies of Metalation and Diprotonation
A diverse range of reactivities is reported for Cu(II) incorporation into meso-tetrakis (σ-alkylamidopheny)porphyrins in organized media (SDS micelles and AOT reversed micelles) as side-chain length and atropisomer structure are varied. Much more comparable reactivities are noted in homogeneous solution. The reactivity patterns in the organized assemblies are consistent with two separate, equilibrating interfacial orientations for the 4,0 atropisomer whose relative proportions vary with side chain length. The proposed orientations result in an inverted reactivity order for the short chain compounds in organized media (i.e. 4,0 < 3,1 < cis 2,2 < irans 2,2) as compared to that in homogeneous solution (i.e. 4,0 >3,1 > cis 2,2 > trans 2,2). A strong correlation between porphyrin core protonation constants and metalation anionic reactivities at the interfaces confirms the orientational hypothesis while catalytic metalation and elevated porphyrin basicities strongly support interfacial solubilization.
Atropisomer, Picket Fence, Porphyrin, Metalation, Micelle, Reversed Micelle.
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