Kishore RSK, Paululat T, Schmittel M. From Supramolecular Porphyrin Tweezers to Dynamic AnBmClDk Multiporphyrin Arrangements Through Orthogonal Coordination.
Chemistry 2006;
12:8136-49. [PMID:
16862633 DOI:
10.1002/chem.200600463]
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Abstract
A dynamic, supramolecular, three-component A(n)B(m)C(l) bis(zinc porphyrin) tweezer has been prepared quantitatively using the heteroleptic bisphenanthroline (HETPHEN) concept. Upon addition of nitrogenous spacers of different length, namely, the extended bipyridine 3 a, 4,4'-bipyridine (3 b), and 1,4-diazabicyclo[2.2.2]octane (DABCO; 3 c), to set up an additional orthogonal binding motif (Zn(Por)-N(spacer)), three structurally different, still dynamic, four-component A(n)B(m)C(l)D(k) assemblies were cleanly formed, as indicated by UV/Vis and NMR titrations as well as by DOSY investigations. The structures were identified as a bridged monotweezer A(2)BC(2)D, a doubly bridged double tweezer A(4)B(2)C(4)D(2), and a triply bridged double tweezer A(4)B(2)C(4)D(3), the latter resembling a porphyrin stack. Notably, the same structures were equally formed directly from a mixture of the constituents A, B, C, and D put together in any sequence if the correct stoichiometry was applied.
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