ja983983x_si_001.pdf (1.05 MB)
Design Strategies for Solid-State Supramolecular Arrays Containing Both Mixed-Metalated and Freebase Porphyrins
journal contribution
posted on 1999-01-29, 00:00 authored by C. V. Krishnamohan Sharma, Grant A. Broker, Jonathan G. Huddleston, Jeffrey W. Baldwin, Robert M. Metzger, Robin D. RogersThe design of predictable multichromophoric supramolecular arrays of freebase and metallo porphyrins
constitutes an essential first step toward the synthesis of light-harvesting complexes. We now report crystal
engineering strategies to achieve the synthesis of controllable and predictable porphyrinic multichromophores
in the solid state. The coordination complexes of metal halides, MX2 (M = Cd, Hg, Pb; X = Br, I), with
freebase tetrapyridylporphyrin (TPyP) form either 1D, [(HgX2)2TPyP]·2TCE, 1, or 2D, [(MX2)TPyP]·4TCE,
(M = Pb, 2; Cd, 3) polymeric networks. The porphyrin cavities in these crystalline networks can be selectively
populated with various metal cations to generate ordered multiporphyrinic supramolecular arrays without
distorting the coordination networks, either by (a) crystallizing the metal halides and TPyP in the presence of
suitable metal salts or by (b) reacting metal halides with a mixture of freebase and metallo porphyrins in
specific stoichiometric ratios. A design limit has been reached following approach b, synthesis of the complexes
using 100% metalated TPyP results in a change in structure due to intermolecular MTPyP coordination. The
UV/vis and fluorescence spectra recorded on partially metalated complexes indicate the presence of the expected
absorption and emission bands. Additionally, complex 1 reveals an unusual clathration behavior, wherein the
stacking features perpendicular to the porphyrin plane adjust to allow inclusion of variable amounts of identical
guest solvent molecules without modification of the layered structure.