Six-Coordinate Zinc Porphyrins for Template-Directed Synthesis of Spiro-Fused Nanorings

J Am Chem Soc. 2015 Nov 18;137(45):14256-9. doi: 10.1021/jacs.5b10126. Epub 2015 Nov 6.

Abstract

Five-coordinate geometry is the standard binding mode of zinc porphyrins with pyridine ligands. Here we show that pseudo-octahedral six-coordinate zinc porphyrin complexes can also be formed in solution, by taking advantage of the chelate effect. UV-vis-NIR titrations indicate that the strength of this second coordination is ca. 6-8 kJ mol(-1). We have used the formation of six-coordinate zinc porphyrin complexes to achieve the template-directed synthesis of a 3D π-conjugated spiro-fused array of 11 porphyrin units, covalently connected in a nontrivial topology. Time-resolved fluorescence anisotropy experiments show that electronic excitation delocalizes between the two perpendicular nanorings of this spiro-system within the experimental time-resolution of 270 fs.

Publication types

  • Research Support, Non-U.S. Gov't