Supramolecular Recognition within a Nanosized "Buckytrap" That Exhibits Substantial Photoconductivity.

We report here a nanosized "buckytrap", , constructed from two bis-zinc(II) expanded-TTF (exTTF) porphyrin subunits. Two forms, and , differing in the axial ligands, HO vs tetrahydrofuran (THF), were isolated and characterized. Discrete host-guest inclusion complexes are formed upon treatment with fullerenes as inferred from a single-crystal X-ray structural analyses of with C. The fullerene is found to be encapsulated within the inner pseudohexagonal cavity of . In contrast, the corresponding free-base derivative () was found to form infinite ball-and-socket type supramolecular organic frameworks (3D-SOFs) with fullerenes, (C) or (•C). This difference is ascribed to the fact that in and the axial positions are blocked by a HO or THF ligand. Emission spectroscopic studies supported a 1:1 host-guest binding stoichiometry, allowing association constants of (2.0 ± 0.5) × 10 M and (4.3 ± 0.9) × 10 M to be calculated for C and C, respectively. Flash-photolysis time-resolved microwave conductivity (FP-TRMC) studies of solid films of the Zn-complex revealed that the intrinsic charge carrier transport, i.e., pseudo-photoconductivity (ϕ∑μ), increases upon fullerene inclusion (e.g., ϕ∑μ = 1.53 × 10 cm V s for C⊂() and ϕ∑μ = 1.45 × 10 cm V s for C⊂() vs ϕ∑μ = 2.49 × 10 cm V s for ) at 298 K. These findings provide support for the notion that controlling the nature of self-assembly supramolecular constructs formed from exTTF-porphyrin dimers through metalation or choice of fullerene can be used to regulate key functional features, including photoconductivity.