Tapes, Sheets, and Prisms. Identification of the Weak C−F Interactions that Steer Fullerene−Porphyrin Cocrystallization

Abstract

Tetra(pentafluorophenyl)porphyrin (H 2 TPFPP) has been cocrystallized with C 60 from arene solvents to give H 2 TPFPP‚ C 60 , 1, H 2 TPFPP‚C 60 ‚8Benzene, 3, and 3H 2 TPFPP‚2C 60 ‚6Toluene, 4. Their X-ray structures have been determined to identify the supramolecular interactions that lead to tape, sheet, and prismatic packing motifs. In addition to close fullerene-porphyrin π-π interactions, attractive C-F‚‚‚H-C interactions are important in connecting the C 6 F 5 groups of one porphyrin to the pyrrole positions of a neighbor. This interaction is also seen in the structure of the free-base porphyrin H 2 TPFPP‚3p-Xylene, 2.

Fullerene−Porphyrin Constructs

“…An informative example is provided by the cocrystallate H 2 TPFP‚C 60 (H 2 TPFP ) tetra(pentafluorophenyl)porphyrin), which, as shown in Figure 4, combines the strict tetragonal register of alternating fullerenes and porphyrins with 2D sheets connected by (pentafluorophenyl)porphyrin C-F‚‚‚H-C hydrogen bridge interactions. 17 Although this structure postdated the fullerenepillared sheet structures discussed below, it illustrates the developing concept of engineering extended framework solids using the fullerene-porphyrin molecular attraction as a primary organizational element.…”

Self-Organized Porphyrinic Materials

“…This shorter separation has been attributed to an additional interaction between the electron density of a 6:6 ring juncture of the fullerene and the electropositive center of the porphyrin. Moreover, DFT calculations have shown that in the case of TPP the ortho -C-H··· π interactions increases π-π interactions for as much as 20% the when four C-H bonds are involved 266. Fullerenes are known to encapsulate various species, and the co-crystallization of a metal oxide cluster inside an icosahedral C 80 fullerene with Ni OEP was recently reported by Balch et al306…”

“…These cocrystals have been shown to form ordinate arrays of various shapes, ranging from tapes to sheets and other 3-D architectures that are largely dictated by the size of the C 60 and the substituents on the porphyrin. Pre-assembled porphyrins arrays can be used as well 266,267,279,284,305. The photonic properties of these materials depend on the electronic interactions between the two components, which arises from the solid state architecture.…”

“…Another structure by Hosseini et al266 finds C-F···H-C interactions between the perfluorophenyl groups on one porphyrin to the pyrrole β-H on a neighboring porphyrin results in several nanoarchitectures such as sheets, tapes, and prisms (Figure 18). This builds upon earlier work on the formation perfluorphenylporphyrin – C 60 cocrystals 264.…”

Self-organization of a new fluorous porphyrin and C60 films on indium-tin-oxide electrode

“…Samples stored in air and ambient light are stable for more than one month with no observed decomposition of the chromophores indicated by UV-visible spectroscopy. Considering the previous crystallographic data, 9 one possible molecular arrangement is with C 60 sandwiched between porphyrin molecules. Using the crystal data (fullerene diameter of 0.75 nm, and a porphyrin–C 60 distance of 0.26 nm) a 7 nm thick film would have ca.…”