The Perfluoro Cage Effect: A Search for Electron-Encapsulating Molecules

Abstract

Quantum chemical calculations have for some time predicted that perfluorinated polyhedral organic molecules should exhibit a low-energy LUMO consisting of the overlapping inward-pointing lobes of the C−F σ* orbitals. Accordingly, these molecules should be able to encapsulate an electron within the interior of their cavities. Inspired by the recent confirmation of this prediction for perfluorocubane, we have sought to identify additional perfluorinated cage molecules capable of this remarkable behavior, which we refer to as the perfluoro cage effect (PCE). Using DFT calculations with multiple well-tested exchange-correlation functionals and large STO-QZ4P basis sets, we have identified several systems including [n]prismanes (n = 3−6), [n]asteranes (n = 3−5), twistane, and two norbornadiene dimer cages that clearly exhibit the PCE. In other words, they exhibit a low-energy LUMO belonging to the total symmetric irreducible representation of the point group in question and adiabatic electron affinities ranging from somewhat under 1 eV to over 2 eV. A pronounced size effect appears to hold, with larger cages exhibiting higher electron affinities (EAs). The largest adiabatic EAs, well over 3 eV, are predicted for perfluorinated dodecahedrane and C 60 . In contrast, the PCE is barely discernible for perfluorinated tetrahedrane and bicyclo[1.1.1]pentane.

From Diaminosilylenes to Silapyramidanes: Making Sense of the Stability of Divalent Silicon Compounds

“…Besides optimized geometries, we calculated vertical and adiabatic ionization potentials (IPs), electron affinities (EAs) and singlet–triplet gaps ( E S‑T ’s) in the hope that they would shed light on the special stability of π-complexes of decamethylsilicocene (Cp* 2 Si) and silapyramidanes (Table ). Based on long-standing − and recent − calibration studies in our laboratory, the present level of theory was expected to yield vertical ionization potentials to within 0.1–0.2 eV of experimental values derived from photoelectron spectroscopy. Indeed, for parent silylene, SiH 2 , the calculated adiabatic IP and EA (Table ) agree to within 0.1 eV with experimental values, 8.92 eV , and 1.12 eV, respectively, providing excellent calibration for the present calculations .…”

Pattern Formation in Evaporative Drying of a Polymer Solution Droplet over a Soft Swellable Substrate

“…Under actual experimental conditions, it is totally obvious that the peripheral zone surrounding the core region of the droplet had spatial variation in its thickness, and the dimples appeared over the thinnest regions. 56 Subsequently, a dimple also appears over the central zone of the drop after t E ≈ 43 s (Figure 1J). With periphery grow and form radial wrinkles, as can be seen in frames K−M of Figure 1.…”

About Perfluoropolyhedranes, Their Electron‐Accepting Ability and Questionable Supramolecular Hosting Capacity

“…Moreover, calculations indicate that a non‐negligible portion of the added electron spin distribution is actually located outside the carbon frame, near the fluorine atoms (Figure 7). Noteworthily, the computed electron affinities were predicted to be strongly size‐dependent, being almost nil for F ‐tetrahedrane, larger for F ‐cubane and F ‐adamantane, and even larger for F ‐dodecahedrane (Table 2) and hypothetical F ‐fullerene C 60 F 60 (3.9–4.5 eV), [88h] denoting that electrons are not insensitive to roominess.…”