Moving Atoms and Small Molecules out of Open Containers

Abstract

Density functional theory with the M05-2X exchange/correlation functional is used to study the barriers for expulsion of atoms and small molecules (N2, CO, H2, Ar, Kr, Xe, H2O) out of open fullerenes (I20) and related molecular containers (C40H20, [5]beltene, cucurbit[5]uril). The reactions are examples where dispersion plays a critical role in determining the barrier heights. Calculations are compared with experimental kinetic data for N2@I20, CO@I20, and Xe@cucurbit[5]uril (Xe@CB[5]). Comparing the four molecular containers, the activation barriers for escape of an atom or small molecule correlate with the binding energies. A new open-fullerene model container C40H20 (C40) was constructed from C60 with a constriction at both ends formed by five methylene groups around the rim. The activation barriers for escape of N2 and CO from the model container are similar to those from the I20 open-cage fullerene. In the case of H2O@C40, charge analysis reveals an interesting charge transfer at the transition state as the escaping guest is "squeezed" out of the host container.

Using dispersion-corrected density functional theory to understand supramolecular binding thermodynamics

“…The barriers for expulsion of atoms and small molecules (N 2 , CO, H 2 , Ar, Kr, Xe, H 2 O) from an open C 60 fullerene cage (I20) and related molecular containers (C 40 H 20 , [5]beltene, cucurbit [5]uril) determined on the M05-2X/6-311+G(d,p)//M05-2X/6-31(d) level of theory were reported in ref. 65. The SMD method with standard parameters was used to calculate free energies of solvation when comparison was made to measurements in solution.…”

First Analysis of the 1–v″ Progression of the Ångström (B1Σ+–A1Π) Band System in the Rare 13C17O Isotopologue

“…The CO molecule is also important in other branches of science, including research on chemical physics, microbiology, molecular biology, environment of Earth, technology of new materials, metallurgy, engineering processes, etc. − Due to this fact, it is an important and open issue to thoroughly and comprehensively study all natural isotopologues of the CO molecule to derive precise values of quantum-mechanical parameters and molecular constants of all excited states of the molecule under consideration. In this respect, high resolution spectroscopy based on a high accuracy dispersive optical method is very useful.…”

Cucurbit[5]uril derivatives as oxygen carriers

“…For example, per-hydroxylated cucurbit [6]uril, similar to (OH)10CB [5] 3 but containing 6 glycoluril units instead of 5, has been grafted on silica gel for applications in chromatography (17,18) and in the biodegradation of aliphatic hydrocarbons (19) Cucurbiturils are able to bind neutral small molecules (21)(22)(23), including noble gases (24)(25)(26)(27) and non-noble gases (27,28). They are located in the cavity, while cations are located at the portals (29)(30)(31).…”