Confinement induced thermodynamic and kinetic facilitation of some Diels–Alder reactions inside a CB[7] cavitand

Abstract

The effect of geometrical confinement on the Diels-Alder reactions between some model dienes viz. furan, thiophene, cyclopentadiene, benzene, and a classic dienophile, ethylene has been explored by performing density functional theory-based calculations. The effect of confinement has been imposed by a rigid macrocyclic molecule cucurbit[7]uril (CB[7]). Results indicate that all the reactions become thermodynamically more favorable at 298.15 K temperature and one atmospheric pressure inside CB[7] as compared to the corresponding free gaseous state reactions. Moreover, the rate constants associated with the reactions experience manifold enhancement inside CB[7] as compared to the "unconfined" reactions. Suitable contribution from the entropy factor makes the concerned reactions more facile inside CB[7]. The energy gap between the frontier molecular orbitals of the dienes and dienophiles decrease inside CB[7] as compared to that in the free state reactions thereby allowing facile orbital interactions. The nature of interaction as well as bonding has been analyzed with the help of atoms-in-molecules, noncovalent interaction, natural bond orbital as well as energy decomposition analyses. Results suggest that all the guests bind with CB[7] in an attractive fashion. Primarily, noncovalent interactions stabilize the host-guest systems. © 2017 Wiley Periodicals, Inc.

Electronic structure of first and second row atoms under harmonic confinement

“…Later on, they used a variety of theoretical methodologies to show that confinement has a significant effect on many classical chemical reactions. For example, they used a relative big molecular host to confine some model Diels‐Alder reactions and find the catalytic changes due to the confinement . The theoretical models they used range from numerical Hartree‐Fock (HF) to more sophisticated quantum‐fluid‐dynamics time‐dependent density functional methods developed by his group.…”

“…For example, they used a relative big molecular host to confine some model Diels-Alder reactions and find the catalytic changes due to the confinement. [25][26][27] The theoretical models they used range from numerical Hartree-Fock (HF) to more sophisticated quantum-fluid-dynamics time-dependent density functional methods developed by his group. Very recently, they wrote a feature article summarizing their results.…”

Toward Understanding CB[7]-Based Supramolecular Diels-Alder Catalysis

“…We have previously found that binding in CB favors the closed conformation of the reactants, in agreement with experimental NMR measurements. The confinement of the reacting molecules have also been taken into account by computations (Chakraborty and Chattaraj, 2018 ). However, these binding effects amounting to 1–2 kcal/mol, only partially explain the catalytic effects of 4–5 kcal/mol, which have so far been unresolved.…”

Computational Description of a Huisgen Cycloaddition Inside a Self‐Assembled Nanocapsule

“…Computational chemistry could be helpful in this concern, but relatively few computational studies have been published on the operating mode of supramolecular catalysts, [8,9,[17][18][19][20] although things may have changed in the last two years. [21][22][23][24] The systems are intrinsically challenging for computational chemistry: a large number of conformers, complicated reaction networks, and need for a sufficiently accurate description of weak interactions.…”