Host-Guest Preorganization and Complementarity: A Molecular Mechanics and Molecular Dynamics Study of Cation Complexes of a Cyclic Urea-Anisole Spherand
NEW JERSEY INST OF TECH NEWARK DIV OF CHEMISTRY
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Cram and coworkers have optimized the binding efficiency of spherands for their cationic guests by using the principles of preorganization and complementarity to guide the design of the molecular architecture of these macrocyclic hosts. In the present work, we provide a quantitative interpretation of these principles in terms of the inter- and intramolecular energy components associated with the formation of the host-guest complex. To that end, molecular mechanics energy optimizations and molecular dynamics simulations are carried out for 1 and for the complexes of 1 with alkali metal cations and t-BuNH3. Host preorganization is interpreted in terms of the spherand reorganization energy, that is, the change in the strain and nonbonded energy of the spherand upon complexation. Electrostatic complementarity is explored by evaluation of the change upon complexation in 1 the electrostatic component of the ion-spherand interaction energy and 2 the molecular electrostatic potential pattern presented by the spherand to the guest. Keywords Organic chemistry.
- Organic Chemistry