ISSN:
1573-1111
Keywords:
Calixarenes
;
molecular dynamics
;
binding selectivity
;
ion pairs
;
solvent effect
;
molecular recognition
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract We report a theoretical study of the NR4+salts (R = H; Me; Et) of the t-butylcalix[4]arenemonooxyanion L- inacetonitrile solution, to compare the endocomplexes NR4+ inside the cone of thehost) with the exo ones. For a given cation, wefind that the complexes display structures of similartype in the gas phase and in acetonitrile solution.Intrinsically, the endo forms are more stablethan exo ones, but they are less well solvated.As a result, exo complexes are predicted to bemore stable than the endo ones in acetonitrile.In the gas phase and in solution, the exocomplexes of NMe4+ and NEt4+display interesting examples of fluctional intimateion pairs, where the cation oscillates between theoxygen lower rim region of L- and exoπ stacking with the phenolic rings ofL-. Based on free energy perturbation calculations,we compare endo NH4+/NMe4+complexes and find that the hypotheticalNH4+ complex is more stable in acetonitrile solution.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1007928016353
Permalink
