New Molecular Tweezers for Anion RecognitionJose M. Hermida Ramón and Carlos M. Estévez

Department of Physical Chemistry. Facultade de Químicas. Universidade de Vigo.

Goal = to design molecular tweezers with their MEP in the concave side more positive than the concave one, which can hold anions.

Methods: DFT/6-31+G* geometry optimizations.

Truhlar’s functional MPW1B95.2

Counterpoise for BSSE on the complexes optimized geometries.

Proposed molecular tweezer

Complexation with halide anions

Cl- Br- I-

∆Ecomplex= -29.47 kcal mol-1

Edeformation= 2.73 kcal mol-1

∆Ecomplex= -26.45 kcal mol-1

Edeformation = 2.79 kcal mol-1

∆Ecomplex= -26.14 kcal mol-1

Edeformation = 2.04 kcal mol-1

References:

1 Hermida-Ramón, J. M., Estévez, C.M.; ESPA2006 oral presentation.

2 Zhao, Y, Truhlar, D. G.; J.Phys. Chem. 108 (33): 6908-6918 2004

3 Klärner, F.-G., Kahlert, B.; Acc. Chem. Res. 36 (12): 919-932 2003

MEP in a.u.

MEP in the molecular plane MEP in the center of the cavity

Klärner´s molecular tweezers: can bind to electrodeficient molecules

After fluorine substitution, can hold

anions.1

The MEP in the concave side is almost neutral and less positive than in the convex one.1

I-

F

O

concave side MEP > convex side MEP

∆Ecomplex, complexation energies (corrected for BSSE), slightly larger that the corresponding ones for cation complexes with Klärner´s molecular tweezers.3