A theoretical ab initio study of the capacity of several binding units for the molecular recognition of anions

Noncovalent bonding between anions and the it-cloud of electron-deficient aromatic rings has recently attracted considerable attention. Complexes of bromide with different electron-deficient aromatic rings and with other binding units based on hydrogen bonding (urea, thiourea and squaramide) have been studied and compared using high level B3LYP/6-31++G** ab initio and Molecular Interaction Potential with polarization (MIPp) calculations. Our findings reveal that electron-deficient aromatic rings are excellent candidates for constructing anion receptors and that the interaction strength can be modulated by the nature of the ring. Supporting experimental evidence has been obtained from X-ray structures retrieved from the Cambridge Structural Database. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.