Collect. Czech. Chem. Commun. 2004, 69, 1063-1079

Experimental and Theoretical Evidence of the Bidentate Binding Mode of Dichloroacetamido Groups at the Upper Rim of Calix[4]arene Hydrogen-Bonding Anion Receptors

Alessandro Casnatia,*, Francesca Bonettia, Francesco Sansonea, Franco Ugozzolib and Rocco Ungaroa,*

a Dipartimento di Chimica Organica e Industriale, Università di Parma, Parco Area delle Scienze 17/A, I-43100 Parma, Italy
b Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica, Università di Parma, Parco Area delle Scienze 17/A, I-43100 Parma, Italy


Calix[4]arenes in the 1,3-alternate conformation (1-3) and bearing activated amide groups at the upper rim have been synthesized and their anion binding properties studied and compared with conformationally mobile (4) or cone (Ib) receptors having the same binding groups. Association constants determined in CDCl3 show a stronger complexation for Y-shaped carboxylate anions and a higher efficiency for receptors (Ib and 3) bearing dichloroacetamido moieties as hydrogen bonding donor groups. Molecular modeling studies performed on the cone derivative (Ib) and its 1,3-alternate isomer (10) and ab initio calculations on 4-methoxyaniline derivatives (11-13) used as simplified models, reveal that the α,α-dichloroacetamido moieties bind anions in a bidentate fashion using both the N-H and the CHCl2 as hydrogen bonding donor groups. This explains the higher efficiency in carboxylate binding found for Ib and 3 that incorporate the dichloroacetamido binding unit in their structures.

Keywords: Calixarenes; Molecular modeling; Anion recognition; α,α-Dichloroacetamides; Hydrogen bonds; Conformation analysis; Carboxylate binding.

References: 26 live references.