Pyrrole-Pyridine and Pyrrole-Naphthyridine Hosts for Anion Recognition

Abstract

The association constants of the complexes formed by two hosts containing pyrrole, amide and azine (pyridine and 1,8-naphthyridine) groups and six guests, all monoanions (Cl−, CH3CO2−, NO3−, H2PO4−, BF4−, PF6−), have been determined using NMR titrations. The X-ray crystal structure of the host N2,N5-bis(6-methylpyridin-2-yl)-3,4-diphenyl-1H-pyrrole- 2,5-dicarboxamide (1) has been solved (P21/c monoclinic space group). B3LYP/6-31G(d,p) and calculations were carried out in an attempt to rationalize the trends observed in the experimental association constants.