M. Scott Goodman

Metal templated receptors for the effective complexation of dicarboxylates

Abstract In this paper we show that a thiourea-functionalized terpyridine unit can be induced to form, in the presence of ruthenium (II), a well-ordered recognition site for dicarboxylate ions. Strong binding to the self-assembled receptor can be followed by 1 H NMR in DMSO and association constants of >10 4 M −1 were measured in certain cases.

Nitronate anion recognition and modulation of ambident reactivity by hydrogen-bonding receptors.

Nitronate anions were shown to form complexes in DMSO with hydrogen-bonding receptors such as 1,3-dimethylthiourea 1 (K(a)= 120M(-1)) and bicyclic guanidinium 2 (K(a) = 3200M(-1)). A ditopic bis-thiourea exhibited increased association with substrates, that contained either two nitronates (K(a)= 7000M(-1)) or a combination of nitronate and carboxylate (K(a)=7200M(-1)). Complexation of nitronate resulted in a change in the ambident reactivity during alkylation with p-nitrobenzyl bromide. The predominant reaction pathway was shifted from oxygen alkylation to carbon alkylation as receptor binding strength increased. Kinetic analysis indicated an overall inhibition of nitronate reactivity, and this suggests that greater suppression of the oxygen pathway allows carbon alkylation to predominate.

A self-assembling receptor for dicarboxylic acids

In this paper we describe a simle binding subunit that self-assembles in the presence of metal ions to form a receptor for dicarboxylic acids. The resultant binding site is chiral and strong complexation to dicarboxylic acids in CDCl3 can be detected by both NMR and UV-vis spectroscopies.