understanding of host–guest noncovalent interactions lies at the very heart of supramolecular chemistry. Often a minute change to the structure of a host molecule'sbindingsite can have a dramatic impact on a prospective host–guestbinding event, changing the relative selectivity for potential guest molecules. With the overall goal of aiding the rational design of selective and effective receptors for anions
The azulene moiety has been investigated as a new buildingblock for optical sensors for anions. In the course of these studies, amide and thioamide derivatives of azulene-5,7-dicarboxylic acid were synthesized. Their affinity towards anions and structural preferences are described. The X-ray analysis of the thioamide revealed the formation of a supramolecular helix.
The preferred conformations and the dynamic processes of the title compounds have been determined by variable temperature 1H-NMR analysis. Molecular mechanics calculations suggested the detail course of the conformational interconversion.
The thermolysis of 1-substituted 4-morpholino-3,3a,8,8a-tetrahydroazulene-5,6-dicarboxylates derivatives (7a—c) under catalytic dehydrogenation conditions was studied. The reaction substrates were prepared by a several-step sequence involving the [2+2] cycloaddition of bicyclc morpholino enamines with dimethyl acetylenedicarboxylate, and a subsequent electrocyclic opening of the cyclobutene ring as