title: Bisamides derived from azulene-1,3- and -5,7-dicarboxylic acids as new building blocks for anion receptors.
abstract: Bisamides based on the azulene moiety were investigated as building blocks for anion receptors. In the course of these studies, derivatives of azulene-1,3- and -5,7-dicarboxylic acid were synthesized and thoroughly characterized. The anion affinities of the derivatives based on functionalization in the five-membered ring and in the seven-membered ring were determined by (1)H NMR titration. The structural analysis of these building blocks was performed by X-ray diffractometry, molecular modelling and 2D NMR spectroscopy. The five-membered ring derivatives are easy to obtain, offer a binding site preorganized in the syn-syn conformation and bind anions with a strength similar to those of pyrrole-based analogues. There is also strong evidence for aromatic CH...anion interactions. The ligands substituted at the 5- and 7-positions offer a binding cleft with an uncommon geometry that originates from the seven-membered ring and seems to be complementary to the chloride anion.
authors: Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
authors: Tomasz
authors: T
authors: Zieliński
authors: Mariusz
authors: M
authors: Kedziorek
authors: Janusz
authors: J
authors: Jurczak