Dendrophanes: Water‐Soluble Dendritic Receptors. Preliminary communication

Abstract

AbstractThe dendritic cyclophanes (dendrophanes )1–3 containing a [6.1.6.1]paracyclophane as the initiator core embedded in dendritic poly(ether‐amide) shells of first (1), second (2), and third (3) generation were prepared and characterized. The X‐ray crystal‐structure analyses of esters 7 and 4, derivatives of cyclophane core 9 and first‐generation dendrophane 1, respectively, displayed open cavity binding sites suitable for the inclusion complexation of aromatic substrates. With their carboxylate surface groups, dendrophanes 1–3 were readily soluble in aqueous phosphate buffer (pH 8.0), and the complexation of naphthalene derivatives was investigated by 1H‐NMR and fluorescence titrations. The binding studies demonstrated that the cyclophane cavity remains open and accessible to appropriate substrates even at higher dendritic generations. The 1:1 complexes formed in aqueous buffer were of similar stability to those formed by the unbranched core 9 (Ka between 1000 and 10000 1 mol−1, 300 K). Investigations with the fluorescent probe 6‐(p‐toluidino)naphthalene‐2‐sulfonate (12) showed that the micropolarity at the dendrophane core decreases with increasing generation number.