Design of differently P-substituted 4i PO fluorescent tetraphosphonate cavitands

Experimental approaches to tetraphosphonate cavitands bearing fluorenyl-phosphonate bridges are reported. Different routes are described depending on the substitution on the cavitand structure. Tetra-, tri- and di-bridged phosphonate cavitands have been prepared as precursors of fluorescent hosts, for which the stereochemistry is highly dependent on the substitution at the wide rim of the resorcin[4]arene scaffold. The conformational change in 3io tetraphosphonate cavitands has been characterised by X-ray diffraction. These new molecular receptors have been used for the recognition of acetylcholine.