Cation interaction with phosphine oxide functionalized

Cation Interaction with Phosphine Oxide Functionalized Calix[4]arenes... 

Derivative 141 (Scheme 4.40) was designed as a fluorescent molecular sensor exploiting the presence of a triphenylphosphine oxide function, which is known to coordinate cations and the fluorescent phenylacetylene moieties [74b]. This compound is prepared in ca. 30 % yield according to the route depicted in Scheme 4.40. As observed with the structurally related styryl-substituted phosphine oxides 119 (Scheme 4.35), there is only an extremely weak (if any) interaction between the chromophores in the ground state for 141. As expected, phosphine oxide 141 is strongly fluorescent with quantum yields varying from 0.71 to 0.89 % according to the nature of the solvent. 

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