Synthesis and binding studies of new N-aryl aza-crown ether derivatives as possible sensing devices

A series of p-phenylenediamine, phenyl and m- or p-chlorophenyl substituted azacrown ether derivatives were synthesized through sequential nucleophilic substitution of [(eta5-cyclopentadienyl)(eta6-( m- or p-dichlorobenzene))]iron hexafluorophosphate by aza-crown ethers and cyclohexaamines. Monoamination is the main reaction from azacrown ethers, and monoarylation is the main reaction for diaza-crown ethers. The overall yield from the starting complex is 50--96% for multiple steps.*; Different types of fluorescent photoinduced electron transfer molecules were built up by attachment of either an anthracene or a dansyl group to the above new N-aryl azacrown ethers. Molecules with an anthracene pendent use the ring nitrogen as electron donor to quench the anthracene fluorescence, while dansyl molecules use p-phenylenediamine as electron donor to quench the dansyl fluorescence. Chelation-enhanced fluorescence was observed for all photoinduced electron transfer molecules upon addition of metal perchlorates in CH3CN. The fluorescence of anthracene compounds responds selectively toward Ca2+ over Mg2+, K+ and Na+. Nuclear magnetic resonance studies show that Ca2+ affects the whole molecule significantly; Mg 2+ has a great effect only on part of the molecule; K+ and Na+ each have moderate effect on the molecule. The fluorescence of dansyl compounds responds selectively toward Ca2+ and/or Mg2+, over K+ and Na+ depending on the structure of the compounds. The result shows that both size match between the crown ether cavity and metal cation and charge density sensitivity of the N-aryl moiety play very important role for the selectivity.; *Please refer to dissertation for diagrams.