9-(Cycloheptatrienylidene)-Fluorene Derivatives: For Fluorescent Chemosensor

In this dissertation, 9-(cycloheptatrienylidene)fluorene derivatives function as fluorescent chemosensor for metal ions were designed and discussed.9-(Cycloheptatrienylidene)fluorene derivatives with heterocrown ether structure have been prepared by well known Sonagoshira coupling reaction, and their structures were characterized by ¹H NMR ¹³C NMR and MS. Their optical properties have been measured by UV-vis spectropHotometer and spectrofluorometer, which show the intramolecular charge transfer.2,7-Bis(2-(4-(di(2-(2-ethoxyethoxy)ethyl)amino)pHenyl)ethynyl)-9-(cyclohepta trienylidene)fluorine (7) exhibits high sensitivity and selectivity for Cu²⁺ or Fe³⁺ (no response to Na⁺; Fe²⁺; Ag⁺; Zn²⁺; Co²⁺; Cd²⁺; Ni²⁺; Mg²⁺; Ca²⁺; Hg²⁺; Mn²⁺; K⁺; Ba²⁺; Li⁺; Pb²⁺; Cs⁺; Cr³⁺ and Sm³⁺), and displayed quenched emission when either Cu²⁺ or Fe³⁺ was added into its acetonitrile solution. However, 2, 7-bis(2-(4-(di(2-hydroxyethyl)amino)pHenyl)ethynyl)-9-(cycloheptatrienylidene)flu orine (8) could successfully identify Fe³⁺ or Cu²⁺ by enhanced emission with addition of Fe³⁺ in its methanol or with addition of Cu²⁺ in its acetonitrile.With the futher study, we find that emission enhancement was ascribed to nano-aggregates formation, which was induced by supramolecular self-assembly between non-benzenoid hydrocarbons and metal ions through intermolecular electrostatic force in organic solvent. Both transmission electron microscope (TEM) and dynamic light scattering (DLS) proved the existence of nano aggregates.