| Summary: | Three series of fluorescent phenanthroimidazoles bearing heterocyclic spacers were synthesized in moderate to excellent yields and evaluated as optical chemosensors for ions as well as two-photon absorbing chromophores. Interaction of compounds 5-7 with anions and cations in acetonitrile and acetonitrile/H2O (95 : 5) showed them to be selective receptors for several anions (AcO-, CN- and F-) and cations (Fe3+, Cu2+ and Pd2+), with compound 7a being the most sensitive receptor for Fe3+ and Cu2+. On the other hand, compounds 5a, 7b and 7c were the most sensitive receptors for AcO-, CN- and F-. The binding stoichiometry between the receptors and the anions and cations was found to be 1 : 2 (ligand to anion/metal cation). The binding process was also followed by H-1 NMR titrations. The evaluation of the TPA properties of chosen phenanthroimidazoles 7a-c by the two-photon induced fluorescence method revealed that compound 7c, which contains a bithienyl spacer, exhibited the highest TPA cross-section (sigma(2)) value.
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