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چکیده
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new tetramine bis(2-naphthol)-derivative was synthesized and its structure investigated by 1H- and 13C NMR, UV-Vis absorption and fluorescence spectroscopies, as well as through density functional theory calculations (including time-dependent DFT). The effect of a series of metal ions (Ag+, Al3+, Ba2+, Ca2+, Cd2+, Co2+, Cs +, Cu2+, Fe2+, Fe3+, K+, Mg2+, Mn2+, Ni2+, Pb2+ and Zn2+) on the fluorescence spectra of the synthesized compound was then investigated and it was observed that the presence of Al3+ ion causes a strong increase in the fluorescence emission of the ligand, by about 70 times. This exceptional intensification is specific for Al3+ within the whole series of ions investigated, together with the selectivity found for many of the remaining ions (in particular the ions of Groups I and II of the Periodic Table and Mn2+), makes the compound a promising candidate to act as chemosensor for Al3+. Possible structures for the ligand:Al3+ complex are suggested based on DFT results. TD-DFT calculations performed on these structures suggest that the fluorescence enhancement upon binding of Al3+ to the ligand results most probably from metal-to-ligand charge transfer where the acceptor groups of the ligand are the naphthol moieties
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