Journal of Physical Chemistry A, Vol.115, No.17, 4288-4298, 2011
Synthesis and Photopysical Properties of a Polioxo Ethylene Chain Alkaline Earth Metal Fluorescent Sensor with 2-Aminoanthracene As Terminal Group
A new symmetric polioxo ethylene chain fluorescent probe containing 2-aminoanthracene bichromophoric as the terminal group for the alkaline earth metal cation, 2,2'-[oxybis(3-oxapentamethyleneoxy)]-bis[N-(2-anthryl)benzamide)] (1), has been synthesized. The photo-physical properties of 1 have been studied by means of absorption, fluorescence spectroscopy, and H-1 NMR. The difference in emission spectra response to concentration of model compound 2-acetamido-anthracene and 1 in acetonitrile implies that intermolecular excited dimers is likely to occur. Fluorescence decay profiles of 2-acetamido-anthracene can be described by a biexponential fit, while three lifetimes, two of which are similar as those of 2-acetamido-anthracene, are found for 1. The third lifetime might be attributed to intramolecular excited dimers. Complex formation with alkaline earth metal ions are investigated in acetonitrile as solvent via fluorimetric titrations. Fluorescence intensity trend of the complex with Mg2+ differed from those of other alkaline earth metal ions. The compound forms 1:2 (ligand/Mg2+) complex with Mg2+ while formed 1:1 complexes with Ca2+, Sr2+, and Ba2+, producing large hypochromic shifts in the emission spectra and significant cation-induced fluorescence amplifications. On the contrary, the addition of Ca2+, Sr2+, or Ba2+ lead to a decrease in the fluorescence emission first, then an increase and blue shift in emission could be found at the end.