Theoretical design of a fluorescence sensor with configuration-transformed metal ion recognition of aza-18-crown-6

Abstract

ABSTRACTA novel configuration-transformed metal-ion-recognizing fluorescent molecular sensor was designed. The ground state geometries of the free ligand L(L1, L2)and their metal ion complex L/Mn+ have been investigated theoretically by density functional theory (DFT). The interaction of L and a series of alkaline earth metal ions have been carried out by the natural bond orbital (NBO) and mayer bond order. The calculated results reveal that the metal ion Sr2+ has strong interaction with the free ligand L. The excited states, absorption spectra and fluorescence emission spectra of the free ligands L1, L2 and their complexes L/Mn+ were performed by the time-density functional theory (TD-DFT). The UV-vis results show that the absorption peak of L2/Sr2+ has an obvious change compared with that of L2, which indicates that the free ligand L2 can specifically identify the metal ion Sr2+. Furthermore, L2/Sr2+ is superior fluorescent molecular sensor compared with other molecules.