Ratiometric Cu^Ⅱ Fluorescent Probe Based On Internal Charge Transfer (ICT)

copper is a vital trace element and plays an important role in living systems such as those occurring in the human nervous system, gene expression, and the functional and structural enhancement of proteins. Therefore the fluorescent probes for fast detection of Cuâ…¡in aqueous solution or biosystems is significant for life sciences and environmental sciencesIn this article, two new ratiometric Cuâ…¡fluorescent probes (probe 1 and probe 2) with naphthalimide as an electron donor and an acceptor (EDA) group was designed based on the mechanism of internal charge transfer (ICT). The two probes were designed based on probe B for the high selectivity with the similar tetradentate receptor, the addition of a carbonyl group at the side of aniline not only provided the more Lewis basic binding site to bind Cuâ…¡more strongly within the cavity but also reduced the steric hindrance by avoiding the interaction of two aniline groups. This design strategy would help to extend the development of ratiometric fluorescent probes for other metal ions.Probe 1 was synthesized from acenaphthene following a literature procedure, however the Synthesis route of probe 2 was fail for the intermediat compound couldn't be synthesized by experiments. The optical behaviours of probe 1 showed that it contains advantages of A and B, displaying colorimetric response with fluorescence spectra from yellow to green which was useful for easy detection of Cuâ…¡with a ratiometrically and exclusively selectivity in the presence of a variety of other metal ions in aqueous solutions.50nm blue shift emission were attributed to the reduction of the electron-donating ability of the two amino groups conjugated to the naphthalene ring. And especially, probe 1 can be used to successfully detect Cuâ…¡in cultured cells with the same fluorescent change. It should be potentially useful for the study of the toxicity or bioactivity of Cuâ…¡in living cells.On the basis of research for probe 1, we designed probe 3 and probe 4 used acenaphtho-pyrazine as a chromophore. Acenaphtho-pyrazine has a large conjugated group and strong electron-withdrawing ability, and its fluorescence emission wavelength can reach more than 600nm. So the optical behaviours of acenaphtho-pyrazine can reduce the interference from the background of biological organisms and duffusion. We have synthesized some kinds of intermediate compouds through multistep reactions. Especially, we have finished the acylchlorination reaction sucessfully. Both of probe 3 and probe 4 will be got after finish the final step reaction, however the products were complex and hard to purify. As a result, we discussed the difficulty of the synthesis in details and proposed some ideas for the synthesis of them.