.1,8 - Synthesis And Luminescence Properties Of Nalidixic System Of Small Molecule Compounds

With the fast development of new academic fields, luminescent materials and technology have attracted much attention. Today, luminescent materials play important roles in many fields of the society, and the research work on them still have a lot to explore. Up to now, few reports about the properties of 1,8-naphthyridine has yet found in the literature. From the view of molecular design, a new series of 7-amino-4- methy-1, 8- naphthyridine with different electron donating or withdrawing substituted group in position 2, 7 and 6, and two mental complex have been synthesized in the present paper. Their structures are determined by IR, UV, lH NMR, MS, TOF, elemental analysis, and X-ray diffraction. The optical properties of them are investigated in solution and solid-state. The impact of varying polarity solvent, PH and ionic species such as Zn2+, Cu+ are also studied on absorption and emission spectra. The results are as follows:1. It shows that their absorption spectra almost keep invariable with increasing of solventpolarity. Red shift of emission spectra in different polar solvents is obviously observed. For these compounds with different electron donating groups or withdrawing groups, red shift depends on the change of substitutes characters.2.The optical properties of this series of 1,8-naphthyridines are sensitive to PH due to a function of protonation and deprotonation. This series of 1,8-naphthyridines all show basic property with the nitrogen as possible basic centers. Results show that when acid condition is established, their spectra changes can be obviously observed, when solution is basified, only the compounds hydroxyl group as possible acidic centers show spectra changes. The results point out that, for the asymmetric conjugated compounds with different electron donation or withdrawing groups, the changes of substitutes' character have great influence on the luminescence.3. The changes of substitutes' character have great influence on the luminescence when they are complexed with metals. Chelation-enhanced fluorescence (CHEF) appears when compounds with electron donating groups are complexed with Zn2+. Fluorescence of these compounds is quenched when they are complexed with trasition metal ions such as Cu+ which have quenching potential.4. Both absorption and emission measurements reveal that the optical behavior of them are sensitive upon microenvironmental changes. The intention of this paper is to introduce thesecompounds, due to their sensitivity to the environment, as potential florescence probes.