Novel Naphthalimide Fluorescent Sensors: Molecular Design, Synthesis And Recognition For Metal Ions

The analysis and detection of the transition metal ions is currently of significant importance for chemistry, as they are closed with biology, environment and clinic. The method of fluorescence is not only simple but also can realize real space, real time, high sensitive and selective. So the fluorescence supramolecular sensors, which are composed of traditional receptors connecting fluorophores, to metal ions are attracting many people's attentions.Three naphthalimide fluorescent probes were designed based on PET principle and synthesized for studying the recognition mechanism of the fluorescent probes to transition metal ions in organic solvents, and the spectra of the probes in the absence or presence of metal ions in different solvents were studied. The results showed that the fluorescence enhancement corresponding to transition metal ions of the probes in fluorophore-spacer-receptor format in organic solvent, might be induced by protons, which originated from the hydrolysis of transition metal ions in the presence of trace water in solvents or in metal ions hydrate salts, the fluorescence enhancement might not be from the direct interaction between probes and metal ions in organic solvents.The novel fluorosensors of 4,5-disubstituted-N-alkyl-l,8-naphthalimides derivatives(Hl, H2, H3) with double ethylenediamino receptors, double propylenediamino receptors or one methylpiperazine receptor were designed and synthesized, respectively, their fluorescence and absorption spectra in the presence or absence of metal ions in tris-HCl buffer aqueous solution were studied. In the presence of Ag+, the H1's absorption displayed color change from yellow-green to red, its quenching and red shift in fluorescence were also remarkable. Similarly, H1's fluorescence was also strongly quenched in the presence of Cu2+.The novel fluorosensors of 4,5-di(2-hydroxylethyleneamino) ethyleneamino -N-dodycyl-1, 8-naphthalimides and its analogues(Cl, C2, C3), which can formedcrown ether-like receptors through the intramolecular hydrogen-bonding of hydroxyl groups at the end, were designed and synthesized. Their fluorescent spectra in tris-HCl buffer aqueous solution were recorded in the presence or absence of transition metal ions. Cl showed a strong quenching and a considerable blue shift response to Cu2+ and Co2+, and both of the fluorescence intensity and absorption of Cl were proportional to the concentration of Cu2+ or Co2+ in the range of 0-1 xl0"5 mol/l. The crown fluorosensors C4-C8 was designed and synthesized. And the fluorescence intensity of C8 was enhanced when zinc ions was added to its methanol-tetramethylhydroxylammonium solution.The naphthalimide cationic surfactants with piperazine were synthesized (SI, S2, S3, S4), and the cmc values of this kind of compounds were determined. The interaction of S1 with DNA was studied by resonance light scatting (RLS) in common fluorescent spectrameter, and the assay of determined DNA using S1 as RLS probe was built. In the absence of salt and surfactants, the RLS intensity of SI in DNA system was enhanced obviously compared with S1 or DNA single system with pH at 2.28. The increasing of RLS intensity is proportional to the concentration of DNA in the range of 0-4 u?ml for ct-DNA when the concentration of SI is l.0xl0-5 mol/l, and the detection limit (S/N = 5) is 9.5 ng/ml.Phosphorescence (RTP) of halogen naphthalic anhydride at room temperature was studied. The results showed that halogen naphthalic anhydride could emit strong and stable room temperature phosphorous when Na2SO3 as a chemical deoxygenator, P-CD as a protective medium and without heavy atom perturber, which imply that halogen naphthalic anhydride may be used as phosphor.