Synthesis Of Schiff Base Fluorescent Probe For Metal Ions Based On O-phenylenediamine And The Research On Its Properties

Metal ions play an important role in environmental chemistry and living organisms, and it is one of the hot research objects in areas of chemistry, environmental science, life science and medicine. So the recognition and detection for environmental metal ions has very important significance. There has many common metal ions detection method, for example, high performance liquid chromatography (HPLC), atomic absorption spectrometry (AAS), spectrophotometry, etc. But fluorescence analysis method can high selectivity, high sensitivity detect the metal ions, today it has become a mainstream way to detect the metal ions, and many scholars pay attention to it.The fluorescence analysis method detection metal ions is based on a good ligand complexes with the specific metal ion, resulting in the ligand’s chemical environment changes, and causing the fluorescence spectral intensities enhancement or quenching before and after complexation occurs. In the alternative ligand structure, fluorescence probes with schiff base structure have strong ligand ability and good light stability, therefore that using schiff base structure to design the fluorescent probe molecule and research its fluorescent properties is research focus in organic chemistry applications.In this paper,3 kinds of schiff base were synthesized by o-phenylenediamine and different functional groups substituted benzaldehyde, in which have two kinds of salen type fluorescent probes. The auther has studied these three fluorescent probe synthesis methods, physical and chemical properties and its recognition performance on metal ions.1. A single schiff base N-4-hydroxybenzaldehyde-1,2-phenylenediamine (TM1) was synthesized by 4-hydroxybenzaldehyde with o-phenylendiamine, and its structure was characterized by Nuclear Magnetic Resonance Hydrogen spectrum (1H NMR) and Nuclear Magnetic Resonance Carbon spectrum (13C NMR) to determine the correctness of the compound structure. On the basis, the recognition performance on the metal ions in the aqueous solution of the single schiff base has researched with ultraviolet spectrometer and fluorescence spectrometer. The study showed that:at room temperature, when the probe TM1 with a concentration of 2×10-5 mol/L, acetonitrile-water (7/3 v/v) as the solvent,2 mL blank probe solution was added 5 times Cu2+, Cu2+ can quickly cause TM1 fluorescence significantly enhanced, and other 19 coexisting ions has no interference; pH range can reach a wide range of 4～10; in the Cu2+ concentration 5.0×10-7～3.2×10-5 mol/L showed a good linear relationship with fluorescence spectral intensity increaseing, and the detection limit is 1.26×10-7 mol/L; TM1 and Cu2+ can form a stable complex with the coordination coefficient of 1:1, the stability constant being K=1.079×105 (mol/L)-1, and the process is irreversible. These conclusions provide a good reference method for Cu2+ fast real-time detection in water samples.2. A Salen type schiff base N,N’-(hydroxy-benzaldehyde)-1,2phenylenediamine (TM2) was synthesized by o-phenylendiamine with 4-hydroxybenzaldehyde, and its structure was characterized by 1H NMR,13C NMR to determine the correctness of the compound structure. On the basis, the recognition performance on the metal ions in the aqueous solution of the single schiff base has researched with ultraviolet spectrometer and fluorescence spectrometer. The study showed that:at room temperature, when probe TM2 with a concentration of 5 x 10-5 mol/L, DMF-water (2/3 v/v) as the solvent,2 mL blank probe solution was added 5 times Fe3+, Fe3+ can quickly cause TM2 fluorescence significantly decreasd, and other 19 coexisting ions has no interference; pH range can reach a wide range of 4～12; in the Fe3+ concentration 1.0×10-6～1.9×10-4 mol/L showed a good linear relationship with fluorescence spectral intensity decreasing, and the detection limit is 2.197×10-6 mol/L; TM2 and Fe3+ can form a stable complex with the coordination coefficient of 1:1, the stability constant being K=8.274×105 (mol/L)-1, and the process is irreversible. These conclusions provide a good reference method for Fe3+ detection in water samples.3. A Salen type schiff base N,N’-2(3-methoxy-4-hydroxy benzaldehyde)-1,2 phenylenediamine (TM3) was synthesized by o-phenylendiamine with 3-methoxy-4-hydroxy benzaldehyde, and its structure was characterized by 1H NMR, 13C NMR to determine the correctness of the compound structure. On the basis, the recognition performance on the metal ions in the aqueous solution of the single schiff base has researched with ultraviolet spectrometer and fluorescence spectrometer. The study showed that:at room temperature, when probe TM3 in a concentration of 2×10-5 mol/L, DMF as the solvent,2 mL blank probe solution was added 5 times Cu2+, Cu2+ can quickly cause TM3 fluorescence significantly decreasd, and other 19 coexisting ions has no interference; when the Cu2+ concentration is between 2.0×10-9～2.0×10-4 mol/L, it showed a good linear relationship with fluorescence spectral intensity decreasing, and the detection limit is 2.89×10-8 mol/L; TM3 and Cu2+ can form a stable complex with the coordination coefficient of 1:1, the stability constant being K =3.375×104 (mol/L)-1, and the process is irreversible. This will be a simple method of detecting Cu2+.