Synthesis Fluorescent Probe And Study On ItsRecognition Propertis Conataining Aza-15-crown-5 Group

Fluorescent chemosensors have wide prospect because of their advantages such as high selectivity, sensitivity, simplicity and real-time detecting. Improving the selectivity of chemosensors is recognized as a difficult problem in the field of chemical sensing technology. Searching for novel fluorescent molecular recognition ionophores with high selectivity has attracted much attention of current analytical chemistry. Styryl compounds linked to azacrown ether were reported to have high selectivity for alkaline metal and alkali earth metal used as the fluorescent probe, but most of these compounds are apt to occur trans-cis isomerization under the radiation of light because the torsion of double bond, which make probes instable and impact storage and use. In the paper, a novel styryl fluorescent probe 1 was designed and synthesized based on aza-15-crown-5 as the acceptor and fluorene as fluorescent group. Ethylene unit isomerizated behavior in the probe 1 is avoided because of ethylene unit connected directly with fluorene at the 9H position. We proved that prober 1 is a stable and switch fluorescence chemical probe of barium ion based on the intra-molecular charge transfer (PET) mechanism.Probe 1 complexes with Ba2+ mailnly depending on the aza-15-crown-5 acceptor, but there are still two doubt:firstly, whether adjacent nitro and ethylene substituents involve in the coordination process; secondly, whether the diffirent position of substituents has any effect on the selectivity, sensitivity of the probe 1. So probes 2 and 3, two isomers of probe 1 were designed and synthesized. Experiment proved that nitro and ethylene unit did not participate in complexation processes to Ba2+ and the influence of the position of substituents is limited in most of these compounds.The molecular'wires'property of conjugate polymer make the fluorescent intensity shapely amplify.For this reason, the conjugate polymer fluorescent probe draw much attention. Although the 'on-off' fluorescent probes of conjugate polymers have been reported, rarely for the 'off-on' probes. In the paper, three'off-on' conjugated polymer probes P1,P2,P3, with 15-crown-5 as side chains, were designed and synthesized. Proved that probes Pl,P2 have highly selectivity and sensitivity to barium ion, and probe P3 shows no recognition performance to metal ions.