Preparation And Properties Of Novel Mercury/Silver Fluorescent Sensors And Photochromic Fabrics

Heavy metal ions are a major hazard to humans and the environment,especially silver and mercury ions,which are mainly responsible for soil and water pollution,and mercury ion can cause neurological toxicity in humans.Therefore,two series of fluorescent probes for mercury and silver ions were designed and synthesized in this study.12 new compounds were synthesized.Among them,the B series probes are eight new fluorescent probes prepared by condensation of isophorone and aromatic aldehydes.The D series probes are new fluorescent probes containing sulfonic acid groups.Four D series fluorescent probes containing water-soluble groups-sulfonic acid groups have been prepared by condensation of benzindole derivatives with aromatic aldehydes.The structures of the new compounds were validated by NMR,MS and FTIR spectroscopy.Selective recognition of mercury and silver ions by B1 was tested in the B series.UV selectivity and fluorescence selectivity tests of B1 showed excellent recognition of silver and mercury ions in ethanol solution.The UV absorption and fluorescence emission spectra are significantly shifted by the addition of silver and mercury ions,and the solutions show different colours in the UV and visible light.The probe B1 has good immunity to silver and mercury ions,with a short response time of 4 min for silver ions and a long response time of 50 min for mercury ions.The detection limits of B1 for silver and mercury ions were 0.48μM and 6μM,respectively.In addition,the probe B1 can detect silver ions at p H=1–7.Finally,the detection mechanism of the probe B1 for mercury ions was verified by NMR and mass spectrometry.The ability of D4 to recognise mercury ions in water was tested in the D series.Upon addition of mercury ions,the UV spectrum of D4 was significantly shifted,while the emission spectrum showed a decrease in fluorescence intensity.Moreover,anti-interference tests show a more pronounced effect of Na⁺,Ni²⁺on the recognition of mercury ions by the probe D4.The response time of the probe D4 for mercury ions was 20 min and the detection limit was 27.8μM.Stability tests of the probe D4 at different p H showed that the colour of the probe changed from yellow to purplish red under alkaline conditions,and the fluorescence emission spectrum changed significantly.Under acidic conditions,the fluorescence intensity in the emission spectrum of the probe is significantly reduced,which also affects the detection of mercury ions by the probe D4.Therefore,the probe D4 can only detect mercury ions under neutral conditions.Finally,we have prepared a novel photochromic cotton fabric for application in the field of optical information storage and information encryption.Synthesised photochromic compound（SO）containing terminal olefins was covalently grafted onto cotton fabrics via thiol-ene click chemistry.The formation of covalent bonds between SO and cotton fabrics was verified by Raman spectroscopy,infrared spectroscopy,EDS-mapping and X-ray photoelectron spectroscopy.The covalent bonds are stronger than conventional adsorption methods.The prepared photochromic cotton fabrics saturate in colour after 30 s of 365 nm irradiation and return to their original state in50 s of darkness,and have excellent resistance to washing and fatigue.Photochromic cotton fabrics have excellent UV resistance and offer great prospects for development in the field of UV protective clothing.In addition,the photochromic cotton fabric has a message encryption function,the information to be encrypted will be printed on the photochromic cotton fabric,when the photochromic cotton fabric is irradiated by ultraviolet light,the encrypted information will appear,thus achieving the role of information encryption.Therefore,the photochromic cotton fabric in the military,science and technology and other information encryption field has potential development space.