Design,Synthesis And Recognition Of Cyanide Ion Fluorescent Probes Based On Anthraquinone Derivatives

As we all know,cyanide is widely used in various industries such as mining,electroplating,metal cleaning and pharmaceuticals.However,as one of the deadliest anionic poisons,excessive cyanide ions can cause serious damage to organisms and the environment.It can not only disrupts cell respiration,affect the electron transfer in mammalian mitochondria,and severely damage the central nervous system,but also may induce the pollution of water resources,thereby forming a huge threat to human health.Therefore,the detection of cyanide ions in environmental and biological systems has attracted much attention by chemists.At present,artificial fluorescent probes for sensing of anion are favored due to their advantages such as high sensitivity,high selectivity,simplicity and economy.Therefore,it is urgent for us to design and develop new fluorescent probes for detecting cyanide in various environments.Anthraquinone is composed of three conjugated aromatic rings with good rigid plane,and be similar to the anthracene ring system.It is stable and not easy to be oxidized and reduced.In addition,anthraquinone and its derivatives is an important dye molecule,which is widely used in coatings,pharmaceutical industry,energy storage systems and other fields.The structural modification of anthraquinone can cause different changes in the spectrum.Therefore,researchers have shown great interest in the anthraquinone signal unit.Furthermore,the design of novel anthraquinone-based cyanide ion probes has also become a promising research hotspot.Based on the previous research of our group,two anthraquinone-based probes were designed and synthesized by a series of classical organic reaction with high sensitivity,high selectivity and reversible detection of CN^-.Recognition mechanism for CN^-was confirmed by the experiments such as UV-vis absorption spectroscopy,fluorescence emission spectroscopy,¹H NMR titrations experiments and DFT calculation.Finally,the application of probes in test paper and food was also further explored.In Chapter 2,anthraquinone derivatives（3a-d）have been easily prepared via nucleophilic substitution of 1-chloroanthraquinone with substituted phenylacetonitriles,with only nitro-substituted anthraquinone 3d displaying colorimetric sensor capabilities.These visible color and absorption spectra changes were ascribed to enhanced acidity of C-H proton due to the presence of the strong electron-withdrawing group（-NO₂）as well as cooperative intramolecular hydrogen bonds（IHBs）between C=O group of anthraquinone and activated C-H group promoting auxiliary binding with cyanides.The sensor showed good selectivity,reversibility and reusability toward cyanide detection,as well as efficient naked-eye color change from colorless to blue-purple in a neutral aqueous medium.The deprotonation mechanism of CH was investigated by NMR spectroscopy and supported by DFT calculations.Furthermore,the sensor 3d was successfully loaded onto test strips as a convenient and efficient solid-state sensor for cyanide detection.It was utilized for cyanide detection in cassava flour and bitter almonds food samples,as well as displaying excellent performance in real-world water samples.In Chapter 3,we present a novel anthraquinone chromene-derived fluorescent probe 5feature as a potential intramolecular hydrogen bonding=NH···O=C,which allows the selective recognition of cyanide ions through ESIPT processes.At ground state,the compound 5 could form intramolecular=NH···O=C hydrogen bonding,exhibiting a normal form（N）.Upon cyanide-induced,ESIPT occurs and a tautomer form（T）is produced bearing=N···HO hydrogen bonds.Meanwhile,the deprotonation mechanism of NH was investigated by NMR spectroscopy.Furthermore,the probe 5 was successfully loaded onto test strips as a convenient and efficient solid-state probe for cyanide detection.It was also utilized for cyanide detection in cassava flour and bitter almonds food samples.