Coumarin Immobilized SBA-15 Material Used For Recognition And Adsorption Of Metal Ions

Detecting the level of heavy metal ions is of great interest to many scientists, including chemists, biologists, clinical biochemists and environmentalists.The advantages of fluorescent probes include convenience, high sensitivity and selectivity, observation in situ, etc. Most of probes only demonstrate the extence of metal ions in the homogeneous phase solution, but they are not suitable for the separation, removal and enrichment of target ions, These defects greatly restrict their practical application. In order to overcome above defects, scientists prepare organic-inorganic hybrid materials via immobilizing fluorescent probe onto mesoporo-us silica for utilization in detection and adsorption of heavy metal ions. Mesoporous silica not only offer open ordered mesoporous channels for conveniently grafting fluorescent probes in high density, but also enable rapid diffusion of analytes, thereby yielding a rapid response.Four coumarin-based inorganic-organic hybrid fluorescence materials SBA-C?SBA-K?SBA-A?SBA-T have been designed and synthesized. The characterization results of FT-IR,TEM,XRD demonstrate that coumarin derivative is successfully grafted onto the inner surface of SBA-15, and its ordered mesoporous structure is not broken. The recognition and adsorption properties of four hybrid materials are investigated for metal ions(Na+?K+?Mg2+?Ca2+?Co2+?Zn2+?Ni2+?Cd2+?Cu2+?Fe3+?Cr3+?Pb2+?Hg2+?Ag+). SBA-C exhibits Cu2+-only sensitive in MeCN. Upon the addition of Cu2+, there are a 14.5-fold fluorescence enhancement and a 68 nm blue-shift. Furthermore, SBA-C displays high adsorption capacity of 90.8% for Cu2+.SBA-K exhibits Fe3+-only turn-off fluorescence recognition among metal ions in HEPES(0.02 M,CH3OH/water = 99.5/0.5,v/v,pH=7.2)suspension. Upon the addition of Fe3+, there are a fluorescence quenching of 98% and an obvious color change from colorless to pale brown. Furthermore, SBA-K displays high adsorption capacity of 92.7% for Fe3+. SBA-A which has similar structure with SBA-K exhibits poor selectivity to Fe3+ in above system.SBA-T is capable of specific recognition for Cu2+ in MeCN. Upon the addition of Cu2+, there are a 2.9-fold fluorescence enhancement and a 12 nm blue-shift. SBA-T still diaplays a good selectivity to Cu2+ in the presence of small amount of water. Other metal ions have no interference for SBA-T to detect Cu2+. Besides, SBA-T displays high adsorption capacity of97.8% for Cu2+.