title: Fluorescent probes for Pd2+ detection by allylidene-hydrazone ligands with excellent selectivity and large fluorescence enhancement.
abstract: Because palladium is widely used in various catalysts and converters, which results in a high level of contamination of water systems and the soil by residual palladium, there is an urgent need for Pd(2+)-sensitive and -selective probes. Based on the special affinity of Pd(2+) to conjugated double-bond ligands, two fluorescence probes (RPd2 and RPd3) that contain conjugated allylidene-hydrazone ligands that link to colorless rhodamine-spirolactam have been developed. The results show that conjugated allylidene-hydrazones have a much better affinity toward Pd(2+), and consequently provide the probes with more acute color change and fluorescence enhancement (≈170-fold), and better selectivity over other metal ions (especially platinum-group elements, or PGEs) than the unconjugated allyl-hydrazine. With richer electron density and a more suitable stereo effect in the allylidene-hydrazone group, RPd2 displays the best specificity toward Pd(2+) and affords convenient detection by the naked eye. Its potential application for Pd(2+)-contaminated water and soil-sample analysis is revealed by proof-of-concept experiments.
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology, 158 Zhongshan Road, Dalian 116012, P.R. China.
authors.forename: Honglin
authors.initials: H
authors.lastname: Li
authors.forename: Jiangli
authors.initials: J
authors.lastname: Fan
authors.forename: Fengling
authors.initials: F
authors.lastname: Song
authors.forename: Hao
authors.initials: H
authors.lastname: Zhu
authors.forename: Jianjun
authors.initials: J
authors.lastname: Du
authors.forename: Shiguo
authors.initials: S
authors.lastname: Sun
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Peng
mesh_terms: D000465:Algorithms; D004784:Environmental Monitoring / Q000379:methods*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D006835:Hydrazones / Q000138:chemical synthesis* / Q000737:chemistry; D008024:Ligands; D015394:Molecular Structure; D010165:Palladium / Q000032:analysis*; D012235:Rhodamines / Q000138:chemical synthesis* / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D005456:Fluorescent Dyes; D006835:Hydrazones; D008024:Ligands; D012235:Rhodamines; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D010165:Palladium