Toward Iron Sensors: Bioinspired Tripods Based on Fluorescent Phenol-oxazoline Coordination Sites

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• 作者：Raghavendra Kikkeri ; Hassan Traboulsi ; Nicolas Humbert ; Elzbieta Gumienna-Kontecka ; Rina Arad-Yellin ; Galina Melman ; Mourad Elhabiri ; Anne-Marie Albrecht-Gary ; Abraham Shanzer
• 刊名：Inorganic Chemistry
• 出版年：2007
• 出版时间：April 2, 2007
• 年：2007
• 卷：46
• 期：7
• 页码：2485 - 2497
• 全文大小：216K
• 年卷期：v.46,no.7(April 2, 2007)
• ISSN：1520-510X

文摘

In the quest for fast throughput metal biosensors, it would be of interest to prepare fluorophoric ligands with surface-adhesive moieties. Biomimetic analogues to microbial siderophores possessing such ligands offer attractive modelcompounds and new opportunities to meet this challenge. The design, synthesis, and physicochemical characterizationof biomimetic analogues of microbial siderophores from Paracoccus denitrificans and from the Vibrio genus aredescribed. The (4S,5S)-2-(2-hydroxyphenyl)-5-methyl-4,5-dihydro-1,3-oxazole-4-carbonyl group (L^a), noted here asan HPO unit, was selected for its potential dual properties, serving as a selective iron(III) binder and simultaneouslyas a fluorophore. Three tripodal symmetric analogues cis-L^b, cis-L^c, and trans-L^c, which mainly differ in the lengthof the spacers between the central carbon anchor and the ligating sites, were synthesized. These ferric-carrierswere built from a tetrahedral carbon as an anchor, symmetrically extended by three converging iron-binding chains,each bearing a terminal HPO. The fourth chain could contain a surface-adhesive function (L^c). A combination ofabsorption and emission spectrophotometry, potentiometry, electrospray mass spectrometry, and electrochemistrywas used to fully characterize the corresponding ferric complexes and to determine their stability. The quenchingmechanism is consistent with an intramolecular static process and is more efficient for the analogue with longerarms. Detection limits in the low nanogram per milliliter range, comparable with the best chemosensors based onnatural peptide siderophores, have been determined. These results clearly demonstrate that these tris(phenol-oxazoline) ligands in a tripodal arrangement firmly bind iron(III). Due to their fluorescent properties, the coordinationevent can be easily monitored, while the fourth arm is available for surface-adhesive moieties. The tripodal systemis therefore an ideal candidate for integration with solid-state materials for the development of chip-based devicesand analytical methodologies.