Boronate‐Based Fluorescence Probes for the Detection of Hydrogen Peroxide. Issue 3 (26th January 2018) - Lampard, Emma V.
Abstract: In this work, we synthesized a series of boronate ester fluorescence probes ( E )‐4, 4, 5, 5‐tetramethyl‐2‐(4‐styrylphenyl)‐1, 3, 2‐dioxaborolane (STBPin), ( E )‐ N, N ‐dimethyl‐4‐(4‐(4, 4, 5, 5‐tetramethyl‐1, 3, 2‐dioxaborolan‐2‐yl)styryl)aniline (DSTBPin), ( E )‐4‐(4‐(4, 4, 5, 5‐tetramethyl‐1, 3, 2‐dioxaborolan‐2‐yl)styryl)benzonitrile (CSTBPin), ( E )‐2‐(4‐(4‐methoxystyryl)phenyl)‐4, 4, 5, 5‐tetramethyl‐1, 3, 2‐dioxaborolane (MSTBPin), ( E )‐ N, N ‐dimethyl‐4‐(4‐(4, 4, 5, 5‐tetramethyl‐1, 3, 2‐dioxaborolan‐2‐yl)styryl)naphthalen‐1‐amine (NDSTBPin ), and N, N ‐dimethyl‐4‐(2‐(4‐(4, 4, 5, 5‐tetramethyl‐1, 3, 2‐dioxaborolan‐2‐yl)phenyl)oxazol‐5‐yl)aniline (DAPOX‐BPin ) for the detection of hydrogen peroxide (H2 O2 ).DSTBPin andMSTBPin displayed an "Off–On" fluorescence response towards H2 O2, owing to the loss of the intramolecular charge transfer (ICT) excited state. Whereas, CSTBPin displayed a decrease in fluorescence intensity in the presence of H2 O2 owing to the introduction of an ICT excited state.STBPin, on the other hand, produced a small fluorescence decrease, indicating the importance of an electron‐withdrawing or electron‐donating group in these systems. Unfortunately, the longer wavelength probe, NDSTBPin, displayed a decrease in fluorescence intensity. Oxazole‐based probeDAPOX‐BPin produced a "turn‐on" response. Regrettably, DAPOX‐BPin required large concentrations of H2 O2 (>3 mm ) to produce noticeable changes in fluorescence intensity and, therefore, no change in fluorescence was observed in the cell imaging experiments. Abstract : Laying the foundations : Boronate stilbene and oxazole fluorescent probes are synthesized and are shown to demonstrate a reasonable fluorescence response towards H2 O2 . N, N ‐Dimethyl‐4‐(2‐(4‐(4, 4, 5, 5‐tetramethyl‐1, 3, 2‐dioxaborolan‐2‐yl)phenyl)oxazol‐5‐yl)aniline (DAPOX‐BPin ) ( λ ex =350 nm/ λ em =455) nm produces a fluorescence "turn‐on" response towards H2 O2 with a limit of detection of approximately 3 mm .