Adam C. Sedgwick

Simple Aza-Conjugate Addition Methodology for the Synthesis of Isoindole Nitrones and 3,4-Dihydroisoquinoline Nitrones

Aryl-aldehydes containing ortho-substituted α,β-unsaturated carboxylic acid derivatives react with hydroxylamine to afford reactive N-hydroxy-carbinolamine intermediates that undergo intramolecular aza-conjugate addition reactions to afford isoindole nitrones and 3,4-dihydroisoquinoline nitrones in good yield. Conditions have been developed to reduce these isoindole nitrones to their corresponding hydroxylamine, enamine, and amine derivatives. Isoindole nitrones react with dimethyl acetylenedicarboxylate (DMAD) via a [4 + 2]-cycloaddition/deamination pathway to afford substituted naphthalene derivatives, while 3,4-dihydroisoquinoline nitrones react with DMAD via a [1,3]-dipolar cycloaddition pathway to afford tricyclic heteroarenes.

Reaction-based indicator displacement assay (RIA) for the colorimetric and fluorometric detection of hydrogen peroxide

Based on the complexation of phenylboronic acid (PBA) with Alizarin Red S (ARS), we developed a new chemosensor for the detection of hydrogen peroxide (H2O2) in aqueous media. This platform has demonstrated its ability to detect H2O2via colorimetric, fluorometric, and electrochemical measurements. The experimental observations reveal that the system displays a red-shifted visible colour change, on–off fluorescence response indicating release of indicator (ARS) and turn-on electrochemical signal indicating generation of phenol, after reaction with H2O2. With this work we have demonstrated that our reaction-based indicator displacement assay (RIA) systems, can be employed as an assay for H2O2 and hydrogen peroxide-related species for environmental and physiological detection.

Selective electrochemiluminescent sensing of saccharides using boronic acid-modified coreactant

We report a strategy for modulating the electrogenerated chemiluminescence (ECL) response by integrating a boronic acid to the chemical structure of coreactants. Excellent selectivity for d-glucose was achieved by tuning the linker length of a bis-boronic acid amine coreactant.

A simple umbelliferone based fluorescent probe for the detection of nitroreductase

A simple nitrobenzyl-umbelliferone (NCOU1) was synthesised containing a nitroreductase (NTR) trigger moiety. The presence of NTR, resulted in the fragmentation of the parent molecule and release of the highly emissive fluorophore umbelliferone via an NTR-catalyzed reduction of the nitro group. In the presence of the NTR enzyme, NCOU1 gave rise to a 5-fold increase in fluorescence intensity at 455 nm and was selective for NTR over other reductive enzymes. These results indicate that NCOU1 can be used as a simple assay for the detection of NTR.

Boronate-Based Fluorescence Probes for the Detection of Hydrogen Peroxide

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 (H2O2). DSTBPin and MSTBPin displayed an “Off–On” fluorescence response towards H2O2, owing to the loss of the intramolecular charge transfer (ICT) excited state. Whereas, CSTBPin displayed a decrease in fluorescence intensity in the presence of H2O2 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 probe DAPOX‐BPin produced a “turn‐on” response. Regrettably, DAPOX‐BPin required large concentrations of H2O2 (>3 mm) to produce noticeable changes in fluorescence intensity and, therefore, no change in fluorescence was observed in the cell imaging experiments.

Dye Displacement Assay for Saccharides using Benzoxaborole Hydrogels

Abstract Dye displacement assays are a simple but effective method to determine the concentration of target analytes. Previously, we have shown that phenylboronic acid pinacol ester hydrogels (borogels) can be used to develop a boronic acid–Alizarin red S dye displacement assay for the determination of fructose (orange to red). In this work, benzoxaborole hydrogels (BOBgels) were developed, and these BOBgels demonstrated an enhanced apparent binding affinity towards monosaccharides, in particular towards glucose.

Virtual Issue: Chemosensors

Abstract Chemosensors are compounds that incorporate a receptor unit and a reporter unit in a single molecule. A chemosensor transforms the action of binding to a specific analyte into a readable signal. Chemosensors have enabled the study of molecular interactions in a range of different media and interfaces. This offers a non‐invasive approach to observe living biological samples in real time without the sample being destroyed. For example, fluorescence‐based chemosensors are designed to have a high sensitivity and specificity, allowing them to interact selectively with a single target within a complex biological environment. As a result, such chemosensors can be used for fluorescence imaging, allowing for high spatial and temporal resolution of biological samples. Consequently, chemosensors have been used for a broad range of applications including clinical diagnostics and for the detection of environmental, agriculture, and industrial pollutants, making them critically important for public health and safety.

Data from "A bodipy based hydroxylamine sensor"

This repository contains the experimental data discussed in the manuscript. Including, 1H NMR, 13C NMR (FID and PDF) and Mass Spectra for all the intermediates (A-H); probe 1; the hydroxylamine nitrone cyclic product; N-Methylhydroxylamine cyclic product; N,O,-BocHydroxylamine alkyne and N-Hydroxylamine alkyne. Fluorescence analysis data of probe 1 including the hydroxylamine titration curve; selectivity data against other hydroxylamines; amines and amino acids, Fluorescence intensity changes for probe 1 as a function of time with increasing concentrations of hydroxylamine (time drive) and cell images.