Colorimetric and fluorescence sensing of pH with a Schiff-base molecule

Organic–inorganic hybrid sol–gel materials doped with a fluorescent triarylimidazole derivative

“…37,38 Therefore, the development of optical pH probes, besides its application in the eld of civil engineering, has attracted much attention due to the crucial role of pH in various physiological processes. 39,40 In this sense, imidazole derivatives are versatile compounds and interesting candidates as pHsensitive molecules due to the amphoteric nature of the imidazole heterocycle. In fact, the imidazole ring can act as an excellent bond donor moiety in anion receptors since the acidity of the NH proton of the imidazole can be tuned by changing the electronic properties of the imidazole substituents.…”

An Amphiphilic Pyridinoyl-hydrazone Probe for Colorimetric and Fluorescence pH Sensing

“…Within non-electrochemical methods, optical response is a common strategy. Most of the well-established optical methods for pH detection are based on sensors able to respond to pH by a colorimetric and/or fluorescence change in water [9,10]. Sensory technology based on water-soluble molecules has attracted considerable interest [11,12,13].…”

“…Sensory technology based on water-soluble molecules has attracted considerable interest [11,12,13]. Although in some applications pH electrode is irreplaceable, numerous chemosensors for biologically relevant targets in aqueous systems have been developed [9]. An important target is the lysosome, which is distinct from other cellular organelles because of its low pH [14].…”

“…In chemosensor-based pH detection, the probe molecules have a chromophore/fluorophore capable of existing in different tautomeric forms depending on pH. Numerous Schiff base chemosensors with sensing mechanism based on the excited state intramolecular proton transfer (ESIPT) are reported in scientific literature [9,23,24,25]. The inhibition of this intramolecular transfer is responsible for colour/fluorescence switch of the probe molecule.…”

“…The inhibition of this intramolecular transfer is responsible for colour/fluorescence switch of the probe molecule. Aryl and aroyl hydrazone structures formally contain both the Schiff base moiety and an amidic fragment [9,26,27,28]. These probes, known as multitopic ligands for metal-organic architectures [29] and as sensors for cations, anions, neutral molecules [30,31,32,33], undergo keto-enol tautomeric interconversion.…”