Simple bis-thiocarbono-hydrazones as sensitive, selective, colorimetric, and switch-on fluorescent chemosensors for fluoride anions

Simple and efficient colourimetric F- sensors and a test paper for fluorine

A series of colourimetric fluoride ion sensors bearing azo-phenolic hydroxyl and Schiff base groups were synthesised. In CH3CN solutions, these sensors showed colourimetric single selectivity for F-. An easy-to-prepare test paper based on the sensor was developed, which could colourimetrically conveniently detect fluoride ion.

Recognition and sensing of fluoride anion

Fluoride anion recognition is attracting a mounting interest in the scientific community due to its duplicitous nature. It is a useful chemical for many industrial applications, and it has been used in human diet, but, recently it has been accused for several human pathologies. Here we describe the ample panorama of different approaches the chemists world-wide have employed to face the challenge of fluoride binding, and we outline some of the research which in our view can contribute to the development of this field, especially when fluoride binding has to be achieved in highly competitive protic solvents and water.

Amplified fluorescence response of chemosensors grafted onto silica nanoparticles

In conventional fluorescent chemosensors, the recognition of the target by the receptor unit affects the fluorescence properties of a single covalently coupled fluorescent moiety. Here we show for the first time that when a suitable TSQ derivative is densely grafted onto the surface of preformed silica nanoparticles electronic interactions between the individual chemosensor units enable the free units to recognize the state of the surrounding complexed ones. As a result, the fluorescence transduction is not limited to the local site where binding occurs, but it involves a wider region of the fluorophore network that is able to transfer its excitation energy to the complexed units. Such behavior leads to an amplification of the fluorescence signal. What we report here is the first example of amplification in the case an off-on chemosensor due to its organization onto the surface of silica nanoparticles. We also describe a simple general model to approach amplification in multifluorophoric systems based on the localization of the excited states, which is valid for assemblies such as the supramolecular ones where molecular interactions are weak and do not significantly perturb the individual electronic states. The introduction of an amplification factor f in particular allows for a simple quantitative estimation of the amplification effects.

Study on acetate ion recognition and sensing in aqueous media using a novel and simple colorimetric sensor and its analytical application

A new and simple phenylhydrazone-based sensor 1 for acetate has been investigated in DMSO and even in the 95:5 DMSO/H2O (v/v) mixtures. Binding of anions such as AcO-, F- and H2PO4(-) results in a noteworthy change in the visible region of spectrum (approximately 100 nm red shift), which can be detected by the 'naked-eye'. The further insights to the nature of interactions between the sensor 1 and AcO- were investigated by 1H NMR titration experiments in DMSO-d(6). In particular, analytical application and detection of acetate ion have been also studied in the aqueous.

Photophysical and anion sensing properties of platinum(ii) terpyridyl complexes with phenolic ethynyl ligands

A series of platinum(II) terpyridyl complexes with phenolic ethynyl ligands have been synthesized and characterized. Their photophysical and sensing properties towards anions such as fluoride, acetate and dihydrogenphosphate have been investigated. These complexes show a colorimetric response and fluorescence quenching in the presence of anions including fluoride, acetate and dihydrogenphosphate, and selective sensing towards fluoride in some cases. The sensing mechanism has been investigated by spectrophotometric and 1H NMR titration.