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In this work, a triphenylamine and rhodamine-B (donor–acceptor) hybrid switch (TPRH) was rationally designed, synthesised and characterised as a novel fluorescence resonance energy transfer (FRET) ratiometric fluorescent chemosensor for specific sensing of Al3+ over other important metal ions in mixed aqueous solution. We proposed that the sensor in hand (TPRH) is non-toxic and can be successfully employed to detect the Al3+ ion in human peripheral blood mononuclear cells (PBMCs), showing intracellular 'FRET-ON' mechanism. The orientation of the probe was designed in such a way that the fluorescence (or Förster) resonance energy transfer (FRET) proceeded from the 'donor moiety' triphenylamine to the 'accepter moiety' rhodamine-B. This fluorescent probe was found to be highly selective towards Al3+ over other important guest metal ions, including Fe3+ and Cr3+. Considering the adverse effects of Al3+ ions on human health and also on the environment, the development of sensitive and specific tools for the detection of Al3+ ions is of great value. The limit of detection (LOD) of TPRH was found to be in the order of 10−8 M. The TPRH–Al3+ complex showed reversible binding with demetallation in the presence of EDTA. In accordance with this reversibility, the fluorescence output at 576 nm from two active chemical inputs, namely, Al3+ and EDTA, followed a truth table of an INHIBIT logic gate. Moreover, cytotoxic studies found that the probe was safe to use in a biological system with good cell membrane permeability. More importantly, the bio-imaging of living human peripheral blood mononuclear cells (PBMCs) showed that TPRH could be used as an effective fluorescent probe for a prominent ratiometric in vitro detection of the transition trivalent metal ion Al3+. We evidenced a significant (p < 0.05) shift from blue to red fluorescence when Al3+ was added to the cell suspension, thus proving TPRH as a good candidate to detect intracellular Al3+. [ABSTRACT FROM AUTHOR]

Hydrazine exposure leads to damage of all vital organs of humans and animals, which demands the discovery of a method for the rapid and quantitative detection of hydrazine. Newly designed and synthesized receptor-bearing phenolic –OH, –Br, –CN, –ester and benzthiazole moieties displayed brilliant naked eye fluorescence sensing towards hydrazine with rapid reactivity and very good selectivity over several cation-, anion-, thiol- and amine-containing compounds. The probe showed good cell permeability, low cytotoxicity, fast fluorogenic recognition and “naked eye” detection of hydrazine below the TLV levels, in living cells, drinking water and industrial effluents. [ABSTRACT FROM AUTHOR]

A new visible-light-excitable fluorescence ratiometric probe for OCl- has been developed based on a triphenylamine-diamiomaleonitrile (TAM) moiety. The structure of the dye was confirmed by single-crystal X-ray analysis. It behaves as a highly selective and sensitive probe for OCl- over other analytes with a fast response time (~100 s). OCl- reacts with the probe leading to the formation of the corresponding aldehyde in a mixed-aqueous system. The detection limit of the probe is in the 10-8m range. The probe (TAM) also exhibits solvatofluorochromism. Changing the solvent from non-polar to polar, the emission band of TAM largely red-shifted. Moreover, the probe shows an excellent performance in real-life application in detecting OCl- in human blood cells. The experimentally observed changes in the structure and electronic properties of the probe after reaction with OCl- were studied by DFT and TDDFT computational calculations. [ABSTRACT FROM AUTHOR]