A hydrazone-based spectroscopic off-on probe for sensing of basic arginine and lysine.

A simple probe BHN based on naphthol and benzothiazole is reported for detecting of arginine (Arg) and lysine (Lys) with high selectivity and sensitivity. The BHN in aqueous solution upon reacting with Arg or Lys induced a visible color change from colorless to yellow. The probe BHN can also be employed for fluorescence turn-on sensing of Arg and Lys with the limits of detection (LOD) of 5.20 × 10-2 µM and 3.69 × 10-2 µM, respectively. The naked eye colorimetric and fluorimetric detecting is lack of sensitive to other common amino acids including Gly, Ala, Ser, Pro, Val, Thr, Cys, Leu, Ile, Asn, Asp, Glu, Gln, Met, His, and Phe. The sensing mechanism has been proposed by pH investigation and 1H NMR spectra.

Selective sensing of PPi by fluorogenic Al(III)-probe complex in aqueous medium.

A newly designed Schiff base probe JN has been synthesized. It is highly selective and sensitive towards Al3+ in nearly 100% aqueous medium by exhibiting a dramatic "turn-on" fluorescence response at 495 nm (λex = 450 nm). The sensing mechanism of JN towards Al3+ ions was proposed as the combination of PET, ICT, ESIPT, and CHEF processes according to spectra studies and theory calculations. The in situ generated mononuclear Al(III) complex JN-Al3+ could sequentially detect PPi ions by turn-off fluorescence response. The selectivity and sensitivity of the JN-Al3+ complex towards PPi ions are based on demetalization process. Interestingly, the fact that Al3+ can bind with 1, 2, or 3 PPi has been revealed by HRMS study. The probes JN and JN-Al3+ complexes were able to capture Al3+ and PPi ions, respectively, as demonstrated by fluorescence imaging of the adult zebrafish and onion inner epidermal cells samples.