Palladium contamination causes potential danger to the environment, and a study of its biological safety is still on the way. Here, a fluorescent and colorimetric probe (compound 1) containing oxime-ether for Pd2+ has been developed. 1 can detect Pd2+ in aqueous samples with high selectivity and sensitivity. 1 can also work well in biological samples, which gives access to detect Pd2+ in an organism.

A “turn-on” fluorescent and colorimetric chemosensor (RBS) for Pd2+ has been designed and synthesized through introduction of sulfur as a ligand atom to Rhodamine B. RBS exhibits high selectivity (freedom from the interference of Hg2+ in particular) and sensitivity toward Pd2+ with a detection limit as low as 2.4 nM. RBS is also a reversible sensor, and it can be made into test paper to detect Pd2+ in pure water. Compared to the chemosensors that introduced phosphorus to Rhodamine to detect Pd2+, RBS can be synthesized more simply and economically.Keywords: chemosensor; colorimetric; fluorescent; high selectivity; palladium; reversible

1-Nitronyl nitroxide pyrene (1) has been investigated as a new off–on fluorescent chemosensor for metal ions in CH3CN. Compound 1 shows high selectivity and sensitivity to Cu2+ with a detection limit as low as 3.60 × 10−7 M. A coordination mechanism between compound 1 and Cu2+ has been well proven by UV-vis and ESR results.

A novel pyrene (compound 1) based “off–on” fluorescent chemosensor for cyanide has been designed and synthesized. A prominent fluorescence enhancement of 1·Cu(II) only for cyanide was found in aqueous acetonitrile solution with a detection limit as low as 1.2 × 10−6 M.

2-(4-Pyridyl)imino nitroxide and tetraphenylporphyrin zinc(II) formed a stable complex by noncovalent bonding in a nonpolar solution. Nicotine displaced 2-(4-pyridyl)imino nitroxide when it was added to a solution of 2-(4-pyridyl)imino nitroxide-tetraphenylporphyrin zinc(II). The fluorescence intensity of tetraphenylporphyrin zinc(II) was altered by sequentially addition of 2-(4-pyridyl)imino nitroxide and nicotine. This was used to develop a new method for detection of nicotine.