Phenanthroline-based fluorescence sensors for Eu3+ ion and subsequent enantioselective discriminating of malate

Effective enantioselective recognition by steady-state fluorescence spectroscopy: Towards a paradigm shift to optical sensors with unusual chemical architecture

A series of amino acid-derived 1,2,3-triazoles presenting the amino acid residue and the benzazole fluorophore connected by a triazole-4-carboxylate spacer was studied for enantioselective recognition using only steady-state fluorescence spectroscopy in solution. In this investigation, the optical sensing was performed with D-(-) and L-(+)-Arabinose and (R)-(-) and (S)-(+)-Mandelic acid as chiral analytes. The optical sensors showed specific interactions with each pair of enantiomers, allowing photophysical responses, which were used for their enantioselective recognition. DFT calculations confirm the specific interaction between the fluorophores and the analytes corroborating the observed high enantioselectivity of these compounds with the studied enantiomers. Finally, this study investigated nontrivial sensors for chiral molecules by a mechanism different than turn-on fluorescence and has the potential to broad chiral compounds with fluorophoric units as optical sensors for enantioselective sensing.

Molecular recognition and sensing of dicarboxylates and dicarboxylic acids

The recognition and detection of dicarboxylic acids and dicarboxylates is of significance for a wide variety of applications, including medical diagnosis, monitoring of health and of environmental contaminants, and in industry. Hence small molecule receptors and sensors for dicarboxylic acids and dicarboxylates have great potential for applications in these fields. This review outlines the challenges faced in the recognition and detection of these species, strategies that have been used to obtain effective and observable interactions with dicarboxylic acids and dicarboxylates, and progress made in this field in the period from 2014 to 2020.

Coumarin-based colorimetric-fluorescent sensors for the sequential detection of Zn2+ ion and phosphate anions and applications in cell imaging

Two novel coumarin based fluorescent sensors CHP and CHS have been synthesized for the sequential detection of Zn²⁺ ion and phosphate anion (PA) in DMF/HEPES buffer medium (1/5 v/v, 10 mM, pH = 7.4). On the addition of Zn²⁺ ion to the solution of CHP or CHS resulted in a pronounced fluorescence enhancement, accompanying noticeable color change (under UV or daylight), while there was hardly obvious change with other competing metal ions co-existing. The detection limits (DL) of CHP and CHS toward Zn²⁺ were separately determined as 1.03 × 10^-7 (R² = 0.9886) and 1.87 × 10^-7 (R² = 0.9902). The PET binding processes were affirmed by spectroscopic techniques, HRMS experiments and theoretical calculations. Subsequently, the CHP-Zn²⁺ or CHS-Zn²⁺ complexes showed high selectivity fluorescence quenching toward PA by snatching Zn²⁺ ion from its complex and the binding processes were reversible. DLs were calculated as 2.07 × 10^-7 M (R² = 0.9928) and 2.63 × 10^-7 M (R² = 0.9954), respectively. Furthermore, the cell imaging experiments demonstrated that the sensors were capable of detecting of Zn²⁺ and PA in vitro cells.