A new approach for the detection of hydrogen sulfide (HS) was constructed within vesicles comprising phospholipids and amphiphilic copper complex as receptor. 1,2-Distearoyl- sn-glycero-3-phosphocholine (DSPC) vesicles with embedded metal complex receptor (1.Cu) sites have been prepared. The vesicles selectively respond to HS in a buffered solution and show colorimetric as well as spectral transformation. Other analytes such as reactive sulfur species, reactive nitrogen species, biological phosphates, and other anions failed to induce changes. The HS detection is established through a metal indicator displacement (MIDA) process, where Eosin-Y (EY) was employed as an indicator. Fluorescence, UV-vis spectroscopy, and the naked eye as the signal readout studies confirm the high selectivity, sensitivity, and lower detection limit of the vesicular receptor. The application of vesicular receptors for real sample analysis was also confirmed by fluorescence live cell imaging.

Here, naphthalene diamine-based β-diketone derivative (compound LH) was successfully used as a dual signaling probe for divalent cations, Fe 2+ and Cu 2+ ions, in bimodal methods (colorimetric and fluorometric). It showed fluorescent enhancement for Fe 2+ ion by photoinduced electron transfer mechanism and fluorescence quenching for Cu 2+ ion by charge-transfer process. Binding stoichiometry for [LH–(Fe 2+ ) 2 ] and [LH–(Cu 2+ ) 2 ] was found to be 1:2 by Job’s plot method and, the binding constants were calculated as 1.6638 × 10 10 and 9.22929 × 10 8 M –1 , respectively. Compound LH exhibited OR and XOR logic gate behavior with H + , Fe 2+ , and Cu 2+ as inputs. Further, the compound LH and bovine serum albumin binding interaction showed quenching of fluorescence by Förster resonance energy-transfer mechanism.

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