A copper complex receptor for nanomolar sulfide sensing and applications in DNA/BSA binding

• A novel Cu(II) complex detects sulfide anions with a detection limit of 82.50 nM. • The complex shows selective sulfide recognition even in the presence of excess anions. • DFT and TD-DFT calculations support the spectroscopic characterization of the complex. • The receptor is effective for real-time sulfide detection in diverse water samples. • The receptor exhibits strong binding interactions with CT-DNA and bovine serum albumin (BSA). Traditionally toxic sulfide species (S 2– , HS – , and H 2 S) play indispensable roles in various biological, environmental, and industrial processes. However, excessive exposure to these species can result in numerous chronic diseases. Considering the importance of sulfide recognition, we have synthesized and characterized a simple 1:1 Cu(II) complex of L ( CuCl 2 L receptor) based on a substituted 2,6-dipyrazinylpyridine (dppy) moiety ( L = 4-(2,6-di(pyrazin-2-yl)pyridin-4-yl)- N , N -dimethylaniline). The complex was analyzed both experimentally and computationally using DFT and TD-DFT calculations. The in-situ prepared CuCl 2 L receptor is employed to selectively recognize sulfide species (detection limit: 82.50 nM) in the presence of other anions in higher concentration (ten equivalents of F – , Cl – , Br – , I – , CH 3 CO 2 – , HCO 3 – , H 2 PO 4 – , NO 3 – , SO 3 2– , SO 4 2– , S 2 O 3 2– , CO 3 2– , and HPO 4 2– (10 mM)) in aqueous acetonitrile (2:1 v/v , 10 mM HEPES buffer, pH 7.4) through absorption spectral studies. Furthermore, the receptor is successfully utilized for various real-time detection applications and demonstrated significant intercalative binding interaction with Calf–Thymus DNA (CT-DNA) and good binding interactions with bovine serum albumin (BSA), supported by viscometry and molecular docking studies.