The recognition of anions in aqueous media by synthetic receptors remains a challenging task. The cationic platinum(II) complex [Pt(NCN)CH3CN]OTf, 1 (NCN= 1,3-bis(benzimidazolyl)benzene derivative, OTf= triflate anion) was synthesized &gt;90% yield, structurally determined by single-crystal X-ray diffraction and studied in-depth as a luminescent chemosensor for anions in water and acetonitrile. In neutral aqueous media, the complex 1 exhibits a strong affinity towards chloride (binding constant: log K= 5.27). 1 responds to chloride via green turn-on luminescent signal (505 nm) in a micromolar concentration. This optical change can be used for the detection of chloride in bottled mineral water samples while its bioimaging application for Cl- detection in vivo is ongoing. As evidenced by the crystal structure of chloro-complex [Pt(NCN)Cl] 2, spectroscopic methods (UV-vis absorption, 1H NMR titrations, lifetimes) and DFT calculations, the mode binding of chloride involves the direct coordination Pt-Cl besides formation of rigid intramolecular C-H---Cl-Pt hydrogen bonds. On the other hand, cyanide induces color change from green to blue under UV-light with an on-off emission signal. Based on the crystal structure of cyanide-complex [Pt(NCN)CN] 3 and DFT calculations, the color change is tentatively assigned to solvent-induced aggregation possibly driven by π-π interactions of the ligand. In conclusion, Pt(II) derivative complexes bearing a tridentate NCN ligand allow the opportunity of novel receptors for analytical applications in anion sensing.

Cationic NCN Platinum(II) pincer complex as an efficient luminescent host for Cl- and CN- ions: Structural and chemosensing studies

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.