Design and synthesis of self-assembled Pt(II)-based macrocycle and interaction with thiocyanate ion

Synthesis of a new flexible and ionic Pt(II)-based meatallomacrocycle (M) using a new flexible donor (1) is described. M interacts specifically with thiocyanate ion in the presence of other competing anions. [Display omitted] •Synthesis of a new flexible ditopic ligand (1) with two terminal pyridyl units.•Synthesis of a new flexible, ionic and Pt(II)-based [2 + 2] metallomacrocycle (M)•M selectively detects SCN− in the presence of other competing anions.•Detection limit of thiocyanate ion is ∼ 6 µM.•Thiocyanate ion sensing by M shown in real water samples. We report the synthesis of a new flexible ‘donor’ (1) in one step. Combining 1 and trans-[PtI2(PEt3)2], we synthesized an ionic metallomacrocycle (M) through coordination-driven self-assembly. The newly synthesized compounds were characterized using FT-IR, multinuclear NMR, and ESI-TOF-MS techniques. Subsequently, we explored the interaction of M with various anions. Only harmful thiocyanate (SCN−) interacted appreciably with the macrocycle (M) as observed by UV–Visible spectroscopy. Moderate association constant (Ka) was observed (3.98 × 104 M−1) from Benesi-Hildebrand (B-H) plot. An appreciable limit of detection (LOD) was found (5.895 µM) using the UV–Vis method. The detection of thiocyanate by M was also successful in real water samples (tap and sea water). A plausible mechanism for the interaction was proposed which was based on experimental data.