Synthesis and Photophysical Studies of Calixarene‐Based Alkynylplatinum(II) Terpyridine Complexes with Various Receptor Sites for Colorimetric and Luminescence Sensing of Anions

A series of mononuclear and dinuclear platinum(II) terpyridine complexes with amide‐, sulfonamide‐, and urea‐containing ligands ( 1 – 9 ) has been successfully designed and synthesized, and their photophysical and anion‐binding properties have been studied. The anion‐binding properties of the complexes were studied by electronic absorption, emission, and 1 H NMR spectroscopy. Upon the binding with anions, the dinuclear complexes 1 – 3 exhibit large electronic absorption and emission spectral changes, while for the mononuclear analogues 4 – 6 much smaller spectral changes were observed. Interesting colorimetric responses towards different anions were observed in dinuclear complexes 1 – 3 . Dinuclear complexes 7 – 9 are found to be insensitive to anion‐binding, which could be attributed to the presence of intramolecular Pt⋅⋅⋅Pt interactions and/or π–π stacking in the complexes that led to the reduced anion‐binding affinity.