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.