Synthesis of 2,2′-bIImidazole-based platinum(II) polymetallaynes and tuning their fluorescent response behaviors to Cu²⁺ ions through optimizing the configuration of the organic spacers and steric effect

Under controlled conditions, platinum(ii) polymetallaynes with different 2,2′-biimidazole-based organic spacers have been synthesized readily. Their photophysical properties and fluorescent response behaviors to Cu²⁺ ions have been investigated in detail. By adjusting both the configuration of the 2,2′-biimidazole-based spacers and the steric effect, the fluorescent response behaviors of the polymetallaynes to Cu²⁺ ions can be tuned dramatically. The fluorescent signal from the polymetallayne with an optimized structure can be quenched rapidly by Cu²⁺ ions with a high Stern-Volmer constant K_SV of ca. 6.8 × 10⁴ M^-1 and a low detecting limit (DL) of ca. 0.99 ppm. These results not only highlight the great potential of these polymetallaynes as novel Cu²⁺ sensors, but also provide new strategies for optimizing the sensing abilities of the 2,2′-biimidazole-based ion sensors.