Unsymmetrically substituted four-armed tolanes: new multichromophoric molecules

The selective synthesis of a four-armed tolane with different fluorescent chromophores that are asymmetrically distributed is described. Its optical absorption and emission properties were examined. This multichromophoric molecule exhibits a charge-transfer pathway that has a pronounced effect on the overall optical properties, together with an energy transfer process. Appropriate basic centers are present, meaning that the energy transfer processes can be stopped by the addition of acid—a process that makes this system a fluorescent pH-sensor.