Phosphate and Water Sensing with a Zinc‐Dipicolylamine‐Based Charge‐Transfer Dye. Issue 6 (12th February 2020) - Gayton, Jacqueline
Abstract: A D‐π‐A (donor‐π bridge‐acceptor) dye with a conjugated dipicolylamine group as the donor was synthesized and characterized. When zinc is bound to the dipicolylamine ligand, charge transfer strength from the donor is decreased resulting in a large blue‐shift in the absorption spectrum with a quenching of dye emission. Upon addition of phosphate, changes in both the absorption and emission spectrum are observed with intermediate states between the starting zinc complex and free dye observed. The zinc‐dye complex was found to react with two equivalents of phosphate or trace water to give the free dye. The water response is unexpected given the widespread use of the dipicolylamine group as an anion sensor in water. When the dipicolylamine group is part of conjugated D‐π‐A dye designs with zinc complexes, the dye is observed to act as a humidity sensor at low water amounts. Abstract : A donor‐π bridge‐acceptor dye with a conjugated dipicolylamine donor group was synthesized and characterized with and without a coordinated Zn 2+ atom. Upon addition of phosphate, changes in both the absorption and emission spectrum are observed for the zinc‐bound dye with intermediate states between the starting zinc complex and free dye observed. The zinc‐dye complex was found to react with two equivalents of phosphate rapidly, large quantities of water rapidly, or small quantities of water slowly to give the free dye.