Woo, Hana Cho, Somin Han, Yejee Chae, Weon-Sik Ahn, Dae-Ro You, Youngmin Nam, Wonwoo 2024-01-20T12:34:07Z 2024-01-20T12:34:07Z 2021-09-01 2013-03-27 0002-7863 https://pubs.kist.re.kr/handle/201004/128230 Despite the promising photofunctionalities, phosphorescent probes have been examined only to a limited extent, and the molecular features that provide convenient handles for controlling the phosphorescence response have yet to be identified. We synthesized a series of phosphorescence zinc sensors based on a cyclometalated heteroleptic Ir(III) complex. The sensor construct includes two anionic cyclo-metalating ligands and a neutral diimine ligand that tethers a di(2-picolyl)amine (DPA) zinc receptor. A series of cyclo-metalating ligands with a range of electron densities and band gap energies were used to create phosphorescence sensors. The sensor series was characterized by variable-temperature steady-state and transient photoluminescence spectroscopy studies, electrochemical measurements, and quantum chemical calculations based on time-dependent density functional theory. The studies demonstrated that the suppression of nonradiative photoinduced electron transfer (PeT) from DPA to the photoexcited Ir-IV species provided the underlying mechanism that governed the phosphorescent response to zinc ions. Importantly, the Coulombic barrier, which was located on either the cyclometalating ligand or the diimine ligand, negligibly influenced the PeT process. Phosphorescence modulation by PeT strictly obeyed the Rehm-Weller principle, and the process occurred in the Marcus-normal region. These findings provide important guidelines for improving sensing performance; an efficient phosphorescence sensor should include a cyclometalating ligand with a wide band gap energy and a deep oxidation potential. Finally, the actions of the sensor were demonstrated by visualizing the intracellular zinc ion distribution in HeLa cells using a confocal laser scanning microscope and a photoluminescence lifetime imaging microscope. English AMER CHEMICAL SOC CYCLOMETALATED IRIDIUM(III) COMPLEXES INTRAMOLECULAR PROTON-TRANSFER MODULATING FLUORESCENCE PROPERTIES INTERLIGAND ENERGY-TRANSFER MARCUS INVERTED REGION CHARGE-TRANSFER IR(III) COMPLEXES ANCILLARY LIGANDS ZINPYR FAMILY BIS(PYRIDYLBENZALDEHYDE) COMPLEXES Synthetic Control Over Photoinduced Electron Transfer in Phosphorescence Zinc Sensors Article 10.1021/ja3123202 1 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, v.135, no.12, pp.4771 - 4787 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 135 12 4771 4787 scie scopus 000317032000044 2-s2.0-84875700880 Chemistry, Multidisciplinary Chemistry Article CYCLOMETALATED IRIDIUM(III) COMPLEXES INTRAMOLECULAR PROTON-TRANSFER MODULATING FLUORESCENCE PROPERTIES INTERLIGAND ENERGY-TRANSFER MARCUS INVERTED REGION CHARGE-TRANSFER IR(III) COMPLEXES ANCILLARY LIGANDS ZINPYR FAMILY BIS(PYRIDYLBENZALDEHYDE) COMPLEXES