TY - JOUR

T1 - pH-Responsive N^C-Cyclometalated Iridium(III) Complexes

T2 - Synthesis, Photophysical Properties, Computational Results, and Bioimaging Application

AU - Solomatina, Anastasia I.

AU - Kozina, Daria O.

AU - Porsev, Vitaly V.

AU - Tunik, Sergey P.

N1 - Solomatina, A.I.; Kozina, D.O.; Porsev, V.V.; Tunik, S.P. pH-Responsive N^C-Cyclometalated Iridium(III) Complexes: Synthesis, Photophysical Properties, Computational Results, and Bioimaging Application. Molecules 2022, 27, 232. https://doi.org/10.3390/molecules27010232

PY - 2022/1/1

Y1 - 2022/1/1

N2 - Herein we report four [Ir(NC)(2)(LL)](n+), n = 0,1 complexes (1-4) containing cyclometallated NC ligand (NCH = 1-phenyl-2-(4-(pyridin-2-yl)phenyl)-1H-phenanthro[9,10-d]imidazole) and various bidentate LL ligands (picolinic acid (1), 2,2 '-bipyridine (2), [2,2 '-bipyridine]-4,4 '-dicarboxylic acid (3), and sodium 4,4 ',4 '',4"'-(1,2-phenylenebis(phosphanetriyl))tetrabenzenesulfonate (4). The NCH ligand precursor and iridium complexes 1-4 were synthesized in good yield and characterized using chemical analysis, ESI mass spectrometry, and NMR spectroscopy. The solid-state structure of 2 was also determined by XRD analysis. The complexes display moderate to strong phosphorescence in the 550-670 nm range with the quantum yields up to 30% and lifetimes of the excited state up to 60 mu s in deoxygenated solution. Emission properties of 1-4 and NCH are strongly pH-dependent to give considerable variations in excitation and emission profiles accompanied by changes in emission efficiency and dynamics of the excited state. Density functional theory (DFT) and time-dependent density functional theory (TD DFT) calculations made it possible to assign the nature of emissive excited states in both deprotonated and protonated forms of these molecules. The complexes 3 and 4 internalize into living CHO-K1 cells, localize in cytoplasmic vesicles, primarily in lysosomes and acidified endosomes, and demonstrate relatively low toxicity, showing more than 80% cells viability up to the concentration of 10 mu M after 24 h incubation. Phosphorescence lifetime imaging microscopy (PLIM) experiments in these cells display lifetime distribution, the conversion of which into pH values using calibration curves gives the magnitudes of this parameter compatible with the physiologically relevant interval of the cell compartments pH.

AB - Herein we report four [Ir(NC)(2)(LL)](n+), n = 0,1 complexes (1-4) containing cyclometallated NC ligand (NCH = 1-phenyl-2-(4-(pyridin-2-yl)phenyl)-1H-phenanthro[9,10-d]imidazole) and various bidentate LL ligands (picolinic acid (1), 2,2 '-bipyridine (2), [2,2 '-bipyridine]-4,4 '-dicarboxylic acid (3), and sodium 4,4 ',4 '',4"'-(1,2-phenylenebis(phosphanetriyl))tetrabenzenesulfonate (4). The NCH ligand precursor and iridium complexes 1-4 were synthesized in good yield and characterized using chemical analysis, ESI mass spectrometry, and NMR spectroscopy. The solid-state structure of 2 was also determined by XRD analysis. The complexes display moderate to strong phosphorescence in the 550-670 nm range with the quantum yields up to 30% and lifetimes of the excited state up to 60 mu s in deoxygenated solution. Emission properties of 1-4 and NCH are strongly pH-dependent to give considerable variations in excitation and emission profiles accompanied by changes in emission efficiency and dynamics of the excited state. Density functional theory (DFT) and time-dependent density functional theory (TD DFT) calculations made it possible to assign the nature of emissive excited states in both deprotonated and protonated forms of these molecules. The complexes 3 and 4 internalize into living CHO-K1 cells, localize in cytoplasmic vesicles, primarily in lysosomes and acidified endosomes, and demonstrate relatively low toxicity, showing more than 80% cells viability up to the concentration of 10 mu M after 24 h incubation. Phosphorescence lifetime imaging microscopy (PLIM) experiments in these cells display lifetime distribution, the conversion of which into pH values using calibration curves gives the magnitudes of this parameter compatible with the physiologically relevant interval of the cell compartments pH.

KW - Orthometalated iridium(III) complexes

KW - PH-dependent luminescence

KW - Phosphorescence lifetime imaging

KW - Cell Line

KW - Chemistry Techniques, Synthetic

KW - Magnetic Resonance Spectroscopy

KW - Molecular Conformation

KW - Iridium/chemistry

KW - Models, Molecular

KW - Molecular Imaging

KW - Animals

KW - X-Ray Diffraction

KW - Chemical Phenomena

KW - Ligands

KW - Molecular Structure

KW - Hydrogen-Ion Concentration

KW - Organometallic Compounds/chemical synthesis

KW - DESIGN

KW - IR(III)

KW - CHEMISTRY

KW - phosphorescence lifetime imaging

KW - PROBE

KW - ACIDITY

KW - PHOTOCHEMICAL PROPERTIES

KW - orthometalated iridium(III) complexes

KW - pH-dependent luminescence

UR - http://www.scopus.com/inward/record.url?scp=85122026295&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/5410b2b4-440e-39eb-b84a-7ad34b6c2afd/

U2 - 10.3390/molecules27010232

DO - 10.3390/molecules27010232

M3 - Article

C2 - 35011464

AN - SCOPUS:85122026295

VL - 27

JO - Molecules

JF - Molecules

SN - 1420-3049

IS - 1

M1 - 232

ER -