TY - JOUR
T1 - Near Infrared Phosphorescent Dinuclear Ir(III) Complex Exhibiting Unusually Slow Intersystem Crossing and Dual Emissive Behavior
AU - Shafikov, Marsel Z.
AU - Zaytsev, Andrey
AU - Suleymanova, Alfiya F.
AU - Brandl, Fabian
AU - Kowalczyk, Aleksandra
AU - Gapińska, Magdalena
AU - Kowalski, Konrad
AU - Kozhevnikov, Valery N.
AU - Czerwieniec, Rafał
N1 - Funding information: The financial support from the German Research Foundation (DFG) (Project 389797483) and EPSRC (Project EP/S01280X/1) and support from the University of Łódź are gratefully acknowledged. The authors thank Prof. Dr. Duncan Bruce (University of York) for the help with computational facilities and Dr. Michael Bodensteiner (Universität Regensburg) for X-ray diffraction analysis.
PY - 2020/8/6
Y1 - 2020/8/6
N2 - A dinuclear iridium(III) complex IrIr shows dual emission consisting of near infrared (NIR) phosphorescence (λmax = 714 nm, CH2Cl2, T = 300 K) and green fluorescence (λmax = 537 nm). The NIR emission stems from a triplet state (T1) localized on the ditopic bridging ligand (3LC). Because of the dinuclear molecular structure, the phosphorescence efficiency (φPL = 3.5%) is high compared to those of other known red/NIR-emitting iridium complexes. The weak fluorescence stems from the lowest excited singlet state (S1) of 1LC character. The occurrence of fluorescence is ascribed to relatively slow intersystem crossing (ISC) from state S1 (1LC) to the triplet manifold. The measured ISC rate corresponds to a time constant τISC of 2.1 ps, which is an order of magnitude longer than those usually found for iridium complexes. This slow ISC rate can be explained in terms of the LC character and large energy separation (0.57 eV) of the respective singlet and triplet excited states. IrIr is internalized by live HeLa cells as evidenced by confocal luminescence microscopy.
AB - A dinuclear iridium(III) complex IrIr shows dual emission consisting of near infrared (NIR) phosphorescence (λmax = 714 nm, CH2Cl2, T = 300 K) and green fluorescence (λmax = 537 nm). The NIR emission stems from a triplet state (T1) localized on the ditopic bridging ligand (3LC). Because of the dinuclear molecular structure, the phosphorescence efficiency (φPL = 3.5%) is high compared to those of other known red/NIR-emitting iridium complexes. The weak fluorescence stems from the lowest excited singlet state (S1) of 1LC character. The occurrence of fluorescence is ascribed to relatively slow intersystem crossing (ISC) from state S1 (1LC) to the triplet manifold. The measured ISC rate corresponds to a time constant τISC of 2.1 ps, which is an order of magnitude longer than those usually found for iridium complexes. This slow ISC rate can be explained in terms of the LC character and large energy separation (0.57 eV) of the respective singlet and triplet excited states. IrIr is internalized by live HeLa cells as evidenced by confocal luminescence microscopy.
UR - https://www.scopus.com/pages/publications/85089612138
U2 - 10.1021/acs.jpclett.0c01276
DO - 10.1021/acs.jpclett.0c01276
M3 - Article
C2 - 32615767
AN - SCOPUS:85089612138
SN - 1948-7185
VL - 11
SP - 5849
EP - 5855
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 15
ER -