TY - JOUR
T1 - Trinuclear Cyclometalated Iridium(III) Complex Exhibiting Intense Phosphorescence of an Unprecedented Rate
AU - Shafikov, Marsel Z.
AU - Zaytsev, Andrey
AU - Kozhevnikov, Valery
N1 - Funding information: The financial support from German Research Foundation (DFG) (Project No 389797483), and EPSRC (Project No EP/S01280X/1) is gratefully acknowledged.
PY - 2024/1/15
Y1 - 2024/1/15
N2 - Herein, we present two novel cyclometalated Ir(III) complexes of dinuclear and trinuclear design, Ir
2(dppm)
3(acac)
2 and Ir
3(dppm)
4(acac)
3, respectively, where dppm is 4,6-di(4-tert-butylphenyl)pyrimidine ligand and acac is acetylacetonate ligand. In both cases, rac-diastereomers were isolated during the synthesis. The materials show intense phosphorescence of outstanding rates (k
r = Φ
PL/τ) with corresponding radiative decay times of only τ
r = 1/k
r = 0.36 μs for dinuclear Ir
2(dppm)
3(acac)
2 and still shorter τ
r = 0.30 μs for trinuclear Ir
3(dppm)
4(acac)
3, as measured for doped polystyrene film samples under ambient temperature. Measured under cryogenic conditions, radiative decay times of the three T
1 substates (I, III, and III) and substate energy separations are τ
I = 11.8 μs, τ
II = 7.1 μs, τ
III = 0.06 μs, ΔE(II-I) = 7 cm
-1, and ΔE(III-I) = 175 cm
-1 for dinuclear Ir
2(dppm)
3(acac)
2 and τ
I = 3.1 μs, τ
II = 3.5 μs, τ
III = 0.03 μs, ΔE(II-I) ≈ 1 cm
-1, and ΔE(III-I) = 180 cm
-1 for trinuclear Ir
3(dppm)
4(acac)
3. The determined T
1 state ZFS values (ΔE(III-I)) are smaller compared to that of mononuclear analogue Ir(dppm)
2(acac) (ZFS = 210
-1 cm). Theoretical analysis suggests that the high phosphorescence rates in multinuclear materials can be associated with the increased number of singlet states lending oscillator strength to the T
1 → S
0 transition.
AB - Herein, we present two novel cyclometalated Ir(III) complexes of dinuclear and trinuclear design, Ir
2(dppm)
3(acac)
2 and Ir
3(dppm)
4(acac)
3, respectively, where dppm is 4,6-di(4-tert-butylphenyl)pyrimidine ligand and acac is acetylacetonate ligand. In both cases, rac-diastereomers were isolated during the synthesis. The materials show intense phosphorescence of outstanding rates (k
r = Φ
PL/τ) with corresponding radiative decay times of only τ
r = 1/k
r = 0.36 μs for dinuclear Ir
2(dppm)
3(acac)
2 and still shorter τ
r = 0.30 μs for trinuclear Ir
3(dppm)
4(acac)
3, as measured for doped polystyrene film samples under ambient temperature. Measured under cryogenic conditions, radiative decay times of the three T
1 substates (I, III, and III) and substate energy separations are τ
I = 11.8 μs, τ
II = 7.1 μs, τ
III = 0.06 μs, ΔE(II-I) = 7 cm
-1, and ΔE(III-I) = 175 cm
-1 for dinuclear Ir
2(dppm)
3(acac)
2 and τ
I = 3.1 μs, τ
II = 3.5 μs, τ
III = 0.03 μs, ΔE(II-I) ≈ 1 cm
-1, and ΔE(III-I) = 180 cm
-1 for trinuclear Ir
3(dppm)
4(acac)
3. The determined T
1 state ZFS values (ΔE(III-I)) are smaller compared to that of mononuclear analogue Ir(dppm)
2(acac) (ZFS = 210
-1 cm). Theoretical analysis suggests that the high phosphorescence rates in multinuclear materials can be associated with the increased number of singlet states lending oscillator strength to the T
1 → S
0 transition.
UR - http://www.scopus.com/inward/record.url?scp=85181563343&partnerID=8YFLogxK
U2 - 10.1021/acs.inorgchem.3c03810
DO - 10.1021/acs.inorgchem.3c03810
M3 - Article
C2 - 38154085
SN - 0020-1669
VL - 63
SP - 1317
EP - 1327
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 2
ER -