Table 1.

Photophysical Data for Complexes 1-6 in Acetonitrile.

	λabs/nm (ε/104 L mol−1 cm−1)a	λem/nm (τem/μs); Φemb	kr/103 s−1 c	knr/105s−1 d	theorλphos /nme	λT1-Tn /nm (τT/μs; εT1-Tn / 104 L mol−1 cm−1); ΦTf
1	275 (7.99), 303 (2.30), 325 (0.77), 340 (0.50), 356 (0.58)	455 (4.16), 485 (4.17), 520 (4.12); 0.0040	0.96	2.39	460	370 (4.27; -), 590 (4.52; -), 750 (5.08; -); -i
2	277 (8.65), 302 (5.24), 354 (2.38), 377 (1.95)	525 (17.6), 560 (18.3); 0.0178	1.09	0.60	499	410 (15.9; 1.07), 590 (15.6; 3.24); 0.93
3	276 (10.81), 325 (4.22), 341 (5.12), 382 (1.21), 448 (1.60, br)	660 (−)g; 0.0065	-h	-h	689	539 (33.4; 5.37); 0.34
4	276 (8.10), 297 (4.70), 325 (1.52), 340 (1.44), 354 (1.32)	510 (3.65), 542 (3.75); 0.0067	1.84	2.72	495	380 (3.62; -), 503 (3.32; -); - i
5	275 (9.05), 302 (2.85), 324 (2.30), 341 (2.38), 357 (1.32), 429 (0.70, br)	650 (−)g; 0.0058	-h	-h	680	497 (31.2; -); - i
6	276 (8.73), 308 (5.08), 356 (2.06), 385 (3.20), 403 (3.32)	565 (5.53), 608 (5.47); 0.0190	3.44	1.77	630	450 (5.28; 1.90), 610 (5.68; 3.76); 1

^aAbsorption band maxima (λ_abs) and molar extinction coefficients (ε) at room temperature.

^bEmission wavelengths (λ_em), lifetimes (τ_em), and quantum yields (Φ_em) at room temperature. The lifetimes were measured in the same solution as used in the TA study. The concentration of sample solution was 7.2×10⁻⁵, 1.8×10⁻⁵, 1.9×10⁻⁵, 2.8×10⁻⁵, 3.1×10⁻⁵, and 2.0×10⁻⁵ mol^•L⁻¹ for 1-6, respectively. The emission quantum yields were determined by relative actinometry, in which [Ru(bpy)₃]Cl₂ in degassed CH₃CN (λ_max = 436 nm, Φ_em = 0.097)³³ was used as the reference for complexes 3, 5 and 6, and a 1 N sulfuric acid solution of quinine bisulfate (λ_ex = 347.5 nm, Φ_em = 0.546)³⁴ was used as the reference for complexes 1, 2 and 4.

^cRadiative decay rates (k_r) and nonradiative decay rates (k_nr) calculated by k_r = Φ_em/(Φ_Tτ_em) and k_nr = (1-Φ_em)/(Φ_Tτ_em), respectively. For 2 and 6, the estimated triplet quantum yields (Φ_T) from the TA measurement were used. For 1 and 4, Φ_T was assumed to be 1

^dRadiative decay rates (k_r) and nonradiative decay rates (k_nr) calculated by k_r = Φ_em/(Φ_Tτ_em) and k_nr = (1-Φ_em)/(Φ_Tτ_em), respectively. For 2 and 6, the estimated triplet quantum yields (Φ_T) from the TA measurement were used. For 1 and 4, Φ_T was assumed to be 1.

^eCalculated phosphorescence energies by PBE1PBE for optimized triplet geometry.

^fNanosecond transient absorption band maxima (λ_T1-Tn), triplet extinction coefficients (ε_T1-Tn), triplet excited-state lifetimes (τ_T) and quantum yields (Φ_T) measured in CH₃CN at room temperature. The concentration of sample solution was 7.2×10⁻⁵, 1.8×10⁻⁵, 1.9×10⁻⁵, 2.8×10⁻⁵, 3.1×10⁻⁵, and 2.0×10⁻⁵ mol^•L⁻¹ for 1-6, respectively. SiNc in benzene was used as the reference (ε _Τ1−Τn = 70,000 L mol⁻¹ cm⁻¹ at 590 nm Φ_T = 0.20).³⁷

^gEmission signal was too weak to allow reliable lifetime to be measured.

^hCannot be calculated because the lifetime was unable to be obtained.

^INo bleaching bands were detected, thus the ε_T1-Tn values were unable to be estimated using the singlet depletion method and the Φ_T value was unable to be calculated.