Table 1. Selected photochemical/-physical properties of the sensitizers used in this study.

Sensitizer	ε 532/(M–1 cm–1) a	λ max (em)/nm b	τ 0/μs c	φ em d	α e	k oxygen/(M–1 s–1) f	k TTET/(M–1 s–1) g
Rubpy	720	625	0.6	0.063 (ref. 31)	—	3.2 × 109	1.4 × 109
RuPy1	990	630	2.6	0.058	0.79	2.3 × 109	2.3 × 109
RuPy2	770	613	17.9	0.098	0.99	2.4 × 109	2.1 × 109

^aMolar absorption coefficients of the sensitizers at the excitation wavelength for upconversion (532 nm).

^bMaxima of MLCT emission in H₂O.

^cUnquenched lifetimes of excited sensitizers as determined by the average of absorption and luminescence decay kinetics.

^dLuminescence quantum yields of the MLCT emission using the value of Rubpy as the reference.

^eFraction of pyrene-like triplets in the excited-state equilibrium.

^fRate constants of oxygen quenching (with 0.27 mM of dissolved oxygen in air-saturated water).20

^gRate constants of triplet–triplet energy transfer (TTET) reactions between excited sensitizers and the anthracene derivative MAMA.