Fig. 4. ns-TRE spectra of 1a recorded from (a) 0–42 ns and (b) after a time delay of 1 μs in degassed CH₂Cl₂ (5 × 10^–5 M) at 298 K. Inset shows the emission kinetic decay trace. Decay time constants were fitted as mono-exponential decay (λ _exc = 355 nm).