Ultrafast and long-time excited state kinetics of an NIR-emissive vanadium(iii) complex II. Elucidating triplet-to-singlet excited-state dynamics

Abstract

We report the non-adiabatic dynamics of VIIICl3(ddpd), a complex based on the Earth-abundant first-row transition metal vanadium with d2 electronic configuration which is able to emit phosphorescence in solution in...

Ultrafast and long-time excited state kinetics of an NIR-emissive vanadium(iii) complex I: synthesis, spectroscopy and static quantum chemistry

“…1a). CASSCF calculations reported in the accompanying paper 63 suggest some double excitation character of the ILCT transitions which might well lower the energy of these states. The very weak low-energy band at 702 nm (3 < 100 M À1 cm À1 ) corresponds to metalcentred (MC) transitions from t 2g to e g orbitals ( 3 T 2 ).…”

“…Extended calculations using an even larger active space will be presented in the accompanying paper. 63 Excitation of solid VCl 3 (ddpd-[D 0 ]) with 350 nm (ILCT) at 298 K results in the appearance of two NIR emission bands (Fig. 2a).…”

“…Trajectory surface hopping simulations within a linear vibronic coupling model will derive a detailed kinetic model of the initial dynamics and the efficiency of the ISC processes (s ISC,simulation ¼ 1.7 AE 0.3 ps) in the accompanying paper. 63 Photolysis experiments were carried out in CH 3 CN using an Asahi Spectra Max-303 Xenon Light Source (300 W, Fig. S32, ESI ‡), together with 350 AE 5 nm and 400 AE 5 nm lters, respectively.…”

“…(v) The ISC rate constant from the triplet to the singlet manifold is high (k ISC > 6.7 Â 10 11 s À1 ) as conrmed by the molecular dynamics simulations in the accompanying paper. 63 This high rate could be an effect of the heavier chloride atoms (heavy atom effect), efficient vibronic coupling and/or enhanced SOC due to large differences in orbital type between the two states ( 3 LMCT / 1 MC), 97 although other ultrafast pathways might still compete with ISC.…”

“…A detailed kinetic model of the excited state dynamics will be derived by trajectory surface hopping simulations within a linear vibronic coupling model in the accompanying paper. 63…”