A Vanadium(III) Complex with Blue and NIR-II Spin-Flip Luminescence in Solution

Abstract

Luminescence from Earth-abundant metal ions in solution at room temperature is a very challenging objective due to the intrinsically weak ligand field splitting of first row transition metal ions, which leads to efficient non-radiative deactivation via metal-centered states. Only a handful of 3d n metal complexes (n ≠ 10) show sizeable luminescence at room temperature. Luminescence in the near-infrared spectral region is even more difficult to achieve as further non-radiative pathways come into play. No Earth-abundant first-row transition metal complexes display emission > 1000 nm at room temperature in solution up to now. Here we report the vanadium(III) complex mer-[V(ddpd) 2 ][PF 6 ] 3 yielding phosphorescence around 1100 nm in valeronitrile glass at 77 K as well as at room temperature in acetonitrile with 1.810 -4 % quantum yield (ddpd = N,N '-dimethyl-N,N'-dipyridine-2-ylpyridine-2,6-diamine). In addition, mer-[V(ddpd) 2 ][PF 6 ] 3 shows very strong blue fluorescence with 2 % quantum yield in acetonitrile at room temperature. Our comprehensive study demonstrates that vanadium(III) complexes with d 2 electron configuration constitute a new class of blue and NIR-II luminophores, which complement the classical established complexes of expensive precious metals and rare-earth elements.

Switching on Near-Infrared Light in Lanthanide-doped CsPbCl3 Perovskite Nanocrystals.pdf

“…These values are reasonable in view of the strong susceptibility to nonradiative deactivation of the luminescence in the NIR range by several competing channels such as vibrational quenching or defect. [24,46] To the best of our knowledge, these are the first PLQY values so far provided for Ho 3+ and Nd 3+ in LHP NCs, while few reports exist in the case of Er 3+ . Despite the good emissive performance, the Er 3+ PLQY remains lower than that in Yb 3+ -Er 3+ codoped CsPbCl3 NCs (6%).…”

“…[14][15][16][17][18][19][20][21] Nonetheless, the upper limit of the emission wavelength still remains below 1.0 μm, which greatly restricts the particularly interesting applications of these materials in optoelectronic and photonic devices working in the NIR such as telecommunication, light-emitting diodes, and lasers. [22][23][24] Unlike Yb 3+ -doped CsPbCl3, which exhibits an extremely intense Yb 3+ NIR emission at ~1.0 μm through a quantumcutting effect, [17,19,25] other NIR luminescent lanthanide ions (Ln 3+ ), such as Er 3+ , Nd 3+ and Ho 3+ unexpectedly show negligible emission. This anomalous phenomenon is likely related to the relatively high redox potential of the Yb 3+ /Yb 2+ pair which allows for a transient internal redox mechanism within the CsPbCl3 matrix releasing enough energy to excite two Yb 3+ ions.…”

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

“…In order to overcome these challenges, we recently combined the nonadiabatic trajectory surface hopping method SHARC 24,25 with a linear vibronic coupling (LVC) approach 26 to compute the electronic potentials. 27 In this way, the photodynamics of a number of transition metal complexes have been investigated, 16,[28][29][30] where time-dependent density functional theory (TDDFT) was used to parametrize the LVC potentials. Given its positive tradeoff between accuracy and computational cost, TDDFT is likely the most popular method to study transition metal complexes 31,32 , and it has also been applied in on-the-fly surface hopping studies of other transition-metal complexes.…”

Janus-type dual emission of a Cyclometalated Iron(III) complex

“…7). Dual emission is generally a very rare observation, 29 and it is the rst time that such a behavior is reported for an iron compound at all. Since luminescent complexes of earth-abundant elements are also still very rare, 30 the observation of a Janus-type dual MLCT and LMCT emission is an encouraging development for future substitution of noble by base metals for photochemical applications.…”