A redox-mediator pathway for enhanced multi-colour electrochemiluminescence in aqueous solution

Abstract

A water-soluble Ir(iii) complex is shown to enhance the ‘remote’ mechanism of the most widely used co-reactant ECL reaction of tris(2,2′-bipyridine)ruthenium(ii) with tripropylamine.

Shedding Light on the Oxidizing Properties of Spin-Flip Excited States in a CrIII Polypyridine Complex and Their Use in Photoredox Catalysis

“…We find that the driving-force dependence for photo-oxidation of 10 different electron donors is very similar for both [Cr(dqp) 2 ] 3+ and [Ru(bpz) 3 ] 2+ . Our analysis confirms that the redox potential of the lowest spin-flip excited state in Cr III complexes can be determined in the same manner as for 3 MLCT states in Ru II compounds, despite the very fundamental differences explained earlier (Figure 1). In the second part of this study, we have been able to increase the scope of photoredox catalytic applications of Cr III spin-flip excited states substantially beyond the current state-of-the-art.…”

“…For 2 E/ 2 T 1 -excited [Cr(dqp) 2 ] 3+ , the ΔG ET range is slightly different and ranges from +0.28 to −0.71 eV, due to the 0.19 V difference in excited-state reduction potentials estimated for [Cr(dqp) 2 ] 3+ and [Ru(bpz) 3 ] 2+ on the basis of eq 1. Evidently, the two data sets in Figure 3 are very similar despite the fundamental differences between 3 MLCT states and 2 E/ 2 T 1 spin-flip state outlined above. Quantitatively, the dependence of k q on ΔG ET can be described with the empirical Rehm−Weller equation…”

“…The 2 E state differs from the electronic ground state merely by the change of one electron spin, but otherwise the dorbital occupancy is identical (Figure 1). 20 Evidently, there is no ligand-based electron and no metal-centered hole as in the case of 3 MLCT-excited d 6 metal complexes (Figure 1).…”

“…Transition-metal complexes with the 4d 6 and 5d 6 valence electron configurations are widely employed in photophysics and photochemistry. Prominent representatives are Ru II polypyridine and cyclometalated Ir III complexes, with applications in light-emitting devices, − dye-sensitized solar cells, artificial photosynthesis, − photocatalysis, − and photodynamic therapy. , The versatility of these d 6 metal complexes is largely due to their electronic structure with metal-centered highest occupied molecular orbitals (HOMOs) and ligand-based lowest unoccupied molecular orbitals (LUMOs), leading to an energetically lowest excited state of 3 MLCT type (Figure ). In this photoactive state, the ligand-based excited electron can easily be transferred to suitable acceptors to accomplish photochemical reductions, or the metal-centered electron vacancy can induce photo-oxidations .…”

Glucose/ROS cascade-responsive ceria nanozymes for diabetic wound healing

“…We treated HUVECs with different preparations in a low oxygen (1% O 2 ) environment. Tris(2,2-bipyridine) ruthenium chloride hexahydrate was used as an oxygen-sensitive probe whose fluorescence was specifically quenched by the oxygen molecule [ 60 ], so that the fluorescence intensity was inversely proportional to the oxygen content. As seen in Fig.…”