Role of Spin–Orbit Coupling in Long Range Energy Transfer in Metal–Organic Frameworks

Abstract

Metal−organic frameworks (MOFs) are emerging as a promising platform for solar energy conversion applications. Their potential utilization as efficient chromophores in artificial photosynthesis is closely related to the understanding of light-harvesting and energy transfer processes that occur within these molecular scaffolds. Herein, we present the photophysical investigation of Ru(II), Ir(III), and Os(II) polypyridyl complexes incorporated into the backbone of UiO-67. In this work, we systematically study the effect of spin−orbit coupling on dipole−dipole energy transfer in MOFs using steady-state and time-resolved spectroscopic techniques. The results of our work indicate successful triplet-to-singlet energy transfer and a sizable increase in the transfer kinetics and critical distance, as direct consequences of strong spin−orbit couplings. Remarkably, the reported R 0 value for OsDCBPY (R 0 = 88 ± 10 Å) represents one of the largest Forster distances observed in an MOF. Collectively, this work contributes to the general knowledge of energy transfer in materials and provides groundwork for efficient utilization in artificial photosynthetic assemblies.

Role of a 3D Structure in Energy Transfer in Mixed-Ligand Metal–Organic Frameworks

“…Thus, a rate profile that approaches the 1/ R 6 distance dependence and solely Förster transfer is expected. That said, deviation from the 1/ R 6 distance dependence has been previously observed in chromophore-incorporated MOFs that have characteristic chromophore distances greater than 10 Å …”

“…That said, deviation from the 1/R 6 distance dependence has been previously observed in chromophore-incorporated MOFs that have characteristic chromophore distances greater than 10 Å. 51 The third hypothesis is that the contribution of longdistance exciton hopping (beyond the nearest neighbor) toward the overall energy transfer can strongly influence the n values. So far, we have focused on energy transfers between the two closest chromophores.…”

Highly Efficient Multiphoton Absorption of Zinc‐AIEgen Metal–Organic Frameworks

“…Different luminophores are incorporated into a conjugated framework by coordination linkage, which exhibits novel photoluminescence property arising from the synergistic interaction of various luminophores, as well as charge transfer between ligands and metal ions. [4] Luminescent MOFs exhibit potential applications in the fields of lasing, [5] anisotropic energy transfer, [6] the construction of crystalline host-guest system [7] and high absorption efficiencies. [8] Multiphoton absorption (MPA) materials could simultaneously absorb near-infrared (NIR) photons and generate emission at shorter wavelength.…”

Tuning and Directing Energy Transfer in the Whole Visible Spectrum through Linker Installation in Metal–Organic Frameworks

“…[16][17][18][19][20][21] Model II uses mixed-linker strategy to incorporate two linkers into asingle crystal structure with disordered distribution. [22][23][24] While many interesting and important studies have been done based on these two models,most of these studies are limited to two linkers with restrictions on their absorption and emission properties,w ith very limited capability to tune the ET in the whole visible light range and to control its direction.…”