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 th… Show more
“…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 …”
Section: Resultsmentioning
confidence: 68%
“…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.…”
We present a detailed investigation of the photophysical properties of mixed-ligand pyrene-and porphyrin-based metal−organic frameworks (MOFs) as a function of their 3D structure. Solvothermal reactions between metal salts (InCl 3 , Zr(acac) 4 , and ZrCl 4 ) and suitable ratios of 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy) and meso-tetrakis-(4-carboxyphenyl)porphyrin (TCPP) were performed to prepare a series of mixed-ligand ROD-7, NU-901, and NU-1000 MOFs. Time-resolved and steady-state fluorescence measurements were conducted on the mixed-ligand MOFs to study their photophysics. Based on the results, we concluded that upon excitation of TBAPy linkers in the MOFs, singlet excitation energy migrates across TBAPy linkers until it finds a TCPP unit. TCPP acts as an energy trap and quenches the excitation. The efficiency of TBAPy-to-TBAPy energy transfer was found to be sensitive to the structural parameters of MOFs. Analysis of steady-state and time-resolved fluorescence data revealed that excitation energy transfer (EET) is most efficient in ROD-7, followed by NU-901 and NU-1000. We propose that topology that invokes the shorter interchromophoric distances between TBAPy linkers in ROD-7 is responsible for its higher EET efficiency. The distance dependence of the EET rate constant (k EET ) was investigated to gain insight into the mechanistic aspects of energy transfer in MOFs. This study revealed that (a) energy transfer in MOFs deviates from the classical Forster model and (b) the geometrical arrangement of linkers influences the mechanism of EET in MOFs. A theoretical investigation was also performed to determine energy-transfer rate constants along different directions and assess the directionality of energy transfer in these MOFs. The magnitude of rate constants indicated that energy transfer in ROD-7 should be highly anisotropic along the stacking direction. These findings suggest that ROD-7 is a promising candidate to play the role of the light-harvesting and energy-transfer component in solar energy conversion devices, where directional energy transfer is required.
“…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 …”
Section: Resultsmentioning
confidence: 68%
“…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.…”
We present a detailed investigation of the photophysical properties of mixed-ligand pyrene-and porphyrin-based metal−organic frameworks (MOFs) as a function of their 3D structure. Solvothermal reactions between metal salts (InCl 3 , Zr(acac) 4 , and ZrCl 4 ) and suitable ratios of 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy) and meso-tetrakis-(4-carboxyphenyl)porphyrin (TCPP) were performed to prepare a series of mixed-ligand ROD-7, NU-901, and NU-1000 MOFs. Time-resolved and steady-state fluorescence measurements were conducted on the mixed-ligand MOFs to study their photophysics. Based on the results, we concluded that upon excitation of TBAPy linkers in the MOFs, singlet excitation energy migrates across TBAPy linkers until it finds a TCPP unit. TCPP acts as an energy trap and quenches the excitation. The efficiency of TBAPy-to-TBAPy energy transfer was found to be sensitive to the structural parameters of MOFs. Analysis of steady-state and time-resolved fluorescence data revealed that excitation energy transfer (EET) is most efficient in ROD-7, followed by NU-901 and NU-1000. We propose that topology that invokes the shorter interchromophoric distances between TBAPy linkers in ROD-7 is responsible for its higher EET efficiency. The distance dependence of the EET rate constant (k EET ) was investigated to gain insight into the mechanistic aspects of energy transfer in MOFs. This study revealed that (a) energy transfer in MOFs deviates from the classical Forster model and (b) the geometrical arrangement of linkers influences the mechanism of EET in MOFs. A theoretical investigation was also performed to determine energy-transfer rate constants along different directions and assess the directionality of energy transfer in these MOFs. The magnitude of rate constants indicated that energy transfer in ROD-7 should be highly anisotropic along the stacking direction. These findings suggest that ROD-7 is a promising candidate to play the role of the light-harvesting and energy-transfer component in solar energy conversion devices, where directional energy transfer is required.
“…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.…”
A series of luminescent frameworks was synthesized from the selective combination of aggregation induced emission (AIE)-linker tetra-(4-carboxylphenyl)ethylene (H 4 TCPE) and Zn 2 + . Complex 1 was formed by the close packing of Zn-TCPE hinge, and isostructural complexes 2-5 were constructed by the linkage of Zn-TCPE layer and pillar ligands. These complexes exhibit highly efficient multiphoton excited photoluminescence (MEPL) and concomitant thirdharmonic generation (THG). The multiphoton absorption (MPA) parameters of 1 are superior to other multiphoton emission materials including the perovskite nanocrystals. The incorporation of pillar linkers slows down the charge transfer between layers of Zn-TCPE, and the aromatic core of pillar linkers has a great influence on the MPA performance of the corresponding 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.…”
While limited choice of emissive organic linkers with systematic emission tunability presents ag reat challenge to investigate energy transfer (ET) over the whole visible light range with designable directions,l uminescent metal-organic frameworks (LMOFs) may serve as an ideal platform for such study due to their tunable structure and composition. Herein, five Zr 6 cluster-based LMOFs,HIAM-400X (X = 0, 1, 2, 3, 4) are prepared using 2,1,3-benzothiadiazole and its derivativebased tetratopic carboxylic acids as organic linkers.T he accessible unsaturated metal sites confer HIAM-400X as apristine scaffold for linker installation. Six full-color emissive 2,1,3-benzothiadiazole and its derivative-based dicarboxylic acids (L) were successfully installed into HIAM-400X matrix to form HIAM-400X-L, in whichthe ET can be facilely tuned by controlling its direction, either from the inserted linkers to pristine MOFs or from the pristine MOFs to inserted linkers, and over the whole range of visible light. The combination of the pristine MOFs and the second linkers via linker installation creates ap owerfult wo-dimensional space in tuning the emission via ET in LMOFs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.