Singlet energy transfer from the charge transfer excited state of tris(2,2′-bipyridine)Ru(II)

Demas, J. N.; Mandal, Krishnagopal; Pearson, T. D. L.

doi:10.1016/0047-2670(81)85322-1

Cited by 2 publications

(3 citation statements)

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“…k RET must then, also, be on the order of 10 6 s –1 , therefore outcompeting k dd in deactivation of the emissive 3 MLCT of RuDCBPY and rendering τ obs temperature independent. Similar quenching rate constants on the order of 10 5 M –1 s –1 and 10 6 M –1 s –1 for self-quenching of RuBPY have been observed in cellulose and zirconium phosphates. , Similar quenching rate constants have also been observed for heterogeneous Förster type RET reactions involving RuBPY and its derivatives. − …”

Section: Resultssupporting

confidence: 61%

Solvothermal Growth and Photophysical Characterization of a Ruthenium(II) Tris(2,2′-Bipyridine)-Doped Zirconium UiO-67 Metal Organic Framework Thin Film

et al. 2014

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A thin film of a Ru II (bpy) 2 (dcbpy)Cl 2 , RuDCBPY, doped metal−organic framework of Zr 6 O 4 (OH) 4 (bpdc) 6 , RuDCBPY-UiO67 (where bpy is 2,2′-bipyridine, dcbpy is 5,5′-dicarboxyphenyl-2,2′-bipyridine, and bpdc is 4,4′-biphenyldicarboxylic acid), has been prepared on fluorine-doped tin oxide and glass slides solvothermally. The film is shown to be isostructural with UiO-67 and similarly doped RuDCBPY-UiO67 powders. The photophysical properties of the film show significant line broadening of the diffuse reflectance spectra, a successive red shift of the emission maxima, and biphasic kinetics with increased RuDCBPY doping of UiO-67 films above 10 mm. The two lifetime components are consistent with a dual population of RuDCBPY within the UiO-67 material: a population of RuDCBPY incorporated into the framework of UiO-67 replacing a bpdc ligand and a second population of RuDCBPY encapsulated within the octahedral cavities. The RuDCBPY dopant within the UiO-67 films interact with each other and undergo self-quenching via a resonance energy transfer mechanism. It was determined that the average distance between RuDCBPY is decreased in the film relative to similarly doped powders. This is attributed to an electrostatic effect upon formation of the framework due to increased charge at the bpdc self-assembled monolayer at the surface of the substrate. ■ INTRODUCTIONMetal−organic framework (MOF) materials continue to gain increasing attention due to their large surface areas and applicability toward catalysis, sensing, separations, and photonics. MOF engineering has, in recent years, been extended by the development of thin films, allowing for more specific/specialized applications. 1−30 The current state of the art of MOF thin film fabrication and development has recently been reviewed extensively. 31−33 Films consisting of MOFs have been prepared and grown on a variety of substrates by a number of different methods. Of the preparative methods employed to date, the most straightforward involves incubating the substrate along with the reaction mixture during the solvothermal process. 32,34−37 Solvothermal synthesis of MOF thin films has been shown to be facilitated by prior formation of a self-assembled, oriented, organic layer terminally functionalized to mimic the connectivity of one of the native MOF ligands. 32,38−40 Thin films composed of robust, stable, and porous MOFs are of particular interest in light of the harsh conditions necessary to carry out a variety of reactions and processes. The UiO (University of Oslo) series of zirconium-based materials are promising candidates owing to their exceptional stability under a variety of thermal, mechanical, and solvent conditions. 41−43 The Zr 6 O 4 (OH) 4 (COO) 6 clusters of the UiO-66, -67, and -68 frameworks arrange in such a way that two types of cavities are formed: a tetrahedral and larger octahedral cavity. 44,45 For UiO-67, in which the connecting ligand is a biphenyldicarboxylate, the diameters of the tetrahedral and octahedral pores are 11.5 and 23 Å, respe...

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Section: Resultssupporting

confidence: 61%

Solvothermal Growth and Photophysical Characterization of a Ruthenium(II) Tris(2,2′-Bipyridine)-Doped Zirconium UiO-67 Metal Organic Framework Thin Film

et al. 2014

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“…Second, according to eq , k ″ (where k ″ = k RET = k obs – k ′) ranges between 1.6 × 10 5 to 5.4 × 10 6 s –1 with increased doping. It should be noted that similar k RET have been noted for Förster-type RET reactions involving RuBPY or RuBPY derivatives. − Kenkre and Knox have proposed that the region between the Förster (very weak coupling) and Perrin (weak coupling) regime in which the distance dependence on k RET is either 1/ r 6 or 1/ r 3 , respectively, is not necessarily discontinuous . Therefore, it is possible that a complex system, like RuDCBPY-UiO-67, may lie somewhere along that continuum.…”

Section: Discussionmentioning

confidence: 67%

“…Consequently, the dependence of the RET rate on distance varies depending on the coupling strength regime. A number of examples where homo- and/or hetero-RET behavior has been observed between organic linkers in a number of MOFs have been reported. − Quenching of RuBPY 3 MLCT in a number of different RuBPY-based MOFs has been ascribed to an energy migration via exchange mechanism. ,,, Yet, it is not uncommon for RET involving RuBPY in solution to occur via a dipole–dipole mechanism. − …”

Section: Discussionmentioning

confidence: 99%

Photophysical Characterization of a Ruthenium(II) Tris(2,2′-bipyridine)-Doped Zirconium UiO-67 Metal–Organic Framework

2014

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The photophysical properties of ruthenium(II) tris(5,5′dicarboxy-2,2′-bipyridine), RuDCBPY, doped into the metal organic framework of Zr 6 O 4 (OH) 4 (BPDC) 6 , RuDCBPY-UiO67 (where BPDC is 4,4′-biphenyldicarboxylic acid), are presented as a function of the degree of RuDCBPY doping. Steady-state diffuse reflectance of RuDCBPY-UiO67 powder shows an absorption maxima at 455 nm, which is effectively insensitive to doping concentration. The energy of the emission maxima and excited state lifetimes are, however, quite sensitive to concentration of RuDCBPY in UiO-67. At low doping concentrations, the emission maxima lies at ∼630 nm. The emission decay can be adequately modeled using a single discrete exponential decay function with an observed lifetime of 1.4 μs. The emission lifetime and the energy of the emission maxima are found to decrease with increased RuDCBPY concentration. However, at higher doping the emission decay becomes nonexponential. Equally adequate fits to the data were obtained using stretched exponential and biexponential functions. A two-state model is presented in which the nonexponential behavior observed at higher RuDCBPY doping concentrations is due to two separate solvation environments within UiO-67. It is proposed that a single RuDCBPY preferentially occupies the larger octahedral cages of UiO-67 by incorporation into the backbone of the cage and experiences a dimethylformamide (DMF)-like solvation environment. At higher doping concentrations, in addition to incorporation of RuDCBPY into the backbone of the octahedral cavities, populations of encapsulated RuDCBPY can also be found in separate octahedral UiO-67 cavities. Encapsulation is assumed to restrict the solvent occupancy within the pore; thereby limiting the solvation of RuDCBPY by DMF. This leads to the disparity in lifetimes between the slow (>100 ns) and fast (∼20−30 ns) components of the lifetime decay, as well as the lack of doping concentration dependence on the fast decay component. The decreased lifetime of the slow phase with increased doping concentration is attributed to intermolecular energy transfer between neighboring RuDCBPY molecules incorporated into the backbone of the octahedral cages.

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Singlet energy transfer from the charge transfer excited state of tris(2,2′-bipyridine)Ru(II)

Cited by 2 publications

References 1 publication

Solvothermal Growth and Photophysical Characterization of a Ruthenium(II) Tris(2,2′-Bipyridine)-Doped Zirconium UiO-67 Metal Organic Framework Thin Film

Solvothermal Growth and Photophysical Characterization of a Ruthenium(II) Tris(2,2′-Bipyridine)-Doped Zirconium UiO-67 Metal Organic Framework Thin Film

Photophysical Characterization of a Ruthenium(II) Tris(2,2′-bipyridine)-Doped Zirconium UiO-67 Metal–Organic Framework

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