Stabilized Vanadium Catalyst for Olefin Polymerization by Site Isolation in a Metal–Organic Framework

Comito, Robert J.; Wu, Zhenwei; Zhang, Guanghui; Lawrence, III; Korzyński, Maciej D.; Kehl, Jeffrey A.; Miller, Jeffrey T.; Dincă, Mircea

doi:10.1002/ange.201803642

Cited by 13 publications

(14 citation statements)

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“…Additionally, MOFs with exposed, low-valent early transition metals (particularly V 2+ and Cr 2+ ) have not been widely synthesized to date. 20,21,[76][77][78] At the other end of the first row of transition metals, MOFs with Ni, Cu, and Zn cations are unlikely to result in high O2/N2 selectivities, as they are not predicted to strongly adsorb O2 at the metal centers. We instead recommend the identification and design of MOFs with redox-active Mn 2+ , Fe 2+ , or Co 2+ sites that can be made to strongly favor the adsorption of O2 over N2 without forming metal−peroxo complexes that are often associated with irreversible O2 binding in MOFs.…”

Section: Overview Of Screening Results and Periodic Trendsmentioning

confidence: 99%

Tuning the Redox Activity of Metal−Organic Frameworks for Enhanced, Selective O2 Binding: Design Rules and Ambient Temperature O2 Chemisorption in a Cobalt−Triazolate Framework

Rosen¹,

Mian²,

İslamoğlu³

et al. 2020

Preprint

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Metal−organic frameworks (MOFs) with coordinatively unsaturated metal sites are appealing as adsorbent materials due to their tunable functionality and ability to selectively bind small molecules. Through the use of computational screening methods based on periodic density functional theory, we investigate O2 and N2 adsorption at the coordinatively unsaturated metal sites of several MOF families. A variety of design handles are identified that can be used to modify the redox activity of the metal centers, including changing the functionalization of the linkers (replacing oxido donors with sulfido donors), anion exchange of bridging ligands (considering μ-Br-, μ-Cl-, μ-F-, μ-SH-, or μ-OH- groups), and altering the formal oxidation state of the metal. As a result, we show that it is possible to tune the O2 affinity at the open metal sites of MOFs for applications involving the strong and/or selective binding of O2. In contrast with O2 adsorption, N2 adsorption at open metal sites is predicted to be relatively weak across the MOF dataset, with the exception of MOFs containing synthetically elusive V2+ open metal sites. As one example from the screening study, we predicted that exchanging the μ-Cl- ligands of M2Cl2(BBTA) (H2BBTA = 1H,5H-benzo(1,2-d:4,5-d′)bistriazole) with μ-OH- groups would significantly enhance the strength of O2 adsorption at the open metal sites without a corresponding increase in the N2 affinity. Experimental investigation of Co2Cl2(BBTA) and Co2(OH)2(BBTA) confirms that the former exhibits weak physisorption of both N2 and O2, whereas the latter is capable of chemisorbing O2 at room temperature in a highly selective manner. The O2 chemisorption behavior is attributed to the greater electron-donating character of the μ-OH- ligands and the presence of H-bonding interactions between the μ-OH- bridging ligands and the reduced O2 adsorbate.

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Section: Overview Of Screening Results and Periodic Trendsmentioning

confidence: 99%

Tuning the Redox Activity of Metal−Organic Frameworks for Enhanced, Selective O2 Binding: Design Rules and Ambient Temperature O2 Chemisorption in a Cobalt−Triazolate Framework

Rosen¹,

Mian²,

İslamoğlu³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Additionally, MOFs with exposed, low-valent early transition metals (particularly V 2+ and Cr 2+ ) have not been widely synthesized to date. 20,21,[75][76][77] At the other end of the first row of transition metals, MOFs with Ni 2+/3+ , Cu 2+ , and Zn 2+ cations are unlikely to result in high O2/N2 selectivities, as they are not predicted to strongly adsorb O2 at the metal centers. We instead recommend the identification and design of MOFs with redox-active Mn 2+ , Fe 2+ , or Co 2+ sites that can be made to strongly favor the adsorption of O2 over N2 without forming metal−peroxo complexes that are often associated with irreversible O2 binding in MOFs.…”

Section: Overview Of Screening Results and Periodic Trendsmentioning

confidence: 99%

Tuning the Redox Activity of Metal−Organic Frameworks for Enhanced, Selective O2 Binding

Rosen¹,

Mian²,

İslamoğlu³

et al. 2019

Preprint

View full text Add to dashboard Cite

Metal−organic frameworks (MOFs) with coordinatively unsaturated metal sites are appealing as adsorbent materials due to their tunable functionality and ability to selectively bind small molecules. Through the use of computational screening methods based on periodic density functional theory, we investigate O2 and N2 adsorption at the coordinatively unsaturated metal sites of several MOF families. A variety of design handles are identified that can be used to modify the redox activity of the metal centers, including changing the functionalization of the linkers (replacing oxido donors with sulfido donors), anion exchange of bridging ligands (considering μ-Br-, μ-Cl-, μ-F-, μ-SH-, or μ-OH- groups), and altering the formal oxidation state of the metal. As a result, we show that it is possible to tune the O2 affinity at the open metal sites of MOFs for applications involving the strong and/or selective binding of O2. In contrast with O2 adsorption, N2 adsorption at open metal sites is predicted to be relatively weak across the MOF dataset, with the exception of MOFs containing synthetically elusive V2+ open metal sites. As one example from the screening study, we predict that exchanging the μ-Cl- ligands of M2Cl2(BBTA) (H2BBTA = 1H,5H-benzo(1,2-d:4,5-d′)bistriazole) with μ-OH- groups would significantly enhance the strength of O2 adsorption at the open metal sites without a corresponding increase in the N2 affinity. Experimental investigation of Co2Cl2(BBTA) and Co2(OH)2(BBTA) confirms that the former exhibits only weak physisorption, whereas the latter is capable of chemisorbing O2 at room temperature. The chemisorption behavior is attributed to the greater electron-donating character of the μ-OH- ligands and the presence of H-bonding interactions between the μ-OH- bridging ligands and the O2 adsorbate.

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“…13,14 For example, the family of M-MFU-4l (M = Ti, V, Cr, Ni, Zn) materials achieve ethylene oligomerization and polymerization activities superior to other homogeneous or heterogeneous catalysts. 13,[15][16][17][18] MOF metal nodes therefore offer a unique platform for studying interfacial heterogeneous reactivity, whether for uncovering fundamental parameters difficult to pinpoint in less precise heterogeneous systems, e.g., TiO2, or to discover entirely new chemical transformations. Whereas most reports of catalysis at MOF metal nodes have focused on thermochemical and electrochemical reactions, [19][20][21] investigations into their photochemical reactivity typically involve co-catalysts.…”

Section: Introductionmentioning

confidence: 99%

Tunable Band Gaps in MUV-10(M): A Family of Photoredox-Active MOFs with Earth-Abundant Open Metal Sites

Fabrizio¹,

Lazarou²,

Payne³

et al. 2021

Preprint

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<div> <div> Titanium-based metal—organic frameworks (Ti-MOFs) attract intense research attention because they can store charges in the form of Ti3+ and they serve as photosensitizers for co-catalysts through heterogeneous photoredox reactions at the MOF-liquid interface. Both charge storage and charge transfer depend on redox potentials of the MOF and the molecular substrate, but the factors controlling these energetic aspects are not well understood. Additionally, photocatalysis involving Ti-MOFs relies on co-catalysts rather than the intrinsic Ti reactivity in part because Ti-MOFs with open metal sites are rare. Here, we report that the class of Ti-MOFs known as MUV-10 can be synthetically modified to include a range of redox-inactive ions with flexible coordination environments that control the energies of the photoactive orbitals. Lewis acidic cations installed in the MOF cluster (Cd, Sr , and Ba ) or introduced to the pores (H, Li, Na, K) tune the electronic structure and band gaps of the MOFs. Through use of optical redox indicators, we report the first direct measurement of the Fermi levels (redox potentials) of photoexcited MOFs in situ. Taken together, these results explain the ability of Ti-MOFs to store charges and provide design principles for achieving heterogeneous photoredox chemistry with electrostatic control. </div> </div>

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Stabilized Vanadium Catalyst for Olefin Polymerization by Site Isolation in a Metal–Organic Framework

Abstract: Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Cited by 13 publications

References 50 publications

Tuning the Redox Activity of Metal−Organic Frameworks for Enhanced, Selective O2 Binding: Design Rules and Ambient Temperature O2 Chemisorption in a Cobalt−Triazolate Framework

Tuning the Redox Activity of Metal−Organic Frameworks for Enhanced, Selective O2 Binding: Design Rules and Ambient Temperature O2 Chemisorption in a Cobalt−Triazolate Framework

Tuning the Redox Activity of Metal−Organic Frameworks for Enhanced, Selective O2 Binding

Tunable Band Gaps in MUV-10(M): A Family of Photoredox-Active MOFs with Earth-Abundant Open Metal Sites

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