Latent Ruthenium Benzylidene Phosphite Complexes for Visible-Light-Induced Olefin Metathesis

Eivgi, Or; Vaisman, Anna; Nechmad, Noy B.; Baranov, Mark; Lemcoff, N. Gabriel

doi:10.1021/acscatal.9b05079

Cited by 25 publications

(44 citation statements)

References 49 publications

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“…Previous work by Lemcoff and co-workers has demonstrated two-wavelength olefin metathesis; however, deep UV light and long irradiation times were required for catalyst decomposition-conditions that are unsuitable for AM applications. [30,37] To create a deactivation layer, the kinetics of deactivation-a two-step process involving photolysis of a PBG and subsequent reaction of the liberated base with the active Ru catalytic species-would have to compete with the rates of catalyst initiation and propagation to effectively inhibit curing. We also needed to consider the overall polymerization rate profile, as this factor was directly related to the maximum printing speed that could be achieved.…”

Section: Resultsmentioning

confidence: 99%

“…CH 2 Cl 2 was added in portions (≈1 mL total volume) to fully homogenize these components, consistent with established literature procedures. [27,30,50,51] Twenty grams of DCPD/ENB mixture was then added, and the resin was agitated to homogenize. The photoresin was used immediately after preparation.…”

Section: Methodsmentioning

confidence: 99%

“…[19][20][21] For example, analogues of polyethylene, [22,23] polyurethane, polyamide, [24] poly(acetylene), [25] and poly(p-phenylene vinylidene) [26] have all been prepared via by ROMP of cyclic olefin monomers. While photopolymerization strategies have been developed for ROMP, [27][28][29][30][31] ROMP-based AM using decomposition/deactivation chemistry has yet to be reported. As such, we were motivated to develop a dual-wavelength vat photopolymerization process to combine the chemical and structural diversity of ROMP with the speed of continuous AM.…”

Section: Introductionmentioning

confidence: 99%

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Continuous Additive Manufacturing using Olefin Metathesis

et al. 2022

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The development of chemistry is reported to implement selective dual-wavelength olefin metathesis polymerization for continuous additive manufacturing (AM). A resin formulation based on dicyclopentadiene is produced using a latent olefin metathesis catalyst, various photosensitizers (PSs) and photobase generators (PBGs) to achieve efficient initiation at one wavelength (e.g., blue light) and fast catalyst decomposition and polymerization deactivation at a second (e.g., UV-light). This process enables 2D stereolithographic (SLA) printing, either using photomasks or patterned, collimated light. Importantly, the same process is readily adapted for 3D continuous AM, with printing rates of 36 mm h -1 for patterned light and up to 180 mm h -1 using un-patterned, high intensity light.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Continuous Additive Manufacturing using Olefin Metathesis

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“…This discovery led to the design of novel phosphite containing latent metathesis catalysts. One of these complexes, cis-Ru-5, was designed to possess a chromatic orthogonal kill switch based on the more efficient photochemistry of the 2-nitrobenzyl group (compared to the less efficient supersilyl photochemistry) [57]. The destruction mechanism of the complex, although not completely elucidated, involves the cleavage of the photosensitive 2-nitrobenzyl groups (Figure 7).…”

Section: Development Of the Methodsmentioning

confidence: 99%

Sunscreen-Assisted Selective Photochemical Transformations

Eivgi

Lemcoff

2020

Molecules

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In this review, we describe a simple and general procedure to accomplish selective photochemical reaction sequences for two chromophores that are responsive to similar light frequencies. The essence of the method is based on the exploitation of differences in the molar absorptivity at certain wavelengths of the photosensitive groups, which is enhanced by utilizing light-absorbing auxiliary filter molecules, or “sunscreens”. Thus, the filter molecule hinders the reaction pathway of the least absorbing molecule or group, allowing for the selective reaction of the other. The method was applied to various photochemical reactions, from photolabile protecting group removal to catalytic photoinduced olefin metathesis in different wavelengths and using different sunscreen molecules. Additionally, the sunscreens were shown to be effective also when applied externally to the reaction mixture, avoiding any potential chemical interactions between sunscreen and substrates and circumventing the need to remove the light-filtering molecules from the reaction mixture, adding to the simplicity and generality of the method.

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“… 2020 10 2033 2038 . 4 A new generation of photoactive phosphite complexes for visible-light-induced metathesis and 3D printing applications.…”

Section: Key Referencesmentioning

confidence: 99%

Light-Activated Olefin Metathesis: Catalyst Development, Synthesis, and Applications

et al. 2020

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Conspectus The most important means for tuning and improving a catalyst’s properties is the delicate exchange of the ligand shell around the central metal atom. Perhaps for no other organometallic-catalyzed reaction is this statement more valid than for ruthenium-based olefin metathesis. Indeed, even the simple exchange of an oxygen atom for a sulfur atom in a chelated ruthenium benzylidene about a decade ago resulted in the development of extremely stable, photoactive catalysts. This Account presents our perspective on the development of dormant olefin metathesis catalysts that can be activated by external stimuli and, more specifically, the use of light as an attractive inducing agent. The insight gained from a deeper understanding of the properties of cis -dichlororuthenium benzylidenes opened the doorway for the systematic development of new and efficient light-activated olefin metathesis catalysts and catalytic chromatic-orthogonal synthetic schemes. Following this, ways to disrupt the ligand-to-metal bond to accelerate the isomerization process that produced the active precatalyst were actively pursued. Thus, we summarize herein the original thermal activation experiments and how they brought about the discoveries of photoactivation in the sulfur-chelated benzylidene family of catalysts. The specific wavelengths of light that were used to dissociate the sulfur–ruthenium bond allowed us to develop noncommutative catalytic chromatic-orthogonal processes and to combine other photochemical reactions with photoinduced olefin metathesis, including using external light-absorbing molecules as “sunscreens” to achieve novel selectivities. Alteration of the ligand sphere, including modifications of the N-heterocyclic carbene (NHC) ligand and the introduction of cyclic alkyl amino carbene (CAAC) ligands, produced more efficient light-induced activity and special chemical selectivity. The use of electron-rich sulfoxides and, more prominently, phosphites as the agents that induce latency widened the spectrum of light-induced olefin metathesis reactions even further by expanding the colors of light that may now be used to activate the catalysts, which can be used in applications such as stereolithography and 3D printing of tough metathesis-derived polymers.

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Latent Ruthenium Benzylidene Phosphite Complexes for Visible-Light-Induced Olefin Metathesis

Cited by 25 publications

References 49 publications

Continuous Additive Manufacturing using Olefin Metathesis

Continuous Additive Manufacturing using Olefin Metathesis

Sunscreen-Assisted Selective Photochemical Transformations

Light-Activated Olefin Metathesis: Catalyst Development, Synthesis, and Applications

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