Photochemistry using a host–guest charge transfer paradigm: DMABN as a dynamical probe of ground and excited states

Gera, Rahul; Dasgupta, Jyotishman

doi:10.1039/d1cp00370d

Cited by 4 publications

(5 citation statements)

References 35 publications

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“…We subsequently probed the Raman spectrum of the cavity-trapped Fe(IV)-superoxo species. We recorded the resonance Raman spectrum of 1-O 2 ⊂ Cage prepared in both H 2 16 O + 16 O 2 and H 2 18 O + 18 O 2 separately at 77 K. The Raman spectrum of the empty cage was recorded at RT , to enable assignment of the 1-O 2 features. The Raman vibrations of the complex and cage are enunciated in the low frequency region in the range of 300 to 1200 cm –1 (Supporting Information Figure S22).…”

Section: Resultsmentioning

confidence: 99%

Trapping an Elusive Fe(IV)-Superoxo Intermediate Inside a Self-Assembled Nanocage in Water at Room Temperature

Gera,

De,

Singh

et al. 2024

J. Am. Chem. Soc.

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Molecular cavities that mimic natural metalloenzymes have shown the potential to trap elusive reaction intermediates. Here, we demonstrate the formation of a rare yet stable Fe(IV)-superoxo intermediate at room temperature subsequent to dioxygen binding at the Fe(III) site of a (Et 4 N) 2 [Fe III (Cl)(bTAML)] complex confined inside the hydrophobic interior of a water-soluble Pd 6 L 4 12+ nanocage. Using a combination of electron paramagnetic resonance, Mossbauer, Raman/IR vibrational, X-ray absorption, and emission spectroscopies, we demonstrate that the cage-encapsulated complex has a Fe(IV) oxidation state characterized by a stable S = 1/2 spin state and a short Fe−O bond distance of ∼1.70 Å. We find that the O 2 reaction in confinement is reversible, while the formed Fe(IV)superoxo complex readily reacts when presented with substrates having weak C−H bonds, highlighting the lability of the O−O bond. We envision that such optimally trapped high-valent superoxos can show new classes of reactivities catalyzing both oxygen atom transfer and C−H bond activation reactions.

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Section: Resultsmentioning

confidence: 99%

Trapping an Elusive Fe(IV)-Superoxo Intermediate Inside a Self-Assembled Nanocage in Water at Room Temperature

Gera,

De,

Singh

et al. 2024

J. Am. Chem. Soc.

Self Cite

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“…Typically, these radical pairs recombine within a few picoseconds, hampering the use in diffusion dependent chemistry. 187 However, intercepting the radical pair with a fast chemical reaction from a preorganized substrate could provide a new paradigm for photochemistry. 188 The group of Dasgupta has investigated CT phenomena inside supramolecular cages in detail and provided evidence that such radical pairs can be intercepted.…”

Section: Host−guest Charge Transfer Complexesmentioning

confidence: 99%

“…Irradiation of these CT bands may result in SET from the donor to acceptor, creating a radical pair. Typically, these radical pairs recombine within a few picoseconds, hampering the use in diffusion dependent chemistry . However, intercepting the radical pair with a fast chemical reaction from a preorganized substrate could provide a new paradigm for photochemistry …”

Section: Photoredox Catalysis For the Synthesis Of Complex Moleculesmentioning

confidence: 99%

Supramolecular Coordination Cages for Artificial Photosynthesis and Synthetic Photocatalysis

et al. 2023

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Because sunlight is the most abundant energy source on earth, it has huge potential for practical applications ranging from sustainable energy supply to light driven chemistry. From a chemical perspective, excited states generated by light make thermodynamically uphill reactions possible, which forms the basis for energy storage into fuels. In addition, with light, open-shell species can be generated which open up new reaction pathways in organic synthesis. Crucial are photosensitizers, which absorb light and transfer energy to substrates by various mechanisms, processes that highly depend on the distance between the molecules involved. Supramolecular coordination cages are well studied and synthetically accessible reaction vessels with single cavities for guest binding, ensuring close proximity of different components. Due to high modularity of their size, shape, and the nature of metal centers and ligands, cages are ideal platforms to exploit preorganization in photocatalysis. Herein we focus on the application of supramolecular cages for photocatalysis in artificial photosynthesis and in organic photo(redox) catalysis. Finally, a brief overview of immobilization strategies for supramolecular cages provides tools for implementing cages into devices. This review provides inspiration for future design of photocatalytic supramolecular host−guest systems and their application in producing solar fuels and complex organic molecules.

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“…These absorption bands may undergo a single electron transfer (SET) process from donor to acceptor upon photoirradiation, creating a radical pair. However, these radical pairs are extremely unstable, hampering their use in diffusion-dependent chemistry [ 135 ]. Therefore, photochemical ones are difficult to control due to their intrinsically low reaction barriers upon excitation and highly reactive intermediates.…”

Section: Photocatalysis In Wsmocsmentioning

confidence: 99%

Photocatalysis in Water-Soluble Supramolecular Metal Organic Complex

Shi

Liu

et al. 2023

Molecules

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As an emerging subset of organic complexes, metal complexes have garnered considerable attention owing to their outstanding structures, properties, and applications. In this content, metal-organic cages (MOCs) with defined shapes and sizes provide internal spaces to isolate water for guest molecules, which can be selectively captured, isolated, and released to achieve control over chemical reactions. Complex supramolecules are constructed by simulating the self-assembly behavior of the molecules or structures in nature. For this purpose, massive amounts of cavity-containing supramolecules, such as metal-organic cages (MOCs), have been extensively explored for a large variety of reactions with a high degree of reactivity and selectivity. Because sunlight and water are necessary for the process of photosynthesis, water-soluble metal-organic cages (WSMOCs) are ideal platforms for photo-responsive stimulation and photo-mediated transformation by simulating photosynthesis due to their defined sizes, shapes, and high modularization of metal centers and ligands. Therefore, the design and synthesis of WSMOCs with uncommon geometries embedded with functional building units is of immense importance for artificial photo-responsive stimulation and photo-mediated transformation. In this review, we introduce the general synthetic strategies of WSMOCs and their applications in this sparking field.

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Photochemistry using a host–guest charge transfer paradigm: DMABN as a dynamical probe of ground and excited states

Abstract: Photoexciting charge transfer (CT) transitions arising from host-guest interactions in a confined environment can efficiently yield kinetically trapped radicals. In order to predispose these photogenerated radicals for diffusion limited reactions...

Cited by 4 publications

References 35 publications

Trapping an Elusive Fe(IV)-Superoxo Intermediate Inside a Self-Assembled Nanocage in Water at Room Temperature

Trapping an Elusive Fe(IV)-Superoxo Intermediate Inside a Self-Assembled Nanocage in Water at Room Temperature

Supramolecular Coordination Cages for Artificial Photosynthesis and Synthetic Photocatalysis

Photocatalysis in Water-Soluble Supramolecular Metal Organic Complex

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