Supramolecular catalysis based on discrete heterometallic coordination-driven metallacycles and metallacages

Gao, Wen‐Xi; Zhang, Haining; Jin, Guo‐Xin

doi:10.1016/j.ccr.2019.01.023

Cited by 194 publications

(84 citation statements)

References 90 publications

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“…A plausible mechanism is that the hydrophobic, but cationic surface of the cage stabilises the enolate anion of ID, effectively reducing its pK a , so that when close to the cage, it can be deprotonated even at pH 3.4 when the expected pK a is 7. We emphasise that 'soft' anions such as phenolates have already been shown to have a higher affinity for the cage surface than more highly solvated anions such as hydroxide or chloride [9]. It is also significant that Raymond and co-workers observed that the basicity of an amine could be increased by >4 pK a units when the amine is bound inside a cage host with a charge of −12 [42]: the charge of +16 on H w implies that a comparable increase in the acidity of ID (i.e., stabilisation of the enolate anion) is plausible if the anion is interacting with the cage surface.…”

Section: Discussionmentioning

confidence: 97%

“…The use of self-assembled molecular containers such as coordination cages as catalysts for reactions that occur in the central cavity has provided some remarkable examples of synthetic hosts providing enzyme-like levels of the rate acceleration of reactions. The range of reactions that has been shown to be catalysed is now extensive [1][2][3][4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Catalysis of an Aldol Condensation Using a Coordination Cage

et al. 2020

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The aldol condensation of indane-1,3-dione (ID) to give 'bindone' in water is catalysed by an M 8 L 12 cubic coordination cage (H w ). The absolute rate of reaction is slow under weakly acidic conditions (pH 3-4), but in the absence of a catalyst it is undetectable. In water, the binding constant of ID in the cavity of H w is ca. 2.4 (±1.2) × 10 3 M −1 , giving a ∆G for the binding of −19.3 (±1.2) kJ mol −1 . The crystal structure of the complex revealed the presence of two molecules of the guest ID stacked inside the cavity, giving a packing coefficient of 74% as well as another molecule hydrogen-bonded to the cage's exterior surface. We suggest that the catalysis occurs due to the stabilisation of the enolate anion of ID by the 16+ surface of the cage, which also attracts molecules of neutral ID to the surface because of its hydrophobicity. The cage, therefore, brings together neutral ID and its enolate anion via two different interactions to catalyse the reaction, which-as the control experiments show-occurs at the exterior surface of the cage and not inside the cage cavity.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Catalysis of an Aldol Condensation Using a Coordination Cage

et al. 2020

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“…Along this line,synthetic strategies have been reported to engineer functional coordination innerspace of nanocages via incorporation of either redox-active or photoactive centers, [31][32][33][34] thus generating MOC-based photocatalytic hostguest systems to imitate natural photosynthesis, [9,[35][36][37][38][39] where the spatially separated electron and/or energy transfer processes can facilitate photocatalytic water/H 2 Ss plitting, as well as other chemical transformations.T oa chieve efficient conversion from solar energy to chemical energy in such hostguest systems,one of the fundamental factors is to control the photo-induced redox events in the confined chemical nanospace. [39,40] So far, many research efforts have been devoted to the exploration of electron and energy transfer processes between host and guest molecules,e ither depending on construction of photoactive hosts or resorting to encapsulation of dye guests,r espectively.…”

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confidence: 99%

The Redox Coupling Effect in a Photocatalytic Ru^II‐Pd^II Cage with TTF Guest as Electron Relay Mediator for Visible‐Light Hydrogen‐Evolving Promotion

Kai

Chen

et al. 2019

Angew Chem Int Ed

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An anocage coupling effect from ar edoxR u II -Pd II metal-organic cage is demonstrated for efficient photochemical H 2 production by virtue of redox-guest modulation of the photo-induced electron transfer (PET) process. Through coupling with photoredox cycle of MOC-16, tetrathiafulvalene (TTF) guests act as electron relaym ediator to improve the overall electron transfer efficiency in the hostguest system in al ong-time scale,l eading to significant promotion of visible-light driven H 2 evolution. By contrast, the presence of larger TTF-derivatives in bulk solution without host-guest interactions results in interference with PET process of MOC-16, leading to inefficient H 2 evolution. Suchi nteraction provides an example to understand the interplay between the redox-active nanocage and guest for optimization of redox events and photocatalytic activities in ac onfined chemical nanoenvironment.

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“…Salens, which consist of a disalicylic moiety and an aliphatic diamine, have been extensively studied over the past 80 years, resulting in myriad publications [1]. Catalysis is by far the largest application of these compounds [2,3]; more recently, the focus has also been on other features of these systems, including functional metal-organic frameworks (MOFs) [4,5] and anti-cancer agents [6,7]. Salen systems benefit from Schiff base stability, synthetic flexibility, and versatile coordination potential.…”

Section: Introductionmentioning

confidence: 99%

Unprecedented Water Effect as a Key Element in Salicyl-Glycine Schiff Base Synthesis

et al. 2020

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Salens, as chelating, double Schiff base ligands, are an important group utilized in transition metal catalysis. They have been used to build interesting functional metal-organic frameworks (MOFs). However, salens interacting with amino acids have also found applications in receptors. Here, we intended to form a “green” glycine-derived salen fragment, but the available literature data were contradictory. Therefore, we optimized the synthetic conditions and obtained the desired product as two different crystallographic polymorphs (orthorhombic Pcca and monoclinic P21/c space groups). Their structures differ in conformation at the glycine moiety, and the monoclinic form contains additional, disordered water molecules. Despite the high stability of Schiff bases, these newly obtained compounds hydrolyze in aqueous media, the process being accelerated by metal cations. These studies, accompanied by mechanistic considerations and solid-state moisture and thermal analysis, clarify the structure and behavior of this amino acid Schiff base and shed new light on the role of water in its stability.

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Supramolecular catalysis based on discrete heterometallic coordination-driven metallacycles and metallacages

Cited by 194 publications

References 90 publications

Catalysis of an Aldol Condensation Using a Coordination Cage

Catalysis of an Aldol Condensation Using a Coordination Cage

The Redox Coupling Effect in a Photocatalytic Ru^II‐Pd^II Cage with TTF Guest as Electron Relay Mediator for Visible‐Light Hydrogen‐Evolving Promotion

Unprecedented Water Effect as a Key Element in Salicyl-Glycine Schiff Base Synthesis

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Supramolecular catalysis based on discrete heterometallic coordination-driven metallacycles and metallacages

Cited by 194 publications

References 90 publications

Catalysis of an Aldol Condensation Using a Coordination Cage

Catalysis of an Aldol Condensation Using a Coordination Cage

The Redox Coupling Effect in a Photocatalytic RuII‐PdII Cage with TTF Guest as Electron Relay Mediator for Visible‐Light Hydrogen‐Evolving Promotion

Unprecedented Water Effect as a Key Element in Salicyl-Glycine Schiff Base Synthesis

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The Redox Coupling Effect in a Photocatalytic Ru^II‐Pd^II Cage with TTF Guest as Electron Relay Mediator for Visible‐Light Hydrogen‐Evolving Promotion