Density functional calculations reveal a flexible version of the copper paddlewheel unit: implications for metal organic frameworks

Alzahrani, Khalid Ahmed; Deeth, Robert J.

doi:10.1039/c6dt01474g

Cited by 16 publications

(11 citation statements)

References 23 publications

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“…The compressed pyramidal geometry involves a reduction of the distance of the axial ligand with respect to those of basal oxygens. Furthermore, an inversion of the orbital energy levels occurs, leading to 3d z 2 occupied by an unpaired electron spin above the 3d x 2 – y 2 . It would be a good explanation to the observed reduction of the EPR triplet signal, but it is not compatible with our EXAFS fitting results because we have never found a shorter Cu abs –O w distance than Cu abs –O 1 .…”

Section: Discussioncontrasting

confidence: 61%

“…Furthermore, an inversion of the orbital energy levels occurs, leading to 3d z 2 occupied by an unpaired electron spin above the 3d x 2 −y 2 . 36 It would be a good explanation to the observed reduction of the EPR triplet On the contrary, all of the changes observed in intensity and positions in the peaks of pre-edges and white line together with the significant increase in the Cu abs −Cu distance indicate a square-pyramidal geometry of the Cu abs after 20 days of exposure to air. The effect of the accumulation of water molecules inside the cavities of the matrix is to distance the two Cu 2+ ions, making the environment of the Cu abs more pyramidal than in the pristine material.…”

Section: ■ Discussionmentioning

confidence: 93%

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Determination of Geometry Arrangement of Copper Ions in HKUST-1 by XAFS During a Prolonged Exposure to Air

et al. 2017

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We present an experimental investigation focused on the local structural changes taking place around Cu2+ ions in metal–organic framework (MOF) HKUST-1 for different times of exposure to air by XAFS (X-ray absorption fine structure). The analysis involves both XANES (X-ray absorption near edge structure) and EXAFS (extended X-ray absorption fine structure) regions around the Cu K-edge. Starting from the paddle-wheel structures proposed in literature, a more detailed description of the geometrical environment of Cu2+ ions has been found. In particular, the paddle-wheel structure of a fresh sample, which means a pristine HKUST-1 material with a single water molecule weakly adsorbed on each Cu2+ ion, has been disclosed for the first time. Furthermore, after 20 days of exposure to air, relevant structural changes with respect to the pristine sample have been evidenced. An activation process has demonstrated that these local changes are totally reversible, in agreement with a recent model of the decomposition process of HKUST-1 proposed in literature.

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Section: Discussioncontrasting

confidence: 61%

Section: ■ Discussionmentioning

confidence: 93%

Determination of Geometry Arrangement of Copper Ions in HKUST-1 by XAFS During a Prolonged Exposure to Air

et al. 2017

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“…Nevertheless, the open shell singlets states were calculated to be lower in energy than the triplet state by 0.6 kcal/mol for both complexes. This is in agreement with previous DFT studies in the literature for copper paddlewheel-based systems [91,92,93,94,95]. Thus, all the structures presented in this work were calculated as open shell singlets.…”

Section: Methodssupporting

confidence: 91%

A Reversible Phase Transition of 2D Coordination Layers by B–H∙∙∙Cu(II) Interactions in a Coordination Polymer

et al. 2019

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Materials that combine flexibility and open metal sites are crucial for myriad applications. In this article, we report a 2D coordination polymer (CP) assembled from CuII ions and a flexible meta-carborane-based linker [Cu2(L1)2(Solv)2]•xSolv (1-DMA, 1-DMF, and 1-MeOH; L1: 1,7-di(4-carboxyphenyl)-1,7-dicarba-closo-dodecaborane). 1-DMF undergoes an unusual example of reversible phase transition on solvent treatment (i.e., MeOH and CH2Cl2). Solvent exchange, followed by thermal activation provided a new porous phase that exhibits an estimated Brunauer-Emmett-Teller (BET) surface area of 301 m2 g−1 and is capable of a CO2 uptake of 41 cm3 g−1. The transformation is reversible and 1-DMF is reformed on addition of DMF to the porous phase. We provide evidence for the reversible process being the result of the formation/cleavage of weak but attractive B–H∙∙∙Cu interactions by a combination of single-crystal (SCXRD), powder (PXRD) X-ray diffraction, Raman spectroscopy, and DFT calculations.

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“…This choice of computational methods have been demonstrated to be useful in several previous studies on similar systems. [11][12][13] We have also verified for some species that the energy reported below only changes slightly by using a larger basis such as aug-cc-pVTZ. The full Cu24L24 MOC is modelled by its smallest unit, Cu2L4' with L' = C6H5COO -.…”

Section: Section III Dft Calculationsmentioning

confidence: 56%

Polymer Metal-Organic Cage Gels Based on Cu24L24 Cuboctahedra: Design, Synthesis, and Additive Manufacturing Enabled by Three-State Photoswitching

Oldenhuis¹,

Qin²,

Wang³

et al. 2019

Preprint

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We present a polymer network that can reversibly switch between three distinct states of mechanical and chemical properties, significantly extending the boundaries of state-switching materials. This switching behavior is enabled by a photoreduction mechanism that leverages coumarin-functionalized cuboctahedral Cu24L24 metal-organic cages (MOCs) linked by polymers in a "polyMOC" gel. The properties of each material state can be used in a cooperative fashion to achieve advanced functions such as network toughening, metallic patterning, and additive manufacturing

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Density functional calculations reveal a flexible version of the copper paddlewheel unit: implications for metal organic frameworks

Abstract: Electronic Supplementary Information (ESI) available: full computational details, Cartesian coordinates and total/binding energies. See

Cited by 16 publications

References 23 publications

Determination of Geometry Arrangement of Copper Ions in HKUST-1 by XAFS During a Prolonged Exposure to Air

Determination of Geometry Arrangement of Copper Ions in HKUST-1 by XAFS During a Prolonged Exposure to Air

A Reversible Phase Transition of 2D Coordination Layers by B–H∙∙∙Cu(II) Interactions in a Coordination Polymer

Polymer Metal-Organic Cage Gels Based on Cu24L24 Cuboctahedra: Design, Synthesis, and Additive Manufacturing Enabled by Three-State Photoswitching

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