Dense Alkyne Arrays of a Zr(IV) Metal–Organic Framework Absorb Co₂(CO)₈ for Functionalization

Abstract

Finely dispersed Co(0) and CoO species were efficiently loaded into a stable metal–organic framework to impart catalytic activities to the porous solid. The metalation of the MOF host is facilitated by the dense arrays of accessible alkyne units that boost the alkyne-Co2(CO)8 interaction. The tetrakis­(4-carboxyl­phenyl­ethynyl)­pyrene linker, with eight symmetrically backfolded alkyne side arms, features strong fluorescence and a dendritic Sierpinski shape. The resultant Zr­(IV)-MOF features NU-901 topology (scu net, with rhombus channels) and breathing properties (e.g., the contracted (porous) phase reverts to the as-made phase upon contact with DMF (di­methyl­form­amide)). The inserted Co2(CO)8 guests quickly react with air to form atomically dispersed CoO species (nondiffracting), and subsequent thermal treatment at 600 °C of the CoO-loaded solid generates an electrocatalyst for the oxygen evolution reaction (OER).

Pyrene-based metal organic frameworks: from synthesis to applications

“…The thickness and morphology of the films can be controlled by simply adjusting the depositing time and applied potential. 285 These thin films can be used as molecular switches, 286,287 biasswitchable permselectivity anions membranes, 279 and electrocatalysts for OER, 283,288 HER, 289,290 and CO 2 reduction. 291 Among these applications, electrocatalytic OER and HER are of interest since electrocatalytic water splitting can provide a much more sustainable and carbon-neutral route for energy generation.…”

Linker Deficiency, Aromatic Ring Fusion, and Electrocatalysis in a Porous Ni8-Pyrazolate Network

“…Considering the bulky and disordering sidechains and the corresponding incompatibility with Fm-3m symmetry, the crystal structure is maintained the P1 space group for further optimization. 3,4 The geometrical arrangement of organic linkers and Ni8O6 clusters was maintained to be consistent with the fcu topology, 5,6 followed by Geometry Optimization of Forcite Calculation in Materials Studio by Accelrys. The lattice parameters were modified using the Pawley refinement procedure to match the experimental PXRD, leading to a = 32.366 Å.…”

Uniting Form and Function, Stability and Reactivity in Open Framework Materials

“…20 When the MOF solids are heated above 200°C, the contiguous alkyne units undergo extensive thermocyclization. While the tetratopic-linked, more rigid Zr-Tc8tBu lost crystallinity upon thermocyclization, 21 the linear, more supple Zr-Dc4ms afforded an ordered polycrystalline black covalent solid at 320°C, 22 even with decarboxylation of the linker units (as indicated by solid state 13 C NMR). Above 320°C, however, the crystalline order of the cyclized product quickly degraded.…”

“…For example, in Zr-Tc8tBu, the dense contiguous alkyne arrays effectively take up Co 2 (CO) 8 guests, which then transform in situ into atomically dispersed CoO species as electrocatalyst for oxygen evolution reaction (OER). 21 In Zr-Dc4mo, the electron-donating methoxy groups render the pendant alkyne units reactive towards TCNE (tetracyanoethylene) guests in the [2+2] cycloaddition-retroelectrocyclization (CA-RE) mechanism and extensively establish conjugated (polyene) bridges across the linker molecules (Figure 7). 26 The crosslinking CA-RE reactions convert the coordination network into a covalent solid, while maintaining the crystallinity and greatly enhancing the framework rigidity and redox-active and photochemical properties.…”