Coordination modulated on-off switching of flexibility in a metal–organic framework

Abstract

Stimuli-responsive metal-organic frameworks (MOFs) exhibit dynamic, and typically reversible, structural changes upon exposure to external stimuli. This process often induces drastic changes in their adsorption properties. Herein, we present a...

Low‐Valent Metals in Metal‐Organic Frameworks Via Post‐Synthetic Modification

“…Post‐synthetic metalation [39] of vacant donor sites on framework linkers [39a,c,e] or clusters [15c,17,33,40] offers more expansive options for low‐valent metal integration, because the need to find compatible reaction conditions for both the low‐valent metal precursor and other MOF‐forming components is circumvented. Direct post‐synthetic metalation of framework linkers with low‐valent metals has been accomplished using Ru 0 , [41] Fe 0 , [42] Cr 0 , [39c,43] Co 0 , [44] Ir I , [12a,b,39c,45] Rh I , [9,12a,c,15a,39e,46] Mn I , [47] Cu I , [19b,48] Au I , [12d,48b,c,49] Ag I [48c,50] . (Figure 3) Some examples involve direct exchange of linker supported metals [51] or by in situ reduction of higher‐valent precursors by redox active linkers [52] .…”

“…Here, the framework retains vacant bis ‐pyrazolyl‐ methane N , N ‐chelation sites which are poised to bind guest metal complexes. Remarkably, [Mn 3 (L) 2 L′] maintains crystallinity during metalation and subsequent manipulations, allowing crystallographic characterisation of organometallic catalysts and their catalytic intermediates, [9,15a] as well as ligand and anion exchange products [19b,45,47a,b,48b] . Metalation with [Rh(C 2 H 4 ) 2 Cl] 2 and subsequent anion exchange with BF 4 − or Cl − yielded the respective planar N , N ‐chelated [Rh(C 2 H 4 ) 2 ]X (X=BF 4 , Cl) complex, in which the charge‐balancing anions were located in the MOF pore (Figure 5).…”

Understanding the structural landscape of Mn-based MOFs formed with hinged pyrazole carboxylate linkers

“…The material shows a significant degree of structural flexibility, converting from open and closed forms in response to solvent removal or exposure; 14 and undergoes quantitative post-synthetic metalation (PSMet) with transition metals that modulate its flexibility. 13,15 Coupled with the ability to reliably undertake single crystal X-ray diffraction (SCXRD) on the MOF crystals after PSMet, this MOF has enabled the study of novel adsorption switching processes, 15 insights into reactivity of catalytic complexes, [16][17][18] and photochemical reactions. 19 The node in MnMOF-1 has been observed previously, [20][21][22] and comprises a Mn trinuclear node that is bridged by six carboxylates and capped by four nitrogen donor atoms (Fig.…”

Towards controlled partial desolvation of guest-responsive Metal-Organic Frameworks for precise porosity control

“…[4][5][6][7] The flexible behavior in MOFs might arise for different reasons which include metal-ligand coordination, host-guest interaction, or inherent flexibility of the linkers. [8][9][10][11][12][13] Incorporation of stimuli-responsive functional groups or flexible moieties into the backbone of the organic ligand is one of the viable paths to induce flexibility in MOFs and this seems to be advantageous in terms of crystallinity as well as characterization of the material as the metal-ligand coordination remains intact during the application of external stimuli. The presence of functional moieties such as spiropyran, ester and azo groups along with the rigid segments were shown previously to exhibit stimuli responsive behavior.…”