Interpenetration in coordination polymers: structural diversities toward porous functional materials

Abstract

Interpenetration is a natural phenomenon frequently encountered in porous coordination polymers (PCPs) or metal-organic frameworks (MOFs). Traditionally interpenetration has been considered as a threat to permanent porosity and several strategies have been adopted to control the framework interpenetration. Recent literature reports have unveiled that interpenetration has paramount importance in several material properties particularly in storage and separation of small gas molecules. Such frameworks also show interesting structural flexibility based on shearing or movement of the nets and also reveals guest induced dynamic structural transformation for modulated specific functions. In this review, we will emphasize several interpenetration phenomena observed in coordination polymers, their intriguing structural aspects and fascinating material properties.

Dynamic Entangled Porous Framework for Hydrocarbon (C2–C3) Storage, CO2 Capture, and Separation

“…Such entangled frameworks are often susceptible to structural change/rearrangement upon guest solventremoval as the nets can easily slide over each other or in some cases deform. [26,27,[31][32][33][34][35][36][37] In this case also, three DMF guests out of four can be easily removedu nder vacuum rearranging to an ew structuralp hase,{ [Zn 2 (bdc) 2 (bpNDI)]·DMF} n (1')w ith approximately 27 %c ontractiono ft he cell volume compared to 1 as reported earlier (Figure 1b anddand Figure 2). [30] Structure of 1' showsd eformation of square nets and shearing of two such entangled nets leads to blocking of site Aw hereas site B remains open (Figure1b, 1d).…”

“…In framework 1 , the bpNDI and bdc linkers are arranged in a manner that facilitates internet π⋅⋅⋅π stacking with a distance of 3.35 Å. Such entangled frameworks are often susceptible to structural change/rearrangement upon guest solvent removal as the nets can easily slide over each other or in some cases deform . In this case also, three DMF guests out of four can be easily removed under vacuum rearranging to a new structural phase, {[Zn 2 (bdc) 2 (bpNDI)]⋅DMF} n ( 1′ ) with approximately 27 % contraction of the cell volume compared to 1 as reported earlier (Figure b and d and Figure ) .…”

Hybrid MIL-101(Cr)@MIL-53(Al) composite for carbon dioxide capture from biogas

“…37 Porous networks act as a template for the growth of duplicated frameworks. 38 As the void space of MIL-101 included enough free volume to host an additional SBU, a second independent MOF (MIL-53) was formed. Therefore, with a longer synthesis time, MIL-101 was decomposed and MIL-53 was formed.…”

An Unprecedented Interpenetrating Structure Built from Two Differently Bonded Frameworks: Synthesis, Characteristics, and Efficient Removal of Anionic Dyes from Aqueous Solutions

“…So far,n umerousc ompounds with av ariety of interlocked structures were reported. [18][19][20][21][22][23][24][25] However,c rystalline structures in which the networks consist of different topologies and/or dimensions that interpenetrate are still very rare. Two compounds displayed interesting structural features:one cagewithin-cage porous solid built from two zeolite-type frameworks possessed an interpenetrating structure with Zn 24 @Zn 104 cube-in-sodalite architecture; [24] another metal-organic compound, {[WS 4 Cu 4 (4,4'-bipy) 4 ][WS 4 Cu 4 I 4 (4,4'-bipy) 2 ]·4H 2 O} n ,h ad 3D cationic and anionic coordination polymers in its structure.…”

“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17] For the bottom-up synthesis of those hybrid materials with new components and architectures,s tructure prediction remainso ne of the most difficult challenges. [18][19][20] There are many factors, such as reaction temperature, the ratio of reactants, pH, etc.,that influence the structural buildingu nits and block packing modes, which eventually lead to one-dimensional (1D) chains, 2D networks, 3D frameworks, and interpenetrated structures.C omplicated interpenetrating architectures have stimulated the collaboration between the fields of crystal growth, design,a nd engineering for the fabrication of new topological and/or functional materials. So far,n umerousc ompounds with av ariety of interlocked structures were reported.…”