Metal–Organic Organopolymeric Hybrid Framework by Reversible [2+2] Cycloaddition Reaction

Abstract

Organic polymers are usually amorphous or possess very low crystallinity. The metal complexes of organic polymeric ligands are also difficult to crystallize by traditional methods because of their poor solubilities and their 3D structures can not be determined by single-crystal X-ray crystallography owing to a lack of single crystals. Herein, we report the crystal structure of a 1D Zn(II) coordination polymer fused with an organic polymer ligand made in situ by a [2+2] cycloaddition reaction of a six-fold interpenetrated metal-organic framework. It is also shown that this organic polymer ligand can be depolymerized in a single-crystal-to-single-crystal (SCSC) fashion by heating. This strategy could potentially be extended to make a range of monocrystalline metal organopolymeric complexes and metal-organic organopolymeric hybrid materials. Such monocrystalline metal complexes of organic polymers have hitherto been inaccessible for materials researchers.

Formation of a Syndiotactic Organic Polymer Inside a MOF by a [2+2] Photo‐Polymerization Reaction

“…[1] Crystalline properties arising from the orderly arrangements of polymer chains are well-sought to control mechanical, chemical, optical, and electrical properties for various industrial applications. [5] Here we report the formation of as yndiotactic polymer ligand (shown in Figure 1) incorporated inside another MOF through singlecrystal-to-single-crystal (SCSC) reaction, but the unexpected photoreaction could not be predicted from the crystal packing.I nt he pillared-layer MOF accommodating guest water molecules in the channels,t he spacer ligands undergo pedal motion under UV light prior to photoreaction to meet Schmidt'sc riteria for [2+ +2] cycloaddition reaction. [3] Topochemical polymerization reactions have been used to make an umber of highly crystalline organic polymers in the solid state,b ut making tactic polymers by as olid-state route is elusive.…”

“…[3] Topochemical polymerization reactions have been used to make an umber of highly crystalline organic polymers in the solid state,b ut making tactic polymers by as olid-state route is elusive. [5] Here we report the formation of as yndiotactic polymer ligand (shown in Figure 1) incorporated inside another MOF through singlecrystal-to-single-crystal (SCSC) reaction, but the unexpected photoreaction could not be predicted from the crystal packing.I nt he pillared-layer MOF accommodating guest water molecules in the channels,t he spacer ligands undergo pedal motion under UV light prior to photoreaction to meet Schmidt'sc riteria for [2+ +2] cycloaddition reaction. [5] Here we report the formation of as yndiotactic polymer ligand (shown in Figure 1) incorporated inside another MOF through singlecrystal-to-single-crystal (SCSC) reaction, but the unexpected photoreaction could not be predicted from the crystal packing.I nt he pillared-layer MOF accommodating guest water molecules in the channels,t he spacer ligands undergo pedal motion under UV light prior to photoreaction to meet Schmidt'sc riteria for [2+ +2] cycloaddition reaction.…”

Neutral N-donor ligand based flexible metal–organic frameworks

“…Vittal et al have pioneered the domain of cycloaddition reaction based structural changes in olefin-bearing ligands. 61 Owing to the lack of chemical stability in neutral N-donor ligand based MOFs, solid-state reactions are more favoured for investigation of structural subtleties. The prominent reports among such class of studies are discussed below.…”

In situsingle-crystal to single-crystal (SCSC) transformation of the one-dimensional polymercatena-poly[[diaqua(sulfato)copper(II)]-μ2-glycine] into the two-dimensional polymer poly[μ2-glycine-μ4-sulfato-copper(II)]

“…Recently, reversible SCSC [2,2]-cycloaddition reactions have also been reported (Park et al, 2014). We have, for example, described the transformation of the ionic complex aquachlorido-(2,2 0 :6 0 ,2 00 -terpyridyl-3 N,N 0 ,N 00 )copper(II) chlorido(dithionato-O)(2,2 0 :6 0 ,2 00 -terpyridyl-3 N,N 0 ,N 00 )cuprate(II) dihydrate into the binuclear complex (-dithionato-2 O:O 0 )bis-[chlorido(2,2 0 :6 0 ,2 00 -terpyridyl-3 N,N 0 ,N 00 )copper(II)] monohydrate (Schmitt et al, 2010).…”