Thixotropic Hydrogel Derived from a Product of an Organic Solid-State Synthesis: Properties and Densities of Metal−Organic Nanoparticles

Abstract

Metallogels form from Cu(II) ions and tetratopic ligand rctt-1,2-bis(3-pyridyl)-3,4-bis(4-pyridyl)cyclobutane. The tetrapyridyl cyclobutane has been synthesized in the organic solid state. The gel forms with a variety of counteranions and gels water. The hydrogel is thixotropic and is composed of nanoscale metal-organic particles (NMOPs), a high surface area of which likely accounts for the gelation of the polar aqueous medium. A shear stress profile of the thixotropic hydrogel gave a yield value of 8.33 Pa. A novel combination of atomic force microscopy (AFM) and scanning transmission X-ray microscopy (STXM) is used to assess the densities of individual NMOPs. A density of 1.37 g/cm(3) has been determined. A single-crystal X-ray diffraction study demonstrates the ability of the unsymmetrical cyclobutane 3,4'-tpcb to self-assemble with Cu(II) ions in [Cu(2)(hfac)(4)(3,4'-tpcb)](∞) (where hfac is hexafluoroacetylacetonate) to form a solvated 1D coordination polymer.

A synthetic route to ultralight hierarchically micro/mesoporous Al(III)-carboxylate metal-organic aerogels

“…The formation of MOGs driven by metal–ligand coordination is often difficult because precipitation or crystallization events occur frequently31. Nevertheless, various MOGs with coordination polymers acting as discrete or 1D/2D infinite metallogelators have been achieved27303132. To develop highly porous MOAs, the formation of MOGs that display a sponge-like skeletal matrix and not a normal fibrous scaffold is preferred.…”

“…Various methods have been proposed to control the analogous formation of NMOPs in comparison with nano-MOFPs42425262728, for example, the addition of initiation solvents4 or inhibiting agents28. However, the gelation behaviours of such nanoscale particles remain largely unexplored27.…”

“…On the other hand, various functional materials based on nanoscale metal-organic particles (NMOPs) have already been documented4242526. Recently, thixotropic metallogels derived from NMOPs of 1D coordination chains27 and a colloidal route to the preparation of optical thin films of nanoporous MOFs28 were reported. These works may shed light on the design of MOGs based on crystalline nano-MOFPs; further, it is of interest to produce hierarchically porous metal-organic aerogels (MOAs) at relatively low cost with readily handled shapes that can combine the ordered microporosity of MOFs with the significant accessibility of MOGs.…”

A silver-induced metal-organic gel based on biscarboxyl-functionalised benzimidazole derivative: stimuli responsive and dye sorption

“…ultrasound (15 -18), mechanical stimulation (19), sound as an LMW gelator could be induced to form MOG with (20,21), metallic cations (22), temperature (23), anions selectivity for Ag(I). The L17 MOG also revealed a reversible sol-gel transition induced by the changes of temperature, pH, NH 4 OH, EDTA and Na 2 S. Moreover, it can also be used in dye sorption (methyl orange).…”

Fe(iii) phytate metallogel as a prototype anhydrous, intermediate temperature proton conductor

“…Similar metamorphosis of gelator nanospheres into a gel network has been observed previously. 12 The N 2 sorption studies performed on the FNPA xerogel revealed a BET (Brunauer, Emmett and Teller) surface area of 124 m 2 g –1 (Fig. 3a and S3†).…”