Nitric Oxide Adsorption and Delivery in Flexible MIL-88(Fe) Metal–Organic Frameworks

Abstract

Adsorption and release of the biologically active nitric oxide (NO) was evaluated over a series of highly flexible iron(III) dicarboxylate MOFs of the MIL-88 structure type, bearing fumaric or terephthalic spacer functionalized or not by polar groups (NO2, 2OH). As evidenced by ex situ X-ray powder diffraction and in situ IR spectroscopy, it appears that if the contracted dried forms of MIL-88 do not expand their structures in the presence of NO, the combination of very narrow pores and trimers of iron polyhedra leads to the adsorption of significant amounts of NO either physisorbed (very narrow pores) and/or chemisorbed [iron(II) or iron(III) coordinatively unsaturated metal sites (CUS)]. The delivery of NO under vapor of water or in simulated body fluid does not exceed 20% range of the total adsorbed amount probably due to a partial release that occurs between the adsorption/desorption setup and the chemiluminescence release tests. Some of these solids nevertheless exhibit a significant release at the biological levels over a long period of time (>16 h) that make these biocompatible and biodegradable MOFs of interest for the controlled release of NO.

Activation performance and mechanism of a novel heterogeneous persulfate catalyst: metal–organic framework MIL-53(Fe) with FeII/FeIII mixed-valence coordinatively unsaturated iron center

“…This important feature indicated that the amount of Fe III CUS and Fe II CUS may be changed by thermal activation under vacuum whilst keeping the structure intact [38, 39]. Other studies have also shown that iron-based trimeric MOFs such as MIL-88(Fe) also possess this kind of controlled reducibility property of Fe(III) and Fe(II) CUS [40] through vacuum or inert atmosphere treatment under certain conditions. Although MIL-53(Fe) is one type of iron-based dimeric MOF and possess different secondary building unit (SBU) with MIL-100(Fe) or MIL-88(Fe) [41], this controlled reducibility may still be applicable.…”

Nanomedicine Applications of Hybrid Nanomaterials Built from Metal–Ligand Coordination Bonds: Nanoscale Metal–Organic Frameworks and Nanoscale Coordination Polymers

“…The gas molecules would interact strongly with the materials such that they could be stored in the frameworks for a required time period. 190−194 MOFs have been demonstrated to have the capability to store H 2 , 40,195,196 CO 2 ,197 NO,[198][199][200][201][202][203] etc., among which NO plays an important role in biological signaling. NO delivery has been achieved using polymers, dendrimers, functionalized silica nanoparticles, and zeolites as vehicles.…”

“…MIL-88(Fe) MOFs were also exploited as the delivery vehicle for NO by Morris and co-workers. 201 A significant amount of NO was adsorbed at room temperature by the nontoxic, biodegradable, and flexible MIL-88(Fe) MOFs at a high loading amount of 1−2.5 mmol/g. NO was released from MOFs over a long period of time (>16 h), suggesting these MOFs can adsorb NO with high efficiency and release NO in a controlled manner.…”

Exceptional adsorption-induced cluster and network deformation in the flexible metal–organic framework DUT-8(Ni) observed by in situ X-ray diffraction and EXAFS

“…[3][4][5][6] A feature of MOFs that is unique as compared to other porous crystalline materials is reversible structural switchability between non porous (closed pore structure) and porous (open pore structure) polymorphs. Nevertheless, such MOFs already find a wide interest as switchable or highly selective gas adsorbents, [9][10][11][12] threshold sensors, 13,14 stimuli responsive drug delivery agents, 15 switchable catalysts 16 etc. Although more than 20.000 MOFs are known today only less than 100 of such switchable 3rd generation MOFs are structurally characterized and the theoretical elucidation of flexibility phenomenon is still in its infancy.…”