Exceptional Behavior over the Whole Adsorption−Storage−Delivery Cycle for NO in Porous Metal Organic Frameworks

Abstract

Two porous metal organic frameworks (MOFs), [M2(C8H2O6)(H2O)2] x 8 H2O (M = Co, Ni), perform exceptionally well for the adsorption, storage, and water-triggered delivery of the biologically important gas nitric oxide. Adsorption and powder X-ray diffraction studies indicate that each coordinatively unsaturated metal atom in the structure coordinates to one NO molecule. All of the stored gas is available for delivery even after the material has been stored for several months. The combination of extremely high adsorption capacity (approximately 7 mmol of NO/g of MOF) and good storage stability is ideal for the preparation of NO storage solids. However, most important is that the entire reservoir of stored gas is recoverable on contact with a simple trigger (moisture). The activity of the NO storage materials is proved in myography experiments showing that the NO-releasing MOFs cause relaxation of porcine arterial tissue.

Metal–organic frameworks as potential multi-carriers of drugs

“…Similar shape of the band and its position confirms adsorption on the CUS sites inside the channels of the material and not only physisorption at the external surface. As previously reported, 18 water molecules can trigger the delivery of coordinated NO, replacing them from the open metal sites. Fig.…”

“…This is the case for some zeolites 11 17 Particularly, the Ni 2+ derivative presents a high adsorption-delivery capacity for NO. 18 The presence of coordinatively unsaturated metal sites (CUSs) on the pore walls has a clear effect on the NO adsorption and release processes. Indeed, during the adsorption process, an adduct Ni-NO is formed which makes possible the incorporation and posterior water-triggered release of up to 7 mmol of NO per g of material.…”

Chemistry of Metal-organic Frameworks Monitored by Advanced X-ray Diffraction and Scattering Techniques

“…94 Preferential binding with open Ni-or Co-sites of biologically active H 2 S and NO gases within the Ni-based MOF-74 analogue was determined by XRPD. 95,96 Sorption sites for H 2 were investigated by NPD within desolvated Cu-based NOTT-112 materials possessing Surface adsorption of liquid-like H 2 at 50 K was monitored by NPD. H 2 molecules form a loosely bonded condensed state which is above the critical temperature.…”

Incorporation by coordination and release of the iron chelator drug deferiprone from zinc-based metal–organic frameworks

“…Many MOFs can be prepared with coordinatively unsaturated metal centres, and small bioactive molecules such as NO have been incorporated into such systems by coordination to these metal sites. 8 In this communication, we report our initial studies on the inclusion into MOFs of the iron chelator drug deferiprone (Hdfp), which is used as an oral treatment for haemosiderosis (iron overload) that can occur as a consequence of regular blood transfusions required in the treatment of conditions such as thalassaemia major and haemochromatosis.9 Deferiprone has high selectivity for Fe 3+ over other cations, and it is used clinically in Europe and Asia as an orally active iron chelator. In addition, deferiprone possesses antioxidant properties protecting against oxidative stress, 10,11 and recently it has been studied for potential application in the treatment of neurodegenerative diseases such as Alzheimer's.…”