Journal article

Gradual release of strongly bound nitric oxide from Fe2(NO)2(dobdc)

An iron(II)-based metal-org. framework featuring coordinatively unsatd. redox-active metal cation sites, Fe2(dobdc) (dobdc4- = 2,5-dioxido-1,4-benzenedicarboxylate), is shown to strongly bind nitric oxide at 298 K. Adsorption isotherms indicate an adsorption capacity greater than 16 wt %, corresponding to the adsorption of one NO mol. per iron center. IR, UV-vis, and Mössbauer spectroscopies, together with magnetic susceptibility data, confirm the strong binding is a result of electron transfer from the FeII sites to form FeIII-NO- adducts. Consistent with these results, powder neutron diffraction expts. indicate that NO is bound to the iron centers of the framework with an Fe-NO sepn. of 1.77(1) Å and an Fe-N-O angle of 150.9(5)°. The nitric oxide-contg. material, Fe2(NO)2(dobdc), steadily releases bound NO under humid conditions over the course of more than 10 days, suggesting it, and potential future iron(II)-based metal-org. frameworks, are good candidates for certain biomedical applications.


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