Composites based on nitroprusside cyano-bridged coordination polymer particles and chitosan for NO delivery

Abstract

We report the design of new composite films {Fe[Fe(CN)₅(NO)]}_0.55@C₆H₁₁NO₄ and {Ag₂[Fe(CN)₅(NO)]}_0.28@C₆H₁₁NO₄ based on cyano-bridged coordination polymers Fe^II[Fe^II(CN)₅(NO)] or Ag₂^I[Fe^II(CN)₅(NO)] grown into a chitosan matrix that are able to provide a slow NO radical release under white light irradiation. The characterisation methods such as X-ray diffraction, TGA, SEM-EDX, IR and UV-vis spectroscopies show that these composites are made of ca. 50 wt% of the cyano-bridged coordination polymer as microcrystalline particles embedded into chitosan films. Irradiation for 7 days by using white light results in initiating a 6.5 and 10.6% NO radical delivery for {Fe[Fe(CN)₅(NO)]}_0.55@C₆H₁₁NO₄ and {Ag₂[Fe(CN)₅(NO)]}_0.28@C₆H₁₁NO₄, respectively. The rearrangement of the cyano-bridged coordination compounds after the NO departure leads to the formation of Prussian blue or silver Prussian blue analogues, which limits the unwanted release of cyanide as a side effect.