Immobilized Metal Complexes in Porous Organic Hosts:  Development of a Material for the Selective and Reversible Binding of Nitric Oxide

Abstract

Delivery of NO to specific targets is important in fundamental studies and therapeutic applications. Various methods have been reported for delivery of NO in vivo and in vitro; however, there are few examples of systems that reversibly bind NO. Reported herein is the development of a new polymer (P-1[Co(II)]) that reversibly binds NO. P-1[Co(II)] has a significantly higher affinity for NO compared to O(2), CO(2), and CO. The polymer is synthesized by template copolymerization methods and consists of a porous methacrylate network, containing immobilized four-coordinate Co(II) sites. Binding of NO causes an immediate color change, indicating coordination of NO to the site-isolated Co(II) centers. The formation of P-1[Co(NO)] has been confirmed by EPR, electronic absorbance, and X-ray absorption spectroscopies. Electronic and X-ray absorbance results for P-1[Co(II)] and P-1[Co(NO)] show that the coordination geometry of the immobilized cobalt complexes are similar to those of their monomeric analogues and that NO binds directly to the cobalt centers. EPR spectra show that the binding of NO to P-1[Co(II)] is reversible in the solid state; the axial EPR signal associated with the four-coordinate Co(II) sites in P-1[Co(II)] is quenched upon NO binding. At room temperature and atmospheric pressure, 40% conversion of P-1[Co(NO)] to P-1[Co(II)] is achieved in 14 days; under vacuum at 120 degrees C this conversion is complete in approximately 1 h. The binding of NO to P-1[Co(II)] is also observed when the polymer is suspended in liquids, including water.

Nickel Ions Inhibit Histone Demethylase JMJD1A and DNA Repair Enzyme ABH2 by Replacing the Ferrous Iron in the Catalytic Centers

“…XAS data analysis was done using EXAFS123 (41) for XANES analysis and SixPack (42) for EXAFS analysis. Scattering parameters for SixPack fitting were generated using the FEFF 8 software package (43).…”

Antibacterial and bactericidal activity of nitric oxide-releasing natural zeolite

“…After contacting NZ-NO with either PBS or deionized water, the color turned to that at the initial stage. The color changes are indication of interactions of NO molecules with the coordinatively unsaturated metal sites during the NO loading and replacement of these by metal-water interactions during the release (Padden et al, 2001;Wheatley et al, 2006;McKinlay et al, 2008).…”

Light‐Activated Transfer of Nitric Oxide from a Porous Material

“…In our design, [6,8] substitutionally inert metal complexes containing polymerizable groups are used as templates to form the immobilized sites: Multiple covalent connections of the metal-NO template complex to the polymeric hosts minimizes leaching. Monomeric RuÀNO complexes with ligands related to 1 2À photolytically transfer NO in solution.…”

“…[3,5] A promising approach for such materials utilizes covalently immobilized metal nitrosyl (MÀNO) complexes within porous polymeric hosts. [6] These materials combine the properties of the MÀ NO units, such as reversible NO binding, with those of the porous hosts. We report herein the synthesis and properties of a highly cross-linked, network polymer containing immobilized RuÀNO sites.…”