Bioderived protoporphyrin IX incorporation into a metal-organic framework for enhanced photocatalytic degradation of che
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Synthetic Biology Research Letter
Bioderived protoporphyrin IX incorporation into a metal-organic framework for enhanced photocatalytic degradation of chemical warfare agents Marilyn S. Lee , Sergio J. Garibay , Ann M. Ploskonka , and Jared B. DeCoste , Edgewood Chemical Biological Center, U.S. Army Research, Development, and Engineering Command, 8567 Ricketts Point Rd. Aberdeen Proving Ground, MD 21010, USA Address all correspondence to Jared B. DeCoste at [email protected] (Received 21 November 2018; accepted 6 February 2019)
Abstract Porphyrins absorb light to initiate photocatalytic activity. The complex, asymmetric structures of natural porphyrins such as heme, chlorophyll, and their derivatives hold unique interest. A platform for biosynthesis of porphyrins in Escherichia coli is developed with the aim of producing a variety of porphyrins for examining their photocatalytic properties within a porous material. Bioderived protoporphyrin IX is tethered inside the highly porous metal-organic framework (MOF) NU-1000 via solvent-assisted ligand incorporation. This MOF catalyzes the photocatalytic oxidation of 2-chloroethyl ethyl sulfide with improved performance over an expanded range of the visible spectrum when compared to unmodified NU-1000.
Introduction Porphyrins are aromatic planar macrocycles composed of four pyrrole groups. This class of molecules holds interest in materials development due to their diverse functionality in nature. The π-conjugation of porphyrins gives rise to unique electron mobility which may be controlled by altering certain structural elements. Addition of functional groups at the beta- or mesopositions, controlled intermolecular stacking of the macrocycles, and coordination of different central metal ions all modulate the capability for light absorbance and electron transfer.[1] Furthermore, the activity of porphyrin molecules is strongly influenced by the surrounding matrix. These properties may be harnessed in a variety of materials contexts. For instance, porphyrins have been used in porous materials for photocatalysis,[2] light harvesting,[3] and sensors.[4] Layering porphyrin molecules on conducting surfaces like titanium dioxide enables charge separation in solar cells.[5,6] Oligomerization of porphyrins and addition of linker networks can form molecular electronic components.[7] Since there are many possible variations of porphyrin structure with different capabilities, it is important to develop improved generalized synthesis methods for porphyrins that yield quantities sufficient to evaluate their behavior when incorporated into solid matrices. Porphyrins such as heme and chlorophyll serve many functions in living systems and are naturally produced in most organisms. The Shemin pathway (Fig. 1) initiates the biosynthesis of protoporphyrin IX (PPIX).[8,9] PPIX and related molecules have been used as a photosensitizer in biomedicine, and are capable of oxidation in solution when exposed to
light.[10–12] Other porphyrins produced via this pathway may also have interest
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