Metallated Schiff-Base Macromolecules as Alternative Metalloprotein Electron Transfer Intermediates ()
ABSTRACT
In the construction of biosensors, enzymes function as mediators
converting biological signals generated by
specific biological processes, into electrochemical signals. The ideology of
bio-sensor design is retention of electron transfer activity of the enzyme
utilizing superior interfacial architecture. In this work a Schiff-base
macromolecule has been synthesized by reflux of 2, 3-diaminonaphthalene and
pyrrole-2-carboxaldehyde starting materials. The Schiff-base ligand was
subsequently complexed with FeCl2?4H2O under reflux,
to produce the Fe-Schiff-base complex. The Schiff-base ligand and
Fe-Schiff-base complex were characterized using nuclear magnetic resonance
(NMR) spectroscopy, Ultra Violet/Visible (UV/Vis) spectroscopy, Fourier
transfer infrared resonance (FTIR) and
electron energy loss spectroscopy (EELS) to confirm the structure of the
synthesis products. NMR spectroscopy confirmed the imide linkage of Schiff-base
formation as two symmetrical peaks at 8.1 and 7.7 ppm respectively. Comparison
of starting materials and product spectra by UV/Vis spectroscopy confirmed the
disappearance of the diaminonaphthalene peak at 250 nm as evidence of complete
conversion to product. FTIR spectroscopy of the Schiff-base ligand
confirmed the formation of the imine bond at 1595 cm-1. EELS spectra
comparing FeCl2?4H2O and the Fe-Schiff-base complex,
showed good agreement in the energy loss profiles associated with changes to
the electronic arrangement of Fe d-orbitals. EDS clearly identified a spectral
band for Fe (7 - 8 eV) in the Fe-Schiff-base complex. Electrochemical
evaluation of the Fe-Schiff-base complex was compared to the electrochemical
signature of denatured cytochrome-C using cyclic voltammetry and square wave
voltammetry. The Fe2+/Fe3+ quasi-reversible behavior for
iron in the metallated complex was observed at -0.430 V vs. Ag/AgCl, which is consistent with reference values
for iron in macromolecular structures.
Share and Cite:
Farao, A. , Ajayi, R. , Ward, M. and Baker, P. (2020) Metallated Schiff-Base Macromolecules as Alternative Metalloprotein Electron Transfer Intermediates.
Journal of Surface Engineered Materials and Advanced Technology,
10, 34-54. doi:
10.4236/jsemat.2020.102003.
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