Synthesis and characterization of multiwalled carbon nanotubes functionalized with chlorophyll-derivatives compounds extracted from Hibiscus tiliaceus

Abstract

In this work, we are presenting the synthesis and characterization of compound materials based on multiwalled carbon nanotubes and chlorophyll-derivatives as chlorophyllide-a and pheophorbide-a, extracted from the plant Hibiscus tiliaceus. Three types of multiwalled carbon nanotubes were used: i) pristine carbon nanotubes (diameter < 10 nm); ii) acid-oxidized carbon nanotubes (diameter < 10 nm), and iii) nitrogen doped multiwalled carbon nanotubes (20 nm diameter). Materials were characterized by ultraviolet-visible spectroscopy, Raman spectroscopy, fluorescence spectroscopy, dynamic light scattering, and field effect scanning electron microscopy. The method we have used for the synthesis was straightforward and easy, and also, we have found evidence of interactions between carbon nanotubes and chlorophyll-derivatives. The interaction between both compounds was confirmed by the significant quenching of signals measured by optical techniques as ultraviolet-visible spectroscopy, Raman spectroscopy, and fluorescence spectroscopy. In addition, we found that interaction increased as the time went on. We also found evidence of the formation of covalent bonds because of the shifting of the absorbance peaks, showing the formation of J or H aggregates. Complementary information about the morphology, revealed a significant increase in the nanotubes thickness, in the range from 80 to 160% for nanotubes with diameters < 10 nm, while nitrogen doped nanotubes showed a lower increase (25–40%). In this way, we have synthesized and characterized compound materials based on multiwalled nanotubes and chlorophyll-derivatives compounds, extracted from natural sources. We synthesized compounds with different coatings that can be used in fields as gas sensing or water remediation.