Covalent functionalization and solubilization of multi-walled carbon nanotubes by using zinc and copper complexes of meso-tetra(4-aminophenyl) porphyrin

Zinc (II) and copper (II) complexes of mesotetra(4-aminophenyl) porphyrin (Zn-TAP and Cu-TAP) were covalently connected to multi-walled carbon nanotube (MWCNT) through an amide linkage and characterized by using many spectroscopic techniques. Significant modification in the FT-IR and XP spectra confirms the covalent functionalization of Zn-TAP and Cu-TAP with MWCNT. Linking Zn-TAP and Cu-TAP with MWCNTs substantially improves their solubility in many solvents. TGA plots of MWCNT-ZnTAP and MWCNT-CuTAP reveal that similar to 40 and 23 % weight loss in the temperature range of 180-800 degrees C, respectively. MWCNT-CuTAP shows more thermal stability compared to MWCNT-ZnTAP and also compared to the reported similar nano hybrids. Considerable shift in the absorption and emission spectra of these nano hybrids clearly indicate different electronic interaction between porphyrin and MWCNT due to metal ions substitution. PL spectra of MWCNTZnTAP exhibited fluorescence quenching of Zn-TAP Soret band by MWCNTs in various solvents. This quenching is owing to the covalent functionalization of Zn-TAP with MWCNT molecules in the nano hybrid. This further substantiates the energy or electron transfer between Zn-TAP and the MWCNTs. (C) 2018 Elsevier B.V. All rights reserved.