Fabrication and Optoelectronic Properties of Novel Films Based on Functionalized Multiwalled Carbon Nanotubes and (Phthalocyaninato)Ruthenium(II) via Coordination Bonded Layer-by-Layer Self-Assembly

Abstract

4-(2-(4-pyridinyl)Ethynyl)benzenic diazonium salt (PBD) was used to modify multiwalled carbon nanotubes (MWCNTs) by the self-assembly technique. After the decomposition of the diazonium group in PBD under UV irradiation, the PBD monolayer film covalently anchored on multiwalled carbon nanotubes is very stable. The obtained pyridine-modified MWCNTs (Py(Ar)-MWCNTs) have good solubility in common organic solvents. Furthermore, the layer-by-layer (LBL) self-assembled fully conjugated films of Py(Ar)-MWCNTs and (phthalocyaninato)ruthenium(II) (RuPc) were fabricated on the PBD-modified substrates, and characterized using UV-vis absorption spectroscopy, scanning electron microscopy (SEM), and electrochemistry. The UV-vis analysis results indicate that the LBL RuPc/Py(Ar)-MWCNTs self-assembled multilayer films with axial ligands between the ruthenium atom and pyridine group were successfully fabricated, and the progressive assembly runs regularly with almost equal amounts of deposition in each cycle. A top view SEM image shows a random and homogeneous distribution of Py(Ar)-MWCNTs over the PBD-modified silicon substrate, which indicates well independence between all Py(Ar)-MWCNTs. Moreover, the opto-electronic conversion was also studied by assembling RuPc/Py(Ar)-MWCNTs multilayer films on PBD-modified ITO substrate. Under illumination, the LBL self-assembled films on ITO showed an effective photoinduced charge transfer because of their conjugated structure and the ITO current density changed with the number of bilayer. As the number of bilayers was increased, the photocurrent increases and reaches its maximum value (∼300 nA/cm(2)) at nine bilayers. These results allow us to design novel materials for applications in optoelectronic devices by using LBL self-assembly techniques.

Layer‐by‐Layer Assembly Through Weak Interactions and Their Biomedical Applications

“…At the beginning, only electrostatic interactions were utilized for LbL assembly. Subsequently, other interactions such as covalent bond,38–44 hydrogen bonding,45–51 charge transfer,52, 53 hydrophobic,54–56 host–gest,57–60 and coordination bond61–67 interactions have been investigated to facilitate polymer association for ultrathin film deposition. The most important concept for LbL assembly is how to use the interactions between the polymeric materials.…”

Immune response in hamsters immunised with a recombinant fragment of LigA from Leptospira interrogans, associated with carrier molecules

“…However, the sidewall of CNTs presents an excellent platform for chemical functionalisation, which allows overcoming the problem of processability (Niyogi et al 2002, Pantarotto et al 2003). For instance, MWCNTs can be functionalised with carboxyl groups to improve their dispersion in water (Zhao et al 2010). …”

Self-Assembled Multiwalled Carbon Nanotube Films Assisted by Ureidopyrimidinone-Based Multiple Hydrogen Bonds

“…Just deposited twice, the quartz substrate significantly darkened, because of the strong absorption of the deposited MWNTs in the visible region, 48 which showed it was an effective way for the MWNTs LBL film formation by using the multiple hydrogen bonding as the driving force. In addition, from the inset illustrated in Figure 4, it was shown that the absorbance centered at 260 nm and the optional point at 400 nm both increase linearly with the increase of the number of deposited layers.…”