Fabrication, Electrochemical, and Optoelectronic Properties of Layer-by-Layer Films Based on (Phthalocyaninato)ruthenium(II) and Triruthenium Dodecacarbonyl Bridged by 4,4′-Bipyridine as Ligand

Abstract

4-(2-(4-pyridinyl)ethynyl)benzenic diazonium salt (PBD) was synthesized and used to modify the substrate by self-assembly (SA) technique. Following decomposition of the diazonium group in PBD under UV irradiation, the ionic bonds between the diazonium salt and substrate are converted to covalent bonds. The PBD monolayer film anchored on substrates is very stable. Furthermore, the layer-by-layer (LBL) self-assembled films of bis(4,4'-bipyridine)(phthalocyaninato)ruthenium(II) (RuPc(bipy)2, BPR) and triruthenium dodecacarbonyl (Ru3(CO)12, TRDC) were fabricated on the PBD-modified substrates and characterized using UV-vis absorption spectroscopy, atomic force microscopy (AFM), and electrochemistry. The UV-vis analysis results indicate that the LBL TRDC-BPR self-assembled multilayer films with axial ligands between ruthenium atoms and pyridine groups were successfully fabricated and the progressive assembly runs regularly with almost equal amounts of deposition in each cycle. The AFM images of the seven-bilayer TRDC-BPR film on silicon wafer showed round-shaped small domains with sizes of 30-40 nm. The values of the energy band gap (Eg), the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) of six-bilayer TRDC-BPR on indium-tin-oxide (ITO) glass slides were measured using the UV-vis absorption spectrum and a cyclic voltammogram with values of 1.8, -5.0, and -3.2 eV, respectively. Under illumination, the self-assembled film on ITO showed effective photoinduced charge transfer and changed the current density. As the number of bilayers was increased, the photocurrent increased and reached its maximum value (approximately 150 nA/cm2) at six bilayers. A further increase in the number of bilayers led to a decrease in current due to the increase in cell resistance. The results allow us to design new materials with higher performance for optoelectronic applications.

Nickel(II)‐Catalysed C–H Functionalization and Tandem Coupling of Terminal Alkynes with 1,3‐Dicarbonyls: Expedient Route to Functionalized Furans

“…Solvents were dried by conventional methods and distilled prior to use. The functionalized starting material alkynes have been prepared following the reported procedures . 1 H NMR spectra were acquired on a Bruker Avance III 400 spectrometer using CDCl 3 solvent.…”

A post-functionalization toolbox for diazonium (electro)-grafted surfaces: review of the coupling methods

“…16). 262,263,[265][266][267]271,[274][275][276][277][278][279][280][281] However, these compounds are generally prepared ''in situ'' from diazotization of their amine precursors, as the diazonium species are only stable at low temperature (E0 1C) in the timescale of minutes, preventing their isolation. On the other hand, in some cases, it is convenient to include an alkyl chain as spacer between the coordination moiety of the ligand and the anchoring group.…”

Facile immobilization of pyridine at gold, silver, and carbon surfaces. Generation of multi-strata versatile electrodes

“…A recent work based on the electrocatalysis brought by nitrogen ligands was reported [7]. In the field of surface modification, pyridine immobilization could be indirectly achieved by use of a diazonium intermediate with a rigid phenylethynyl arm [8,9]. Our proposal concerns the electrochemical reactivity {in non-aqueous polar solvents in the presence of tetraalkylammonium salts (TAAX)} of electrophilic reagents from the family of 4-(w-haloalkyl)pyridines, p-(X-…”