Controlled Fabrication and Optoelectrical Properties of Metallosupramolecular Films Based on Ruthenium(II) Phthalocyanines and 4,4′-Bipyridine Covalently Anchored on Inorganic Substrates

Fully conjugated metallosupramolecular self-assembled multilayer films were controllably fabricated based on bibenzonitril-phthalocyaninato ruthenium­(II) (BBPR) and 4,4′-bipyridine (BP) via axially coordination interaction between ruthenium ions and the pyridine groups on the modified substrates. The substrates were first functionalized by 4-(pyridine-4-ylethynyl)­benzenic diazonium salt (PBD) through photodecomposition of diazonium group under UV irradiation. As a result, the pyridine-containing functional groups were vertically and covalently anchored onto the surface of substrate and got a stable monolayer. Soluble ruthenium phthalocyanine, axially coordinated by labile benzonitrile groups, was used to fabricate the layer-by-layer self-assembled films with BP through ligand-exchanging reaction between benzonitrile and pyridine in each self-assembled cycle. The UV–vis analysis results demonstrated the successful fabrication of bi­(4,4′-bipyridine)­phthalocyaninato ruthenium­(II) (BPPR) metallosupramolecular ultrathin films with definite structures on PBD-modified substrate. Under illumination, the BPPR self-assembled multilayer films displayed a quick response to light. The maximum current density reached 120 nA/cm² at six bilayers. The <i>E</i>_g, HOMO, and LUMO of the six-bilayer were quantitatively measured to be 1.68, −5.29, and −3.61 eV, respectively. This strategy supplies a facile method to get full-conjugated metallosupramolecules and a platform for developing higher performance solar cell from the point of adjusting dye aggregate state structure

Control of Electron Flow Direction in Photoexcited Cycloplatinated Complex Containing Conjugated Polymer–Single-Walled Carbon Nanotube Hybrids

Conjugated polymers incorporated with cycloplatinated complexes <b>(P1–Pt</b> and <b>P2–Pt</b>) were used as dispersants for single-walled carbon nanotubes (SWCNTs). Significant changes in the UV–vis absorption spectra were observed after the formation of the polymer/SWCNT hybrids. Molecular dynamics (MD) simulations revealed the presence of a strong interaction between the cycloplatinated complex moieties and the SWCNT surface. The photoinduced electron transfer processes in these hybrids were strongly dependent on the type of the comonomer unit. Upon photoexcitation, the excited <b>P1–Pt</b> donates electrons to the SWCNT, while <b>P2–Pt</b> accepts electrons from the photoexcited SWCNT. These observations were supported by results from Raman and femtosecond time-resolved transient absorption spectroscopy experiments. The strong electronic interaction between the Pt complexes and the SWCNT gives rise to a new hybrid system that has a controllable photoinduced electron transfer flow, which are important in regulating the charge transport processes in SWCNT-based optoelectronic devices