Molecular Modelling and Simulations of Light‐Harvesting Decanuclear Ru‐Based Dendrimers for Artificial Photosynthesis. Issue 5 (16th December 2021)

• Record Type: Journal Article
• Authors: Rogati, Giovanna M. A.; Capecci, Chiara; Fazio, Enza; Serroni, Scolastica; Puntoriero, Fausto; Campagna, Sebastiano; Guidoni, Leonardo
• Is Part Of: Chemistry. Volume 28:Issue 5(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-16
• Subjects: computational chemistry -- dendrimers -- molecular simulations -- ruthenium; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202103310
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The structure of a decanuclear photo‐ and redox‐active dendrimer based on Ru(II) polypyridine subunits, suitable as a light‐harvesting multicomponent species for artificial photosynthesis, has been investigated by means of computer modelling. The compound has the general formula [Ru{(μ‐dpp)Ru[(μ‐dpp)Ru(bpy)2 ]2 }3 ](PF6 )20 (Ru10 ; bpy=2, 2′‐bipyridine; dpp=2, 3‐bis(2′‐pyridyl)pyrazine). The stability of possible isomers of each monomer was investigated by performing classical molecular dynamics (MD) and quantum mechanics (QM) simulations on each monomer and comparing the results. The number of stable isomers is reduced to 36 with a prevalence of MER isomerism in the central core, as previously observed by NMR experiments. The simulations on decanuclear dendrimers suggest that the stability of the dendrimer is not linked to the stability of the individual monomers composing the dendrimer but rather governed by the steric constrains originated by the multimetallic assembly. Finally, the self‐aggregation of Ru10 and the distribution of the counterions around the complexes is investigated using Molecular Dynamics both in implicit and explicit acetonitrile solution. In representative examples, with nine and four dendrimers, the calculated pair distribution function for the ruthenium centers suggests a self‐aggregation mechanism in which the dendrimers are approaching in small blocks and then aggregate all together. Scanning transmission electron microscopy complements the investigation, supporting the formation of different aggregates at various concentrations. Abstract : Molucular simulations on the structure of a decanuclear Ru‐based dendrimer capable to play the role of antenna for artificial photosynthesis is performed. Aggregation of dendrimers is also modelled and compared to experimental results obtained by SAXS, scanning tunneling electron microscopy and energy‐dispersive X‐ray analysis.