A Photostable 1D Ruthenium−Zinc Coordination Polymer as a Multimetallic Building Block for Light Harvesting Systems

Abstract

A luminescent ruthenium complex bearing two 2,6-di(quinolin-8-yl)-pyridine carboxylic acid (dqpCOOH) ligands has been successfully synthesised and fully characterised. The new metalloligand has been coordinated to zinc ions through the terminal carboxylate groups using a one-step solvothermal method, to give a multimetallic photoactive 1D coordination polymer, RuÀ (dqpCOO)À ZnÀ (OOCH) 2 . Through use of X-ray crystallography, advanced microscopy techniques as well as photophysical studies, we have extensively characterised the coordination polymer. The optical properties of the ruthenium complex and corresponding coordination polymer show that the material experiences a dramatic increase in photostability compared to the free parent metalloligand, in solution. Electrochemical measurements of the coordination polymer also confirm the Ru II /Ru III redox couple is maintained in the polymeric network. The development of this material gives a new strategy in the design of novel photoactive materials as multimetallic building blocks for their use in light-based applications.

Enhanced Photostability and Photoactivity of Ruthenium Polypyridyl-Based Photocatalysts by Covalently Anchoring Onto Reduced Graphene Oxide

“…For the synthesis of the two ruthenium complexes [Ru­(tpyCOOH) 2 ] 2+ ( 1 ) and [Ru­(dqpCOOH) 2 ] 2+ ( 2 ), literature procedures were followed. , The unknown crystal structure of 2 , reported here for the first time, was determined using single crystals isolated by hot crystallization from a DMF/H 2 O mixture (Figure S1, Table S2). The crystal structure was solved using ShelxT and refined using ShelxL both of which were operated using the Oscail package .…”

“…Most promisingly, [Ru­(dqpCOOH) 2 ] 2+ , when anchored on rGO, showed an MB photodegradation of 89.1%, a remarked improvement of ca. 10.4% over the free Ru complex in solution, which has been shown to degrade rapidly under intense illumination . It is theorized that due to the extended excited state lifetime of the dqp over that of the tpy, the pathway to degradation of the MB is more readily accessed.…”

“…Ruthenium complexes: Literature procedures were used for the synthesis of [Ru(tpyCOOH) 2 ](PF 6 ) 2 and [Ru(dqpCOOH) 2 ](PF 6 ) 2 . , 1 H NMR spectra were recorded at 400 or 500 MHz as indicated using Bruker spectrometers and were processed using Bruker Topspin software with calibration against solvent peaks according to published values. Crystals of [Ru(dqpCOOH) 2 ] 2+ were developed by the dissolution of 5 mg of the complex in a 3 mL solution of DMF/H 2 O (3:2) and heating to 100 °C.…”

“…39 Recent work in our research group has shown how the incorporation of a [Ru(dqp) 2 ] 2+ species into a photoactive metallopolymer exhibits exceptional photostability under intense solar irradiation, opening potential avenues into the use of these metal complexes in hybrid materials for their application in highly stable photocatalysis. 40 A series of electro-and photocatalytic transformations have been performed previously with [Ru(bpy) 3 ] 2+ derivatives covalently anchored on rGO for CO 2 reduction, 41 watersplitting, 42,43 organic reactions, 44 and light-harvesting, 45,46 highlighting the importance of the covalent linkage in the hybrid materials. Accordingly, we focus on the elaboration of a modified ruthenium polypyridyl complex with carboxylic acids as pending groups, namely, [Ru(dqpCOOH) 2 ] 2+ , whose crystal structure is unveiled in this work.…”

“…By opening the N–Ru–N bite angles of the coordination cage in the tridentate ligand, the photophysical properties can be dramatically improved, including most notably the excited state lifetime, while retaining the geometric advantages of the [Ru­(tpy) 2 ] 2+ complexes. − The family of [Ru­(dqp) 2 ] 2+ complexes have been used in photoredox-active films in the form of metallopolymers formed via electropolymerization, , nevertheless, even when presenting comparable properties than [Ru­(bpy) 2 ] 2+ and [Ru­(tpy) 2 ] 2+ complexes, in terms of absorption profile in the visible region and extinction coefficients, its application in photoresponsive materials can be considered as underexplored . Recent work in our research group has shown how the incorporation of a [Ru­(dqp) 2 ] 2+ species into a photoactive metallopolymer exhibits exceptional photostability under intense solar irradiation, opening potential avenues into the use of these metal complexes in hybrid materials for their application in highly stable photocatalysis …”