Dipyridylmethane Ethers as Ligands for Luminescent Ir Complexes.

Giorgio Volpi,Carlo Nervi,Roberto Gobetto,Claudio Garino

doi:10.3390/molecules26237161

Abstract

This work reports two new cationic heteroleptic cyclometalated iridium complexes, containing ether derivatives of di(pyridin-2-yl)methanol. The new ligands are based on dipyridin-2-ylmethane and are designed to obtain ether-based intermediates with extended electronic conjugation by insertion of π system such as phenyl, allyl and ethynyl. Different synthetic strategies were employed to introduce these units, as molecular wires, between the dipyridin-2-ylmethane chelating portion and the terminal N-containing functional group, such as amine and carbamide. The corresponding complexes show luminescence in the blue region of the spectrum, lifetimes between 0.6 and 2.1 μs, high quantum yield and good electrochemical behavior. The computational description (DFT) of the electronic structure highlights the key role of the conjugated π systems on optical and electrochemical properties of the final products.

Highlights

Dipyridylmethane Ethers as LigandsN,N-bidentate ligands for coordination complexes, such as 2,20 -bipyridines and1,10-phenanthrolines, play a pivotal role in key areas such as photovoltaics, lighting, molecular sensors, biological probes, catalysis, molecular electronics and supramolecular chemistry [1,2,3,4,5]
The dipyridin-2-yl-methane skeleton is well known for being an efficient chelating structure which guarantees good optical properties in the corresponding metal complexes
We have previously developed different synthetic strategies to modify the dipyridin-2ylmethane skeleton starting from di-2-pyridylketone [10,11]

Summary

Introduction

1,10-phenanthrolines, play a pivotal role in key areas such as photovoltaics, lighting, molecular sensors, biological probes, catalysis, molecular electronics and supramolecular chemistry [1,2,3,4,5]. This variety of applications stem from the facts that such ligands, by chelating various transition metals, mix their and metal frontier orbitals, resulting in electron delocalization and interesting new physical, electrochemical and optical properties. Several conjugated π systems, such as phenylene, thienylene and ethynyl groups have been employed for tuning structural, optical and electrochemical behaviors in the corresponding complexes [6,7,8,9]. The dipyridin-2-yl-methane skeleton is well known for being an efficient chelating structure which guarantees good optical properties in the corresponding metal complexes

Methods

Discussion

Conclusion