Iridium(III)porphyrin arrays with tuneable photophysical properties

M Cidália R Castro; Nabiha Ben Sedrine; Teresa Monteiro; Ana V Machado

doi:10.1016/j.saa.2020.118309

Iridium(III)porphyrin arrays with tuneable photophysical properties

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Jul 5:235:118309. doi: 10.1016/j.saa.2020.118309. Epub 2020 Mar 29.

Authors

M Cidália R Castro¹, Nabiha Ben Sedrine², Teresa Monteiro², Ana V Machado³

Affiliations

¹ Institute of Polymers and Composites (IPC) and Institute of Nanostructures, Nanomodelling and Nanofabrication (i3N), University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal. Electronic address: cidaliacastro@dep.uminho.pt.
² Physics Department and Institute of Nanostructures, Nanomodelling and Nanofabrication (i3N), University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
³ Institute of Polymers and Composites (IPC) and Institute of Nanostructures, Nanomodelling and Nanofabrication (i3N), University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.

PMID: 32272426
DOI: 10.1016/j.saa.2020.118309

Abstract

The photophysical properties of iridium(III) porphyrins complexes with two different axial ligands (Cl(CO) and bipyridine (bpy)) in solution and in cellulose acetate polymer matrix were investigated. The axial ligands substitution was made aiming to evaluate the photophysical properties and the solubility in different solvents. Therefore, dissimilar from the free porphyrin, non-polar solvents (as toluene) favours the quantum yield of iridium(III)porphyrins and ligands with a more extended π-conjugated compound as bpy results in higher yields. Moreover, despite all the porphyrins reveals a negative solvatochromism, the substitution of Cl(CO) ligand by bpy ligand exhibits similar solubility either on non-polar or polar solvents. The observed photoluminescence (PL) at room temperature appears at NIR region in contrast to the previously reported iridium(III) porphyrins. Comparing with free porphyrin H₂TTP, the red/NIR PL spectra of the iridium(III)porphyrins (either in solution and in the polymer matrix) reveals remarkable changes. Particularly, a more significative decrease of the red/NIR intensity ratio was detected for [Ir(ttp)(bpy)₂] 2 where the maxima of the NIR emission can be adjusted under suitable excitation wavelength.

Keywords: Axial ligand effects; Iridium porphyrin; NIR photoluminescence; Optical sensor.