Manipulating the Excited States of Cyclometalated Iridium Complexes with β-Ketoiminate and β-Diketiminate Ligands

The photodegradation behavior of four well-established iridium emitters was investigated. Irradiation of the samples in different solvents and under atmospheric as well as inert conditions helped to identify several pathways that can contribute to the deterioration of these compounds. Degradation via singlet oxygen or the excited states of the emitters as well as the detrimental influence of halogenated solvents are discussed for the different investigated iridium complexes. Some of the resulting degradation products could be identified by using LC–MS or other analytical techniques. The results show how even small structural changes can have a huge influence on rate and mechanism of the photodegradation. The observations from this study may help to better understand degradation processes occurring during the handling of the materials, but also during device processing and operation.

Download Full-text

[Cu(bcp)DPEPhos]+: a Versatile and Efficient Copper-Based Photoredox Catalyst and Photosensitizer

SynOpen ◽

10.1055/a-1504-6972 ◽

2021 ◽

Author(s):

Samuel Oger ◽

Hajar Baguia ◽

Tuan-Anh Phan ◽

Titouan Teunens ◽

Jérôme Beaudelot ◽

...

Keyword(s):

Excited States ◽

Copper Complex ◽

Copper Complexes ◽

Organic Dyes ◽

Iridium Complexes ◽

Chemical Transformations ◽

Redox Potentials ◽

Photoredox Catalysis ◽

Radical Species ◽

The Core

The development of photoredox catalysis has recently enabled the design of remarkably powerful synthetic tools now commonly used in a wide array of chemical transformations, and notably for the generation of radical species under mild, safe and environmentally friendly conditions. This field is largely dominated by ruthenium and iridium complexes, the main alternative to the use of these photocatalysts mostly relying on the use of organic dyes, which poses problems not only in terms of cost - therefore strongly limiting synthetic applications of photocatalysis - but also, more importantly, for the design of new light-mediated transformations. Much less attention has been devoted to the use of copper complexes in photoredox catalysis, despite their strong potential not only as cheaper catalysts but also for the activation of a broader range of substrates. Most copper complexes are indeed known to be poor photocatalysts, mostly due to their short-lived excited states and low redox potentials. Over the last decade, one copper-based copper complex has however emerged as a remarkably efficient and general photoredox catalyst, which is at the core of this Spotlight that highlights its applications as a photosensitizer and its potential.

Download Full-text

β-Diketonate ancillary ligands in heteroleptic iridium complexes: a balance between synthetic advantages and photophysical troubles

Photochemical & Photobiological Sciences ◽

10.1039/c8pp00052b ◽

2018 ◽

Vol 17 (9) ◽

pp. 1169-1178 ◽

Cited By ~ 3

Author(s):

Marta Penconi ◽

Marco Cazzaniga ◽

Sagar Kesarkar ◽

Clara Baldoli ◽

Patrizia R. Mussini ◽

...

Keyword(s):

Dft Calculations ◽

Excited States ◽

Iridium Complexes ◽

Triplet Energy ◽

Ancillary Ligands ◽

Phosphorescence Emission ◽

Triplet Excited States ◽

Shed Light

How the triplet energy of β-diketonate ancillary ligands in Ir(iii) complexes affects the phosphorescence emission: photochemical and electrochemical investigations and DFT calculations shed light on the dark triplet excited states.

Download Full-text

Vuv Spectra Y to Mo

International Astronomical Union Colloquium ◽

10.1017/s0252921100107808 ◽

1988 ◽

Vol 102 ◽

pp. 239

Author(s):

M.S.Z. Chaghtai

Keyword(s):

Excited States ◽

Spectral Analyses ◽

Vuv Spectra

Using R.D. Cowan’s computations (1979) and parametric calculations of Meinders et al (1982), old analyses are thoroughly revised and extended at Aligarh, of Zr III by Khan et al (1981), of Nb IV by Shujauddin et Chaghtai (1985), of Mo V by Tauheed at al (1985). Cabeza et al (1986) confirmed the last one largely.Extensive studies have been reported of the 1–e spectra, Zr IV (Rahimullah et al 1980; Acquista and Reader 1980), Nb V (Shujauddin et al 1982; Kagan et al 1981) and Mo VI (Edlén et al 1985). Some interacting 4p54d2levels of these spectra have been reported from our laboratory, also.Detailed spectral analyses of transitions between excited states have furnished complete energy values for J ≠ 1 levels of these spectra during 1970s and 80s. Shujauddin et al (1982) have worked out Nb VI and Tauheed et al (1984) Mo VII from our lab, while Khan et al (1981) share the work on Zr V with Reader and Acquista (1979).

Download Full-text