880468-65-5Relevant academic research and scientific papers
1H NMR spectroscopy as a tool to determine accurate photoisomerization quantum yields of stilbene-like ligands coordinated to rhenium(I) polypyridyl complexes
Frin, Karina Passalacqua Morelli,Itokazu, Melina Kayoko,Iha, Neyde Yukie Murakami
, p. 294 - 300 (2010)
In this work, the use of proton nuclear magnetic resonance, 1H NMR, was fully described as a powerful tool to follow a photoreaction and to determine accurate quantum yields, so called true quantum yields (Φtrue), when a reactant and photoproduct absorption overlap. For this, Φtrue for the trans-cis photoisomerization process were determined for rhenium(I) polypyridyl complexes, fac-[Re(CO)3(NN)(trans-L)]+ (NN = 1,10-phenanthroline, phen, or 4,7-diphenyl-1,10-phenanthroline, ph2phen, and L = 1,2-bis(4-pyridyl)ethylene, bpe, or 4-styrylpyridine, stpy). The true values determined at 365 nm irradiation (e.g. ΦNMR = 0.80 for fac-[Re(CO)3(phen)(trans-bpe)]+) were much higher than those determined by absorption spectral changes (ΦUV-Vis = 0.39 for fac-[Re(CO)3(phen)(trans-bpe)]+). ΦNMR are more accurate in these cases due to the distinct proton signals of trans and cis-isomers, which allow the actual determination of each component concentration under given irradiation time. Nevertheless when the photoproduct or reactant contribution at the probe wavelength is negligible, one can determine Φtrue by regular absorption spectral changes. For instance, Φ313 nm for free ligand photoisomerization determined both by absorption and 1H NMR variation are equal within the experimental error (bpe: ΦUV-Vis = 0.27, ΦNMR = 0.26; stpy: ΦUV-Vis = 0.49, ΦNMR = 0.49). Moreover, 1H NMR data combined with electronic spectra allowed molar absorptivity determination of difficult to isolate cis-complexes.
Improved singlet oxygen generation in rhenium(I) complexes functionalized with a pyridinyl selenoether ligand
Calvo-Castro, Jesus,Cunha, Rodrigo L. O. R.,Henrique de Macedo, Leonardo,Morelli Frin, Karina P.,Santos de Oliveira, Samuel
, (2021/11/11)
The synthesis, characterization, electrochemical and photophysical properties of three novel polypyridine rhenium(I) complexes coordinated to an organoselenide ligand, 4-(phenylseleno)-pyridine (PhSepy), and structurally related polypyridine ligands, fac-[Re(CO)3(NN)(PhSepy)]+ NN = 1,10-phenanthroline (phen), 4,7-diphenyl-1,10-phenanthroline (ph2phen) and pyrazino[2,3-f]-1,10-phenanthroline (dpq), are reported. In addition, their ability to act as a photosensitizer agent for the generation of singlet oxygen was investigated. Cyclic and differential pulse voltammetry experiments showed an overlap of the redox waves characteristic of the 4-(phenylseleno)-pyridine ligand and the Re(I) complex. This finding is consistent with a strong contribution of the pyridine-based ligand on the HOMO levels of the three investigated complexes, further supported by quantum mechanical calculations. Moreover, the lowest energy band observed in the absorption spectra of the complexes was also influenced by the organoselenide ligand, with a combination of the usual MLCTRe→NN transition with a ligand-to-ligand charge transfer (LLCT) one. The three complexes showed typical emission spectra for this class of compounds ascribed to 3MLCTRe→NN, with excellent quantum yields for the singlet oxygen generation (ΦΔ = 0.65–070). Remarkably, these are significantly larger (15–29%) than those for structurally related complexes with non-functionalized pyridyl ligands, revealing a significant ability as a photosensitizer agent. Therefore, we envisage this work to be of interest to those engaged in the development of novel rhenium(I) complexes for optoelectronic applications.
Combatting AMR: A molecular approach to the discovery of potent and non-toxic rhenium complexes active against C. albicans-MRSA co-infection
Crochet, Aurélien,Pavic, Aleksandar,Radakovic, Natasa,Roch, Paul,Sovari, Sara Nasiri,Zobi, Fabio
supporting information, (2021/09/28)
Antimicrobial resistance (AMR) is a major emerging threat to public health, causing serious issues in the successful prevention and treatment of persistent diseases. While the problem escalates, lack of financial incentive has lead major pharmaceutical co
Z to E light-activated isomerization of α-pyridyl-N-arylnitrone ligands sensitized by rhenium(I) polypyridyl complexes
Mamud, Julia F.,Biazolla, Giovanna,Marques, Caroline S.,Cerchiaro, Giselle,de Queiroz, Thiago B.,Keppler, Artur F.,Polo, André S.
, (2020/10/02)
A series of rhenium(I) polypyridyl compounds, bearing photoisomerizable nitrones as ligands, was synthesized and characterized by several techniques. The photochemical and photophysical behaviors of the compounds were investigated. Upon irradiation, acetonitrile solutions of the nitrones, or their respective complexes, exhibit changes in absorption, emission, and FTIR spectra. FTIR revealed the formation of the respective anilide as the photoproducts of irradiation of the uncoordinated nitrones, while irradiation of the complexes resulted in Z → E due to the photosensitized isomerization of the coordinated ligand, also confirmed by HPLC-MS and 1H NMR. The photoisomerization quantum yields are dependent on the nature of the nitrone substituent, which changes the energy of the 3ILZ-NitX excited state, which is populated by photosensitization. 3MLCT becomes the lowest-lying excited state in the E-product and results in an increase in emission intensity. The changes in spectroscopic properties of the Z or E coordinated nitrones can be exploited for molecular devices such as photosensors.
