Synthesis, characterization and fluorescent properties of ferrocenyl pyrazole and triazole ligands and their palladium complexes

Amoah, Cephas; Obuah, Collins; Ainooson, Michael K.; Muller, Alfred

doi:10.1016/j.jorganchem.2020.121664

Cited by 7 publications

(4 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…That is, we have produced an amplification of the luminescence of several orders of magnitude, which is a very scarce phenomenon despite the fact that intensely luminescent Pd complexes are known . In fact, this is the opposite behavior to what is commonly found in Pd complexes, because in most reported cases, the incorporation of the palladium causes a big decrease or almost complete loss of luminescence. ,, Aiming to gain more insight about the intimate reasons for this amplification, we have tried to correlate the molecular parameters with the observed fluorescence. Following the crystallographic analysis performed in complexes 3c , 3d , 3g , and 6h , detailed in the Supporting Information, it is possible to observe that molecules with similar distortions (for instance, 3c and 3d ) show very different values of quantum yield (<1 and 7%, respectively) or that highly distorted molecules as 5h (by similarity with 6h ) show high values of quantum yield (15% for 5h ).…”

Section: Resultsmentioning

confidence: 99%

Fluorescence Amplification of Unsaturated Oxazolones Using Palladium: Photophysical and Computational Studies

et al. 2023

View full text Add to dashboard Cite

Weakly fluorescent (Z)-4-arylidene-5-(4H)-oxazolones (1), ΦPL < 0.1%, containing a variety of conjugated aromatic fragments and/or charged arylidene moieties, have been orthopalladated by reaction with Pd(OAc)2. The resulting dinuclear complexes (2) have the oxazolone ligands bonded as a C^N-chelate, restricting intramolecular motions involving the oxazolone. From 2, a variety of mononuclear derivatives, such as [Pd(C^N-oxazolone)(O2CCF3)(py)] (3), [Pd(C^N-oxazolone)(py)2](ClO4) (4), [Pd(C^N-oxazolone)(Cl)(py)] (5), and [Pd(C^N-oxazolone)(X)(NHC)] (6, 7), have been prepared and fully characterized. Most of complexes 3–6 are strongly fluorescent in solution in the range of wavelengths from green to yellow, with values of ΦPL up to 28% (4h), which are among the highest values of quantum yield ever reported for organometallic Pd complexes with bidentate ligands. This means that the introduction of the Pd in the oxazolone scaffold produces in some cases an amplification of the fluorescence of several orders of magnitude from the free ligand 1 to complexes 3–6. Systematic variations of the substituents of the oxazolones and the ancillary ligands show that the wavelength of emission is tuned by the nature of the oxazolone, while the quantum yield is deeply influenced by the change of ligands. TD-DFT studies of complexes 3–6 show a direct correlation between the participation of the Pd orbitals in the HOMO and the loss of emission through non-radiative pathways. This model allows the understanding of the amplification of the fluorescence and the future rational design of new organopalladium systems with improved properties.

show abstract

Section: Resultsmentioning

confidence: 99%

Fluorescence Amplification of Unsaturated Oxazolones Using Palladium: Photophysical and Computational Studies

et al. 2023

View full text Add to dashboard Cite

show abstract

“…In 2020, Obuah et al [ 93 ] explored the impact of incorporating palladium into ferrocene-based organic fluorophores, which combine the fluorescent properties of ferrocene with those of a fluorophore. It was observed that the incorporation of Pd in compounds 88 and 89 , shown in Figure 24 , resulted in a decrease in both fluorescence intensity and quantum yield compared to the free ligand, this quenching due to the heavy atom effect.…”

Section: Palladium Coordination Complexesmentioning

confidence: 99%

“… Ferrocenyl pyrazolyl (Red) and ferrocenyl triazolyl (Blue) ligands and their palladium metal complexes ( 88 and 89 ). Adapted from [ 93 ]. …”

Section: Figurementioning

confidence: 99%

Luminescence and Palladium: The Odd Couple

Dalmau

Urriolabeitia

2023

Molecules

View full text Add to dashboard Cite

The synthesis, photophysical properties, and applications of highly fluorescent and phosphorescent palladium complexes are reviewed, covering the period 2018–2022. Despite the fact that the Pd atom appears closely related with an efficient quenching of the fluorescence of different molecules, different synthetic strategies have been recently optimized to achieve the preservation and even the amplification of the luminescent properties of several fluorophores after Pd incorporation. Beyond classical methodologies such as orthopalladation or the use of highly emissive ligands as porphyrins and related systems (for instance, biladiene), new concepts such as AIE (Aggregation Induced Emission) in metallacages or in coordination-driven supramolecular compounds (CDS) by restriction of intramolecular motions (RIM), or complexes showing TADF (Thermally Activated Delayed Fluorescence), are here described and analysed. Without pretending to be comprehensive, selected examples of applications in areas such as the fabrication of lighting devices, biological markers, photodynamic therapy, or oxygen sensing are also here reported.

show abstract

“…Due to these properties, pyrene has been the subject of interest in numerous studies aimed at its modification to obtain useful fluorophores for practical applications in various branches of science, ranging from optoelectronics to biology and medicine [4,7,[10][11][12][13][14]. Pyrazoles are another class of small molecule fluorophores exhibiting intense and tunable emission, thoroughly studied in recent years [15][16][17][18][19][20]. Therefore, it seemed interesting to synthesize molecules with conjugated pyrene-pyrazole cores and to study their luminescent properties.…”

Section: Introductionmentioning

confidence: 99%

Highly Fluorescent Dyes Containing Conformationally Restrained Pyrazolylpyrene (Pyrazoolympicene) Chromophore

Wrona-Piotrowicz

Makal

2022

Molecules

View full text Add to dashboard Cite

The triflic-acid-promoted cyclization of 1-phenyl-3-(pyren-1-yl)-1H-pyrazole-4-carbaldehyde afforded a mixture of 9-phenyl-7,9-dihydropyreno (10,1-fg)indazole and 9-phenylpyreno(10,1-fg)indazole-7(9H)-one, readily separable by column chromatography. Both products contained a rigid six-ringed pyrazoolympicene backbone and exhibited bright fluorescence in chloroform solution and a weak fluorescence in the solid state. DFT and TD DFT calculations revealed that the lowest excited state (S1) of these compounds is populated via HOMO →LUMO π-π * transition. Furthermore, the synthesized compounds behaved as weak bases and their emission spectra showed substantial changes upon protonation. Therefore, they may be of interest for sensing of strongly acidic fluorophore environments.

show abstract

Synthesis, characterization and fluorescent properties of ferrocenyl pyrazole and triazole ligands and their palladium complexes

Cited by 7 publications

References 19 publications

Fluorescence Amplification of Unsaturated Oxazolones Using Palladium: Photophysical and Computational Studies

Fluorescence Amplification of Unsaturated Oxazolones Using Palladium: Photophysical and Computational Studies

Luminescence and Palladium: The Odd Couple

Highly Fluorescent Dyes Containing Conformationally Restrained Pyrazolylpyrene (Pyrazoolympicene) Chromophore

Contact Info

Product

Resources

About