Fluorescence amplification of unsaturated oxazolones using palladium: photophysical and computational studies

Dalmau, D. ; Crespo, O. (Universidad de Zaragoza) ; Matxain, J. M. ; Urriolabeitia, E. P.

Resumen: 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.

Idioma: Inglés

DOI: 10.1021/acs.inorgchem.3c00601

Año: 2023

Publicado en: Inorganic Chemistry 62, 25 (2023), 9792-9806
ISSN: 0020-1669

Factor impacto JCR: 4.3 (2023)

Categ. JCR: CHEMISTRY, INORGANIC & NUCLEAR rank: 8 / 44 = 0.182 (2023) - Q1 - T1

Factor impacto CITESCORE: 7.6 - Inorganic Chemistry (Q1) - Physical and Theoretical Chemistry (Q1)

Factor impacto SCIMAGO: 0.928 - Chemistry (miscellaneous) (Q1) - Physical and Theoretical Chemistry (Q1) - Inorganic Chemistry (Q1)

Financiación: info:eu-repo/grantAgreement/ES/AEI/PID2019-104379RB-C21
Financiación: info:eu-repo/grantAgreement/ES/AEI/PID2019-106394GB-I00
Financiación: info:eu-repo/grantAgreement/ES/DGA/E07-23R
Financiación: info:eu-repo/grantAgreement/ES/DGA/E17-23R

Tipo y forma: Artículo (Versión definitiva)

Área (Departamento): Área Química Inorgánica (Dpto. Química Inorgánica)