Orthopalladation of GFP-Like Fluorophores Through C-H Bond Activation: Scope and Photophysical Properties

Collado, S. ; Pueyo, A. ; Baudequin, C. ; Bischoff, L. ; Jimenez, A.I. (Universidad de Zaragoza) ; Cativiela, C. (Universidad de Zaragoza) ; Hoarau, C. ; Urriolabeitia, E.P. (Universidad de Zaragoza)

Resumen: The luminescence of oxazolones R-1-C6H4CH=CC(O)O-CN(R-2) (1a-1j) and imidazolones R-1-C6H4CH=CC(O)NR3CN(R-2) (1k-1q) has been examined. The new GFP-like imidazolones (GFP = Green Fluorescent Protein) (1k-1q) have been prepared by reaction of the oxazolones with amines H2NR3 and bis(trimethylsilyl)acetamide. The most intense fluorescence was found in push-pull systems containing simultaneously strong electron-donating and electron-withdrawing substituents. The incorporation of the Pd atom into the molecular skeleton of oxazolones and imidazolones notably changes their luminescence. The reaction of oxazolones (1a-1j) and imidazolones (1k-1q) with Pd(OAc)(2) (1:1 molar ratio) in carboxylic acids gives the dinuclear [Pd{R-1-C6H3CH=CC(O)OCN(R-2)}(mu-carboxylate)](2) (2a-2j) and [Pd{R-1-C6H3CH=CC(O)NR3CN(R-2)}(mu-carboxylate)](2) (2k-2q) through regioselective C-H bond activation of the ortho position of the respective 4-arylidene rings. Complexes 2a-2q react with LiCl in MeOH to give the chloride-bridge derivatives [Pd{R-1-C6H3CH=CC(O)OCN(R-2)}(mu-Cl)](2) (3a-3j) and [Pd{R-1-C6H3CH=CC(O)NR3CN(R-2)}(mu-Cl)](2) (3k-3q), which further react with Tl(acac) (acac = acetylacetonate) to give the mononuclear species [Pd(R-1-C6H3CH=CC(O)OCN(R-2)(acac)] (4a-4j) and [Pd{R-1-C6H3CH=CC(O)NR3CN(R-2)(acac)}] (4k-4q). Complexes 4o and 4q, having an orthopalladated push-pull imidazolone, are strongly fluorescent, showing a notable increase of the quantum yield with respect to the free ligands 1o and 1q up of one order of magnitude.

Idioma: Inglés

DOI: 10.1002/ejoc.201800966

Año: 2018

Publicado en: European Journal of Organic Chemistry 44 (2018), 6158-6166
ISSN: 1434-193X

Factor impacto JCR: 3.029 (2018)

Categ. JCR: CHEMISTRY, ORGANIC rank: 16 / 57 = 0.281 (2018) - Q2 - T1

Factor impacto SCIMAGO: 0.987 - Physical and Theoretical Chemistry (Q1) - Organic Chemistry (Q1)

Financiación: info:eu-repo/grantAgreement/EUR/COST/CA15106-CHAOS
Financiación: info:eu-repo/grantAgreement/ES/DGA-FEDER/E19-17R
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CTQ2013-40855-R

Tipo y forma: Article (PostPrint)

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