Heteroleptic Cycloplatinated N-Heterocyclic Carbene Complexes: A New Approach to Highly Efficient Blue-Light Emitters

Fuertes, S. ; Chueca, A.J. ; Arnal, L. ; Martín, A. (Universidad de Zaragoza) ; Giovanella, U. ; Botta, C. ; Sicilia, V. (Universidad de Zaragoza)

Resumen: New heteroleptic compounds of platinum(II)-containing cyclometalated N-heterocyclic carbenes, [PtCl(R-C^C*)(PPh3)] [R-CH^C*-?C* = 3-methyl-1-(naphthalen-2-yl)-1H-imidazol-2-ylidene (R-C = Naph; 1A), 1-[4-(ethoxycarbonyl)phenyl]-3-methyl-1H-imidazol-2-ylidene (R = CO2Et; 1B), and [Pt(R-C^C*)(py)(PPh3)]PF6 (py = pyridine; R-C = Naph, 2A; R = CO2Et, 2B], have been prepared and fully characterized. All of them were obtained as the trans-(C*, PPh3) isomer in high yields. The selectivity of their synthesis has been explained in terms of the degree of transphobia (T) of pairs of ligands in trans positions. X-ray diffraction studies on both 2A and 2B revealed that only in 2A, containing a C^C* with a more extended p system, do the molecules assemble themselves into head-to-tail pairs through intermolecular p···p contacts. The photophysical properties of 2A and 2B and those of the related compounds [Pt(NC-C^C*)(PPh3)L]PF6 [NC-CH^C*-?C* = 1-(4-cyanophenyl)-3-methyl-1H-imidazol-2-ylidene; L = pyridine (py; 2C), 2, 6-dimethylphenylisocyanide (CNXyl; 3C), and 2-mercapto-1-methylimidazole (MMI; 4C)] have been examined to analyze the influence of the R substituent on R-C^C* (R-C = Naph; R = CO2Et, CN) and that of the ancillary ligands (L) on them. Experimental data and time-dependent density functional theory calculations showed the similarity of the electronic features associated with R-C^C* (R = CN, CO2Et) and their difference with respect to R-C^C* (R-C = Naph). All of the compounds are very efficient blue emitters in poly(methyl methacrylate) films under an argon atmosphere, with QY values ranging from 68% (2B) to 93% (2C). In the solid state, the color of the emission changes to yellowish-orange for compounds 2A (?max = 600 nm) and 3C (?max = 590 nm) because of the formation of aggregates through intermolecular p···p interactions. 2C and 3C were chosen to fabricate fully solution-processed electroluminescent devices with blue-light (2C), yellow-orange-light (3C), and white-light (mixtures of 2C and 3C) emission from neat films of the compounds as emitting layers.

Idioma: Inglés

DOI: 10.1021/acs.inorgchem.6b02826

Año: 2017

Publicado en: Inorganic Chemistry 56, 9 (2017), 4829-4839
ISSN: 0020-1669

Factor impacto JCR: 4.7 (2017)

Categ. JCR: CHEMISTRY, INORGANIC & NUCLEAR rank: 5 / 44 = 0.114 (2017) - Q1 - T1

Factor impacto SCIMAGO: 1.892 - Chemistry (miscellaneous) (Q1) - Physical and Theoretical Chemistry (Q1) - Inorganic Chemistry (Q1)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E21
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CTQ2015-67461-P

Tipo y forma: Artículo (PostPrint)

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