Synthesis and Photoluminescence Properties of Heteroleptic Europium(III) Complexes with Appended Carbazole Units

A new aromatic carboxylate ligand, 4-[4-(9H-carbazol-9-yl)butoxy]benzoic acid (HL), has been synthesized by the replacement of the hydroxyl hydrogen of 4-hydroxy benzoic acid with a 9-butyl-9H-carbazole moiety. The anion derived from HL has been used for the support of a series of lanthanide coordination compounds [Ln = Eu (1), Gd (2) and Tb (3)]. The new lanthanide complexes have been characterized by a variety of spectroscopic techniques. Complex 3 was structurally authenticated by single-crystal X-ray diffraction and found to exist as a solvent-free 1D coordination polymer with the formula [Tb(L) 3 ] n . The structural data reveal that the terbium atoms in compound 3 reside in an octahedral ligand environment that is somewhat unusual for a lanthanide. It is interesting to note that each carboxylate group exhibits only a bridging-bidentate mode, with a complete lack of more complex connectivities that are commonly observed for extended lanthanide-containing solid-state structures. Examination of the packing diagram for 3 revealed the existence of two-dimensional molecular arrays held together by means of CH-π interactions. Aromatic carboxylates of the lanthanides are known to exhibit highly efficient luminescence, thus offering the promise of applicability as optical devices. However, due to difficulties that arise on account of their polymeric nature, their practical application is somewhat limited. Accordingly, synthetic routes to discrete molecular species are highly desirable. For this purpose, a series of ternary lanthanide complexes was designed, synthesized and characterized, namely [Eu(L) (6) and [Tb(L) 3 (tmphen)] (7) ( phen = 1,10-phenanthroline and tmphen = 3,4,7,8-tetramethyl-1,10-phenanthroline). The photophysical properties of the foregoing complexes in the solid state at room temperature have been investigated. The quantum yields of the ternary complexes 4 (9.65%), 5 (21.00%), 6 (14.07%) and 7 (32.42%), were found to be significantly enhanced in the presence of bidentate nitrogen donors when compared with those of the corresponding binary compounds 1 (0.11%) and 3 (1.45%). Presumably this is due to effective energy transfer from the ancillary ligands.

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“…Tb(L) 3 (tmphen) (7). Elemental analysis (%): calcd for C 85 H 76 TbN 5 O 9 (1470.46): C, 69.43;H, 5.21;N, 4.76;found C, 69.18;H, 5.27;N, 5.23.…”

Section: 10mentioning

confidence: 99%

“…Moreover, there is an increase of solubility in common organic solvents. 7 The newly synthesized lanthanide benzoates have been fully characterized and their luminescent properties have been investigated in detail.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, crystal structure and photophysical properties of lanthanide coordination polymers of 4-[4-(9H-carbazol-9-yl)butoxy]benzoate: the effect of bidentate nitrogen donors on luminescence

et al. 2012

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“…Several d-block metal complexes, from popular Ir(III) (d 6 ) [8], Ru(II) (d 6 ) [9] and Pt(II) (d 8 ) [10] to unconventional Cu(I) [11], Ag(I) [12] and Au(I) [13] (d 10 ), have been photophysically investigated and tested in devices. On the other hand, also rare earth elements (f-block) are suitable candidate as emitters in devices thanks to their (i) relative abundance [14], (ii) color purity due to intense line-like emission bands [15], (iii) versatile coordination chemistry [7] and (iv) multiplet nature of the f-f electronic transitions leading to an efficient conversion in electroluminescence (EL) [16].…”

Section: Introductionmentioning

confidence: 99%

“…The synthesis of brightly emitting metal complexes for the preparation of organic light emitting devices (OLEDs) [1] has become an intense area of research activity during the last 15 years [2][3][4][5][6][7]. Several d-block metal complexes, from popular Ir(III) (d 6 ) [8], Ru(II) (d 6 ) [9] and Pt(II) (d 8 ) [10] to unconventional Cu(I) [11], Ag(I) [12] and Au(I) [13] (d 10 ), have been photophysically investigated and tested in devices.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and photoluminescence properties of heteroleptic Eu3+, Tb3+ and Tm3+ complexes

Accorsi

Armaroli

Cardinali

et al. 2009

Journal of Alloys and Compounds

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“…9,10 Recentemente, uma nova classe de ligantes orgânicos, os derivados carbazólicos, passaram a ser estudados como bons transferidores de energia para íons TR 3+ . [11][12][13][14] Bo et al 12 estudaram o comportamento luminescente de complexos de [Tb(czb) 3 (H 2 O) 2 ] e [Eu(czb) 3 (H 2 O) 2 ] (em que czb corresponde ao ligante aniônico 4-(9H-carbazol-9-il) benzoato), observando uma eficiente transferência de energia do czb para o Tb 3+ . Nesse caso, a obtenção da energia do estado triplete do ligante foi realizada utilizando o benzoato de sódio.…”

Section: Introductionunclassified

Estudos fotoluminescentes em compostos de íons terras raras coordenados por um derivado carbazólico

Martins¹,

Neri²,

Filho³

et al. 2010

Quím. Nova

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Recebido em 30/6/10; aceito em 6/10/10; publicado na web em 3/11/10 PHOTOLUMINESCENCE STUDIES IN RARE EARTH IONS COORDINATED BY A CARBAZOLIC DERIVATIVE.[ RE(czb) ; and czb = 4-(9H-carbazol-9-yl)benzoato) have been synthesized and characterized. The Gd 3+ complex was used to determine the triplet state energy of the czb ligand. Photoluminescence measurements of the complexes have been carried out under UV excitation. The Tb 3+ complex exhibited a strong green luminescence indicating an efficient antenna effect, whereas the Eu 3+ complex showed low red luminescence and the Gd 3+ complex a blue-green luminescence from the ligand. The luminescence lifetimes and quantum yields have also been measured for the evaluation of the spectroscopic behavior of the complexes.Keywords: rare earth; luminescence; carbazolic ligand. INTRODUÇÃOLuminóforos de terras raras (TR) vêm sendo intensamente estudados e utilizados para produzir luz visível monocromática ou branca nas chamadas lâmpadas "fluorescentes". Destaca-se ainda seu uso em vários dispositivos de visualização como em computadores, telefones celulares, radares, detectores de radiação, dentre outros.1 Os íons de terras raras complexados a ligantes orgânicos podem apresentar a intensificação das emissões características nos estados 4f. O ligante cromóforo absorve luz como resultado de uma transição eletrônica do estado singlete fundamental (S 0 ) para estados singlete excitados (S n ). Em determinadas situações dos estados S n , geralmente do S 1 , o ligante relaxa de forma não radiativa passando para um estado triplete excitado (T 1 . Nesse caso, a obtenção da energia do estado triplete do ligante foi realizada utilizando o benzoato de sódio.Em sistemas contendo íons TR 3+ , frequentemente se utilizam os espectros de emissão dos complexos de gadolínio, normalmente a baixa temperatura (minimizando efeitos vibracionais), para a determinação do estado triplete T 1 de ligantes.10 O nível excitado de mais baixa energia do Gd 3+ ( 6 P 7/2 , ~32000 cm -1 ) apresenta energia mais elevada do que o estado T 1 de grande maioria dos ligantes. Por apresentar elevado paramagnetismo (S=7/2) e efeito de átomo pesado, o Gd 3+ pode induzir um forte cruzamento intersistema singlete/ triplete em seus ligantes e, consequentemente, uma maior taxa de população do estado triplete. Pelo acoplamento spin-órbita, o estado triplete adquire um caráter singlete parcial e as regras de seleção não são obedecidas completamente, resultando em uma intensificação da fosforescência. [15][16][17][18] Neste trabalho, estudos envolvendo a determinação da energia do estado triplete T 1 do ligante czb foram realizados a partir do complexo [Gd(czb) PARTE EXPERIMENTAL Síntese dos compostosA preparação do ácido 4-(9H-carbazol-9-il)benzoico (Hczb) foi realizada em duas etapas reacionais através do método reportado por Wu et al.(Esquema 1).

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Synthesis and Photoluminescence Properties of Heteroleptic Europium(III) Complexes with Appended Carbazole Units

Cited by 29 publications

References 38 publications

Synthesis, crystal structure and photophysical properties of lanthanide coordination polymers of 4-[4-(9H-carbazol-9-yl)butoxy]benzoate: the effect of bidentate nitrogen donors on luminescence

Synthesis, crystal structure and photophysical properties of lanthanide coordination polymers of 4-[4-(9H-carbazol-9-yl)butoxy]benzoate: the effect of bidentate nitrogen donors on luminescence

Synthesis and photoluminescence properties of heteroleptic Eu3+, Tb3+ and Tm3+ complexes

Estudos fotoluminescentes em compostos de íons terras raras coordenados por um derivado carbazólico

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