Ternary Europium Complexes Research Articles

Computational and optoelectronic investigations of red-emissive europium (III) β-diketonate with n-donor ligands for display applications

Europium complexes exhibiting red luminescence were prepared by employing β-diketone as main ligand and 1,10-phenanthroline as an additional ligand. Various methods, including 1H NMR, IR spectroscopy and analysis of optical band gap were employed to examine these complexes. The luminescent photophysical properties were investigated using PL spectroscopy and theoretical calculations were conducted to explore radiative transitions probabilities and Judd-Ofelt (J-O) parameters for transitions of type 5D0 → 7F2, 4. J-O parameters were determined using the JOES computer program and results were in good agreement with the outcomes obtained experimentally. The luminescence analysis results have verified the vibrant, single-color red emission of the prepared complexes. The band gap of ternary europium complexes, determined optically, electronically, and theoretically, falls within the range of 3–4 eV. This similarity indicates that these complexes are potentially suitable as semiconductor materials. The results from absorption, electrochemical and photophysical analyses indicate the potential use of synthesized complexes in lighting and display applications.

Deciphering intersystem crossing and energy transfer mechanisms in a nonacoordinated ternary europium(iii) complex: a combined spectroscopic and theoretical study.

A monochromatic red emitting nonacoordinate organoeuropium complex with the formula [Eu(hfaa)3(Ph-TerPyr)] (Eu-1) incorporating hexafluoroacetylacetone (hfaa) primary ligands and a tridentate 4'-phenyl-2,2':6',2''-terpyridine (Ph-TerPyr) ancillary ligand has been synthesized. The complex was characterized by analytical and spectroscopic methods, and its structure was established by single crystal X-ray diffraction (SC-XRD) analysis at low temperature, which explicitly confirms that the coordination sphere is composed of a EuO6N3 core. Under the UV excitation, Eu-1 displayed typical red emission in solution with a long-excited state lifetime (τ obs = 1048.06 ± 9.39 μs) with a good photoluminescence quantum yield (Q L Eu = 41.14%). We have utilized pump-probe ultrafast transient absorption spectroscopy in tandem with the time-dependent density functional theory (TD-DFT) and the Lanthanide Luminescence Software Package (LUMPAC) to explore the intricate photophysical event that occurs in the vicinity of the ligands of Eu-1 sensitized photoluminescence (PL).

Highly Luminescent Europium(III) Complexes in Solution and PMMA-Doped Films for Bright Red Electroluminescent Devices.

This paper reports the synthesis, structure, photophysical, and optoelectronic properties of five eight-coordinate Europium(III) ternary complexes, namely, [Eu(hth)3(L)2], bearing 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)-1,3-hexanedione (hth) as a sensitizer and L = H2O (1), dpso (diphenyl sulphoxide, 2), dpsoCH3 (4,4'-dimethyl diphenyl sulfoxide, 3), dpsoCl (bis(4-chlorophenyl)sulphoxide, 4), and tppo (triphenylphosphine oxide, 5) as co-ligands. The NMR and the crystal structure analysis confirmed the eight-coordinate structures of the complexes in solution and in a solid state. Upon UV-excitation on the absorption band of the β-diketonate ligand hth, all complexes showed the characteristic bright red luminescence of the Europium ion. The tppo derivative (5) displayed the highest quantum yield (up to 66%). As a result, an organic light-emitting device, OLED, was fabricated with a multi-layered structure-ITO/MoO3/mCP/SF3PO:[complex 5] (10%)/TPBi:[complex 5] (10%)/TmPyPB/LiF/Al-using complex 5 as the emitting component.

Two new red-emitting ternary europium(III) complexes with high photoluminescence quantum yields and exceptional performance in OLED devices.

Two new organo-europium complexes (OEuCs) [Eu(btfa)3(Bathphen)] (OEuC-1) and [Eu(tta)3(Bathphen)] (OEuC-2) where btfa and tta are the anions of 4,4,4-trifluoro-1-phenyl-1,3-butanedione and 2-thenoyltrifluoroacetone while Bathphen = Bathophenanthroline have been synthesized and characterized. Both complexes in the solid state exhibit strong red emissions with photoluminescence quantum yields (PLQYs) of 80% ± 10%. These complexes were tested as dopants in the emitting layer (EML) to fabricate red organic light emitting diodes (R-OLEDs). Through device engineering involving the amalgamation of appropriate host materials and complexes, we have achieved exceptional overall R-OLED performance for an OEuC-2 based device, with maximum current efficiency (CEmax) = 9.91 cd A-1, maximum power efficiency (PEmax) = 9.15 lm W-1, maximum external quantum efficiency (EQEmax.) = 6.24%, brightness (B) of 545 cd m-2, and (CIE)x,y = 0.620, 0.323 at J = 10 mA cm-2.

Highly sensitive and selective gas sensing of methylamine and aniline with a new ternary europium complex material

A new fluorescent amine probe of complex Eu(TTolB)3(Phen) (1) (Phen = 1,10-phenanthroline, TTolB = 4-Trifluoro-1-(4-methylphenyl)−1,3-butanediketonate) is designed and synthesized. Single-crystal X-ray diffraction shows that 1•hexane crystallizes into solvated mononuclear ternary molecules. This material exhibits strong red emission dominated by the Eu3+ (5D0→7F2) transition not only in solid but also in doped film. Based on this probe, a thin film fluorescence sensor with highly sensitive and selective response to aniline and methylamine was developed by PMMA composite and cellulose-paper support. When the sensor was exposed to aniline/methylamine vapor, its photoluminescence (PL) emission showed a sensing behavior of rapid quenching.

Computational and spectroscopic evaluation of 1,10-phenanthroline based Eu(III) fluorinated β-Diketonate Complexes for displays

Highly red luminescent octacoordinated complexes were synthesized by coordination of Eu(III) ion with thenoyltrifluoroacetone (TTA) and heteroaromatic 1,10-phenanthroline derivatives as auxiliary ligands. To examine their photophysical properties, the ternary europium complexes were characterized spectroscopically. The photoluminescence emission spectra of complexes exhibit characteristic peaks of Eu3+ ion attributed to 5D0→7FJ (J = 0–4) transitions in reddish region. Their photoluminescence characteristics clearly specify that ligands have effectively sensitized the trivalent europium ion via antenna effect. Decay time, Judd-Ofelt parameters, transition rates and quantum efficiency were calculated from photoluminescence emission data. Structural and energy transfer parameters were determined from LUMPAC software. Color parameters estimated from photoluminescence spectral data suggest the red luminous behaviour of synthesized complexes. The outcomes ascertain the adaptability of complexes for the fabrication of solid state lighting, OLEDs and flat panel displays when red emission is required for display.

Red emissive ternary europium complexes: synthesis, optical, and luminescence characteristics

Solid ternary europium complexes consisting of fluorinated β-diketone (thenoyltrifluoroacetone, TTFA) and heteroaromatic bidentate auxiliary ligands were synthesized. The luminescence features of the complexes were estimated using various spectral measurements and clearly proved that the Eu3+ ion is efficiently sensitized by ligands by an antenna effect. Photoluminescence excitation spectra have shown that Eu(III) complexes are excited effectively in the ultraviolet (UV) region and the corresponding emission spectra consist of characteristic peaks attributed to the 5 D0 →7 FJ transitions of the europium ion with the strongest emission peak at 611 nm (5 D0 →7 F2 ). From photoluminescence (PL) data, decay time, Judd-Ofelt parameters, transition rates, and quantum efficiency of the complexes were also determined. The Commission Internationale de l'éclairage (CIE) colour coordinates indicated the bright red emission of ternary europium complexes. Correlated colour temperature values indicated the utilization of these complexes in display devices. Judd-Ofelt and photophysical parameters were also estimated theoretically using LUMPAC software. Various frontier molecular orbitals and their respective energy were determined. These red emissive europium complexes could be utilized for fabricating solid-state lighting systems.

2,2′-Bipyridine based fluorinated β-Diketonate Eu(III) complexes as red emitter for display applications

• A series of Eu(III) fluorinated β-diketonate complexes have been synthesized and characterized. • Photophysical parameters were estimated experimentally as well as theoretically via LUMPAC. • Energy of frontier molecular orbitals and global reactivity parameters were estimated. • These conductive ternary europium complexes could be utilized as red emanating materials for display applications. Synthesis and photoluminescence performance of a series of heteroleptic europium complexes with fluorinated chromophoric ligand and 2,2′-bipyridine or their derivatives as ancillary ligand are reported here. The structure of the synthesized complexes was analyzed by various spectroscopic techniques. The photoluminescence emission spectra of complexes show the existence of characteristic peaks corresponding to Eu 3+ ion attributed to 5 D 0 → 7 F J transitions. PL outcomes and color parameters have specified the red emissive nature of prepared complexes. Various photophysical parameters were estimated experimentally and theoretically from LUMPAC software. The structure and energy of various frontier molecular orbitals of the complexes were evaluated. Theoretical parameters estimated by LUMPAC corroborate with experimental data and prove the effectiveness of this method. These conducting and luminous complexes might be utilized as red light emitting materials in various display devices.

A new ternary Eu(III) β‐diketonate complex with diimine ligand and its application as fluorescent probe for highly sensitive and selective ammonia sensor

The rapid and accurate detection of ammonia is very important for manufacture and environmental monitoring, which needs to be developed urgently. Herein, a thin film‐based fluorescence sensor is fabricated by using a ternary europium (III) complex probe for ammonia. The new complex Eu(TPM)3(2‐PBO) (1) was designed and synthesized by utilizing a trifluoromethyl substituted β‐diketone ligand TPM and a diimine ligand 2‐PBO (TPM = 1,1,1‐trifluoro‐5,5‐dimethyl‐2,4‐hexanedione, 2‐PBO = 2‐(2′‐pyridyl)‐benzoxazole). This complex probe was synthetically characterized by elemental analysis, crystallographic and spectroscopic analysis, and photoluminescence (PL) study. The crystallographic analysis revealed complex 1 as a neutral complex structure with the Eu(III) center in a distorted square antiprism EuO6N2 coordination polyhedron. Based on this complex probe, a thin film fluorescence sensor with highly sensitive and selective response to ammonia was developed by polymethyl methacrylate (PMMA): complex composite and cellulose paper support. When the paper‐based sensor was exposed to ammonia, its PL emission showed a sensing behavior of rapid quenching. Surprisingly, this new method can achieve excellent limit of detection as low as 2.740 × 10−6 ppm.

Red luminous ternary europium complexes: Optoelectronic and photophysical analysis

Four luminescent ternary europium complexes of general formula Eu(PBD)3L were synthesized and characterized. Here, L represents auxiliary unit (2,2′-bipyridine and its derivatives) and PBD (1-phenyl-1,3-butanedione) is an organic chromophoric ligand. Elemental composition and complexation has been estimated by elemental and spectroscopic studies. Photoluminescence emission spectra clearly indicate the chromophoric nature of diketone ligand that has effectively sensitized the energized level of Eu3+ ion through antenna effect. The detailed photophysical parameters of the complexes were evaluated theoretically and experimentally. Theoretical parameters were estimated via LUMPAC software and their outcomes were found to be in good concurrence with experimentally derived data. Luminescence decay curve were recorded by monitoring the wavelength corresponding to hypersensitive 5D0→7F2 transition. Geometry of the complexes was resolved via Avogadro software. Colorimetric and photoluminescence spectral analyses suggest the red luminous nature of ternary europium complexes. These red emissive materials might be utilized in designing display devices.

Red luminous Eu(III) complexes: Preparation, spectral, optical and theoretical evaluation

A series of luminous europium complexes were synthesized with general formula Eu(DAM)3L; DAM symbolizes diacetylmethane and L refers to the substituted 1,10-phenathroline derivatives. Results of spectral analyses affirm the binding of Eu3+ ion with DAM and heteroaromatic auxiliary units via oxygen and nitrogen atoms respectively. From Tauc’s plot, optical band gap was determined which shows the conducting behavior of synthesized complexes. Energy transfer mechanism reveals the effective sensitization of Eu3+ ion via antenna effect. Photoluminescence emission spectra have displayed most intense peak at ∼612 nm corresponding to 5D0→7F2 electric dipole transition. Synthesized ternary europium complexes exhibit red emission which is further confirmed by the position of chromaticity coordinates in CIE triangle. Structure and energy of various frontier molecular orbitals were determined computationally. These thermally stable red emissive complexes could be utilized in solid state lighting and displays.

Luminescent Features of Ternary Europium Complexes: Photophysical and Optoelectronic Evaluation.

Trivalent europium complexes exhibit good luminescent characteristics. A series of octacoordinated ternary europium complexes with fluorinated diketone and heteroaromatic auxiliary unit were synthesized. The synthesized europium complexes were characterized by elemental, thermal, electrochemical and spectroscopic analyses. Band gap values lie in range of semiconductors which confirm the conducting behavior of prepared complexes. Photoluminescence spectra were recorded in solid state and DMSO solvent. Emission spectral profiles have displayed most intense peak at ~ 612nm corresponding to hypersensitive 5D0 → 7F2 transition. Colorimetric parameters suggest red luminous nature of europium complexes. The luminescent heteroleptic europium complexes might be utilized as emissive materials for fabricating display.

Influence of coordinating environment on photophysical properties of UV excited sharp red emitting material: Judd Ofelt analysis

The photophysical and optoelectronic characteristics of a series of ternary europium complexes having general formula [Eu(TFNB)3L] were estimated in detail. The synthesized octa coordinated complexes have different heteroaromatic ancillary ligand (L) i.e., 1,10-phenanthroline (Phen) derivatives. The synthesized heteroleptic europium complexes were thoroughly characterized by various techniques. Photoluminescence emission spectra specify that β-diketone ligand has efficiently sensitized Eu (III) ion through antenna effect which results in excellent luminescent intensity and long decay time. Most intense peak accredited to 5D0→7F2 is accountable for red luminescence of complexes. By investigating the PL emission data, CIE color coordinates were calculated which indicates that subsequent complexes give emission in red region. The Judd-Ofelt parameters of trivalent europium complexes were calculated and also derived theoretically via computational methods. The higher value of hypersensitive electric dipole Ω2 intensity parameter displays the existence of highly polarizable chemical environment around central metal ion. Red light emanating materials might have found good significance in solid state electronics, flat panel devices and OLEDs.

Heteroleptic luminous ternary europium Complexes: Synthesis, electrochemical and photophysical investigation

We have synthesized a series of heteroleptic luminescent europium moieties based on 1,10-phenanthroline and its derivatives (L) namely Eu(BAP)3L; BAP = 2-benzoylacetophenone. The structural inspection of complexes was done by several spectroscopic techniques. Energy band gap values of complexes lie in region of semiconductors. Metal-ligand interaction results a notable effect on the η (quantum efficiency) and Ω2 (JO parameters) of the prepared complexes. A detailed explanation about photophysical characteristics of the complexes was studied via theoretical and experimental methods. With the help of LUMPAC, theoretical photophysical properties were calculated and discovered to be in good concurrence with experimental values. The hypersensitive electric dipole peak positioned at 612 nm (5D0→7F2) is reasonable for the red emission. The color coordinates are also situated in the red region of CIE triangle. Therefore, these efficient materials could be utilized as red emanating material in designing various display devices.

Red-emitting β-diketonate Eu(III) Complexes With Substituted 1,10-phenanthroline Derivatives: Optoelectronic and Spectroscopic Analysis.

A series of europium diketonate complexes with 1-phenyl-1,3-butanedione (PBD) and 1,10-phenanthroline derivatives were synthesized and explored spectroscopically. Photophysical characteristics of synthesized complexes have been investigated experimentally as well as theoretically. Photoluminescence emission spectra of complexes do not contain any peak of ligand revealing efficient transferal of energy from ligand to Eu3+ ion. Presence of peak at 611nm corresponding to 5D0 → 7F2 transition is responsible for red emanation of ternary europium complexes. Photophysical parameters viz., Judd-Ofelt, quantum efficiency, radiative and non radiative decay rates were also estimated theoretically from LUMPAC software. Geometry optimization of complexes was done via Avogadro software. All synthesized trivalent complexes exhibit red emission which was further sustained by the position of chromaticity coordinates in CIE triangle. These red emanating materials could be utilized in designing electroluminescent display devices.

Synthesis, photophysical characteristics and geometry optimization of Tris(2-benzoylacetophenonate)europium complexes with 2, 2′-Bipyridine derivatives

A series based on octa coordinated tris(2-benzoylacetophenonate)europium complexes were synthesized with bidentate heteroaromatic auxiliary ligands. 2,2′-Bipyridine (Bpy) and its derivatives synthesized in the laboratory were used as auxiliary ligands. The structural analysis of synthesized materials was done by various spectroscopic techniques. Their photoluminescent characteristics specified the effective sensitization of trivalent europium ion via antenna effect. As an outcome of this sensitization, these complexes demonstrate good luminescence intensity, high quantum efficiency and long luminescence lifetime. The CIE chromaticity coordinates (x, y and u’, v’) were designed to indicate bright red emission. Luminescence decay time data were calculated by investigating the λem well-suited with the transition of the type 5D0→7F2. The molecular parameters of the geometrically optimized complexes were derived from the semi-empirical Sparkle/RM1 method. Theoretical Judd-Ofelt and photophysical parameters were estimated by LUMPAC software ascribed with experimental data, indicating the efficacy of this method. Furthermore, these luminous ternary europium complexes can be utilized as red light emitting material in designing flat panel displays and various optoelectronic devices.

Synthesis and photophysical properties of ternary β-diketonate europium(III) complexes incorporating bipyridine and its derivatives

Two new octa-coordinated ternary europium(III) complexes of the type [Eu(btfa)3(Br2-bpy)] (Eu-1) and [Eu(btfa)3(PhE2-bpy)] (Eu-2) (where btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedione, Br2-bpy = 5,5′-dibromo-2,2′-bipyridine, PhE2-bpy 5,5′-bis(phenylethynyl)-2,2′-bipyridine) together with a previously reported complex [Eu(btfa)3(bpy)] (Eu-3) have been synthesized. The complexes have been characterized by analytical and spectroscopic methods. The photophysical properties of the complexes have also been analyzed both experimentally and theoretically. The contribution of each ligand to the sensitized Eu(III) photoluminescence (PL) has been analyzed and is discussed. An energy transfer (ET) mechanism is proposed and discussed for the sensitized Eu(III) emission using experimental and theoretical data. The Eu(III) complex incorporating the parent bpy showed impressive performance as a double-emitting layer (EML) red organic light emitting diodes (R-OLEDs).

Preparation and Luminous Performance of Ternary Complexes of Rare Earth Europium (III)

Using Eu2O3 as source of tritium, anhydrous ethanol as solvent system, three β-diketone compounds of 2-thienyl trifluoroacetone (TTA), acetylacetone (Hacac), 1-(4-Methoxyphenyl)- 3-(4-tert-butylphenyl)-1,3-propanedione (Avobenzone) as first ligand and 1,10-phenanthroline (Phen) as second ligand, the three kinds europium (III) ternary complexes were prepared by precipitation method at 60 °C. The complexes were characterized by fluorescence spectroscopy (FS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry and differential scanning calorimetry (TG-DSC) and color coordinates. The results show that three red light-emitting europium (III) ternary complexes can emit strong red characteristic fluorescence. Thereinto, Eu(TTA)3Phen has the best luminescent performance. The excitation spectrum of Eu(TTA)3Phen is 395 nm, the characteristic emission peak is at 612 nm, and the color coordinate is (0.66, 0.34). Eu(TTA)3Phen show good thermal stability which is decomposed more than 200 °C.

Synthesis and Characterization of Eu3+ + 2-thenoyltrifluoroacetone + triphenylphosphine Oxide Ternary Complex

Rare earth europium ion (Eu3+) can emit red characteristic fluorescence under UV excitation and is preferred for the preparation of red phosphors for near-UV white LEDs. In this paper, the effects of solvent, reflux time and preparation method on the preparation of europium ternary complexes were studied with europium ion as the central coordination ion, 2-thenoyltrifluoroacetone as the first ligand and triphenylphosphine oxide as the second ligand. The results showed that the better reaction solvent was anhydrous ethanol and the better reflux time was 8 hours. Both the common synthesis method and the solvothermal method could successfully synthesize the europium ternary complex, and the solvothermal method has a higher yield. The europium ternary complex was characterized by inductively coupled plasma emission spectroscopy, element analysis and infrared spectroscopy, and it was proved that the europium complex could emit a strong characteristic red fluorescence of europium with the structure of Eu(TTA)3(TPPO)2 in 1:3:2 coordination ratio.

Bright and efficient red emitting electroluminescent devices fabricated from ternary europium complexes

[Eu(btfa)3DPEPO] and [Eu(nta)3DPEPO] are bright, red emitting complexes. They have been incorporated into single and double emitting layer electroluminescent devices.