Hypersensitivity in the Luminescence and 4f?C4f Absorption Properties of Mono- and Dinuclear EuIII and ErIII Complexes Based on Fluorinated ??-Diketone and Diimine/ Bis-Diimine Ligands

The results of our investigation on the sensitized luminescence properties of three Eu(III) ??-diketonate complexes of the form [Eu₂(fod)₆(??-bpm)], [Eu(fod)₃(phen)] and [Eu(fod)₃(bpy)] and 4f?C4f absorption properties of their Er(III) analogues ( fod = anion of 6,6,7,7,8,8,8- heptafluoro-2,2-dimethyl-3,5-octanedione, bpm = 2,2??-bipyrimidine, phen = 1,10-phenanthroline and bpy = 2,2??-bipyridyl) in a series of non-aqueous solvents are presented. The Eu(III) complexes are highly luminescent and their luminescence properties (intensity and band shape) are sensitive to the changes in the inner coordination sphere of the Eu(III) ion. The luminescence intensity of the mononuclear complexes in pyridine is drastically decreased. The coordination structure of the complexes in pyridine is transformed into a more symmetrical one which results into a slow radiative rate of the emission from the complexes. The ancillary ligands, phen and bpy are found better co-sensitizers as compared to the bpm to sensitize Eu(III)-luminescence. The 4f?C4f absorption properties (oscillator strength and band shape) of the Er(III) complexes demonstrate that ⁴G_11/2 ?? ⁴I_11/2 and ²H_11/2 ?? ⁴I_15/2 hypersensitive transitions of Er(III) are very sensitive in some coordinating solvents which reflects complex?Csolvent interaction in solution. The hypersensitive transitions of [Er(fod)₃(phen)] remain unaffected in any of the solvents and this complex retains its bulk composition in solution. The erbium complexes as well as the Er(fod)₃ chelate are invaded by DMSO. This solvent enters the inner coordination sphere by replacing heterocyclic ligand and the complexes acquire similar structure [Er(fod)₃(DMSO)₂] in this solvent. The results reveal that the luminescence and absorption properties of lanthanide complexes in solution can be controlled by tuning the coordination structure through ancillary ligands and donor solvents. This work shall prove useful in designing new biological applications with such probes.     

Structural Investigation and Photoluminescent Properties of Gadolinium(III), Europium(III) and Terbium(III) 3-Mercaptopropionate Complexes

This work reports on the synthesis, crystallographic determination and spectroscopic characterization of gadolinium(III), terbium(III) and europium(III) 3-mercaptopropionate complexes, aqua-tris(3-mercaptopropionate)lanthanide(III) - [Ln(mpa)₃(H₂O)]. The Judd-Ofelt intensity parameters were experimentally determined from emission spectrum of the [Eu(mpa)₃(H₂O)]complex and they were also calculated from crystallographic data. The complexes are coordination polymers, where the units of each complex are linked together by carboxylate groups leading to an unidimensional and parallel chains that by chemical interactions form a tridimensional framework. The emission spectrum profile of the [Eu(mpa)₃(H₂O)] complex is discussed based on point symmetry of the europium(III) ion, that explains the bands splitting observed in its emission spectrum. Photoluminescent analysis of the [Gd(mpa)₃(H₂O)] complex show no efficient ligand excitation but an intense charge transfer band. The excitation spectra of the [Eu(mpa)₃(H₂O)] and [Tb(mpa)₃(H₂O)] complexes do not show evidence of energy transfer from the ligand to the excited levels of these trivalent ions. Therefore the emission bands are originated only by direct f-f intraconfigurational excitation of the lantanide(III) ions.     

Structural and luminescence properties of [Ln(ODA)(phen)·4H2O] complexes (Ln=Sm and Dy, ODA=oxydiacetate, phen=1,10-phenanthroline)

Two novel complexes of Sm(III) and Dy(III) with mixed oxydiacetate (ODA) and 1,10-phenanthroline (phen) ligands were synthesized and their structure and luminescence properties were characterized. The complexes of [Ln(ODA)(phen)·4H₂O]Cl·5H₂O [Ln=Sm and Dy] crystallize in the monoclinic space group P2₁/n with Sm: a=12.3401(14) Å, b=16.821(2), c=12.6847(11) Å, β=107.939(10)°, V=2505.0(5) Å³, Z=4 and ρ=1.841 mg/m³, and with Dy: a=12.289(7) Å, b=16.805(6) Å, c=12.705(4) Å, β=108.144(18)°, V=2493.4(19) Å³, Z=4 and ρ=1.786 mg/m³. The complexes of [Sm(ODA)(phen)·4H₂O]⁺ and [Dy(ODA)(phen)·4H₂O]⁺ excited by UV light produce orange red and lightly white emissions, respectively, via the nonradiative energy transfer from phen to the metals. The quantum yield of the sensitized luminescence of [Dy(ODA)(phen)·4H₂O]⁺ (Q=19%) is much greater than that of [Sm(ODA)(phen)·4H₂O]⁺ (Q=1.4%). The luminescence decay times of the complexes were in a few microsecond range and independent of temperature.     

Synthesis and Photoluminescent Properties of Lanthanides Acetoacetanilide Complexes

This work reports on the photoluminescent properties of three new lanthanide complexes with acetoacetanilide (aaa), a β-diketonate ligand. The complexes have the general molecular formulae [RE(aaa)₃(H₂O)], they are soluble in organic solvents such as ethanol and chloroform and insoluble in water. The energy of the triplet state was determined at about 4,700 cm^?1 higher than the ⁵D₄ emitting level of the Tb(III) ion, leading to an absolute quantum yield of 22 % for the [Tb(aaa)₃(H₂O)] complex. The photoluminescent properties were studied and the luminescence parameters of the [Eu(aaa)₃(H₂O)] complex were experimentally determined. The photostabilities of the complexes under continuous UV irradiation were measured and the data indicate low stability of the [Tb(aaa)₃(H₂O)] complex when the system is excited at the band attributed to energy transfer from the ligand to terbium(III) ion. However, its photostability is significantly improved under inert atmosphere.     

Syntheses and Fluorescence Properties of Two Novel Lanthanide (III) Perchlorate Complexes with Bis(benzylsulfinyl)methane

A novel ligand with double sulfinyl groups, bis(benzylsulfinyl)methane, was synthesized by a new method and its two lanthanide (III) complexes were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis, IR, TG-DSC, ¹HNMR and UV spectra. The results indicated that the composition of these complexes was REL_2.5(ClO₄)₃·3H₂O (RE = Tb (III), Dy (III), L = C₆H₅CH₂SOCH₂SOCH₂C₆H₅). The FT-IR results revealed that the perchlorate group was bonded with the lanthanide ion by the oxygen atoms, and the coordination was bidentate. The fluorescent spectra illustrated that both the Tb (III) and Dy (III) complexes displayed characteristic fluorescence in solid state, especially for the Tb (III) complex, the peak of ⁵D₄ → ⁷ F₅ of the Tb (III) ion in 544 nm was stronger than that of others. It indicated that the Tb (III) complex could emit purer green fluorescence. By analysis fluorescence and phosphorescence spectra, it was found that the ligand had the advantage to absorb energy and transfer it to the Tb (III) and Dy (III) ions. The phosphorescence spectra and fluorescence lifetimes of the complexes were also measured.     

Efficient Sensitized Luminescence of Binuclear Ln(III) Complexes Based on a Chelating Bis-Carbacylamidophosphate

Binuclear rare earth complexes Ln₂L₃phen₂ (Ln^III?=?Nd^III, Sm^III, Eu^III, Tb^III, Dy^III, Yb^III and Y^III) with bis-CAPh type ligand - tetramethyl N,N′-(2,2,3,3,4,4-hexafluoro-1,5-dioxopentane-1,5-diyl)bis(phosphoramidate) (H₂L) and 1,10-phenanthroline (phen) were synthesized and characterized by elemental analysis, IR, NMR, absorption and luminescence spectroscopy. Luminescence measurements were performed for all the complexes in solid state and for the Eu^III, Tb^III and Y^III complexes - in solution in DMSO as well. The effective energy transfer from organic ligands to Ln^III ions strongly sensitizes the Ln^III ions emission and under excitation by UV light, the complexes exhibited bright characteristic emission of lanthanide metal centers. It was found that the energy level of the ligands lowest triplet state in the complexes matches better to resonance level of Eu^III rather than Tb^III ion. Depending on temperature the emission decay times of solid europium and terbium complexes were in the range of 1.5–2.0 ms. In solid state at room temperature the Eu^III complex possess intense luminescence with very high intrinsic quantum yield 91% and decay time equal 1.88 ms.

     

Spectroscopic studies of the lanthanide(III) ions with pyridine carboxylic acid N-oxide ligands and in mixed ligand complexes

A series of Ln(III) complexes with pyridine carboxylic acid-N-oxides (L) Ln-L, and mixed ligand complexes of Ln-L plus bipyridine (bipy) or 1,10-phenanthroline (O-phen) (X) Ln-L-X have been studied. These complexes were characterized in solution using Nd(III) absorption in the spectral range of the ⁴I_9/2 → ⁴G_5/2 transition corresponding to the hypersensitive band, and in the solid state with the use of IR and Eu(III) luminescence spectroscopy. In solutions a series of Nd(III) complexes and mixed ligand complexes has been examined and the formation of binary LnL and LnL₂ complexes and mixed ligand LnL₂X complexes evidenced. Solid complexes of Eu(III) with nicotinic acid N-oxide and ternary with nicotinic acid N-oxide plus phen were studied with the use of Eu(III) luminescence lifetime measurements and IR spectroscopy, proving the formation of binary [Eu(nicN-oxide)₃(H₂O)₂].2H₂O and ternary [Eu(nicN-oxide)₃phen].H₂O complexes.     

稀土配合物RE(Et2dtc)3(phen)的光谱性质

以铜试剂(NaEt2 dtc·3H2O)和邻菲咯啉(o-phen·H2O)与水合氯化稀土(RECl3·xH2O)(RE=La,Pr,Nd,Sm～Er;x=3～4)在无水乙醇中反应,制得三元固态配合物RE(Et2dtc)3(phen).IR光谱研究表明配合物中RE3+与NaEt2dtc中的硫原子和o-phen中的氮原子均双齿配位;UV光谱显示配合物中o-phen与稀土离子之间的能量传递是主要过程,配合物的最大吸收与o-phen相比有微小的红移;FS光谱表明配合物Sm(Et2dtc)3(phen)和Eu(Et2dtc)3(phen)分子内能量传递效率高,显示了很强的荧光性质.     

Synthesis and luminescence of Eu(III) complexes with macrocyclic azacrown ethers and 1,10-phenanthroline

Complexes of Eu(III) with mixed macrocyclic azacrown ethers and 1,10-phenanthroline (phen) were synthesized and their luminescence properties measured. The specific azacrown ethers used were 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetate (TETA) and 1,4,8,12-tetraazacyclopentadecane ([15]aneN₄). The phen-coordinated complexes excited by UV light produced a very bright red emission via an intra-molecular energy transfer from phen to Eu(III). For [Eu(TETA)·(phen)·(H₂O)]⁻ and [Eu([15]aneN₄)·(phen)₂]³⁺, the quantum yields of sensitized luminescence were 8.4% and 7.8%, respectively, and were much greater than those from non-sensitized luminescence of 1.2% and 4.4%, respectively. The decay times of the corresponding phen-coordinated complexes, as measured at room temperature, were 1.6 and 0.6 ms, respectively, and were much longer than those of the phen-uncoordinated complexes of 0.3 and 0.2 ms, respectively.     

Synthesis and Luminescent Properties of Lanthanide Complexes with Structurally Related Novel Multipodal Ligands

To explore the relationship between the structure of the ligands and the luminescent properties of the lanthanide complexes, a series of lanthanide nitrate complexes with two novel structurally related multipodal ligands, 1,3-bis{[(2’-(2-picolylaminoformyl))phenoxyl]methyl}benzene (L ^I ) and 1,2-bis{[(2’-(2-picolylaminoformyl))phenoxyl]methyl}benzene (L ^II ), have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Eu(III) and Tb(III) nitrate complexes in solid state and the Tb(III) nitrate complexes in solvents were investigated at room temperature. Under the excitation of UV light, these complexes exhibited characteristic emissions of central metal ions. The lowest triplet state energy levels T₁ of these ligands both match better to the lowest resonance energy level of Tb(III) than to Eu(III) ion. The influence of the structure of the ligands on the luminescent intensity of the complexes was also discussed.     

Relative Study of Luminescent Properties with Judd-Ofelt Characterization in Trivalent Europium Complexes Comprising ethyl-(4-fluorobenzoyl) Acetate

Five new europium(III) complexes Eu(p-EFBA)₃.(H₂O)₂ (C1), Eu(p-EFBA)₃.neo (C2), Eu(p-EFBA)₃.batho (C3), Eu(p-EFBA)₃.phen (C4), Eu(p-EFBA)₃.bipy (C5) have been synthesized by using ethyl-(4-fluorobenzoyl) acetate (p-EFBA) as β-ketoester ligand and neocuproine (neo), bathophenanthroline (batho), 1,10-phenanthroline (phen) and 2,2-bipyridyl (bipy) as ancillary ligands. The synthesized complexes C1-C5 were characterized by elemental analysis, nuclear magnetic resonance spectroscopy (¹H-NMR), infrared (IR) spectroscopy, thermogravimetric analysis (TG/DTG), UV-visible and photoluminescence (PL) spectroscopy. The relative study of luminescence spectra of complexes with the previously reported complexes of isomeric ligand (ortho and meta substituted ligand) indicate the higher luminescence properties of complexes as an effect of fluorine position on β-ketoester ligand. The para substituted ligand shows a remarkable effect on quantum efficiencies and Judd-Ofelt intensity parameters (Ω_2, Ω₄) of the complexes. The higher value of intensity parameter Ω₂ associated with hypersensitive ⁵D₀ → ⁷F₂ transition of europium(III) ion revealing highly polarizable ligand field. The purposed energy transfer mechanism of complexes indicates the efficient energy transfer in complexes.     

Synthesis and Fluorescence Properties of Lanthanide (III) Perchlorate Complexes with Bis(benzoylmethyl) Sulfoxide

A ligand with two carbonyl groups and one sulfinyl group has been synthesized by a new method and its several lanthanide (III) complexes were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis, IR, TG-DSC, ¹H NMR and UV spectra. The results indicated that the composition of these complexes is REL₅(ClO₄)₃·3H₂O (RE = La(III), Pr(III), Eu(III), Tb(III), Yb(III), L = C₆H₅COCH₂SOCH₂COC₆H₅). The fluorescent spectra illustrate that both the Tb (III) and Eu (III) complexes display characteristic metal-centered fluorescence in solid state, indicating the ligand favors energy transfer to the excitation state energy level of them. However, the Tb (III) complex displays more effective luminescence than the Eu (III) complex, which is attributed to especial effectively in transferring energy from the average triplet energy level of the ligands (T) onto the excited state (⁵D₄) of Tb (III) than that (⁵D₀) of Eu (III), showing a good antenna effect for Tb(III) luminescence. The phosphorescence spectra and the relationship between fluorescence lifetimes and fluorescence intensities were also discussed.     

Photoluminescence, optical absorption and hypersensitivity in mono- and dinuclear lanthanide (Tb and Ho) β-diketonate complexes with diimines and bis-diimine bridging ligand

The photoluminescence properties of three Tb(III) complexes of the form [Tb₂(fod)₆(μ-bpm)], [Tb(fod)₃(phen)] and [Tb(fod)₃(bpy)] and optical absorption properties of their Ho(III) analogues (fod=anion of 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione, bpm=2,2′-bipyrimidine, phen=1,10-phenanthroline and bpy=2,2′-bipyridyl) in a series of solvents are presented. The luminescence of the complexes is sensitive to changes in environment (ligand/solvent) around Tb(III) and co-sensitization of the ancillary ligands. The enhancement of the luminescence intensity in coordinating solvents is attributed to the transformation of eight-coordination into less symmetric nine-coordination structure around Tb(III). Among phen and bpy, the phen is better co-sensitizer while bpm has been observed as poor co-sensitizer. The enhancement of the oscillator strength of ⁵G₆←⁵I₈ hypersensitive transition in the 4f-4f absorption in some coordinating solvents is attributed to decrease in the symmetry of the field around Ho(III) ion. The [Ho(fod)₃(phen)] is inert towards the solvents and retains its bulk structure and composition in solution. The transformation of the holmium complexes in DMSO into [Ho(fod)₃(DMSO)₂] species is found. The results reveal that the luminescence and 4f-4f absorption properties of lanthanide complexes in solution can be modulated by tuning the coordination structure through ancillary ligands and donor solvents.     

Mononuclear Co(III) and Ni(II) Complexes with Polypyridyl Ligands, [Co(phen)2(taptp)]3+ and [Ni(phen)2(taptp)]2+: Synthesis, Photocleavage and DNA-binding

Two novel, mixed ligand complexes of cobalt(III) and nickel(II), [Co(phen)₂(taptp)]³⁺ (1) and [Ni(phen)₂(taptp)]²⁺ (2) (phen = 1,10-phenanthroline and taptp = 4,5,9,18-tetraazaphenanthreno [9,10-b]triphenylene), were synthesized and characterized by elemental analyses, UV-visible and NMR spectroscopies. The binding interactions of the two complexes with DNA have been investigated using absorption and emission spectroscopy methods and electrophoresis measurement mode. The intrinsic binding constants for these complexes to DNA are in the order of 10⁵. In Tris buffer, the Co(III) complex shows a moderate luminescence which was enhanced after binding to DNA. However for complex Ni(II), no emission was observed in Tris buffer. The [Co(phen)₂(taptp)]³⁺ and [Ni(phen)₂(taptp)]²⁺ can cause the photocleavage of DNA supercoiled pBR322 upon irradiation by 360 nm light. Based on the data, an intercalative mode of DNA binding is suggested for the two complexes.     

Fluorescence enhancement of lanthanide(III) perchlorate by 1,10-phenanthroline in bis(benzoylmethyl) sulfoxide complexes and luminescence mechanism

Two novel ternary rare earth complexes LnL₅L′(ClO₄)₃2H₂O (Ln=Eu(III), Tb(III); L=bis(benzoylmethyl) sulfoxide, L′=phen) were synthesized and characterized by elemental analysis, coordination titration analysis, molar conductivity, IR, TG-DSC,¹H NMR and UV spectra. The fluorescence spectra illustrated that both the Eu(III) and Tb(III) ternary complexes displayed strong characteristic metal-centered fluorescence in solid state. After the introduction of the second ligand phen group, the relative emission intensities and fluorescence lifetimes of the ternary complex EuL₅L′(ClO₄)₃2H₂O (L=C₆H₅COCH₂SOCH₂COC₆H₅, L′=phen) enhanced more obviously than that of the binary complex EuL₅(ClO₄)₃3H₂O. This indicated that the presence of both organic ligands bis(benzoylmethyl) sulfoxide and the second ligand phen could sensitize fluorescence intensities of Eu(III) ions, and the introduction of phen group was resulted in the enhancement of the fluorescence properties of the Eu(III) ternary rare earth complexes. The phosphorescence spectra are also discussed.     

New Insights into Optoelectronic Features of Eu(III) Complexes with Heterocyclic Ligand for Advanced Optical Applications

Our present technological society needs the assistance of lanthanide luminescence in almost every field to meet the global energy demands. In present research work we have synthesized five (one binary and four ternary) 5-(4-methylphenyl)-2- furoic acid based Eu(III) complexes with ancillary ligands, namely, aqua (H₂O), neocuproine (neo), 2, 2’-bipyridyl (bipy), bathophenanthroline (batho) and 1, 10-phenanthroline (phen). The spectroscopic analysis and photophysical features are characterized by the use of different investigative techniques. All the findings obtained from EDAX, elemental (CHN) analysis, FT-IR, NMR, UV–visible spectroscopy declared the coordination of ligand binding sites with the europium ion. These Eu(III) complexes possess good thermal stability and excellent optoelectronic features as predicted with the help of TGA and PL analysis. Diffuse reflectance spectral studies confirm their applications in the wide band gap semiconductors. The Judd–Ofelt analysis and monoexponential behavior of lifetime reveals the existence of asymmetric and single local environment around europium ion. All the complexes show sharp red emission validated by CIE color coordinates, color purity, asymmetric ratio and CCT values. SEM analysis tells that the bulk of these complexes comprised of spherical shaped particles with uniform distribution.

     

Photophysics of the Lanthanide Complexes with Conjugated Carboxylic Acids by Low Temperature Fluorescent Spectroscopy

In the context, some lanthanide (Eu³⁺, Tb³⁺ and Sm³⁺) complexes with conjugated carboxylic acids (pyridine-carboxylic acids derivatives) have been synthesized and characterized. The low temperature fluorescent spectra for these complexes have been measured at nitrogen atmosphere (77 K), indicating that the central Ln³⁺ ions locate in an equivalent coordination environment with low symmetry for most of these lanthanide complexes belonging to dimeric or polymeric structure. Therefore, the electronic dipole transition (supersensitive transition) (⁵D₀ → ⁷F₂ for Eu³⁺, ⁵D₄ → ⁷F₆ for Tb³⁺, ⁴G_5/2 → ⁶H_9/2 for Sm³⁺) and magnetic dipole transition (⁵D₀ → ⁷F₁ for Eu³⁺, ⁵D₄ → ⁷F₅ for Tb³⁺, ⁴G_5/2 → ⁶H_5/2 for Sm³⁺) show the regular change in the corresponding split number of fluorescent spectra, which can be realized to predict the fine structure of lanthanide complexes.     

Luminescence properties of lanthanide(III) ions in concentrated carbonate solution

Luminescence properties of lanthanide(III) ions (Ln = Nd, Sm, Eu, Gd, Tb, Dy and Tm) were investigated by measuring the excitation and emission spectra, and emission lifetimes in H₂O and D₂O solutions of 3 moll^?1 K₂CO₃, where anionic tetra-carbonate complexes, [Ln(CO₃)₄]^5- were the predominant species.

Electronic transitions of the carbonato complex corresponding to both the excitation and emission spectra were assigned from the energy level diagrams of Ln(III) and compared with those of the aqua ion. Enhancement of emission intensity of the complex was observed at particular excitation transitions of Eu(III), Gd(III) and Tb(III), and at particular emission transitions of Sm(III), Eu(III), Dy(III) and Tm(III). The enhancement at the emission transition was estimated quantitatively as a branching ratio from the lowest emitting state of Ln(III), and discussed in terms of hypersensitivity.

Emission lifetimes of the carbonato complexes were all longer than those of aqua ions in H₂O solution, while the lifetimes of the complexes for Eu(III) and Tb(III) shorter than those in D₂O solution. The difference in non-radiative decay constants for the excited complex in H₂O and D₂O solutions was found to be proportional to an exponential of the energy gap of Ln(III). The lifetime ratio between the H₂O and D₂O solutions showed the order of Sm > Dy > Eu > Tb, corresponding to the opposite order of the energy gap. These were discussed in terms of an energy gap law, i.e. a relationship between the energy gap of Ln(III) and vibration energies of the ligand or water molecules.     

Synthesis and Fluorescence Properties of Lanthanide (III) Perchlorate Complexes with Naphthyl-Naphthalinesulphonylpropyl Sulfoxide

A ligand with double sulfinyl groups, naphthyl-naphthalinesulphonylpropyl sulfoxide(dinaphthyl disulfoxide, L), was synthesized by a new method and its several lanthanide (III) complexes were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis, IR, TG-DTA, ¹HNMR and UV spectra. The composition of these complexes, were RE₂(ClO₄)₆·(L)₅·nH₂O (RE = La, Nd, Eu, Tb, Yb, n = 2 ∼ 6, L = C₁₀H₇SOC₃H₆SOC₁₀H₇). The fluorescent spectra illustrated that the Eu (III) complex had an excellent luminescence. It was supposed that the ligand was benefited for transferring the energy from ligand to the excitation state energy level (⁵D₀) of Eu (III). The Tb (III) complex displayed weak luminescence, which attributed to low energy transferring efficiency between the average triplet state energy level of ligand and the excited state (⁵D₄) of Tb (III). So the Eu (III) complex displayed a good antenna effect for luminescence. The phosphorescence spectra and the relationship between fluorescence lifetime and fluorescence intensity were also discussed.     

Influences of compositions and ligands on photoluminescent properties of Eu(III) ions in composite europium complex/PMMA systems

Three kinds of europium complexes; Eu(phen)₂Cl₃(H₂O)₂, Eu(DN-bpy)phenCl₃(H₂O)₂ and Eu(DB-bpy)phenCl₃(H₂O)₂ (phen: 1,10-phenanthroline, DN-bpy: 4,4′-Dinonyl-2,2′-dipyridyl, DB-bpy: 4,4′-Di-tert-butyl-2,2′-dipyridyl) were prepared and then incorporated into polymethyl methacrylate (PMMA) matrix with different molar ratios of CO groups/Eu³⁺ ions. The final solid composites were formed by a self-assembly process among Eu³⁺ ion, the ligands and PMMA during the solvent evaporation process, and then the ligands re-coordinate to Eu(III). It was found that the ligands affect not only the emission properties of the pure complexes, but also the miscibility of the complexes and PMMA. More than one kind of symmetric sites of Eu³⁺ ions were formed in the composites due to the coordination of CO in PMMA to Eu³⁺ ions. The micro-environments of Eu(III) in the composites were changed with the compositions and the ligands, leading to the change in the crystalline structure, and consequently, the emission characteristics.