A mixed lanthanide complex was synthesized hydrothermally with two kinds of organic ligands, adenine and biphenyl-4,4′-dicarboxylic acid, and is formulated as Ad/Tb_0.999Eu_0.001/BPDC (Ad = adeninate, BPDC = biphenyl-4,4′-dicarboxylate). The photophysical properties, especially the fluorescent sensing properties, have been studied in detail and compared to those of Tb_0.999Eu_0.001/BPDC, with a single ligand. It can be used as a ratiometric luminescent thermometer on the basis of the energy transfer from Tb³⁺ to Eu³⁺, whose color will change from green–yellow to red from 100 K to 300 K.

A series of photoactive polymer hybrid films fabricated with both lanthanide complexes and ZIF-8 [zeolite imidazole framework, a kind of metal organic framework, Zn(MeIM)₂, MeIM = 2-methylimidazole] was prepared. ZIF-8 and the lanthanide complexes Ln-L [Ln = Eu, Tb; L = AA (acetylacetonate), phen (1,10-phenanthroline), TAA (trifluoroacetylacetonate), TTA (trifluoroacetylacetonate)] were assembled with the the monomers 4-vinyl pyridine (VPD) and ethylene-methyl acrylate (EMA), forming the final hybrid polymer films after initiation with benzoyl peroxide (BPO). The products are are indicated as PEMA-PVPD⊃Ln-L/ZIF-8 [PEMA-PVPD: copolymer of poly 4-vinyl pyridine (PVPD) and polyethylene-methyl acrylate (PEMA)]. The SEM images of these hybrid films indicate homogeneous dense packing and a high degree of coverage of the crystals on the ITO glass. The luminescent behavior of all the hybrid films was studied in detail. Discrete luminescence of the ZIF-8 unit and the lanthanide complexes was observed in which energy coupling between the two emissive centers does not exist. Therefore, by selectively exciting these hybrid films with different wavelengths, the luminescence colors of them can be tuned from blue (for ZIF-8) to red (for Eu³⁺), green (for Tb³⁺), yellow (for Eu³⁺/Tb³⁺) and even to white by integrating the emission of both Eu³⁺/Tb³⁺ into the polymer unit (PEMA-PVPD). These results are useful and have potential application in optical devices for displays or encoding.

A special multifunctional ionic liquid compound (1-methyl-3-(2-(thiocarboxyoxy)-ethyl)-2H-imidazole-1,3-diium bromide (SHIL)) is used as the chemical bridge to link lanthanide beta-diketonates and polymer resin, which are designated as Ln(L)₄-SHIL-WR/MR (Ln = Eu, Tb, Sm; L = thenoyltrifluoroacetonate (TTA), acetylacetonate (AA), dibenzoylmethane (DBM); WR = Wang resin, MR = Merrifield resin). Among SHIL and polymer resin are assembled to form covalently bonded system through condensation reaction. Then tetrakis lanthanide beta-diketonates are linked to SHIL through ion-exchange reaction. Physical characterization and especially the photoluminescent performance of the multicomponent hybrids are studied. The hybrid materials possess good stability and excellent luminescent property. The results provide useful path to obtain luminescent hybrids for further practical application.

Four kinds of luminescent hybrid soft gels have been assembled by introducing the lanthanide (Eu³⁺, Tb³⁺) tetrakis β-diketonate into the covalently bonded imidazolium-based silica through electrostatic interactions. Here, the imidazolium-based silica matrices are prepared from imidazolium-derived organotriethoxysilanes by the sol–gel process, in which the imidazolium cations are strongly anchored within the silica matrices while anions can still be exchanged following application for functionalization of lanthanide complexes. The photoluminescence measurements indicated that these hybrid soft gels exhibit characteristic red and green luminescence originating from the corresponding ternary lanthanide ions (Eu³⁺, Tb³⁺). Further investigation of photophysical properties reveals that these soft gels have inherited the outstanding luminescent properties from the lanthanide tetrakis β-diketonate complexes such as strong luminescence intensities, long lifetimes and high luminescence quantum efficiencies.

A series of luminescent ion exchanged zeolite are synthesized by introducing various ions into NaY zeolite. Monometal ion (Eu³⁺, Tb³⁺, Ce³⁺, Y³⁺, Zn²⁺, Cd²⁺, Cu²⁺) exchanged zeolite, rare-earth ion (Eu³⁺, Tb³⁺, Ce³⁺) exchanged zeolite modified with Y³⁺ and rare-earth ion (Eu³⁺, Tb³⁺, Ce³⁺) exchanged zeolite modified with Zn²⁺ are discussed here. The resulting materials are characterized by Fourier transform infrared spectrum radiometer (FTIR), XRD, scanning electronic microscope (SEM), PLE, PL and luminescence lifetime measurements. The photoluminescence spectrum of NaY indicates that emission band of host matrix exhibits a blueshift of about 70 nm after monometal ion exchange process. The results show that transition metal ion exchanged zeolites possess a similar emission band due to dominant host luminescence. A variety of luminescence phenomenon of rare-earth ion broadens the application of zeolite as a luminescent host. The Eu³⁺ ion exchanged zeolite shows white light luminescence with a great application value and Ce³⁺ exchanged zeolite steadily exhibits its characteristic luminescence in ultraviolet region no matter in monometal ion exchanged zeolite or bimetal ions exchanged zeolite.

A series of organic–inorganic hybrids are prepared with magnetic mesoporous silica nanosphere supported europium(III) tetrakis(β-diketonate) complexes with ionic liquid compounds as linker {denoted as MMS·Im⁺·[Eu(β-diketonate)₄]^–}. Firstly, Fe₃O₄ nanoparticles were synthesized through the coprecipitation of ferrous and ferric ion solutions and were incorporated into mesoporous silica nanospheres. Secondly, europium(III) tetrakis(β-diketonate) complexes [β-diketonate = 2-thenoyltrifluoroacetonate (TTA), 4,4,4-trifluoro-1-phenyl-1,3-butanedionate (BTA), trifluoroacetylacetonate (TAA), acetylacetone (ACAC), hexafluoroacetylacetone (HFACAC)] and the ionic liquid 1-methyl-3-[3-(trimethoxysilyl)propyl]imidazolium chloride (Im⁺Cl^–) were prepared. The ionic liquid was then covalently attached to the magnetic mesoporous silica nanospheres through the Si–O network. Finally, europium(III) tetrakis (β-diketonate) complexes were attached by an anion exchange reaction. The physical characterization, magnetic, and especially luminescent properties are discussed in detail. These results reveal that the resultant nanocomposites possess high surface area and superparamagnetic properties at 300 K. Additionally, the MMS·Im⁺·[Eu(TTA)₄]^– and MMS·Im⁺·[Eu(BTA)₄]^– hybrids exhibit high luminescent quantum efficiencies.

9-Hydroxy-2-methyl-phenalenone (MHPO) was synthesized and modified with 3-(triethoxysilyl)propyl isocyanate (TEPIC) through a hydrogen atom addition reaction to achieve a new chemical linkage (named as MHPOSi). SBA-15 mesoporous silica organically functionalized with MHPOSi was synthesized. The MHPOSi was linked to tetraethoxysilane (TEOS) through a condensation process in the presence of Pluronic P123 surfactant as a template. New Ln³⁺ (Eu³⁺, Nd³⁺, Yb³⁺) organic–inorganic mesoporous hybrid materials were prepared, in which the Ln³⁺ complexes are covalently attached to SBA-15 and have 1,10-phenanthroline (phen) as a second ligand. The resultant mesoporous hybrids were characterized by FTIR spectroscopy, small-angle X-ray diffraction, N₂ adsorption–desorption measurements, thermal analysis, and UV/Vis spectroscopy. They all have high surface areas, uniform mesostructures, and good crystallinity. The photophysical properties of the functionalized mesoporous SBA-15 networks are discussed in detail and they still present excitation capability in the visible region despite the modification of the organic silane. Subsequently, they exhibit characteristic visible (Eu³⁺) and near-infrared (NIR) luminescence (Nd⁺ and Yb³⁺).

Rare earth doped fluorides (BaMgF₄, aYF₄ and BaYF₅/BaLuF₅) have been synthesized and dispersed in an ionic liquid compound, (3-triethoxysilyl) propyl-3-methylimidazolium chloride (denoted as IM⁺Cl⁻). Through the cohydrolysis and copolycondensatoin reaction between the alkoxy group (3-triethoxysilyl) of IM⁺ and tetraethoxysilane in the presence of carboxylic acids (formic acid) as catalyst and water source, luminescent hybrid ionogels form subsequently. ¹H NMR spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy and especially up-conversion (UC) luminescence spectroscopy are used to characterize the precursors and the resulted hybrid ionogels. These hybrid ionogels exhibit the UC luminescence properties of immobilized rare earth fluoride nanocrystals (BaMgF₄, NaYF₄ and BaYF₅/BaLuF₅) doped Er³⁺/Tm³⁺, Yb³⁺.

In the present work, two new chemical linkages (BPDA-PAM, BPDA-DG) are synthesized through the reaction between 4,4′-biphthalic anhydride (BPDA) and acrylamide (AM), diethylene glycol (DG), respectively. Then two novel series of multicomponent rare earth (Eu³⁺, Tb³⁺, Sm³⁺) polymeric hybrids have been assembled through the coordination bonding: one is from the linkage BPDA-PAM to form the hybrids BPDA-PAM-RE-phen(bipy) (2,2′-bipyridine (bipy) and 1,10-penanthroline (phen)), the other is from the linkage BPDA-DG to compose the hybrids BPDA-DG-RE-PVP and PVP (PVP = poly vinylpyridine). These hybrids are characterized and especially the photophysical properties (luminescence spectra, lifetimes and quantum efficiencies) are discussed in detail.

A series of novel organic/inorganic rare earth (europium, terbium) hybrid materials through the coordination bond and covalent bond are synthesized and form an inorganic Si–O–Si by the sol-gel process. Mercapto-functionalized 4-mercaptobenzoic acid (MBA-Si) is obtained by using MBA and 3-(triethoxysilyl)-propyl isocyanate (TESPIC) as an organic bridge molecule, and then the carboxyl group of the precursor MBA-Si is used to modify the titanium dioxide, so as to sensitize the luminescence of rare earth ions. CdS-TiO₂ is added to observe the influence of photoluminescence. 3-mercaptopropyltrimethoxysilane (MPS) is also used to modify the CdS quantum dot and obtain MPS functionalized MPS-CdS nanocomposite. These multicomponent hybrids with double cross-linking siloxane (MBA-Si) covalently bonding MPS-CdS are characterized. Subsequently, 1,10-phenanthroline (Phen) and 2,2,-bipyridyl (Bipy) as the assistant ligands together with water molecules are introduced into the rare earth hybrid system. The FT-IR, X-ray diffraction, UV–Vis, thermogravimetry and especially the photoluminescence properties of them are studied in detail.

Polysilsesquioxane bridges are obtained through the single modification of 3-(triethoxysilyl)propyl isocyanate (TEPIC) by two β-diketone ligands [thenoyltrifluoroacetylacetone (TTA) and trifluoroacetylacetone (TA)], which behave as linkages between the europium ion and composite host Si–O–M (M = B or Ti) xerogels by controlling the hydrolysis rate of the alkoxy compounds (tetraethyl orthosilicate, titanium butoxide and tributyl borate). Subsequently, luminescent europium hybrid xerogels are assembled and characterized by NMR, Fourier transform infrared (FTIR), ultraviolet absorption and ultraviolet/visible diffuse reflection spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and photoluminescence spectroscopy through which the decay times (τ) and quantum efficiency (η) can be determined. These results reveal that the lanthanide complexes have been covalently immobilized into the composite inorganic xerogels and the obtained hybrids have the excellent ability of light absorption and emission. The hybrids with composite Si–O–B xerogels possess the matched photoluminescent properties (red emission intensity, lifetimes, and quantum efficiency) as the pure silica oxygen network, both of which show a superior luminescence performance than the hybrids with composite Si–O–Ti xerogels. Besides, the single modification of TTA is favorable for the luminescence of the hybrid xerogels.

Zinc sulfide (ZnS) quantum dot is modified with 3-mercaptopropyltrimethoxysilane (MPTMS) to obtain MPTMS functionalized SiO₂/ZnS nanocomposite. Novel rare earth/inorganic/organic hybrid materials are prepared by using 3-(triethoxysilyl)-propyl isocyanate (TESPIC) as an organic bridge molecule that can both coordinate to rare earth ions (Eu³⁺, Tb³⁺, Sm³⁺ and Dy³⁺) and form an inorganic Si–O–Si network with SiO₂/ZnS nanocomposite after cohydrolysis and copolycondensation through a sol-gel process. These multicomponent hybrids with double cross-linking siloxane (TESPIC-MPTMS) covalently bonding SiO₂/ZnS and assistant ligands (Phen = 1,10-phenanthroline, Bipy = 2,2′-bipyridyl) are characterized and especially the photoluminescence properties of them are studied in detail. The luminescent spectra of the hybrids show the dominant excitation of TESPIC-MPTMS-SiO₂/ZnS unit and the unique emission of rare earth ions, suggesting that TESPIC-MPTMS-SiO₂/ZnS unit behaves as the main energy donor and effective energy transfer take place between it and rare earth ions. Besides, the luminescent performance of Bipy-RE-TESPIC-MPTM-SiO₂/ZnS hybrids are superior to that of Phen-RE-TESPIC-MPTMS-SiO₂/ZnS ones (RE=Eu, Tb, Sm, Dy), which reveals that Bipy or Phen only act as structural ligand within the hybrid systems.

According to coordination chemistry principle and molecular assembly technology, series of ternary lanthanide centered hybrid systems have been constructed through coordination bonds. Among one component (ligand) is organically modified Si–O network, which originates from the functional molecular bridge (BFPPSi) by the functionalization of 1,3-bis(2-formylphenoxy)-2-propanol (BFPP) with 3-(triethoxysilyl)propyl isocyanate. In the second component (ligand), three different organic polymeric chains are introduced, poly-(methyl methacrylate) (PMMA, from the polymerization of MMA with the benzoyl peroxide [BPO] as the initiator), poly-(methyl acrylic acid) (PMAA, from the polymerization of MAA with the BPO as the initiator), polyvinyl pyridine, respectively. All these ternary hybrid materials show homogeneous, regular microstructure, suggesting the existence of assembly process of lanthanide centers, inorganic Si–O network and organic polymer chain. Compared to the binary hybrids without polymer chain, the photoluminescent properties of these ternary hybrids present stronger luminescent intensities, longer lifetimes and higher luminescent quantum efficiencies indicating that the introduction of organic polymer chain is favorable for the luminescence of the whole hybrid systems.

4-Vinylphenylboronic acid ligand (VPBA) is functionalized with two crosslinking reagents (3-(triethoxysilyl)-propylisocyanate [TEPIC] and 3-(trimethoxysilyl) propyl methacrylate [TMPMA]) to achieve the two special molecular bridge VPBA-TEPIC and VPBA-TMPMA. Meanwhile, beta-diketone ligands (2-thenoyltrifluoroacetone [TTA], acetyl acetone [ACAC]) as the second ligands play the role of the main energy donor, which absorb abundant energy in ultraviolet–visible extent and then transfer the energy to the corresponding lanthanide ions (Eu³⁺_, Tb³⁺) to sensitize their emission of them. Eight binary and ternary Eu³⁺, Tb³⁺ hybrids with VPBA-TEPIC (VPBA-TMPMA) and TTA (ACAC) have been constructed, whose photoluminescence properties are studied in depth and suggest that the ternary hybrids show the favorable characteristic luminescent properties (longer lifetime and higher quantum efficiency).

Two organic ligands derived from thiazole were modified by 3-(triethoxysilyl)propyl isocyanate (TESPIC) to achieve the molecular precursors (P1 and P2). Then, the organic–inorganic hybrid materials (LnM1 and LnM2, Ln = Eu and Tb) were obtained by using these as bridging molecules to coordinate with lanthanide ions and form inorganic Si–O networks with tetraethoxysilane (TEOS) after cohydrolysis and copolycondensation processes, whose composition, microstructures, and photophysical properties were studied. All of the materials were amorphous and no phase separation occurred. The photoluminescence properties of these materials revealed that all these hybrids can show the characteristic luminescence of lanthanide ions. The ratios of red/orange, decay times, emission quantum efficiency of Eu³⁺ hybrid materials were also determined. Furthermore, the number of water molecules coordinated to the Eu³⁺ ion was theoretically estimated on the basis of emission spectra and the lifetime of the ⁵D₀ state.

A series of ternary organic/inorganic/polymer hybrid materials have been assembled on the basis of the coordination chemistry principle. Mercapto-functionalized MBA-Si from MBA (4-mercaptobenzoic acid) behaves as the first coordination unit, which forms sulfide linkages, resulting in an inorganic Si–O network after hydrolysis and copolycondensation with TEOS (tetraethoxysilane). The organic polymers PVPD [poly(4-vinylpyridine)] and PMMA [poly(methyl methacrylate)] play a role of the second coordination unit, whose organic polymeric C–C chain originates from addition polymerization of the monomers 4-VPD (4-vinylpyridine) and MMA (methyl methacrylate), respectively. These hybrids are characterized in detail to compare with the binary hybrids without an organic polymer unit, whose results reveal that the microstructure, the thermal stability, and especially the photoluminescence properties of the hybrid system are improved with the introduction of the polymer as the coligand.

This work focuses on the synthesis of a series of silica-based organic–inorganic hybrid materials, containing different Schiff-base organic compounds, through a covalent self-assembly process. We first prepared three functional molecular bridges that can both coordinate to lanthanide ions (Eu³⁺ and Tb³⁺) and form inorganic Si–O–Si networks with tetraethoxysilane (TEOS) from cohydrolysis and copolycondensation processes. Meanwhile, we selected N-heterocyclic ligands [1,10-phenanthroline (Phen) and 2,2′-bipyridine (Bipy)] as the second ligands to act as the main energy donor to absorb abundant energy in the UV/Vis region and to transfer the energy to the corresponding lanthanide ions to sensitize their emission. The introduction of the second ligand can also take the place of the coordinated H₂O and thus reduce the quenching effect of the OH group. Measurements of the photoluminescent properties of these materials show that the ternary lanthanide/inorganic/organic hybrids present stronger luminescent intensities and higher emission quantum efficiencies. The resulting amorphous materials exhibit regular, uniform microstructures and no phase separation occured since the organic and inorganic compounds were covalently linked through Si–O bonds through a self-assembly process.

In this paper, the functionalized monomer (TFAASi) behaves as a linkage to be immobilized into inorganic composite host gels through covalent bonds. Subsequently two kinds of Eu-centered chemically bonded hybrid gels (Eu-TFAA-Si-O-Ti, Eu-TFAA-Si-O-B) with composite hosts have been prepared and characterized. The covalently bonded Si-O-B hybrid gel presents stronger red/orange intensity ratio, longer lifetimes and higher quantum efficiency than covalently bonded Si-O-Ti one, suggesting that SiO₂-B₂O₃ composite gel is more suitable for the emissions of Eu³⁺ than SiO₂-TiO₂ composite gels.

The functional silica microspheres are derived from the three different silane crosslinking reagents, and then the polyvinyl pyridine-based rare earth hybrids are synthesized through free radical copolymerization of rare earth–vinyl pyridine complex monomer with these functionalized silica microspheres (RE = Eu, Tb). The obtained hybrids are characterized by Fourier transform infrared, X-ray diffraction, Scanning electronic microscope and photoluminescence spectra. The intramolecular energy transfer process between rare earth ions and polymer polyvinyl pyrrolidone matrices took place within these polymer-based hybrids and especially the quantum efficiency of europium hybrids are determined, suggesting that the hybrid material systems derived from different functional silica microspheres present different luminescence efficiencies.

A series of ternary rare earth complexes were covalent grafted to the inorganic Si–O networks through the novel bifunctional silylated monomer BBMSSi (BBMS = Bis [benzoylmethyl] sulfoxide). FT–IR, NMR, XRD, TGA, SEM, DRS and photoluminescence properties were used to characterize the obtained hybrid materials. Scanning electron micrograph results revealed hybrids exhibiting homogeneous morphology with large particle size of 100–200 μm and no phase separation. Photoluminescence measurements indicated hybrids with characteristic red and green luminescence. In addition, the existence of the polymeric chain PMMA and 1,10-phenanthroline in different hybrid systems present different microstructure and luminescence behavior.

In this article, dibenzoylmethane (DBM) was first grafted with the coupling reagent 3-(triethoxysilyl)-propyl isocyanate (TESPIC) to form precursor DBM–Si, and ZnO quantum dot was modified with 3-mercaptopropyltrimethoxysilane (MPS) to form SiO₂/ZnO nanocomposite particle. Then the precursor DBM–Si and the terminal ligand 1,10-phenthroline (phen) were coordinated to Eu³⁺ion to obtain ternary hybrid material phen–Eu–DBM–SiO₂/ZnO after hydrolysis and copolycondensation between the tetraethoxysilane (TEOS), water molecules and the SiO₂/ZnO network via the sol–gel process. In addition, for comparison, the binary hybrid material with SiO₂/ZnO network and ternary hybrid material with pure Si–O network were also synthesized, denoted as Eu–DBM–SiO₂/ZnO and phen–Eu–DBM–Si, respectively. The results reveal that hybrid material with SiO₂/ZnO network phen–Eu–DBM–SiO₂/ZnO exhibits the stronger red light, the longer lifetimes and higher quantum efficiency than hybrid material with pure Si–O network phen–Eu–DBM–Si, suggesting that SiO₂/ZnO is a favorable host matrix for the luminescence of rare earth complexes.

1,3-Diphenyl-1,3-propanepione (DBM)-functionalized SBA-15 and SBA-16 mesoporous hybrid materials (DBM-SBA-15 and DBM-SBA-16) are synthesized by co-condensation of modified 1,3-diphenyl-1,3-propanepione (DBM-Si) and tetraethoxysilane (TEOS) in the presence of Pluronic P123 and Pluronic F127 as a template, respectively. The as-synthesized mesoporous hybrid material DBM-SBA-15 and DBM-SBA-16 are used as the first precursor, and the second precursor poly(methylacrylic acid) (PMAA) is synthesized through the addition polymerization reaction of the monomer methacrylic acid. These precursors then coordinate to lanthanide ions simultaneously, and the final mesoporous polymeric hybrid materials Ln(DBM-SBA-15)₃PMAA and Ln(DBM-SBA-16)₃PMAA (Ln=Eu, Tb) are obtained by a sol-gel process. For comparison, binary lanthanide SBA-15 and SBA-16 mesoporous hybrid materials (denoted as Ln(DBM-SBA-15)₃ and Ln(DBM-SBA-16)₃) are also synthesized. The luminescence properties of these resulting materials are characterized in detail, and the results reveal that ternary lanthanide mesoporous polymeric hybrid materials present stronger luminescence intensities, longer lifetimes, and higher luminescence quantum efficiencies than the binary lanthanide mesoporous hybrid materials. This indicates that the introduction of the organic polymer chain is a benefit for the luminescence properties of the overall hybrid system. In addition, the SBA-15 mesoporous hybrids show an overall increase in luminescence lifetime and quantum efficiency compared with SBA-16 mesoporous hybrids, indicating that SBA-15 is a better host material for the lanthanide complex than mesoporous silica SBA-16.

A series of novel photoactive hybrid materials with organic parts covalently linked to inorganic parts via the acylamino group have been assembled by sol–gel process. The organic parts as molecular bridge derive from α-hydroxypyridine (HP) functionalized by 3-(triethoxysilyl)-propyl isocyanate (TESPIC). Finally homogeneous, molecular-based hybrid materials with different microstructure (uniform spherical or clubbed) are obtained, in which no phase separation is observed. This may be ascribed as the different coordination behavior of metal ions (Eu³⁺ (Tb³⁺) or Zn²⁺). Red emission of Eu–HP–Si, green emission of Tb–HP–Si and violet-blue luminescence of Zn–HP–Si hybrids can be achieved within these molecular-based hybrid materials. Besides, both Eu(Tb) and Zn are introduced into the same hybrid systems (Eu(Zn)–HP–Si or Tb(Zn)–HP–Si) through the covalent Si–O bond, whose sphere particle size can be modified. Especially the photoluminescence behavior can be enhanced, suggesting that intramolecular energy transfer takes place between inert Zn²⁺ and Eu³⁺ (Tb³⁺) in the covalently bonded hybrid systems.