Coordination bonding construction, characterization and photoluminescence of ternary lanthanide (Eu(3+), Tb(3+)) hybrids with phenylphenacyl-sulfoxide modified bridge and polymer units

A novel polysilsesquioxane bridge (PPSSi) is synthesized with methylene group modification of phenylphenacyl sulfoxide by isocyanate group from 3-(triethoxysilyl)propyl isocyanate (TEPIC). Then ternary lanthanide (Eu, Tb) hybrids of polysilsesquioxane bridge (PPSSi) and four kinds of polymer chain (polyacrylamide (PAM), polyvinylpyrrolidone (PVP), polymethyl methacrylate (PMMA) and polyethyl methacrylate (PEMA) were assembled wth coordination bonding. To explore the influence of the different polymeric chains on the properties of lanthanide hybrids, the microstructure and photoluminescent properties of these lanthanide coordination polymer hybrids (PPSSi-Ln-PAM (PVP, PMMA, PEMA)) are compared in detail. Four organic polymer chains with different structures not only can coordinate to the lanthanide ions by their own carbonyl groups, but also can form a polymeric matrix together with the inorganic Si-O network. The results show that all the obtained hybrids could show efficient intramolecular energy transfer and lead to excellent characteristic emission of lanthanide ions. Moreover, the different structures of the polymers induce different microstructures and different photoluminescent behavior (lifetime and quantum efficiency) for these hybrid systems. The PPSSi-Ln-PMMA hybrid leads to the longest lifetime and highest quantum efficiency.     

Rare-earth/inorganic/organic polymeric hybrid materials: molecular assembly, regular microstructure and photoluminescence

2-Hydroxynicotinic acid (HNA) was grafted by 3-(triethoxysilyl)propyl isocyanate (TEPIC) to achieve the molecular precursor HNA-Si through the hydrogen-transfer nucleophilic addition reaction between the hydroxyl group of HNA and the isocyanate group of TEPIC. Then, a chemically bonded rare-earth/inorganic polymeric hybrid material (A) was constructed using HNA-Si as a bridge molecule that can both coordinate to rare-earth ions (HNA-Si-RE) and form an inorganic Si-O network with tetraethoxysilane (TEOS) after cohydrolysis and copolycondensation processes. Further, three types of novel rare-earth/inorganic/organic polymeric hybrids (B-D) were assembled by the introduction of three different organic polymeric chains into the above system. First, methacrylic acid (MAA) [or methacrylic acid and acrylamide (ALM) in the molar ratio of 1:1] was mixed to polymerize (or copolymerize) with benzoyl peroxide (BPO) as the initiator to form poly(methacrylic acid) (PMAA) [or poly(methacrylic and acrylamide) (PMAALM)], and then PMAA or PMAALM was added to the precursor HNA-Si before the assembly of HNA-Si-RE, resulting in the hybrid materials HNA-Si-RE-PMAA (B) and HNA-Si-RE-PMAALM (C). Second, poly(vinylpyrrolidone) (PVP) was added to coordinate to the rare-earth ions by the carbonyl group in the complex HNA-Si-RE, to achieve the hybrid HNA-Si-RE-PVP (D). All of these hybrid materials exhibit homogeneous, regular, and ordered microstructures and morphologies, suggesting the occurrence of self-assembly of the inorganic network and organic chain. Measurements of the photoluminescent properties of these materials show that the ternary rare-earth/inorganic/organic polymeric hybrids present stronger luminescent intensities, longer lifetimes, and higher luminescent quantum efficiencies than the binary rare-earth/inorganic polymeric hybrids, indicating that the introduction of the organic polymer chain is a benefit for the luminescence of the overall hybrid system.     

Lanthanide (Eu3+, Tb3+) centered hybrid materials using modified functional bridge chemical bonded with silica: molecular design, physical characterization, and photophysical properties

1,3-Bis(2-formylphenoxy)-2-propanol (BFPP) was first synthesized and then grafted to 3-(triethoxysilyl)propyl isocyanate (TESPIC) to achieve a molecular precursor BFPP-Si through the hydrogen-transfer nucleophilic addition reaction between the hydroxyl group of BFPP and the isocyanate group of TESPIC. Then, a chemically bonded lanthanide/inorganic/organic hybrid material (BFPP-Si-Ln) was constructed using BFPP-Si as a bridge molecule that can both coordinate to lanthanide ions (Eu3+ or Tb3+) and form an inorganic Si-O network with tetraethoxysilane (TEOS) after cohydrolysis and copolycondensation processes. Furthermore, two types of ternary rare-earth/inorganic/organic hybrids (BFPP-Si-Dipy-Ln and BFPP-Si-Phen-Ln) were assembled by the introduction of the second ligands (4,4'-bipyridyl and 1,10-phenanthroline) into the above system. All of these hybrid materials exhibit homogeneous microstructures and morphologies, suggesting the occurrence of self-assembly of the inorganic network and organic chain. Measurements of the photoluminescent properties of these materials show that the ternary rare-earth/inorganic/organic hybrids present stronger luminescent intensities, longer lifetimes, and higher luminescent quantum efficiencies than the binary hybrids, indicating that the introduction of the second ligands can sensitize the luminescence emission of the lanthanide ions in the ternary hybrid systems.     

Lanthanide-centered organic-inorganic hybrids through a functionalized aza-crown ether bridge: coordination bonding assembly, microstructure and multicolor luminescence

This work focuses on the synthesis of a series of chemically bonded lanthanide/inorganic/organic hybrid materials (CE-15-Si-Ln, CE-16-Si-Ln, CE-18-Si-Ln) containing a novel aza-crown ether organic component. The materials show red emission (Ln = Eu), green emission (Ln = Tb) and near-infrared (NIR) luminescence (Ln = Nd). Three functional molecular precursors (denoted as CE-15-Si, CE-16-Si, CE-18-Si) have been synthesized with two or three N-substituted pendant arms containing chelating groups which can not only fulfill the high coordination numbers of Ln(3+) ions but also form an inorganic Si-O-Si network with tetraethoxysilane (TEOS). The resulting amorphous materials exhibit regular uniform microstructures for the organic and the inorganic components which are covalently linked through Si-O bonds via a self-assembly process. These hybrids present strong luminescent intensities in red, green and NIR ranges by embedding selected Ln(3+) ions into the hybrid system, which may lead to potential applications in organic electroluminescence displays, light emitting devices, functional membranes or chemical/biomedical sensors.     

Coordination bonding assembly and photophysical properties of Europium organic/inorganic/polymeric hybrid materials

Ternary organic/inorganic/polymeric hybrid material PVP-Eu-(DBM-Si)₃ (DBM = dibenzoylmethane; PVP = poly(4-vinylpyridine)) have been synthesized through the coordination bonds. The precursor DBM-Si is obtained by the modification of DBM molecule with a cross-linking reagent TEPIC (3-(triethoxysilyl)-propyl isocyanate), which is used to form the inorganic Si–O–Si networks with TEOS (tetraethoxysilane) after a hydrolysis and polycondensation process. PVP, which is obtained through the polymerization reaction using 4-vinylpyridine as the monomer in the presence of BPO (benzoyl peroxide), is used to form the organic polymeric C–C chains. For comparison, the binary organic/inorganic hybrid material Eu-(DBM-Si)₃ was also synthesized simultaneously. FT-IR (Fourier-transform infrared spectra), UV (ultraviolet absorption spectra), UV-DR (ultraviolet–visible diffuse reflection absorption spectra), SEM (scanning electron micrograph), PL (photoluminescence spectroscopy) and LDT (luminescence decay time) measurements are used to investigate the physical properties of the obtained hybrid materials. The results reveal that the ternary hybrids presents more regular morphology, higher red/orange ratio, stronger luminescent intensity, higher ⁵D₀ luminescence quantum efficiency and longer lifetime than the binary one, suggesting the property of the overall hybrid system is improved with the introduction of the organic polymer PVP.     

Coordination assembly and characterization of red-emitting europium (III) organic/inorganic polymeric hybrids

Novel luminescent ternary organic-inorganic-polymeric hybrid material has been assembled by Eu(3+) complex incorporating into poly (methyl methacrylate) (PMMA) matrix. The functionalized silylated precursor PDC-Si derived from PDC (2,6-pyridinedicarboxylic acid chloride) behaves as the coordination units of Eu(3+) ion. The organic polymer was introduced into the system by directly dissolving PMMA in solution of Eu(PDC-Si)(3) complex and N-N-Dimethyl Formamide (DMF) with subsequent addition of tetraethoxysilane to promote hydrolysis and condensation. The structure and photophysical properties of the resulting hybrids are characterized by Fourier transform infrared spectra, X-ray diffraction (XRD), scanning electronic microscopy and photoluminescence spectra. The luminescence quantum yield was calculated based on the emission spectra and luminescence lifetimes. XRD reveals its amorphous structure. Efficient energy transfer process occurs between PMMA and Eu(3+), and replacement of water molecule by PMMA in the first coordination sphere was confirmed by comparing with the binary hybrid.     

Toward the rational design of lanthanide coordination polymers: a new topological approach

The implementation of four bidentate building blocks into a high-denticity linker with a flexible spacer leads to a predisposed ligand that allows one to direct the self-assembly of 1D functional coordination polymers. This is illustrated by the assembly under mild conditions of the luminescent metal-organic framework [Tb(Htpabn)] . 14H2O infinity (1; H4tpabn = N,N,N',N'-tetrakis[(6-carboxypyridin-2-yl)methyl]butylenediamine). The X-ray crystal structure shows that the monoprotonated Htpabn binds two equivalent lanthanide ions to form a one-directional staircase chain. The high ligand denticity prevents solvent coordination and leads to a high luminescence quantum yield (Q = 39%), which is maintained after solvent removal.     

Tuning the self-assembly and luminescence properties of lanthanide coordination polymers by ligand design

Two new structure-related tripodal ligands featuring salicylamide pendant arms, 1,3,5-tris{[(2'-furfurylaminoformyl)phenoxyl]methyl}-2,4,6-trimethylbenzene (L(I)) and 1,1,1-tris{[(2'-furfurylaminoformyl)phenoxyl]methyl}ethane (L(II)) have been designed and synthesized with the ultimate aim of self-assembling lanthanide polymers with interesting luminescent properties. Among two series of Ln(III) nitrate complexes (Ln = Pr, Nd, Sm, Eu, Gd, Tb or Dy) which have been characterized by elemental analyses, XRD, TGA and IR spectra, three new coordination polymers have been determined by X-ray diffraction analysis. The coordination polymer type {[Ln(NO(3))(3)(L(I))].nH(2)O}(n) possesses an unusual ladderlike double chain which can be further connected through pi-pi stacking interactions constructing a three-dimensional supramolecular structure. In contrast, the coordination polymer type {[Ln(NO(3))(3)(L(II))].nCH(3)OH}(n) displays a (3,3)-connected puckered two-dimensional net with 4.8(2) topological notation. The photophysical properties of the Sm, Eu, Tb and Dy complexes at room temperature are investigated. The present work substantiates the claim that the supramolecular structure as well as the luminescent properties of the coordination polymer can be tuned by varying either the backbone group or the terminal group of the organic ligand.     

N-甲基-N-(2-羟乙基)-对-甲苯胺存在下甲基丙烯酸甲酯的自由基聚合

测定了在N-甲基-N-(2-羟乙基)-对-甲苯胺(HMT)存在下,MMA以过氧化物引发的聚合速率和聚合表观活化能.发现HMT对BPO、LPO引发的MMA聚合有促进作用,提高聚合速率.由聚合物端基分析证实了含有HMT的碎片,表明由芳叔胺HMT与BPO反应产生的自由基能引发单体聚合,BPO-HMT引发聚合为一氧化还原引发聚合.     

Photoluminescent Eu3+/Tb3+ hybrids from the copolymerization of organically modified silane

A novel series of organic/inorganic/polymeric hybrid materials have been constructed from covalently bonding rare earth complexes into the inorganic matrix and polymer backbone. Among functional linkage, 3-chloropropyltrimethoxysilane is used to modify the hydroxyl group of p-hydroxycinnamic acid via substitution reaction to form the precursor, and the precursor is subsequently used to covalently bonding to acrylic acid, methyl acrylate, and vinyltriethoxysilane, respectively, through copolymerization reaction to form the organic/inorganic/polymeric network. In addition, we introduce the monomer 1,10-phenanthroline as the second reagent ligand for constructing the ternary luminescent hybrid material systems (abbreviated as HC-PMA-RE, HC?=?p-hydroxycinnamic acid and 3-chloropropyltrimethoxysilane). The physical characterization and especially the photoluminescence property of ternary system are studied in detail, which present the regular microstructure and characteristic photoluminescence.     

Photoactive rare earth (Eu3+, Tb3+) hybrids with organically modified silica covalently bonded polymeric chain

1,3-Bis(2-formylphenoxy)-2-propanol (BFPP) is grafted to 3-(triethoxysilyl)-propyl isocyanate (TESPIC) to prepare the organic precursor BFPP-Si. Then, the organic precursor BFPP-Si is coordinated with rare earth ion to obtain the luminescent center RE-BFPP-Si. Allylamine monomer (AM) is modified by TESPIC to form the precursor AM-Si which is then polymerized with the benzoyl peroxide as the initiator to form the polymer precursor PAM-Si. The other polymer precursor polyethylene glycol (PEG)-Si is achieved through the grafting reaction between PEG and TESPIC. Subsequently, the hybrid materials RE-BFPP-Si-PAM or RE-BFPP-Si-PEG are assembled in which RE-BFPP-Si and PAM-Si or PEG-Si connected with Si-O bonds through sol-gel process and characterized with scanning electronic microscopy, X-ray diffraction, and TG-DSC curves. Their photophysical properties are especially studied in details, indicating that the introduction of organic polymer chain is favorable for the luminescence lifetime and quantum efficiency.     

Photoactive Hybrid Materials of Lanthanide (Eu3+, Tb3+, Sm3+) Beta‐Diketonates and Polymer Resin Through Ionic Liquid Bridge

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.     

Lanthanide (Eu3+, Tb3+) Centered Mesoporous Hybrids with 1,3‐Diphenyl‐1,3‐Propanepione Covalently Linking SBA‐15 (SBA‐16) and Poly(methylacrylic acid)

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.     

有机过氧化物与N-甲基-N-2-羟乙基苯胺引发体系的研究

 测定了有机过氧化物与N-甲基-N-2-羟乙基苯胺(HMA)体系引发MMA聚合的动力学方程和聚合表现活化能。由过氧化物/HMA/MNP的ESR波谱证实芳叔胺HMA中,与氮原子相连的亚甲基的氢被摘去形成相应的碳自由基,它能引发单体聚合成为聚合物的端基。这也由聚合物的UV光谱所证实,由实验结果提出这类体系的引发机理。     

有机过氧化物与N-甲基-N-2-羟乙基苯胺引发体系的研究

测定了有机过氧化物与N-甲基-N-2-羟乙基苯胺(HMA)体系引发MMA聚合的动力学方程和聚合表现活化能。由过氧化物/HMA/MNP的ESR波谱证实芳叔胺HMA中,与氮原子相连的亚甲基的氢被摘去形成相应的碳自由基,它能引发单体聚合成为聚合物的端基。这也由聚合物的UV光谱所证实,由实验结果提出这类体系的引发机理。     

Photofunctional hybrids of rare earth complexes covalently bonded to ZnO core-shell nanoparticle substrate through polymer linkage

A novel series of multi-component hybrids are assembled based on rare earth coordinated to rare earth ion (Eu(3+), Tb(3+), Sm(3+), Dy(3+)) complex systems and ZnO nanocomposites through three different ester units (ethyl methacrylate (EMA), 2-hydroxyethyl methacrylate (HEMA) and 2,2,3,4,4,4-hexafluorobutyl methacrylate (HFMA)) as functional polymer linkages. Methacrylic-group-modified ZnO nanoparticles (designated ZnO-MAA) are synthesized based on the reaction between zinc methacrylate and LiOH with the molar ratio 1 : 3.5 via sol-gel process. The final hybrid materials are prepared by introducing rare earth complexes into ZnO-MAA matrix via addition polymerization reaction in the presence of benzoyl peroxide (BPO) as the initiator. The detailed characterization and luminescence of these hybrid materials are discussed. It is found that ZnO-MAA-HEMA/EMA/HFBMA-RE-phen hybrid systems have effective intramolecular energy transfer process and exhibit longer lifetime and higher quantum efficiency.     

Calix[4]arene derivative functionalized lanthanide (Eu, Tb) SBA-15 mesoporous hybrids with covalent bonds: assembly, characterization and photoluminescence

Three kinds of novel macrocylic calix[4]arene derivatives functionalized SBA-15 type of mesoporous hybrids (Calix-S15, Calix-NO(2)-S15 and Calix-NH(2)-S15) are synthesized by co-condensation of tetraethoxysilane (TEOS) and modified organic ligand (Calix-Si, Calix-NO(2)-Si and Calix-NH(2)-Si) in the presence of Pluronic P123 surfactant as a template. The structural preservation of these three parent materials is confirmed by FTIR spectra, (29)Si MAS NMR spectra, XRD pattern, and N(2) adsorption-desorption measurements. The ternary mesoporous luminescent hybrids containing Ln(3+) (Eu(3+), Tb(3+)) complexes covalently attached to the functionalized ordered mesoporous SBA-15, which are designated as Ln(Calix-S15)phen, Ln(Calix-NO(2)-S15)phen and Ln(Calix-NH(2)-S15)phen, are obtained by introducing lanthanide ions and 1,10-phenanroline into the corresponding parent material via covalent bond assembling methods. XRD pattern, TEM and N(2) adsorption-desorption measurements are employed to characterize the mesostrcture of the resulting lanthanide mesoporous hybrids. The photoluminescent behavior (luminescence, lifetime, quantum efficiency, and energy transfer) for these chemically bonded mesoporous hybrids is studied in detail. Also, their quantum efficiencies are determined, which indicates that the different mesoporous hybrid material systems derived from different functionalized calix[4]arene derivative bridges present different luminescence behavior.     

Molecular assembly and photophysical properties of quaternary molecular hybrid materials with chemical bond

In this paper, two long chain aliphatic carboxylic acids (oleic acid [OLA] and stearic acid [STA]) are modified with cross-linking molecules (N-2-aminoethyl-3-aminopropyl-methyl-dimethoxylsiliane, (AEAPMMS, H(2) N(CH(2))(2)HN(CH(2))(3)SiCH(3)(OCH(3))(2) and 3-aminopropyl-methyl-diethoxylsiliane (APMES, H(2) N(CH(2))(3)SiCH(3)(OC(2)H(5))(2)) resulting in four new kinds of structural molecular bridge OLA (STA)-AEAPMMS (APMES). Subsequently, ternary molecular complex systems with four molecular bridges OLA (STA)-AEAPMMS (APMES) and 2,2-bipyridyl (bipy) of lanthanides (terbium and europium) or zinc ions were assembled, which resulted in four novel kinds of quaternary molecular hybrid materials (named as bipy-Ln (Zn)-OLA (STA)-AEAPMMS (APMES) with strong chemical bonds (N-Ln(Zn)-O coordination bonds and Si-O covalent bonds) after a sol-gel (cohydrolysis and copolycondensation) process of the modified molecular bridges (as structural ligand) with inorganic precursor (tetraethoxysilane, TEOS). And especially bipy behaves as functional ligand to sensitize the luminescence of terbium or europium ions through the effective intramolecular energy transfer process, which gives rise to the characteristic emission of metal ions. The design and assembly from structural and functional ligands can help achieve a candidate technology for molecular hybrids.     

Rare-earth (Eu, Tb) hybrids through amide bridge: Chemically bonded self-assembly and photophysical properties

This work focuses on the construction of a series of chemically bonded rare-earth/inorganic/organic hybrid materials (TCH-Si-Ln, TCH-Si-Ln-Phen and TCH-Si-Ln-Bipy: Phen = 1,10-phenanthroline, Bipy = 2,2′-bipyridyl) using TCH-Si as an organic bridge molecule that can both coordinate to rare-earth ions (Eu³⁺ and Tb³⁺) and form an inorganic Si-O-Si network with tetraethoxysilane (TEOS) after cohydrolysis and copolycondensation through a sol-gel process. All of these hybrid materials exhibit homogeneous microstructures and morphologies, suggesting the occurrence of self-assembly of the inorganic network and organic chain. Measurements of the photoluminescent properties of these materials show that the ternary europium systems present stronger luminescent intensities than the binary hybrids, indicating that the introduction of the second ligands can sensitize the luminescence emission of the europium hybrid systems. However, in the terbium systems, this phenomenon was not observed.     

Controllable synthesis of functionalized CdS nanocrystals and CdS/PMMA nanocomposite hybrids

We reported controllable synthesis of CdS nanocrystal-polymer transparent hybrids by using polymethylmethacrylate (PMMA) as a polymer matrix. In a typical run, the appropriate amounts of cadmium chloride (CdCl₂) and sodium sulfide (Na₂S) in the presence of 2-mercaptoethanol (ME) as the organic ligand are well dispersed in H₂O/DMF solution without any aggregation. From a combination of transmission electron microscopy (TEM) and a computing method of Brus’s model according UV-vis absorption spectra, the particle size of as-prepared hydroxyl-coated CdS nanocrystal was determined to be about 5 nm. Then, with the surface treatment with methacryloxypropyltrimethoxysilane (MPS), CdS-PMMA hybrids were obtained via free radical polymerization in situ. FT-IR characterization indicates the formation of robust bonding between CdS nanocrystals and the organic ligand and the formation of double-bond functional CdS nanocrystals. The TGA measurement displays CdS-PMMA hybrids possess better thermal stability compared with pure PMMA polymer. The fluorescence measurement shows that CdS nanocrystals and CdS-PMMA hybrids exhibit good optical properties. Also, the luminescent photographs taken under ultraviolet light prove the luminescence properties.