Intramolecular Energy Transfer Process Research Articles

Elucidation of Intramolecular Energy Transfer Process of 9,9'Spirobifluorene ${via}$ the Measurement of Time-resolved Fluorescence Anisotropy

Elucidation of Intramolecular Energy Transfer Process of 9,9'Spirobifluorene ${via}$ the Measurement of Time-resolved Fluorescence Anisotropy

Molecular design and photophysical properties of acylamido side functionalized polysiloxanes with lanthanide ions as luminescent centers

Two series of acylamido side functionalized polysiloxanes were designed and synthesized from the modifications of amino silane with different acylating agents. They were complexed with lanthanide ions (Tb 3+, Eu 3+, Dy 3+ and Sm 3+) to obtain functionalized polysiloxane–lanthanide ions composite materials and exhibit the molecular assembly behaviors. The structures of products were characterized by Fourier transform infrared (FT-IR), 1H-NMR spectra and diffuse reflectance ultraviolet–visible spectra (DRUVS). Thermal stability was investigated by thermogravimetric analysis (TGA). Narrow-width red and green emissions of the functionalized polysiloxane–lanthanide ions complexes were recorded under the exposure to ultraviolet light. The results show that four kinds of lanthanide ions were all cooperated successfully with the functionalized polysiloxanes and an intra-molecular energy transfer process took place in these systems. Further investigations into the luminescence properties of the functionalized polysiloxane–lanthanide ions composite materials show that the triplet state energy of the benzoylamido side functionalized polysiloxane is more suitable for the emissive energy level of lanthanide ions than that of acetamido side functionalized polysiloxane. According to the rules between photophysical properties and diverse chromophoric conjugate groups, we could design and control the properties of the polysiloxane–lanthanide ion assembly complexes.

Poly(p‐phenylenevinylene) Derivatives with Defined Conjugation Segments and Post‐Polymerization Modification with Sterically Enshrouded Chromophores

Two poly(p-phenylenevinylene) derivative alternating copolymers (P1-I and P2-I) have been prepared featuring iodo substituents and m-phenylene units to periodically disrupt conjugation. P1-I was derivatized with various chromophores to yield P1a-f. In P1a-f, the chromophores were positioned within a sterically protected pocket shielding them from interchain interactions so that intrachain interactions between polymer segments could be observed. Solution and film properties of polymers have been examined. Post-polymerization chromophore modification leads to new photophysical properties such as intramolecular charge transfer and fluorescent resonance energy transfer processes in some cases.

Boron Dipyrromethene (Bodipy) Phosphorescence Revealed in [Ir(ppy)2(bpy-C≡C-Bodipy)]+

The synthesis, structural characterization, electrochemistry, and molecular photophysics of [Ir(ppy)(2)(bpy-C[triple bond]C-Bodipy)](PF(6)), where ppy is 2-phenylpyridine and bpy-C[triple bond]C-Bodipy is 5-ethynyl-2,2'-bipyridine-8-phenyl-1,3,5,7-tetramethyl-4,4-bis(2,5-dioxaoct-7-ynyl)-4-bora-3a,4a-diaza-s-indacene (4), is presented. Static and dynamic photoluminescence and absorption measurements in conjunction with cyclic voltammetry were employed to elucidate the nature of the intramolecular energy transfer processes occurring in the excited state of the title chromophore. Parallel studies were performed on appropriate model chromophores (2 and 3) intended to represent the photophysics of the isolated molecular subunits, that is, triplet metal-to-ligand-charge-transfer ((3)MLCT) and triplet Bodipy intraligand ((3)IL) excited states, respectively. Upon charge transfer excitation of the title chromophore, the (3)MLCT based phosphorescence readily observed in 2 (Phi(em) = 0.027, tau = 243 ns) is quantitatively quenched resulting from production of the (3)Bodipy excited state through intramolecular triplet-triplet energy transfer. The formation of the (3)Bodipy-localized excited state is confirmed by features in the transient absorption difference spectrum, extended excited-state lifetime (tau = 25 micros), as well the observation of (3)IL Bodipy-based phosphorescence detected at 730 nm at 77 K. The low temperature Bodipy phosphorescence is readily produced in 4 as a result of the internal Ir(III) heavy atom.

Synthesis, crystal structure and photophysical properties of a novel Pt(II) complex with multi-functionalized cyclometalating ligand

A novel Pt(II) complex [(L)PtCl] (HL = 4-{4p-[N-(4-(9-carbazole))butyl-N-phenyl] aniline}-6-phenyl-2,2'-bipyridine) has been synthesized and verified by H-1 NMR, elemental analysis and X-ray crystallography. The crystal (C44H35N4ClPt, M-r = 850.30) belongs to monoclinic system, space group P2(1)/c, with a = 21.864(6), b = 9.306 (3), c = 17.240(5) angstrom, beta = 96.483(6)degrees, Z = 4, V = 3485.3(16) angstrom(3), D-C = 1.620 g/cm(3), mu(Mo-K alpha) = 4.141 mm(-1), F(000) = 1688, R-1 = 0.0591, wR(2) = 0.0976. The coordinate geometry of the Pt atom is a distorted square planar configuration. The complex molecules are stacked by a weak pi-pi interaction in a head-to-tail fashion along the b axis to form 1D chain and the alternating 10 chains are packed to form the 2D lamellar system. The complex shows an intense metal-to-ligand charge transfer ((MLCT)-M-1) (d pi(Pt) -> pi*(L)) transitions (epsilon similar to 2 x 10(4) dm(3) mol(-1) cm(-1)) at 448 nm in the UV-Vis absorption spectrum and a strong phosphorescence at 592 nm in CH2Cl2 solution at room temperature. An intramolecular energy transfer process from the carbazole unit to the arylamine-modified (C boolean AND N boolean AND N)PtCl] emissive center exists in the complex. (C) 2010 Elsevier B.V. All rights reserved.

Ultrafast inter- and intramolecular vibrational energy transfer between molecules at interfaces studied by time- and polarization-resolved SFG spectroscopy

We present experimental results on femtosecond time-resolved surface vibrational spectroscopy aimed at elucidating the sub-picosecond reorientational dynamics of surface molecules. The approach, which relies on polarization- and time-resolved surface sum frequency generation (SFG), provides a general means to monitor interfacial reorientational dynamics through vibrations inherent in surface molecules in their electronic ground state. The technique requires an anisotropic vibrational excitation of surface molecules using orthogonally polarized infrared excitation light. The decay of the resulting anisotropy is followed in real-time. We employ the technique to reveal the reorientational dynamics of vibrational transition dipoles of long-chain primary alcohols on the water surface, and of water molecules at the water-air interface. The results demonstrate that, in addition to reorientational motion of specific molecules or molecular groups at the interface, inter- and intramolecular energy transfer processes can serve to scramble the initial anisotropy very efficiently. In the two exemplary cases demonstrated here, energy transfer occurs much faster than reorientational motion of interfacial molecules. This has important implications for the interpretation of static SFG spectra. Finally, we suggest experimental schemes and strategies to decouple effects resulting from energy transfer from those associated with surface molecular motion.

Highly efficient visible light sensitized red emission from europium tris[1-(4-biphenoyl)-3-(2-fluoroyl)propanedione](1,10-phenanthroline) complex grafted on silica nanoparticles

A novel class of efficient visible light sensitized antenna complexes of Eu3+ based on the use of a highly conjugated β-diketonate, namely, 1-(4-biphenoyl)-3-(2-fluoroyl)propanedione (HBFPD) and 1,10-phenanthroline as an ancillary ligand has been designed, synthesized, characterized and their photophysical properties (PL) investigated. PL measurement results indicated that suitably expanded π-conjugation in the complex molecules makes the excitation band red shift to the visible region and hence the Eu3+ complexes exhibit intense red emission under blue light excitation (440 nm) with a solid-state quantum yield of 32 ± 3%, which is the highest so far reported in the literature. Further, in the present work, the visible sensitized Eu3+complex has been covalently anchored to the ordered mesoporous MCM-41 via the modified HBFPD ligand for the first time to the best of our knowledge. β-Diketonate grafted to the coupling agent 3-(triethoxysilyl)propylisocyanate was used as the precursor for the preparation of mesoporous nanomaterials. MCM-41 consisting of ternary complex Eu(SiBFPD)3(phen) covalently bonded to the silica-based network, which was designated as Eu(SiBFPD)3(Phen)/MCM-41 (3), was obtained by interacting europium nitrate, SiBFPD-Na and 1,10-phenanthroline into the hybrid material via a ligand-exchange reaction. The designed material was further characterized by powder X-ray diffraction, dynamic light scattering (DLS) technique, thermogravimetric analysis, N2 adsorption-desorption, SEM, TEM, FT-IR, FT-Raman, 13C and 29Si CPMAS NMR and photoluminescence spectroscopic techniques. The hybrid material covalently bonded to MCM-41 exhibits an efficient intramolecular energy transfer process from the silylated β-diketonate to the central Eu3+, namely, the “antenna effect”, which favored a stronger red/orange intensity ratio, longer lifetime, and high thermal stability than the precursor complex.

Highly efficient luminescent hybrid materials covalently linking with europium(iii) complexes via a novel fluorinated β-diketonate ligand: synthesis, characterization and photophysical properties

A novel highly fluorinated beta-diketonate ligand, 1-(3,5-bis(benzyloxy)phenyl)-4,4,5,5,5-pentafluoropentane-1,3-dione (HBBPPF) and its corresponding europium(III) ternary complex, Eu(BBPPF)(3)(DDXPO) [DDXPO = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene oxide] were synthesized via a dexterously designed routine, characterized and its photophysical properties (PL) investigated. PL measurement results indicated that the europium(III) ternary complex exhibits intense red emission under UV light excitation with a solid-state quantum yield of 39%. An organic-inorganic mesoporous luminescent hybrid material was also constructed by linking the ternary europium(III) complex to the functionalized hexagonal mesoporous MCM-41 through the modified beta-diketonate ligand (SiBBPPF-Na). Beta-diketonate grafted to the coupling agent 3-(triethoxysilyl)propyl isocyanate was used as the precursor for the preparation of mesoporous materials. A modified MCM-41 mesoporous material containing ternary europium(iii) complex covalently bonded to the silica-based network, designated as Eu(BBPPF-Si)(3)(DDXPO)/MCM-41, was obtained by interacting SiBBPPF-Na with europium nitrate, DDXPO and MCM-41 via a ligand-exchange reaction. The new mesoporous hybrid material was characterized by powder X-ray diffraction, nitrogen adsorption-desorption, thermogravimetry, transmission electron microscopy, dynamic light scattering, FT-IR, (29)Si CP MAS NMR and (13)C NMR solid-state techniques, and photoluminescence spectroscopy. Eu(BBPPF-Si)(3)(DDXPO)/MCM-41 exhibits an efficient intramolecular energy transfer process from the silylated beta-diketonate to the central Eu(3+), namely, the "antenna effect", which favours a strong luminescent intensity (quantum yield = 43%). Thermogravimetric analysis on Eu(BBPPF-Si)(3)(DDXPO)/MCM-41 demonstrated that the thermal stability of the lanthanide complex was evidently improved as it was covalently bonded to the mesoporous MCM-41 matrix.

A new way to construct luminescent functionalized silicon hybrid material derived from methyldichlorosilane

The functional precursor (PySi) was derived from the hydrosilylation reaction of methyldichlorosilane and 4-vinylpyridine, and then two series of novel luminescent hybrid materials (RE-PySi, where RE = Tb, Dy) with organic fragments covalently linked to inorganic parts were assembled by a sol–gel process, and characterized by the X-ray diffraction, scanning electron microscopy, and spectroscopy. It is found that the sol–gel treatment has an influence on the organization and microstructure of the hybrid materials, indicating that the hybrid material systems derived from different solvents exhibit different textures. The photoluminescent behavior of these chemically bonded hybrids was studied in detail. The observed green luminescence suggested that the intra-molecular energy-transfer process between the lanthanide ion and the pyridyl group takes place among these molecular-based hybrids.

Synthesis, characterization, photophysics and intramolecular energy transfer process in bimetallic rhenium(I)–ruthenium(II) complexes

Two new heterobimetallic complexes of rhenium(I) and ruthenium(II) [(CO) 3(NN)Re(4,4′-bpy)Ru(NN) 2Cl](PF 6) 2 and already known monometallic complexes [Cl(NN) 2Ru(4,4′-bpy)](PF 6) and [(CO) 3(NN)Re(4,4′-bpy)](PF 6) and bimetallic complexes [Cl(NN) 2Ru(4,4′-bpy)Ru(NN) 2Cl](PF 6) 2, [(CO) 3(NN)Re(4,4′-bpy)Re(NN)(CO) 3](PF 6) 2 (NN = 2,2′-bipyridine, 1,10-phenanthroline; 4,4′-bpy = 4,4′-bipyridine) are synthesized and characterized by spectral techniques. The photophysical properties of all the complexes are studied. It is found that attachment of rhenium(I) altered the photophysical characteristics of ruthenium(II). Excited state energy transfer from the rhenium(I) chromophore to the ruthenium(II) is observed upon excitation at 355 nm.

Photoluminescence study of new lanthanide complexes with benzeneseleninic acids

New lanthanide complexes with benzeneseleninic (ABSe) and 4-chloro-benzeneseleninic (ABSeCl) acids have been synthesized and characterized by elemental analysis, infrared and UV–visible spectroscopies. The emission spectra of the trivalent europium complexes presented the typical electronic 5D 0→ 7F J transitions of the ion ( J=0–4). The ground-state geometries of the europium complexes have been calculated by using the Sparkle/AM1 model. From these results, the 4f–4f intensity parameters and energies of the ligand singlet and triplet excited states have been obtained. The lower emission quantum yield for the [Eu(ABSe) 3(H 2O) 2](H 2O) 2 compound, as compared to the [Eu(ABSeCl) 3(H 2O) 2] one, can be associated to the higher numbers of water molecules, in the first and second coordination spheres, that contribute to the luminescence quenching. The [Eu(ABSe) 3(H 2O) 2](H 2O) 2 complex presents an intermediate state whose energy difference with respect to the first excited singlet state is resonant with three phonons from the water molecules, favouring a multiphonon relaxation process from the singlet state followed by a fast internal conversion process; this effect is less pronounced in the complex with the ABSeCl ligand. The luminescence decay curves of the gadolinium complexes indicate that the level responsible for the intramolecular energy transfer process has a triplet character for both compounds. The nephelauxetic effect in these compounds was investigated under the light of a recently proposed covalency scale based on the concept of overlap polarizability of the chemical bond.

Lanthanide (Tb3+, Eu3+) functionalized MCM-41 through modified meta-aminobenzoic acid linkage: Covalently bonding assembly, physical characterization and photoluminescence

Novel luminescent organic–inorganic mesoporous materials were synthesized by linking lanthanide (Tb3+, Eu3+) complexes to the functionalized ordered mesoporous MCM-41 with modified meta-aminobenzoic acid (MABA-Si) by co-condensation of tetraethoxysilane (TEOS) in the presence of the cetyltrimethylammonium bromide (CTAB) surfactant as template. meta-Aminobenzoic acid (MABA) grafted to the coupling agent 3-(triethoxysilyl)-propyl isocyanate (TEPIC) was used as the precursor for the preparation of mesoporous materials. The luminescence properties of these resulting materials (denoted as Ln-MABA-MCM-41, Ln=Tb, Eu) were characterized in detail, and the results reveal that luminescent mesoporous materials have high surface area, uniformity in the mesopore structure and good crystallinity. Moreover, the mesoporous material covalently bonded Tb3+ complex (Tb-MABA-MCM-41) exhibits the stronger characteristic emission of Tb3+ and longer lifetime than Eu-MABA-MCM-41 due to the triplet state energy of organic ligand MABA-Si matches with the emissive energy level of Tb3+ very well. Compared with pure Tb(MABA)3 complex, the increase of luminescence intensity in Tb-MABA-MCM-41 shows that the mesoporous MCM-41 is an excellent host for the luminescence Tb(MABA)3 complex. In addition, the luminescence lifetime and emission quantum efficiency of 5D0 Eu3+ excited state also indicates that a more efficient intramolecular energy transfer process in Tb-MABA-MCM-41 than in Eu-MABA-MCM-41.

Lanthanide/zinc centered photoactive hybrids with functional sulfonamide linkage: Coordination bonding assembly, characterization and photophysical properties

In this paper, two novel kinds of organic–inorganic monomer, SUA-APEMS and SUA-APS, have been achieved by modifying 5-sulfosalicylic acid (SUA) with 3-aminopropyl-methyl-diethoxylsilane (APEMS) and 3-aminopropyl trimethoxysilane (APS). These two organic–inorganic monomers were used as multi-functional bridged components, which can coordinate to metal ions (Tb 3+/Eu 3+/Zn 2+) with carbonyl groups, strongly absorb ultraviolet and effectively transfer energy to metal ions through their triplet excited state, as well as involve in the sol–gel process with inorganic host precursor tetraethoxysilane (TEOS), resulting two series of molecular hybrid materials (named as SUA-APEMS/APS-RE) with double chemical bond (RE(Zn)–O coordination bond and Si–O covalent bond). The effective intra-molecular energy transfer process gives rise to the characteristic emission of metal ions and the chemical bond make the hybrid materials owning better properties.

Chemically bonded metallic (Eu, Tb, Zn) hybrid materials through sulfide linkage: Molecular construction, physical characterization and photophysical properties

In this paper, a kind of aromatic carboxylic acid of sulfhydryl group (2-mercaptonicotinic acid) is modified with four silane crosslinking reagents (3-methacryloyloxypropyltrimethoxysilane (S 1), 3-glycidoxypropyltrimethoxysilane (S 2), 3-aminopropyltrimethoxysilane (S 3), and 3-(triethoxysilyl)propylisocyanate (S 4)) to achieve four new kinds of functionalized molecular bridge (P i ( i = 1–4)). Subsequently, four molecular bridges and lanthanides (europium and terbium) or zinc ions have been assembled via chemical bonds through a sol–gel (cohydrolysis and copolycondensation) process with inorganic precursor (tetraethoxysilane, TEOS), resulting in four novel series of chemically bonded hybrid materials which named as Ln (Zn)–M i ( i = 1–4). The coordinated bonding makes metal ions evenly dispersed in a stable hybrid system. The intramolecular energy transfer process between lanthanide ions and the molecular bridges take place within these molecular-based hybrids and especially the luminescent quantum efficiency of them are determined, suggesting that the hybrid material systems derived from different molecular bridges present different luminescence efficiencies.

Molecular assembly, physical characterization and photophysical properties of ternary lanthanide hybrids containing functional 1,2,4-triazole and 1,10-phenanthroline

This work focuses on the preparation and the study of the luminescence properties of series ternary lanthanide molecular hybrid materials. We selected 1,10-phenanthroline as a second ligand to introduce into the binary hybrid system in which an organic functional compound 1,2,4-triazole was included. The further investigation of the luminescence properties proves that, after the addition of the 1,10-phenanthroline, the energy levels matching degree between the organic segments and RE ions is more suited and appropriate so that the final ternary hybrid materials show stronger luminescence intensity, which substantiating that the heterocyclic ligand would become the main energy donor and has the possibility to sensitize Ln 3+ ions via an intramolecular energy transfer process, at the same time, the luminescent quantum efficiencies of the ternary systems are also highly improved compared with the binary systems. Besides, the introduction of the second ligands don’t change the disorder structure of the siliceous skeleton and thus no phase separation be observed in the hybrid systems. We may expect to obtain stable and efficient hybrid materials in optical or electronic areas from this method.

Lanthanide-centered inorganic/organic hybrids from functionalized 2-pyrrolidinone-5-carboxylic acid bridge: Covalently bonded assembly and luminescence

Abstract A series of organic–inorganic hybrid material with chemically bonding have been prepared through the precursor (PDCA-Si) derived from 2-pyrrolidinone-5-carboxylic acid, which exhibits a self-organization cooperation interaction under the coordination to RE 3+ (Eu 3+ , Tb 3+ ). The pure organic silica hybrids (PDCA-Si) without RE 3+ presents the small particle size and main blue luminescence with maximum peak 462 nm occupying a broad band from 425 to 550 nm. When Eu 3+ and Tb 3+ are introduced, the particle size of the hybrids increases, indicating the coordination effect has influence on the microstructure of hybrids. Besides, the corresponding Eu and Tb hybrids (Eu–PDCA-Si, Tb–PDCA-Si) show the characteristic red and green luminescence of Eu 3+ and Tb 3+ , respectively, which suggests that the efficient intramolecular energy transfer process take place between carboxylic groups and lanthanide ions take place. The luminescence lifetimes and quantum efficiencies of them are determined and energy transfer efficiency between PDCA-Si and Eu 3+ (Tb 3+ ) is calculated.

Functionalization of Calix[4]arene as a Molecular Bridge To Assemble Luminescent Chemically Bonded Rare-Earth Hybrid Systems

The functional macrocyclic precursors (abbreviated as BC[4]Si and C[4]Si) derive from two kinds of calix[4]arenes, p-tert-butylcalix[4]arene (BC[4]) and calix[4]arene (C[4]) grafted by 3-(triethoxysilyl)propyl isocyanate (TESPIC) through base-initiated nucleophilic addition, and then three series of novel luminescent chemically bonded hybrid material systems (BC[4]Si, RE-BC[4]Si, C[4]Si, and RE-C[4]Si, where RE = Eu, Tb) with organic parts covalently linked to inorganic parts via the functionalized calix[4]arene linkages have been assembled by a sol-gel process, which is characterized by the X-ray diffraction, thermogravimetry/differential scanning calorimetry, scanning electron microscopy, and spectroscopy. It is found that the coordination of rare-earth ions has an influence on the organization and microstructure of the hybrid systems. The photoluminescent behavior (luminescence, lifetime, quantum efficiency, and energy transfer) for these chemically bonded hybrids is studied in detail. Three color luminescences are checked, blue (BC[4]Si and C[4]Si), green (Tb-BC[4]Si and Tb-C[4]Si), and red (Eu-BC[4]Si and Eu-C[4]Si), respectively, suggesting that the intramolecular energy-transfer process between the rare-earth ion and the host takes place within these molecular-based hybrids. Also, especially their quantum efficiencies are determined, which indicates that the different hybrid material systems derived from different functionalized calix[4]arene bridges present different luminescence behavior.

A Mechanically Interlocked [3]Rotaxane as a Light‐Harvesting Antenna: Synthesis, Characterization, and Intramolecular Energy Transfer

A mechanically interlocked light-harvesting system [3]rotaxane A has been synthesized in high yield through Cu(I)-catalyzed azide-alkyne cycloaddition; the hexyl-substituted truxene units are introduced into the wheels as donors and an oligo(para-phenylenevinylene) (OPV) unit into the axis as the acceptor. The structure and the purity of [3]rotaxane A were confirmed by (1)H and (13)C NMR spectroscopy and ESI HRMS. The azide-alkyne cycloaddition is demonstrated to be an efficient stoppering method in the synthesis of the rotaxane containing dibenzo[24]crown-8 and dibenzyl ammonium units. Detailed steady-state UV/Vis absorption, photoluminescent, and time-resolved fluorescence spectroscopy were performed to investigate the photophysical properties of [3]rotaxane A and its reference compounds in solution and as thin films. Even in dilute solution, efficient energy transfer from the truxene-functionalized wheels to the OPV-based axis, through the dibenzo[24]crown-8 and dibenzyl ammonium interaction, is observed in [3]rotaxane A. The unique topology of [3]rotaxane A not only efficiently promotes the intramolecular energy-transfer process, but also prevents intermolecular aggregation in the solid state. The new antenna system opens up the possibility of controllable light-harvesting molecular machines or other optoelectronic devices on the nanometer scale.

Highly luminescent europium(iii) complexes containing organosilyl 4,4,5,5,5-pentafluoro-1-(naphthalen-2-yl)pentane-1,3-dionate ligands grafted on silica nanoparticles

A novel organic–inorganic mesoporous luminescent hybrid material was designed by linking a ternary Eu3+ complex to the functionalized hexagonal mesoporous MCM-41 with the modified β-diketone, 4,4,5,5,5-pentafluoro-1-(naphthalen-2-yl)pentane-1,3-dione (HPFNP), which contains a polyfluorinated alkyl group as well as the long conjugated naphthyl group. β-Diketone grafted to the coupling agent 3-(triethoxysilyl)propylisocyanate was used as the precursor for the preparation of mesoporous materials. MCM-41, consisting of ternary complex, Eu(PFNP-Si)3(bath) covalently bonded to the silica-based network, which was designated as Eu(PFNP-Si)3(bath)/MCM-41, was obtained by interacting europium nitrate, SiPFNP-Na and 4,7-diphenyl-1,10-phenanthroline (bath) into the mesoporous material via a ligand-exchange reaction. The synthesized luminescent hybrid material was fully characterized by various spectroscopic techniques, and its photophysical properties were investigated. Eu(PFNP-Si)3(bath)/MCM-41 exhibits an efficient intramolecular energy transfer process from the silylated β-diketone to the central Eu3+, namely, the “antenna effect”, which favoured highly luminescent behaviour in the modified hexagonal mesoporus silica.

Photoluminescent hybrid thin films fabricated with lanthanide ions covalently bonded silica

Silica-based organic–inorganic hybrid thin solid films were fabricated via a spin coating sol–gel process technology. Among tetraethoxysilane (TEOS) and a kind of modified monomer (abbreviated as PZC-APTES) derived from grafted 2-pyrazinecarboxylic acid (PZC) with (3-aminopropyl)triethoxysilane (APTES) were used as the inorganic and organic components. Through the hydrolysis and polycondensation process of both TEOS and PZC-APTES, lanthanide ions were introduced in the hybrid systems through the coordination to the monomer. Controlling the sol–gel process by spin coating over the quartz substrate for 2 days, the hybrid thin films were achieved. The final solid films exhibited strong red luminescence (Eu 3+) and green luminescence (Tb 3+), suggesting that the intramolecular energy transfer process occurs for the suitable energy match between the triplet state energy of organic ligand and the emissive energy level of lanthanides.