Mesoporous hybrids containing Eu complexes covalently bonded to SBA-15 functionalized: Assembly, characterization and photoluminescence

A novel series of luminescent mesoporous organic-inorganic hybrid materials has been prepared by linking Eu³⁺ complexes to the functionalized ordered mesoporous SBA-15 which was synthesis by a co-condensation process of 1,3-diphenyl-1,3-propanepione (DBM) modified by the coupling agent 3-(triethoxysilyl)-propyl isocyanate (TEPIC), tetraethoxysilane (TEOS), Pluronic P123 surfactant as a template. It was demonstrated that the efficient intramolecular energy transfer in the mesoporous material Eu(DBMSi-SBA-15)₃phen mainly occurred between the modified DBM (named as DBM-Si) and the central Eu³⁺ ion. So the Eu(DBMSi-SBA-15)₃phen showed characteristic emission of Eu³⁺ ion under UV irradiation with higher luminescence quantum efficiency. Moreover, the mesoporous hybrid materials exhibited excellent thermal stability as the lanthanide complex was covalently bonded to the mesoporous matrix.     

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 (S₁), 3-glycidoxypropyltrimethoxysilane (S₂), 3-aminopropyltrimethoxysilane (S₃), and 3-(triethoxysilyl)propylisocyanate (S₄)) 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.     

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.     

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.     

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

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 RE³⁺ (Eu³⁺, Tb³⁺). The pure organic silica hybrids (PDCA-Si) without RE³⁺ presents the small particle size and main blue luminescence with maximum peak 462 nm occupying a broad band from 425 to 550 nm. When Eu³⁺ and Tb³⁺ 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 Eu³⁺ and Tb³⁺, 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 Eu³⁺ (Tb³⁺) is calculated.     

Assembly, characterization, and photoluminescence of hybrids containing europium(III) complexes covalently bonded to inorganic Si-O networks/organic polymers by modified beta-diketone

1-(2-naphthoyl)-3,3,3-trifluoroacetonate (NTA) was grafted to the coupling agent 3-(triethoxysilyl)-propyl isocyanate (TEPIC) and used as the first kind of precursor, and other kinds of precursors (PVPD, PMAA, and PVPDMAA) were synthesized through the addition polymerization reactions of the monomer 4-vinylpyridine and methacrylic acid. Then, these precursors coordinated to rare earth ions, and the three kinds of hybrid polymeric materials were obtained after hydrolysis and copolycondensation with the tetraethoxysilane (TEOS) via a sol-gel process. FTIR, ultraviolet, ultraviolet-visible diffuse reflection and photoluminescent spectra, electronic microscopy diagraphs, room-temperature X-ray diffraction patterns, and TG plots were characterized, and the results reveal that the hybrid materials imbedded into the single polymer (PVPD and PMAA) showed more uniformity in the microstructure, more efficient intramolecular energy transfer between europium ions and the modified ligand NTA-Si and more excellent characteristic emission of europium ions under UV irradiation with higher (5)D(0) luminescence quantum efficiency and longer lifetime than the hybrid materials imbedded into the multipolymer (PVPDMAA).     

Charge-transfer hybrids containing covalently bonded polyoxometalates and ferrocenyl units

Two new charge-transfer hybrids with one or two ferrocenyl units covalently attached to a hexamolybdate cluster through an extended pi-conjugated bridge have been prepared using Pd-catalyzed coupling reactions on monoiodo- or diiodo-functionalized cluster substrates in over 60% yields. These hybrids have been characterized by (1)H NMR, FTIR, electrospray ionization mass spectrometry, and X-ray diffraction. The electronic spectra of these hybrids show a broad absorption tail extending beyond 550 nm, indicating the existence of charge-transfer transition from the ferrocenyl donor to the cluster acceptor. The observation of the clear charge-transfer transition indicates the contribution of charge-transfer resonance to the ground state in both 2a and 2b even though the donor-acceptor separation distance of 11.29 A is rather long, signaling a through-bond charge-transfer nature made possible by the organic pi-conjugated bridge. Cyclic voltammetry studies reveal a one-electron oxidation wave and a one-electron reduction wave for the hybrid with one ferrocenyl unit. For the one with two ferrocenyl units, a lower reduction potential and a two-electron oxidation wave are observed, indicating negligible electronic interactions between the two ferrocenyl units.     

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 (Tb³⁺/Eu³⁺/Zn²⁺) 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.     

Porous phosphate heterostructures containing CdS quantum dots: assembly, characterization and photoluminescence

The synthesis and characterization of cadmium sulphide (CdS) quantum dots, conjugated in a porous phosphate heterostructure functionalized with aminopropyl groups is described. The resulting material has fluorescence properties with maximum emission intensity at 575 nm. The fluorescent materials are not soluble in water and exhibit high stability in aqueous solution in the pH ranges from 2 to 9. Energy dispersive X-ray spectroscopy confirmed the qualitative elemental composition of the synthesized materials and X-ray photoelectron spectra showed a surface S/Cd atomic ratio of 1.09. SEM images show that the materials are amorphous, possessing porous with sizes of several tens nanometres, homogeneous and exhibit a layered morphology. The adsorption–desorption analysis by N₂ at 77 K showed the accessibility of the CdS quantum dots onto the pores of the structure. The CdS quantum dots were stabilized by mercaptopropionic acid and bounded to the host materials by amine groups.     

Rare earth (Eu, Tb) mesoporous hybrids with calix[4]arene derivative covalently linking MCM-41: Physical characterization and photoluminescence property

MCM-41 mesoporous silica has been functionalized with two kinds of macrocylic calixarene derivatives Calix[4] and Calix[4]Br (Calix[4]=P-tert-butylcalix[4]arene, Calix[4]Br=5.11,17.23-tetra-tert-butyl-25.27-bihydroxy-26.28-bibromopropoxycalix[4]arene) through condensation approach of tetraethoxysilane (TEOS) in the presence of the cetyltrimethylammonium bromide (CTAB) surfactant as a template. Novel organic-inorganic mesoporous luminescent hybrid containing RE³⁺ (Eu³⁺, Tb³⁺) complexes covalently attached to the functionalized ordered mesoporous MCM-41, which are designated as RE-Calix[4]-MCM-41 and RE-Calix[4]Br-MCM-41, respectively, are obtained by sol-gel process. It is found that they all have high surface area, uniform in the mesostructure and good crystallinity. Measurement of the photoluminescence properties show the mesoporous material covalently bonded Tb³⁺ complexes (Tb-Calix[4]-MCM-41 and Tb-Calix[4]Br-MCM-41) exhibit the stronger characteristic emission of Tb³⁺ and longer lifetime than the corresponding Eu-containing materials Eu-Calix[4]-MCM-41 and Eu-Calix[4]Br-MCM-41 due to the triplet state energy of modified organic ligands Calix[4]-Si and Calix[4]Br-Si match with the emissive energy level of Tb³⁺ very well.     

Interface of covalently bonded phospholipids with a phosphorylcholine head: characterization, protein nonadsorption, and further functionalization

Surface anchored poly(methylhydrosiloxane) (PMHS) thin films on oxidized silicon wafers or glass substrates were functionalized via the SiH hydrosilylation reaction with the internal double bonds of 1,2-dilinoleoyl-sn-glycero-3-phosphorylcholine (18:2 Cis). The surface was characterized by X-ray photoelectron spectroscopy, contact angle measurements, atomic force microscopy, and scanning electron microscopy. These studies showed that the PMHS top layer could be efficiently modified resulting in an interfacial high density of phospholipids. Grafted phospholipids made the initially hydrophobic surface (θ = 106°) very hydrophilic and repellent toward avidin, bovine serum albumin, bovine fibrinogen, lysozyme, and α-chymotrypsin adsorption in phosphate saline buffer pH 7.4. The surface may constitute a new background-stable support with increased biocompatibility. Further possibilities of functionalization on the surface remain available owing to the formation of interfacial SiOH groups by Karstedt-catalyzed side reactions of SiH groups with water. The presence of interfacial SiOH groups was shown by zeta potential measurements. The reactivity and surface density of SiOH groups were checked by fluorescence after reaction of a monoethoxy silane coupling agent bearing Alexa as fluorescent probe.     

Preparation and characterization of chemically bonded aramid-titania hybrids using isocyanatopropyltrimethoxysilane

Transparent aramid based titania hybrid films have been prepared by the sol–gel process. A mixture of m- and p-phenylenediamines was reacted with terephthaloyl chloride forming aromatic polyamide chains in dimethylacetamide solvent. The titania network was generated insitu in this matrix by the hydrolysis and condensation of the various amounts of tetraethylorthotitanate. Hybrid films with concentrations of titania varying from 2.5 to 12.5 wt% were prepared; the higher percentages of titania in the organic matrix showed a tendency towards phase separation. These films were tested for their thermo-mechanical properties. To achieve a further improvement in properties of the matrix, the aramid chain was functionalized and the inorganic network was chemically bonded using isocyanatopropyltrimethoxysilane. The bonded hybrids showed a narrower distribution of titania particles and these were distributed as a co-continuous phase. The glass transition temperature (Tg) of the hybrid films measured through dynamic mechanical analysis showed a relatively higher increase with inclusion of titania in the covalently bonded hybrids. The maximum value of Tg noted in the chemically bonded composites with 12.5 wt% titania was 361 °C and the storage modulus value was 5.214 GPa at 100 °C, showing an increase of 62 % over the pure polymer. The hybrid films with titania showed an improved UV-stability as compared to the pure polymer.     

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.     

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.     

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.     

Synthesis, characterization, and luminescence properties of the ternary europium complex covalently bonded to mesoporous SBA-15

A novel mesoporous SBA-15 type of hybrid material (phen-SBA-15) covalently bonded with 1,10-phenanthroline (phen) ligand was synthesized by co-condensation of tetraethoxysilane (TEOS) and the chelate ligand 5-[N,N-bis-3-(triethoxysilyl)propyl]ureyl-1,10-phenanthroline (phen-Si) in the presence of Pluronic P123 surfactant as a template. The preservation of the chelate ligand structure during the hydrothermal synthesis and the surfactant extraction process was confirmed by Fourier transform infrared (FTIR) and (29)Si MAS NMR spectroscopies. SBA-15 consisting of the highly luminescent ternary complex Eu(TTA)(3)phen (TTA = 2-thenoyltrifluoroacetone) covalently bonded to a silica-based network, which was designated as Eu(TTA)(3)phen-SBA-15, was obtained by introducing the Eu(TTA)(3).2H(2)O complex into the hybrid materials via a ligand exchange reaction. XRD, TEM, and N(2) adsorption measurements were employed to characterize the mesostructure of Eu(TTA)(3)phen-SBA-15. For comparison, SBA-15 doped with Eu(TTA)(3).2H(2)O and Eu(TTA)(3)phen complexes and SBA-15 covalently bonded with a binary europium complex with phen ligand were also synthesized, and were named SBA-15/Eu(TTA)(3), SBA-15/Eu(TTA)(3)phen, and Eu-phen-SBA-15, respectively. The detailed luminescence studies on all the materials showed that, compared with the doping sample SBA-15/Eu(TTA)(3)phen and binary europium complex functionalized sample Eu-phen-SBA-15, the Eu(TTA)(3)phen-SBA-15 mesoporous hybrid material exhibited higher luminescence intensity and emission quantum efficiency. Thermogravimetric analysis on Eu(TTA)(3)phen-SBA-15 demonstrated that the thermal stability of the lanthanide complex was evidently improved as it was covalently bonded to the mesoporous SBA-15 matrix.     

Bismuth 2,6-pyridinedicarboxylates: assembly of molecular units into coordination polymers, CO2 sorption and photoluminescence

Six inorganic-organic bismuth 2,6-pyridinedicarboxylate (pdc) compounds, [Bi(2,6-pdc)(3)]·3(dma), 1, [Bi(2,6-pdc)(3)]·3(dma)·2(H(2)O), 2, [Bi(2,6-pdc)(2)(dmf)]·(dma), 3, Bi(2,6-pdc)(2,6-pdcme)(MeOH), 4, [LiBi(2,6-pdc)(3)(H(2)O)]·2(dma), 5, and Li(5)Bi(2,6-pdc)(4)(H(2)O)(2), 6 (where dma = dimethyl ammonium cation, dmf = dimethylformamide and 2,6-pdcme = 6-methyl-oxycarbonyl pyridine 2-carboxylate) have been synthesized under solvothermal conditions and their structures determined by single crystal X-ray diffraction. Compounds 1-4 have molecular structures whereas compounds 5 and 6 form one- and three-dimensional frameworks, respectively. Compounds 1 and 2, both having similar monomeric bismuth coordination units, which are connected non-covalently into a (4,4)-connected square lattice by H-bonding interactions through dma cations. Compounds 3 and 4, both have a similar dimeric bismuth coordination unit. In 3, the dimers are connected into a one-dimensional chain by H-bonding interactions through dma cations. In the partially esterified and neutral 4, there was no such H-bonding interactions due to the absence of any dma cations. Compounds 5 and 6 have a similar monomeric bismuth coordination unit to that seen in 1 and 2. In 5, the monomers are connected through lithium cations into one-dimensional chains, which further interact non-covalently by H-bonding interactions through dma cations. In the lithium-rich 6, the monomers are connected by the lithium cations and 2,6-pdc anions into a three dimensional structure with intramolecular H-bonding interactions involving the water molecules. The non-porous 5 and 6 exhibit a reasonable amount of H(2) and CO(2) sorptions, respectively. Tb(3+)- and Eu(3+)-doped and co-doped 4 and 5 emit characteristic sensitized green/red/yellow-orange luminescence.     

Hydrothermal synthesis, physical characterization and photoluminescence of homologous-SBA-15 fabricated with Eu

Two series of Eu³⁺-doped homologous-SBA-15 materials (abbreviated as MPTMS-SBA-15: Eu³⁺ and CTMS-SBA-15: Eu³⁺) have been synthesized by a hydrolysis-controlled technology, in which two novel silane crosslinking reagents (3-(methacryloyloxy) propyltrimethoxysilane (MPTMS) and 3-(chloropropyl) trimethoxysilane (CTMS)) are used as silicate precursor instead of traditional tetraethoxysilane (TEOS). It can be found that the different silicate precursors with different functional groups have influence on the physical properties of the corresponding homologous materials. In comparison to the pure SBA-15, the BET surface area and pore size of the modified mesoporous materials have been changed. Finally, the characteristic luminescence is observed for the ⁵D₀ → ⁷F_J (J = 0, 1, 2) transition of Eu³⁺ ion, suggesting that these kind of homologous-SBA-15 materials are potential host for the luminescence of Eu³⁺, whose excitation energy can be quenched by Eu³⁺ to some extent.     

Chiral molecular polygons based on the Pt-alkynyl linkage: Self-assembly, characterization, and functionalization

Treatment of 2,2′-diacetoxy-1,1′-binaphthyl-6,6′-bis(ethyne), L-H₂, with one equiv of trans-Pt(PEt₃)₂Cl₂ led to a mixture of different sizes of chiral metallocycles [trans-(PEt₃)₂Pt(L)]_n (n = 3-8, 1-6). Each of the chiral molecular polygons 1-6 was purified by silica-gel column chromatography and characterized by ¹H, ¹³C{¹H}, and ³¹P{¹H} NMR spectroscopy, MS, IR, UV-Vis, and circular dichroism (CD) spectroscopies, size exclusion chromatography, and microanalysis. Chiral molecular square 2 was also characterized by single-crystal X-ray diffraction. The acetyl groups of 2 were readily deprotected under mild conditions to generate 2a which possesses exposed chiral dihydroxy functional groups. The dihydroxy groups were functionalized with n-octadecyl chains or Fréchet-type dendrons to generate dendritic molecules built on a chiral molecular square core. This work shows the potential of generating interesting functional supramolecular systems based on Pt-alkynyl chiral molecular polygons.     

Synthesis, characterization, and near-infrared luminescent properties of the ternary thulium complex covalently bonded to mesoporous MCM-41

The crystal structure of a ternary Tm(DBM)₃phen complex (DBM=dibenzoylmethane; phen=1, 10-phenanthroline) and the synthesis of hybrid mesoporous material in which the complex covalently bonded to mesoporous MCM-41 are reported. Crystal data: Tm(DBM)₃phen C₅₉H₄₇N₂O₇Tm, monoclinic, P21/c, a=19.3216(12) Å, b=10.6691(7) Å, c=23.0165(15) Å, α=90°, β=91.6330(10)°, γ=90°, V=4742.8(5) Å³, Z=4. The properties of the Tm(DBM)₃phen complex and the corresponding hybrid mesoporous material [Tm(DBM)₃phen-MCM-41] have been studied. The results reveal that the Tm(DBM)₃phen complex is successfully covalently bonded to MCM-41. Both Tm(DBM)₃phen complex and Tm(DBM)₃phen-MCM-41 display typical near-infrared (NIR) luminescence upon excitation at the maximum absorption of the ligands, which contributes to the efficient energy transfer from the ligands to the Tm³⁺ ion, an antenna effect. The full width at half maximum (FWHM) centered at 1474 nm in the emission spectrum of Tm(DBM)₃phen-MCM-41 is 110 nm, which is the potential candidate of broadening amplification band from C band (1530-1560 nm) to S⁺ band (1450-1480 nm) in optical area.