Near-infrared luminescent mesoporous MCM-41 materials covalently bonded with ternary thulium complexes

Two β-diketones 4,4,4-trifluoro-1-2-thenoyl-1,3-butanedione (Htta) and 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione (Htfnb), which contain trifluoroalkyl chain, were selected as the main sensitizer for synthesizing Tm(L)₃phen (L = tta, tfnb) complexes. The two near-infrared (NIR) luminescent thulium complexes have been covalently bonded to the ordered mesoporous material MCM-41 via a functionalized 1,10-phenanthroline (phen) group 5-(N,N-bis-3-(triethoxysilyl)propyl)ureyl-1,10-phenanthroline (phen-Si) [The resultant mesoporous materials are denoted as Tm(L)₃phen–MCM-41 (L = tta, tfnb)]. The Tm(L)₃phen–MCM-41 (L = tta, tfnb) mesoporous materials were characterized by small-angle X-ray diffraction (XRD) and N₂ adsorption/desorption, and they show characteristic mesoporous structure of MCM-41. Luminescence spectra of the Tm(L)₃phen–MCM-41 (L = tta, tfnb) mesoporous materials were recorded and the corresponding luminescence decay curves were obtained. After ligand-mediated excitation, the emission spectra of the Tm(L)₃phen–MCM-41 (L = tta, tfnb) mesoporous materials show the characteristic NIR-luminescence of the Tm³⁺ ion. The full width at half maximum (fwhm) of the 1474-nm emission band are 96 and 100 nm for Tm(tta)₃phen–MCM-41 and Tm(tfnb)₃phen–MCM-41, respectively. The good luminescent performances enable these NIR-luminescent mesoporous materials to have potential applications in optical amplification [broadening amplification band from C band (1530–1560 nm) to S⁺ band (1450–1500 nm)]. Furthermore, the comparison of the luminescence behavior for Tm(tta)₃phen–MCM-41 and Tm(tfnb)₃phen–MCM-41 mesoporous materials was investigated. It shows that Tm(tfnb)₃phen–MCM-41 is somewhat superior to Tm(tta)₃phen–MCM-41 as optical amplifier.     

Monometallic and bimetallic europium(III) and terbium(III) complexes: Synthesis and luminescent properties

Eight new lanthanide complexes of the form Ln(L)₃bipy and [Ln(L)₃]₂bpm were synthesized (where L = 2,2,6,6-tetramethyl-3,5-heptanedione (tmh) and 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione (tdh), bipy = 2,2′-bipyridine, bpm = 2,2′-bipyrimidine and Ln = Tb(III) or Eu(III)). The luminescent spectra are typical of Tb(III) and Eu(III) complexes with intense transitions at 545 nm for Tb(III) and 612 nm for the Eu(III) complexes. Energy gaps between the tmh 1 orbitals and the ⁰D_J manifold of Eu(III) are too large to give efficient energy transfer therefore emission spectra for Eu(tmh)₃bipy and [Eu(tmh)₃]₂bpm were not detected. Lifetimes are greatest for the Tb(III) complexes containing tmh terminal ligands while the longest lifetimes for the Eu(III) complexes occur with the tdh terminal ligands.     

Adsorption of Cr(III) ions using 2-(ureylenemethyl)pyridine functionalized MCM-41

Journal of Porous Materials - Modified MCM-41 material with uniform meropore channels was prepared by surfactant-directed synthesis strategy and post functionalized with 3-(triethoxysilyl)propyl...     

Near-infrared luminescent mesoporous materials covalently bonded with ternary lanthanide [Er(III), Nd(III), Yb(III), Sm(III), Pr(III)] complexes

New near-infrared-luminescent mesoporous materials were prepared by linking ternary lanthanide (Er³⁺, Nd³⁺, Yb³⁺, Sm³⁺, Pr³⁺) complexes to the ordered mesoporous MCM-41 through a functionalized 1,10-phenanthroline (phen) group 5-(N,N-bis-3-(triethoxysilyl)propyl)ureyl-1,10-phenanthroline. The resulting materials (denoted as Ln(hfth)₃phen–M41 and Pr(tfnb)₃phen–M41; Ln = Er, Yb, Nd, Sm; hfth = 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)hexane-1,3-dionate; tfnb = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedionate) were characterized by powder X-ray diffraction, N₂ adsorption/desorption, and elemental analysis. Luminescence spectra of these lanthanide-complex functionalized materials were recorded, and the luminescence decay times were measured. Upon excitation at the absorption of the organic ligands, all these materials show the characteristic NIR luminescence of the corresponding lanthanide (Er³⁺, Nd³⁺, Yb³⁺, Sm³⁺, Pr³⁺) ions by sensitization from the organic ligands moiety. The good luminescent performances enable these NIR-luminescent mesoporous materials to have possible applications in optical amplification (operating at 1300 or 1500 nm), laser systems, or medical diagnostics.     

Novel luminescent samarium(III) chelates

A series of new stable, luminescent samarium(III) chelates were synthesized and their photophysical properties were measured. The iodoacetamido activated chelate coupled to a peptide was used in a caspase-3 assay.     

Design and synthesis of near-IR luminescent mesoporous materials covalently linked with tris(8-hydroxyquinolinate)lanthanide(III) complexes

By using the bifunctional ligand, 8-hydroxyquinoline-functionalized organosilane (Q-Si), the new mesoporous material Q–MCM-41 covalently bonded with 8-hydroxyquinoline was synthesized. Through the ligand exchange reaction, the new near-infrared (NIR) luminescent mesoporous LnQ₃–MCM-41 (Ln = Er, Nd, Yb) materials were prepared by linking the lanthanide quinolinate complexes to the ordered mesoporous Q–MCM-41 material. The LnQ₃–MCM-41 materials were characterized by powder X-ray diffraction and N₂ adsorption/desorption, and they all show the characteristic mesoporous structure of MCM-41 with highly uniform pore size distributions. Fluorescence spectra of these LnQ₃–MCM-41 materials were recorded and the corresponding luminescence decay analyses were measured. After ligand-mediated excitation, all the emission spectra of the LnQ₃–MCM-41 materials show the characteristic NIR-luminescence of the corresponding lanthanide ions via the intramolecular energy transfer from the ligands to the lanthanide ions. The good luminescent performances enable these NIR-luminescent mesoporous materials to have potential applications in optical amplification (operating at 1.3 or 1.5 μm) and laser systems, etc.     

Electrochemical behavior of europium (III) in N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide

N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPyNTf₂) was synthesized and characterized by CHNS elemental analysis, ¹H and ¹³C NMR and IR spectroscopy. Europium tris[bis(trifluoromethylsulfonyl)imide] (Eu(NTf₂)₃) was prepared and studied for the electrochemical behavior of Eu(III) in BMPyNTf₂ at glassy carbon and stainless steel working electrodes at 298-373 K by cyclic voltammetry, chronopotentiometry and chronoamperometry. Cyclic voltammogram of Eu(III) in BMPyNTf₂ consisted of a quasi-reversible cathodic wave at −0.45 V (vs. Fc/Fc⁺, 373 K), which could be attributed to the reduction of Eu(III) to Eu(II) and an irreversible wave at −2.79 V (vs. Fc/Fc⁺) due to reduction of Eu(II) to Eu(0). The diffusion coefficient of Eu(III) in BMPyNTf₂ was determined to be in the range of ∼10⁻⁷ cm² s⁻¹ by various electrochemical methods and the charge transfer rate constant was determined to be ∼10⁻⁵ cm s⁻¹ by cyclic voltammetry.     

二（2—苯并咪唑亚甲基）胺过渡金属配合物的合成及表征

合成了二（２－苯并咪唑亚甲基）胺及其四种全新的过渡金属的双核配合物。通过元素分析,红外光谱和紫外光谱对配体及配合物进行了结构表征。     

二（2—苯并咪唑亚甲基）胺配合物的合成

本文论述了二（２－苯并咪唑亚甲基）胺及配合物的合成方法,并对配合物进行了元素分析,为研究ＳＯＤ提供了基础和数据。     

Novel functionalized bis(imino)pyridine cobalt(II) catalysts for ethylene polymerization

This report describes synthesis and ethylene polymerization in the various conditions by two novel 2,6-bis(imino)pyridine (BIMP) catalysts B and C based on cobalt activated by methylaluminoxane (MAO) in a slurry semi-batch reactor. The catalyst activities as well as polymer properties were affected dramatically by electronic effects of the attached substitutions on the para-position of the pyridine ring. Theoretical study exhibited more positive charge on the central metal of the catalyst B resulted in higher activity at the expense of lower thermal stability and lifetime. The polymer obtained using the catalysts exhibited high molecular weight and almost narrow molecular weight distribution (MWD) ranging from 2.35 to 4.10 at the employed polymerization conditions. The highest and lowest molecular weight of the obtained polymers were produced by the catalyst A and C respectively. Hydrogen could slightly increase the catalyst activities with the exception of the catalyst B. The catalyst C bearing electron-donor OMe substitution at the para-position of the pyridine ring, produced PE with narrower PDI relative to the polymer resulted by catalysts A and B.     

Design and intelligent colour regulation of luminescent silk chemically bonded with Eu(III) and Eu(III)/Tb(III)

Design and successful synthesis of a series of novel luminescent silk chemically modified with europium(III) [Eu(III)] and europium(III)/terbium(III) [Eu(III)/Tb(III)] is reported. The modified silk specimens were characterised by infrared spectroscopy, fluorescence spectroscopy, scanning electron microscopy, and evaluated for their colour fastness. The rare earth ions were linked to the silk fibre via chemical bonds with the aid of tetracarboxylic acids used as the bridging ligands. Therefore, the modified silk had excellent luminescent stability and colour fastness to water and sunlight. Based on the blue fluorescence of silk along with the red and green luminescence of Eu(III) and Tb(III), respectively, under ultraviolet irradiation intelligent colour regulation was easily achieved by adjusting either the amount of Eu(III) or the ratio of Eu(III)/Tb(III). The Commission International de l'Eclairage chromaticity co‐ordinates calculated from the emission spectra also confirm the colour changes. Benefiting from the tunable colour and high stability, the modified silk could be an excellent candidate for applications in anti‐counterfeiting and flexible tunable light‐ emitting materials.     

Immobilization of a zirconium complex bearing bis(phenoxyketimine) ligand on MCM-41 for ethylene polymerization

A novel zirconium complex bearing bis(phenoxyketimine) ligand (1) bis((3,5-di-tert-butyl-C₆H₂-2-O)PhCN(2,4-di-fluoro-C₆H₃))ZrCl₂ (2) was prepared and successfully immobilized on a mesoporous molecular sieve MCM-41 in chemical method. Results of slurry polymerization of ethylene with MCM-41-supported catalyst (MC) indicated that the morphologies of polyethylene obtained differed greatly in heptane and toluene. Homogeneous catalyst 2 exhibited a very high initial activity in ethylene polymerization at room temperature resulting in great viscosity of the system. When immobilized on MCM-41, MC showed a smooth yet highly active kinetic behavior. With MAO as the cocatalyst, the effects of Al/Zr molar ratio and polymerization temperature on catalytic activity and properties of polyethylene obtained were investigated. The results showed that polyethylene obtained with MC possessed higher molecular weight (M_n) and broader molecular weight distribution (M_w/M_n) than those formed with its homogeneous counterpart.     

Activity of Mo(II) allylic complexes supported in MCM-41 as oxidation catalysts precursors

[Mo(η³-C₃H₅)X(CO)₂(NCCH₃)₂] (X = Br, 1a; X = Cl, 1b) complexes reacted with the bidentate ligand RNC(Ph)–C(Ph)NR, R = (CH₂)₂CH₃ (DAB, 2) affording [Mo(η³-C₃H₅)X(CO)₂(DAB)] (X = Br, 4a; X = Cl, 4b), which were characterized by elemental analysis, FTIR and ¹H and ¹³C NMR spectroscopy. The modified silylated ligand RNC(Ph)C(Ph)NR, R = (CH₂)₃Si(OCH₂CH₃)₃ (DAB–Si, 3), was used to immobilize the two complexes in MCM-41 (MCM) mesoporous silica. The new materials were characterized by powder X-ray diffraction, N₂ adsorption analysis, FTIR and ²⁹Si and ¹³C CPMAS solid state NMR spectroscopy. Both the materials and the complexes were tested in the oxidation of cyclooctene and styrene and behaved as active catalyst precursors for cyclooctene and styrene epoxidation with TBHP (t-butylhydroperoxide), leading selectively to epoxides with high conversions and TOFs. Although the homogeneous systems reach 100% conversion of cyclooctene and slightly less for styrene, the loss of catalytic activity in the heterogeneous systems is small, with a 98% conversion of styrene achieved by the chloride containing material.     

Physicochemical evaluation of nanocomposite hydrogels with covalently incorporated poly(vinyl alcohol) functionalized graphene oxide

To avoid the negative effect of graphene oxide (GO) nanosheets aggregation in aqueous solutions on physicochemical properties of GO incorporated nanocomposite hydrogels, poly(vinyl alcohol)-functionalized GO (GO-es-PVA) are synthesized and are used for preparation of nanocomposite hydrogels. By graft copolymerization of GO-es-PVA with poly(AA-co-AAm) chains, the nanocomposite hydrogel samples with covalently incorporated GO-es-PVA are achieved. FTIR spectroscopy, XRD analysis, and SEM and EDAX techniques confirm successful synthesis process. It is clear that GO-es-PVA content has significant effect on physicochemical properties of nanocomposite hydrogels, such as improvement of the water uptake properties, porosity, and gel strength. The hydrogel sample with 1:80 mass ratio of GO-es-PVA/AAm has the best physicochemical properties due to the optimum amount of GO-es-PVA, which gives the hydrogel proper viscoelasticity as well as fine porosity and water uptake rate. Interpenetration of PVA chains into the polymeric networks makes the movement of the polymer chains easier, which leads to softer polymeric networks. This phenomenon is called plasticizing effect. The plasticizing nature of PVA and its high hydrophilicity are the main reasons for the fine physicochemical properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48025.     

Novel photochemical reaction of itaconatopentamminecobalt(III) ion to produce a room temperature luminescent compound

Irradiation of itaconatopentamminecobalt(III) perchlorate complex in the ligand to metal charge transfer absorption band in aqueous solution using 254 nm radiation produced an oxidised ligand free radical, which further reacts with itaconatopentamminecobalt(III) ion and also by radical dimerisation reaction to form a compound which shows broad absorption at 265 nm and emission at 425 nm. The compound is identified to be a derivative of itaconic acid. The photoproduct shows two lifetimes of 1.5±0.1 ns and 5.5±0.5 ns indicating that the photoproduct decomposes at room temperature to give a second compound which is also luminescent.     

The immobilization of iron(III) aminopyridine complex on MCM-41: its preparation and characterization

2-Aminopyridinyl iron(III) complex was grafted on chlorosilane modified mesoporous MCM-41 to give MCM-Py-Fe(III). The immobilization was confirmed by FT-IR, ¹³C, ²⁹Si, ¹⁵N CP/MAS NMR, nitrogen adsorption–desorption study and elemental analysis. The powder XRD and TEM microscopy studies of the hybrid material confirmed the retention of the well-ordered honeycomb hexagonal structure in MCM-Py-Fe(III). The specific surface area of MCM-Py-Fe(III) was found to be 455 m² g^?1 and it had a pore volume of 0.27 cm³ g^?1 with an average pore diameter of 26.7 Å. The ¹³C CP/MAS NMR of MCM-Py-Fe(III) showed chemical shifts in the range of 113–155 ppm, which was assigned to the aromatic carbons in the pyridine ring. The ¹⁵N CP/MAS NMR showed the presence of chemical shifts at 550, 426 and 401 ppm for the three nitrogen atoms in the catalyst.     

Oligomerization of propene on an alumoxane-grafted MCM-41 host with bis(cyclopentadienyl)zirconium dimethyl (Cp2Zr(CH3)2)

The anchoring of alumoxane, synthesized by the in situ hydrolysis of trimethylaluminum, on the internal pore walls of a mesoporous MCM-41 support generates a highly active and selective host for bis(cyclopentadienyl)zirconium dimethyl (Cp₂Zr(CH₃)₂) in the oligomerization of propene. The regioselective preference of the immobilized metallocene is preserved and a typical Flory–Schulz distribution for the propene oligomers is obtained. This revised version was published online in July 2006 with corrections to the Cover Date.     

Voltammetric studies of gold surface modified by bis(octakis(octyloxy) phthalocyaninato) europium(III) adlayers in perchloric acid solution

Bis(octakis(octyloxy) phthalocyaninato) europium(III) (Eu[Pc(OC₈H₁₇)₈]₂) adlayers were self-assembled on the gold surface by means of an improved self-assembling technique. The cyclic voltammograms (CVs) of the Eu[Pc(OC₈H₁₇)₈]₂-modified single-crystalline and poly-crystalline gold electrodes in perchloric acid displayed two pairs of redox waves due to the successive removal or addition of electrons from or to the ligand-based orbitals. The effect of Eu[Pc(OC₈H₁₇)₈]₂ adlayers on the electron transfer rate at electrode/solution interface was investigated by using Fe(CN)₆^3−/4− couple as the redox probe. The redox behavior of Eu[Pc(OC₈H₁₇)₈]₂ adlayers and their accelerating effect on the electron transfer are closely associated with the electronic delocalization of rare earth sandwich complexes. However, in most cases, the Eu[Pc(OC₈H₁₇)₈]₂ adlayers were found to have inhibition role to complicated electrochemical reactions taking place on the gold surface, such as the gold substrate oxidation, the electrochemical reduction of oxygen, the electrochemical oxidation of ascorbic acid (Vitamin C) and the underpotential deposition (UPD) of silver.     

Magnetic polymer microsphere with photoconductivity: preparation and characterization of iron(III) phthalocyanine covalently bonded on to polystyrene microsphere surface

A novel magnetic polymer microsphere displaying photoconductivity was prepared by covalently bonding iron(III) phthalocyanine (FePc) onto a polystyrene microsphere with hydroxyl groups (PSA). PSA was synthesized by dispersion polymerization in the presence of Fe₃O₄ magnetic fluid. The structure and properties of the magnetic polymer microsphere were identified by infrared spectoscopy. elemental analysis and scanning electron microscopy. The results showed that this kind of microsphere combines the merits of magnetic responsiveness and photoconductivity. The application of magnetic polymer microspheres for absorption of bovine serum albumin (BSA) was characterized at different temperatures, different incubation times, different pH values and different initial BSA concentrations. © 2002 Society of Chemical Industry