134 resultados para organic-inorganic composites
Resumo:
目前,国内外对于铕和铽等稀土配合物的可见区发光和应用都有大量研究,但对具有近红外发光(800-1700 nm)性能的稀土配合物的研究还处于起步阶段。由于稀土的近红外发光在光纤通讯、激光系统及诊断学等方面应用具有特殊的优点,越来越引起人们的兴趣和重视。 稀土近红外发光配合物的致命弱点是其光、热和化学稳定性较差,从而限制了其在很多领域的实际应用。而溶胶-凝胶材料和介孔材料具有良好的光、热和化学稳定性,能改善客体分子的结构环境和化学微环境,从而能有效提高客体分子的发光性能。因此,本论文将具有优良近红外发光性能的稀土配合物分别与上述两种基质复合,从实验和理论研究稀土近红外发光杂化材料的性能和应用价值,制备出具有良好稳定性的高效稀土近红外发光杂化材料,以期为光纤通讯、激光等领域提供潜在的候选材料。围绕这一宗旨,开展了如下工作: 通过原位技术分别得到了掺杂和嫁接[Ln(dbm)3phen]化合物(Ln = Er, Nd, Yb)的杂化凝胶材料,Ln-D-P gel和Xerogel-Ln。通过对其近红外发光性能的研究,表明材料中配体能很好的保护稀土离子,并将能量有效的传递给稀土离子。采用Judd-Ofelt理论对所得部分材料进行了光谱分析,基于实验数据和理论分析表明其具有潜在的光放大和激光应用价值。 选择了两种含全氟化烷基链的β-二酮配体Hhfth和Htfnb,通过功能化的phen-Si配体,将三元配合物[Ln(hfth)3phen] (Ln = Er, Nd, Yb, Sm)和[Pr(tfnb)3phen]成功共价嫁接到介孔MCM-41和SBA-15杂化材料中,得到的衍生材料Ln(hfth)3phen–MCM-41、Pr(tfnb)3phen–MCM-41和Ln(hfth)3phen–SBA-15、Pr(tfnb)3phen–SBA-15都保持了高度有序的介孔p6mm结构,并展现出稀土离子特征的近红外发射。所得稀土配合物功能化的材料的发射光谱能完全覆盖对光通讯极具应用价值的1300-1600nm区域。 通过对Er(dbm)3phen–M41(X, Y) (X = 1~14, Y = 3, 6, 12, 18, 24 h)材料系统的比较研究,选择了X = 12, Y = 6作为合成目标材料的优化参数,通过功能化的phen-Si配体将[Ln(dbm)3phen]配合物共价嫁接于有序介孔MCM-41和SBA-15中(Ln = Er, Nd, Yb),所得两类材料Ln(dbm)3phenM41和Ln(dbm)3phenS15都保持了很好的介孔有序性,并具有良好的近红外发光性能。通过对Ln(dbm)3phenM41和Ln(dbm)3phenS15两类材料发光行为的比较,以及两类材料中稀土离子的含量及孔结构的分析,推出以SBA-15为载体得到的材料在相对发光强度和荧光寿命上,均比以MCM-41为载体的材料有所提高。 通过对8-羟基喹啉配体进行改性,合成了具有双功能的配体Q-Si,继而合成了共价嫁接8-羟基喹啉衍生物的介孔杂化材料Q–SBA-15,其形貌均一,并具有高度有序的介孔p6mm结构。通过配体交换反应,得到了嫁接稀土喹啉配合物的具有近红外发光性能的介孔杂化材料LnQ3–SBA-15 (Ln = Er, Nd, Yb),其仍然保持高度有序的介孔结构,且外形呈现与母体材料Q–SBA-15相似的弯曲圆柱状。激发配体的吸收,LnQ3–SBA-15材料都分别展现出相应稀土离子特征的近红外发射,并详细分析和讨论了所得介孔杂化材料的近红外发光性能。
Resumo:
有机/无机杂化功能超薄膜是二十一世纪分子科学的重要发展前沿之一,设计具有功能性的有机/无机杂化薄膜已成为这一领域的挑战性课题。本论文分别采用Lallgmuir-B1odgett(LB)膜技术及溶胶一凝胶薄膜组装技术,将稀土无机配合物和稀土有机配合物分别与有机大分子化合物进行薄膜分子组装,对稀土配合物有机/无机杂化薄膜的光、电性质进行了研究。采用LB技术,将K11Ce(PWllO39)2·22H2O,K11Eu(PW11O39)2·25H2O,K11Gd(PW11O39)2·24H2O,K11Sm(PMo11O39)2·19H2O,K11Ce(PMo11O39)2·23H2O,K11Eu(PMo11O39)2·22H2O,K11Gd(PMo11O39)2·2OH2O,K11La(PMo11O39)2·18H2O八种稀土杂多化合物分别掺杂到聚喳琳中,得到十八胺(十八酸)/聚喳琳/稀土杂多化合物导电杂化LB膜。杂化LB膜表面的稀土杂多化合物颗粒大小在30-80nm之间。电性质研究表明,稀土杂多化合物的掺杂可使聚喳琳的导电性显著提高,且钥系稀土杂多化合物掺杂使聚哇琳的导电性增加更为显著。采用溶胶一凝胶薄膜组装技术,将K13(EuSiW11O39)2·28H2O,K13(EuGewl 1039)2·25H2O,K巧(EuBWllO39)2·22H2O,N钩SmWlo036·18H20,Na9DyS10O36·22H2O五种稀土杂多化合物分别与聚醋进行薄膜组装,得到聚醋/稀土杂多化合物溶胶一凝胶膜。荧光光谱研究表明,稀土离子在溶胶一凝胶膜中格位对称性降低,红橙比和黄蓝比发生了改变。1:11型稀土杂多化合物固体与聚酷/稀土杂多化合物溶胶一凝胶膜有不同的能量转移过程,在溶胶一凝胶膜中,配体能将能量传递给稀土离子。采用原位法将对十六烷氧基苯甲酸试及邻十七酞基苯甲酸试有机配合物分别进行了溶胶一凝胶薄膜组装,对其荧光性质进行了研究。结果表明,芳香梭酸配体与稀土诫离子有较好的能级匹配,能够有效地将吸收的能量传递给Tb3+离子,薄膜具有良好的发绿光性能。
Resumo:
杂化的纳米尺寸的有机/无机化合物开辟了材料科学的新纪元。作为新型功能材料,杂化的有机/无机杂化材料由于在光学、电子、机械、防护涂层、催化、传感器、生物等方面有潜在的应用前景而在材料科学领域引起广泛关注。杂多酸(POMs)作为一种重要的无机化合物,有特异的纳米尺寸结构,优越的物理化学性质和广泛应用价值,因此多酸化合物功能材料的研究引起人们足够的重视。最近,人们把更多的注意力集中到杂化的有机/无机杂化材料范围内,如何更有序的组装杂多酸,因为它们有着更有趣的电、磁、氧化还原和光学性质。1.在4-氨基苯甲酸修饰的玻碳电极表面,我们用层层组装方法制备了六钒取代的理杂多酸(PW6V6)多层膜。表面等离子(SP)技术和循环伏安(CV)法对多层膜进行了表征。结果表明,多层膜生长均匀,平均厚度为2.8nm,并且研究了多层膜对亚硝酸根伽02一)和浪酸根(BrO3-)的催化还原活性。2.研究了通过静电吸附作用,P2W17Fe和QPvP-Os交替组装多层膜。循环伏安(CV),电化学交流阻抗谱(EIS)和紫外一可见光谱(UV-vis)研究结果表明了这种多层膜是均一稳定的。多层膜对H2O2,BrO3-和NO2-有很高的催化活性。特别是EIS成功地监测多层膜的形成过程。随着层数增长,电子传输阻抗Rc,线性增加,氧化还原电对Fe(CN)63/4的电子传输受到抑制,这进一步证实了多层膜的均一性。3,首次在4-氨基苯甲酸修饰的玻碳电极表面成功地构建了含杂多酸P2W15V3的多层膜。值得注意的是,该多层膜对BrO3-和NO2-的还原有显著的电催化活性,而且由于过渡金属钒在P2W15V3起催化作用而有很低的过电位。另外,多层膜中QPVP-O5聚合物的Os中心在抗坏血酸氧化时的催化活性仍然存在,而且通过最外层的调整,多巴胺和抗坏血酸能被分别检测,所以在多巴胺存在时它可用作检测抗坏血酸的电化学传感器。4.迄今为止,人们把更多的注意力集中在杂多酸多层膜的制备,电化学和电催化活性的研究,对杂多酸多层膜功能材料的研究却很少,我们首次够构造了发光的杂多酸多层膜,紫外可见光谱,循环伏安,电化学阻抗技术和荧光光谱证明多层膜生长均匀,室温下,多层膜的发光性能显示Eu3+的特征发射峰是5D0→7Fj(j=1,2,3,4)的跃迁。电化学阻抗谱被成功得应用于监测多层膜的沉积过程。我们发现随多层膜的逐步形成,半圆直径有规律地长大。而且,电荷迁移电阻Rc,随双层数线性增长。可以认为多层膜在基底电极上以非常均匀规律的方式沉积,Fe(CN)63/4氧化还原电对的氧化还原反应逐步被多层膜抑制。5.我们用层层组装方法成功构造了金纳米粒子多层膜,紫外可见光谱,循环伏安和原子力显微技术表征了多层膜的形成,金纳米粒子粒径大约14nm,表面粗糙度6.43nm。
Resumo:
本论文通过聚甲基丙烯酸甲酯-b-聚丙烯睛嵌段共聚物同铁(III)离子络合物([PMMA-b-PAN]-Fe)制备有机一无机杂化薄膜,并利用妨M对薄膜的表面形态进行了表征。结果表明,通过控制[PMMA-b-PAN]-Fe络合物溶液热处理时间(T=120℃)及络合物溶液中精基同铁<III)离子的摩尔比率,可以得到不同表面形态的有机一无机杂化薄膜。并借助抑S对[PMMA-b-PAN〕-Fe络合物配位作用进行了研究,发现铁(III)离子与PMMA-b-PAN嵌段共聚物中的睛基配位。此外,对掺杂有FeSO4·7H2O 的均聚甲基丙烯酸甲酷(PMMA)溶液、均聚丙烯睛(PAN)溶液和FeSO4·7H2O(溶解在DMF中)溶液经不同时间热处理(T=120℃)后的薄膜表面形态进行了研究,结果发现,掺杂有FeSO4·7H2O 的PMMA 溶液经20in热处理后,薄膜的表面形态与FeS04·7H2O。溶液经20in热处理后薄膜的表面形态基本相同,而掺杂有FesO4·7H2O的PAN溶液经不同时间热处理后,薄膜的表面形态没有明显的变化。与此同时,对匡[PMMA-b-PAN]-Fe络合物高温热解制备碳材料进行了初步的研究,研究结果表明,利用PMMA-b-PAN]-e杂化薄膜炭化制备具有纳米尺寸孔洞的碳薄膜是可能的,但控制好热解条件至关重要。
Resumo:
We report a facile strategy to tether lanthanide complexes to organic-inorganic hybrid titania materials via sol-gel processing by employing chemically modified titanium alkoxide as the precursor where the organic ligand sensitizing the luminescence of lanthanide ions is bonded to titanium.
Resumo:
Protein electrochemistry affords a direct method to study the biological electron transfer processes. However, supplying a biocompatible environment to maintain the native state of protein is all-important and challengeable. Here, we chose vaterite, one of the crystalline polymorphs of calcium carbonate, with highly porous nature and large specific surface area, which was doped with phospholipids, as the matrix to immobilize horseradish peroxidase (HRP). The integrity of HRP was kept during the simple immobilization procedure. By virtue of this organic/inorganic complex matrix, the direct electrochemistry of HRP was realized, and the activity of HRP for catalyzing reduction of O-2 and H2O2 was preserved.
Resumo:
Urea bridged organic-inorganic hybrid mesoporous SiO2 materials (U-BSQMs) were synthesized through a sol-gel procedure by co-condensation of bis(triethoxysilyl propyl) urea (BSPU) under basic conditions using cetyltrimethylammonium bromide (CTAB) as organic template. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the mesoporous structure of the sample. Fourier-transform infrared spectroscopy (FT-IR), solid state CP-MAS NMR spectroscopy of Si-29 (Si-29, CP-MAS NMR) and C-13 (C-13 CP NMR) indicated that most of the Si-C bonds are unbroken during the synthesis process.
Resumo:
The < 110 >-oriented perovskite is very rare in the hybrid perovskites family. In this work, an unusual layered < 110 >-oriented hybrid perovskite, which is stabilized by a special organic ligand, 2-(aminoethyl)isothiourea, has been obtained. This ligand combines a primary amine and a formamidine on the two ends of one molecule. Introduction of the special ligand brings about contorted inorganic sheets in the hybrid perovskite structure. The optical properties of the new < 110 >-oriented perovskite were studied.
Resumo:
Two new silica-based organic-inorganic hybrid materials (B104SGs and O104SGs) doped with a binary mixture of imidazolium and phosphonium ionic liquids have been synthesized and used as sorbents in batch system for rare earths (RE) separation. Imidazolium ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate (C(4)mim(+)PF(6)(-)) or 1-octyl-3-methylimidazolium hexafluorophosphate (C(8)mim(+)PF(6)(-)) acted as porogens to prepare porous materials and additives to stabilize extractant within silica gel.
Resumo:
A series of dysprosium complex doped xerogels with the same first ligand (acac = acetylacetone) and different neutral ligands were synthesized in situ via a sol-gel process. The Fourier transform infrared (FTIR) spectra, diffuse reflectance (DR) spectra, and near-infrared (NIR) luminescent properties of dysprosium complexes and dysprosium complex doped xerogels are described in detail. The results reveal that the dysprosium complex is successfully synthesized in situ in the corresponding xerogel. Excitation at the maximum absorption wavelength of the ligands resulted in the characteristic NIR luminescence of the Dy3+ ion, which contributes to the energy transfer from the ligands to the central Dy3+ ion in both the dysprosium complexes and xerogels via an antenna effect.
Resumo:
A urea-based bis-silylated bipyridine ligand derived from 4,4'-diamino-2,2'-bipyridine has been prepared. Organic-inorganic hybrid materials with a high loading of lanthanide 2,2-bipyridine moieties were obtained by using the silylated bipyridine as the only siloxane network precursor in the presence of lanthanide ions (or lanthanide complexes). The in-situ formation of lanthanide complexes from lanthanide ions and the silylated bipyridine during the sol-gel processing was confirmed by the luminescence behavior of the obtained hybrid materials and that of the corresponding pure lanthanide complex [Ln(bpy)(2)Cl-3 center dot 2H(2)O].
Resumo:
A series of novel, colorless, and transparent sot-gel derived hybrid materials Ln-DBM-Si covalently grafted with Ln(DBM-OH)(3)center dot 2H(2)O (where DBM-OH = o-hydroxydibenzoylmethane, Ln = Nd, Er, Yb, and Sin) were prepared through the primary beta-diketone ligand DBM-OH. The structures and optical properties of Ln-DBM-Si were studied in detail. The investigation results revealed that the lanthanide complexes were successfully in situ grafted into the corresponding hybrids Ln-DBM-Si. Upon excitation at the maximum absorption of ligands, the resultant materials displayed excellent near-infrared luminescence.