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首页> 外文期刊>Chemistry: A European journal >Sol-Gel Polycondensation of Tetraethyl Orthosilicate (TEOS) in Sugar-Based Porphyrin Organogels:Inorganic Conversion of a Sugar-Porphyrinic Fiber Library through Sol-Gel Transcription Processes
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Sol-Gel Polycondensation of Tetraethyl Orthosilicate (TEOS) in Sugar-Based Porphyrin Organogels:Inorganic Conversion of a Sugar-Porphyrinic Fiber Library through Sol-Gel Transcription Processes

机译：糖基卟啉有机凝胶中原硅酸四乙酯（TEOS）的溶胶-凝胶缩聚：通过溶胶-凝胶转录工艺对糖-卟啉纤维库的无机转化

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Sugar-appended porphyrins (1a-e) with monosaccharide groups at their periphery have been rationally designed for a new class of gelating reagents.A few of these compounds have the tendancy of form one-dimensional aggregates stable enough to show successful gelation ability for DMF-alcohol mixed solvents.The aggregation mode in the specific columnar super structures has been evaluated in detail by UV-visible spectrometry (UV/Vis),circular dichroism (CD),scanning electron microscopy (SEM),and transmission electron microscopy (TEM).All UV-visible spectra of sugar-appended porphyrinic gels obtained from 1a-c exhibit Soret band absorptions,which shift to lower wave-length and are significantly broadened.This phenomenon indicates that these porphyrin cores strongly interact with each other in an H-aggregate fashion,which drives the generation of a one-dimensional porphyrin-stacking array.The CD spectra of the organogels from 1a and 1b,which are in anomers,exhibit an almost symmetric pattern,whereas the gel from 1c gives a completely different pattern.This implies that the gel fibrils ind themselves in a right- or left-handed fashion;this reflects chirality in the specific molecular structure of the gelators.The results from SEM for the gel fibrils are in good agreement with the CD patterns.The gel fibrils in 1a possess left handed helicity,whereas those in 1b wind themselves right-handedly.Macroscopic helical morphology reflects the microscopic structure well at a molecular level,which gives structural variety of the gel fibrils,which can be defined by the sugar library.Inorganic conversion of the organic helical fibrils by a sol-gel transcription process successfully gives the helical-silica structures,which finely inherit the organic morphology.A striking observation is that a unimolecular porphyrin-stacking array is also transcribed into silica fibers when the optimized sol-gel reaction conditions are selected.A sugar-based organic-fiber library in porphyrinic gels thus provides a variety of inorganic materials through the sol-gel transcription process.
机译：周围带有单糖基团的加糖卟啉（1a-e）已被合理地设计用于新型胶凝剂，其中一些化合物具有形成一维聚集体的趋势，该一维聚集体的稳定性足以显示对DMF的成功胶凝能力-醇混合溶剂。已通过紫外-可见光谱（UV / Vis），圆二色性（CD），扫描电子显微镜（SEM）和透射电子显微镜（TEM）详细评估了特定柱状上部结构中的聚集模式。从1a-c获得的加糖卟啉凝胶的所有紫​​外-可见光谱均显示出Soret带吸收，该吸收带移至较低波长并显着加宽。此现象表明这些卟啉核在H-中相互强烈相互作用。 1a和1b的有机凝胶的CD光谱呈异构体形式，表现出几乎对称的模式，从而形成一维卟啉堆叠阵列。而1c中的凝胶给出了完全不同的模式，这意味着凝胶原纤维以右手或左手方式显示;这反映了凝胶剂特定分子结构中的手性.SEM的结果是凝胶原纤维1a中的凝胶原纤维具有左旋螺旋，而1b中的凝胶原纤维右旋缠绕。宏观的螺旋形形态在分子水平上很好地反映了微观结构，从而给出了凝胶原纤维的结构多样性，通过溶胶-凝胶转录过程对有机螺旋原纤维进行无机转化，成功地形成了螺旋-二氧化硅结构，该结构精细地继承了有机形态。当选择最佳的溶胶-凝胶反应条件时，它也会转录成二氧化硅纤维。卟啉凝胶中的糖基有机纤维库通过溶胶-凝胶转录过程可提供多种无机材料。

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