Perfluorination

全氟化
  • 文章类型: Journal Article
    在水净化中用于非均相催化臭氧化(HCO)的工业上可行的催化剂要求其表面具有活性物质良好分散的特性,臭氧衰减的有效电子转移,和最大的活性物种利用。虽然金属有机骨架(MOFs)代表了HCO的一个有吸引力的平台,未改性MOFs中的金属节点表现出低催化活性。在这里,我们通过用F原子(称为4F-MIL-88B)取代金属化配体上的H原子以诱导结构演变,提出了一种全氟化Fe-MOF催化剂。4F-MIL-88B的路易斯酸度通过Fe节点的形成而增强,调整催化剂表面的电子分布。作为催化剂改性的结果,与未改性催化剂的观察到的相比,目标化合物的降解速率常数增加了约700%。实验证据和理论计算表明,调制的极性和增强的催化剂和臭氧分子之间的电子转移有助于O3在催化剂表面的吸附和转化为·OH。总的来说,这项研究的结果突出了定制金属化配体的重要性,以开发高效和稳定的MOF催化剂用于HCO,并提供对其结构功能演变的深入机理理解,这有望促进基于纳米材料的工艺在水净化中的应用。
    An industrially viable catalyst for heterogeneous catalytic ozonation (HCO) in water purification requires the characteristics of good dispersion of active species on its surface, efficient electron transfer for ozone decay, and maximum active species utilization. While metal-organic frameworks (MOFs) represent an attractive platform for HCO, the metal nodes in the unmodified MOFs exhibit low catalytic activity. Herein, we present a perfluorinated Fe-MOF catalyst by substituting H atoms on the metalated ligands with F atoms (termed 4F-MIL-88B) to induce structure evolution. The Lewis acidity of 4F-MIL-88B was enhanced via the formation of Fe nodes, tailoring the electron distribution on the catalyst surface. As a result of catalyst modification, the rate constant for degradation of the target compounds examined increased by ∼700% compared with that observed for the unmodified catalyst. Experimental evidence and theoretical calculations showed that the modulated polarity and the enhanced electron transfer between the catalyst and ozone molecules contributed to the adsorption and transformation of O3 to •OH on the catalyst surface. Overall, the results of this study highlight the significance of tailoring the metalated ligands to develop highly efficient and stable MOF catalysts for HCO and provide an in-depth mechanistic understanding of their structure-function evolution, which is expected to facilitate the applications of nanomaterial-based processes in water purification.
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  • 文章类型: Journal Article
    多面体分子因其引人注目的结构和独特的化学而吸引人。这样的全氟化,通常会产生很大的应变,是一个重大挑战。它极大地改变了电子分布,结构和属性。值得注意的是,小型高对称性全氟多面体的特征是位于中央,星形低能未占据的分子轨道,可以在多面体框架内承载一个额外的电子,从而产生自由基阴离子,不失去对称性。这种预测的电子托管能力肯定是为全氟卡布确定的,第一个被分离纯的全氟化柏拉图式多面体。承载原子,这种“笼子”结构中的分子或离子是,然而,除了直率,当不是虚幻的时候,提供不容易获得超分子结构。虽然金刚烷和古巴在材料科学中促进了许多应用,医学和生物学,其全氟对应物的具体用途仍有待确定。高氟化碳同素异形体的某些方面,如富勒烯或石墨,简要提及上下文。
    Polyhedral molecules are appealing for their eye-catching architecture and distinctive chemistry. Perfluorination of such, often greatly strained, compounds is a momentous challenge. It drastically changes the electron distribution, structure and properties. Notably, small high-symmetry perfluoropolyhedranes feature a centrally located, star-shaped low-energy unoccupied molecular orbital that can host an extra electron within the polyhedral frame, thus producing a radical anion, without loss of symmetry. This predicted electron-hosting capacity was definitively established for perfluorocubane, the first perfluorinated Platonic polyhedrane to be isolated pure. Hosting atoms, molecules, or ions in such \"cage\" structures is, however, all but forthright, if not illusionary, offering no easy access to supramolecular constructs. While adamantane and cubane have fostered numerous applications in materials science, medicine, and biology, specific uses for their perfluorinated counterparts remain to be established. Some aspects of highly fluorinated carbon allotropes, such as fullerenes and graphite, are briefly mentioned for context.
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  • 文章类型: Journal Article
    合成了基于半胱氨酸的全氟芳烃(六氟苯(HFB)和十氟联苯(DFBP)),并将其确立为化学选择性和可用的核心,以构建从小分子到具有有趣特性的生物分子的分子系统。对于修饰的硫醇分子的单烷基化,DFBP被发现比HFB更有效。作为全氟化衍生物作为不可裂解接头的潜在应用的概念证明,一些抗体-全氟缀合物通过巯基通过两种不同的策略制备,i)通过酰胺键使用还原的胱胺偶联到mAb的羧酸中的硫醇,和ii)使用来自mAb二硫键还原的硫醇。缀合物细胞结合分析表明生物缀合不影响大分子实体。此外,通过光谱表征(FT-IR和19F-NMR化学位移)和理论计算,评价了合成化合物的一些分子性质。计算和实验19F-NMR位移和IR波数的比较给出了极好的相关性,声称是在结构上识别HFB和DFBP衍生物的强大工具。此外,还开发了分子对接来预测基于半胱氨酸的全氟衍生物对拓扑异构酶Il和环氧合酶2(COX-2)的亲和力。结果表明,主要基于半胱氨酸的DFBP衍生物可能是潜在的拓扑异构酶IIα和COX-2结合物,成为潜在的抗癌药物和抗炎治疗的候选药物。
    Cysteine-based perfluoroaromatic (hexafluorobenzene (HFB) and decafluorobiphenyl (DFBP)) were synthesized and established as a chemoselective and available core to construct molecular systems ranging from small molecules to biomolecules with interesting properties. The DFBP was found more effective than HFB for the monoalkylation of decorated thiol molecules. As proof of concept of the potential application of perfluorinated derivatives as non-cleavable linkers, some antibody-perfluorinated conjugates were prepared via thiol through two different strategies, i) using thiol from reduced cystamine coupling to carboxylic acids from mAb by amide bond, and ii) using thiols from reduction of mAb disulfide bond. Conjugates cell binding analysis demonstrated that the bioconjugation does not affect the macromolecular entity. Besides, some molecular properties of synthesized compounds are evaluated through spectroscopic characterization (FTIR and 19 F NMR chemical shifts) and theoretical calculations. The comparison of calculated and experimental 19 F NMR shifts and IR wavenumbers give excellent correlations, asserting as powerful tools in structurally identifying HFB and DFBP derivatives. Moreover, molecular docking was also developed to predict cysteine-based perfluorated derivatives\' affinity against topoisomerase Il and cyclooxygenase 2 (COX-2). The results suggested that mainly cysteine-based DFBP derivatives could be potential topoisomerase II α and COX-2 binders, becoming potential anticancer agents and candidates for anti-inflammatory treatment.
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  • 文章类型: Journal Article
    在放化疗中,解离电子附着(DEA)可能对所用放射增敏剂的效率起着重要作用。因此,合理地调整此类放射增敏剂以使其对DEA更具敏感性,可能会提供一条提高其效率的途径。有可能,这可以通过将重排反应调整到DEA过程中来实现,以便这些反应可以在低入射电子能量下进行,DEA最有效的地方。通过取代有利地改变相应分子的轨道结构是可以采取的促进在电子捕获时解离的另一种途径。在这里,我们提出了与五氟硫酚(PFTP)和2-氟硫酚(2-FTP)有关的DEA的联合实验和理论研究。我们研究了通过DEA形成中性HF的热化学和动力学,作为降低电子捕获到这些化合物上的解离阈值的手段,探索全氟化对其轨道结构的影响。给出了片段离子产量曲线,并计算各个DEA过程的热化学阈值,以及在电子捕获和各个分子阴离子的潜在轨道结构上形成HF的最小能量路径。我们表明,在这些化合物中的芳环的全氟化作用,通过进一步降低该过程的阈值和通过对轨道结构的有利影响,在使HF形成中起着重要作用。这样DEA就得到了提升。我们认为,这种方法可能为定制新型高效的放射增敏剂提供一条途径。
    In chemoradiation therapy, dissociative electron attachment (DEA) may play an important role with respect to the efficiency of the radiosensitizers used. The rational tailoring of such radiosensitizers to be more susceptive to DEA may thus offer a path to increase their efficiency. Potentially, this may be achieved by tailoring rearrangement reactions into the DEA process such that these may proceed at low incident electron energies, where DEA is most effective. Favorably altering the orbital structure of the respective molecules through substitution is another path that may be taken to promote dissociation up on electron capture. Here we present a combined experimental and theoretical study on DEA in relation to pentafluorothiophenol (PFTP) and 2-fluorothiophenol (2-FTP). We investigate the thermochemistry and dynamics of neutral HF formation through DEA as means to lower the threshold for dissociation up on electron capture to these compounds, and we explore the influence of perfluorination on their orbital structure. Fragment ion yield curves are presented, and the thermochemical thresholds for the respective DEA processes are computed as well as the minimum energy paths for HF formation up on electron capture and the underlying orbital structure of the respective molecular anions. We show that perfluorination of the aromatic ring in these compounds plays an important role in enabling HF formation by further lowering the threshold for this process and through favorable influence on the orbital structure, such that DEA is promoted. We argue that this approach may offer a path for tailoring new and efficient radiosensitizers.
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  • 文章类型: Journal Article
    在光电合成细胞中,三种全氟ZnII卟啉被评估为HBr和水分解的n型敏化剂。所有染料的特征在于存在五氟苯基吸电子基团以增加基态氧化电位,并且在核心和负责结合金属氧化物的锚定基团之间的π-共轭接头的性质和位置上有所不同。以评估与半导体耦合的最佳方式。苯基-三唑部分用于将羧基锚定基团连接到内消旋位置上,同时选择乙炔基-苯基接头将羧基和氰基丙烯酸基团桥接到β-吡咯位。电化学的组合,计算,光谱研究证实了全氟卟啉核的强吸电子作用,这确保了所有研究的染料与水氧化催化剂(WOC)偶联所需的高氧化电位。这样一个电子贫乏的核心,然而,影响染料的电荷分离特性,如激发态的空间分布所示,导致非定量电荷注入,尽管分子在半导体表面上的倾斜可以使卟啉环更靠近半导体,提供额外的电荷转移途径。的确,所有的染料证明在水HBr和水的分裂成功,用配备氰基丙烯酸端基的β-取代卟啉敏化的SnO2/TiO2光阳极的最佳结果,在可见光下在HBr和水中实现0.4和0.1mA/cm2的光阳极电流,分别。在IrIV催化剂存在下,氧气析出的法拉第产率超过95%,并且光电阳极运行稳定超过1000s。因此,应考虑在β位具有氰基丙烯酸锚定基团的全氟化卟啉,以进一步开发以改善电荷转移特性。
    Three perfluorinated ZnII porphyrins were evaluated as n-type sensitizers in photoelectrosynthetic cells for HBr and water splitting. All the dyes are featured by the presence of pentafluorophenyl electron-withdrawing groups to increase the ground-state oxidation potential and differ for the nature and position of the π-conjugate linker between the core and anchoring group tasked to bind the metal oxide, in order to assess the best way of coupling with the semiconductor. A phenyl-triazole moiety was used to link the carboxylic anchoring group onto the meso position, while an ethynyl-phenyl linker was chosen to bridge carboxylic and cyanoacrylic groups onto the β-pyrrolic position. A combination of electrochemical, computational, and spectroscopic investigations confirmed the strong electron-withdrawing effect of the perfluorinated porphyrin core, which assures all the investigated dyes of the high oxidation potential required to the coupling with water oxidation catalysts (WOC). Such an electron-poor core, however, affects the charge separation character of the dyes, as demonstrated by the spatial distribution of the excited states, leading to a nonquantitative charge injection, although tilting of the molecules on the semiconductor surface could bring the porphyrin ring closer to the semiconductor, offering additional charge-transfer pathways. Indeed, all the dyes demonstrated successful in the splitting of both aqueous HBr and water, with the best results found for the SnO2/TiO2 photoanode sensitized with the β-substituted porphyrin equipped with a cyanoacrylic terminal group, achieving 0.4 and 0.1 mA/cm2 photoanodic currents in HBr and water under visible light, respectively. The faradaic yield for oxygen evolution in the presence of an IrIV catalyst was over 95%, and the photoanode operation was stable for more than 1000 s. Thus, the perfluorinated porphyrins with a cyanoacrylic anchoring group at the β-position should be considered for further development to improve the charge-transfer character.
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  • 文章类型: Journal Article
    A series of novel α-fluoroalkyl ammonium salts was obtained from the corresponding cyano compounds or nitriles by reaction with anhydrous HF. Room-temperature stable trifluoromethyl ammonium salts were obtained in quantitative yield in a one-step reaction at ambient temperature from the commercially available starting materials BrCN or ClCN. The novel cations [CF3CF2NH3](+), [HCF2CF2NH3](+), and [(NH3CF2)2](2+) were obtained from CF3CN, HCF2CN, and (CN)2, respectively, and anhydrous HF. The aforementioned fluorinated ammonium cations were isolated as room temperature stable [AsF6](-) and/or [SbF6](-) salts, and characterized by multi-nuclear NMR and vibrational spectroscopy. The salts [HCF2NH3][AsF6] and [CF3NH3][Sb2F11] were characterized by their X-ray crystal structure.
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