铪基纳米金属有机骨架材料制备及X射线增强化学动力协同治疗应用

以铪簇作为金属有机骨架的连接点、刚性双羧基配体2，2''-联吡啶-5，5''-二羧酸作为连接器、乙酸或三氟乙酸和水作为结构调节剂，通过溶剂热法合成得到八面体结构(Hf-MOFs-1)和片状结构(Hf-MOFs-2)的铪基纳米金属有机骨架(Hf-nMOFs)，再经Fe³⁺修饰得到多功能金属有机骨架材料(Hf-Fe-MOFs-1和Hf-Fe-MOFs-2)。模拟肿瘤微环境体系中羟基自由基检测结果表明，X射线照射能显著促进Hf-Fe-MOFs-1和Hf-Fe-MOFs-2材料产生羟基自由基，且片状Hf-Fe-MOFs-2羟基自由基产生能力高于八面体Hf-Fe-MOFs-1。进一步地，在细胞层面证实了材料能够成功被细胞摄入并实现低剂量X射线促进的化学动力学协同治疗。     

设计合成nia拓扑的金属有机骨架化合物与CO2吸附

Nia拓扑结构是由两种分别是八面体和三棱柱构型的六连接节点连接形成的三维结构.为了得到具有nia拓扑的金属有机骨架,可以通过连接具有八面体构型的配体和具有三棱柱构型的金属簇实现.常见的三棱柱构型的金属簇为M3O(M=金属,M三价)或者M3OH(M二价).本文通过设计合成的枝状的具有八面体构型的有机配体1,3,5-tris(3,5-di-(4-carboxy-phenyl-1-yl)phenyl-1-yl)benzene(TDCPB),在溶剂热条件下,利用硝酸镍合成了一种新型的具有nia拓扑结构的金属有机骨架化合物JUC-105.通过X射线单晶衍射表征,该金属有机骨架化合物是由六棱柱的Ni3OH金属簇与八面体的TDCPB共同构筑的三维骨架结构,具有较大的孔道(1.1 nm).通过粉末衍射以及热重分析,研究了这种金属有机骨架的结构稳定性.气体吸附数据表明,这种骨架没有氮气吸附能力,但是表现了一定的CO2吸附能力.     

离子对UIO-66-2OH光催化性能的影响（英文）

实际废水中存在的离子会对有机污染物的光催化降解产生影响。以ZrCl_4和2,5-二羟基对苯二甲酸为原料,通过水热合成法成功制备了金属有机骨架材料UIO-66-2OH。通过红外(IR)、X射线粉末衍射(XRD)、X射线光电子能谱(XPS)和扫描电子显微镜(SEM)对UIO-66-2OH的结构进行表征。利用水中常见的金属阳离子和无机阴离子,探索UIO-66-2OH的光催化性能。研究发现,金属阳离子Fe~(3+)和无机阴离子HCO_3~-、CO_3~(2-)可以加快光催化降解的速度。然而,金属离子Na~+、K~+、Ca~(2+)、Mg~(2+)、Cu~(2+)和无机阴离子Cl~-、SO_4~(2-)、PO_4~(3-)会抑制光催化性能,且离子价态越高,抑制效果越明显。     

2种同构紫精配位聚合物的合成及其光致变色性能

变色材料作为一种新型的智能材料,在光存储信息和光学器件等领域具有巨大的应用潜力。以具有柔性骨架的紫精配体1,1’-双(4-羧基苄基)-4,4’-联吡啶二氯化物(H₂BpybcCl₂)作为功能配体,与过渡金属离子Mn²⁺和Cd²⁺自组装,合成2个同构配位聚合物[Mn(Bpybc)Cl₂·H₂O]_n(1)和[Cd(Bpybc)Cl₂·4H₂O]_n(2)。X射线单晶衍射表明,2个化合物为一维链状结构。在紫外灯照射下,光诱导电子转移而产生紫精自由基,2种化合物均表现出明显的光致变色行为。     

羟基修饰MOFs的合成、表征和光催化机理（英文）

合成了具有大的比表面积和结构容易修饰的金属有机框架材料(MOFs)光催化剂:MIL-101(Cr)和MIL-101(Cr)-2OH。利用红外、X射线粉末衍射、X射线光电子能谱等仪器对MIL-101(Cr)和MIL-101(Cr)-2OH光催化剂的结构进行表征分析。通过紫外-可见光漫反射光谱、ζ电位、电喷雾电离质谱系统地分析研究MOFs中不参与配位的给电子基团对光催化降解亚甲基蓝性能的影响。研究发现MIL-101(Cr)-2OH中桥联配体2,5-二羟基对苯二甲酸上不参与配位的2个羟基,可以通过配体-金属的电荷转移作用影响光的吸收,从而调控光催化降解速率     

含苯并噻二唑结构单元的金属有机骨架在可见光催化需氧氧化反应中的应用

设计合成了一个含有苯并噻二唑结构单元的对三联苯二羧酸配体H₂1,将其与二甲基修饰的对三联苯二羧酸配体H₂2以物质的量比1：1在N,N-二甲基甲酰胺溶剂中混合后;在醋酸存在条件下,与ZrCl₄发生溶剂热反应而得到金属有机骨架UiO-68-S.X射线粉末衍射表明该金属有机骨架具有UiO-68类型的框架结构;77 K温度下,氮气吸附等温曲线表明其具有较高的孔隙和比表面.在空气气氛和蓝光LED的照射下,金属有机骨架UiO-68-S可作为硫醚选择性氧化以及芳香硼酸羟基化的非均相光催化剂.     

二维镍配位聚合物(Ni-CP)和Ag@Ni-CP肖特基结的制备及其光催化降解阳离子染料

采用水热法合成了一种新的二维镍配位聚合物(Ni-CP),命名为[Ni(DDB)_0.5(2,2’-bipy)(H₂O)]·H₂O(H₄DDB=1,4-二(3,5-二羰基苯氧基)苯,2,2’-bipy=2,2’-联吡啶),并通过元素分析、热重分析、粉末X射线衍射、扫描电镜和X射线光电子能谱对其进行了表征。单晶结构分析表明,配位聚合物通过DDB^4-配体以μ4方式形成二维波浪状网络结构。采用光还原法制备了具有肖特基结的Ag负载产品(Ag@Ni-CP)。研究了Ni-CP和Ag@Ni-CP的光催化降解性能,后者表现出优异的降解效果,特别是对罗丹明B和亚甲蓝,60 min内降解率快速高达99%,与报道的金属有机骨架催化剂材料相比,Ag@Ni-CP表现出更高更快的降解性能。通过自由基俘获实验研究了Ag@Ni-CP的光催化机理。     

基于氟硅烷改性 UIO-66-OH的疏水金属有机骨架材料的制备及在灰岩类石质文物保护中的应用

疏水材料的研制一直是石质文物保护工作中的难点问题。本工作制备了一种新型疏水金属有机骨架(MOF)材料,即采用氟硅烷修饰含有2-羟基对苯二甲酸桥联配体的Zr-MOF以获得UIO-O-FS材料,并对材料进行了FTIR、X射线衍射、N₂吸附-脱附、热重、扫描电镜和透射电镜等表征分析以及抗侵蚀试验。试验结果表明,该材料具有良好的疏水性、固结性、耐酸性和耐盐性,是一种新型石质文物保护材料。     

氯化原位接枝反应制备羟基官能化CPE——结构表征

以高密度聚乙烯(HDPE)为基体,采用气-固氯化原位接枝反应合成了以氯化聚乙烯(CPE)为骨架聚合物、丙烯酸-2羟基乙酯(HEA)为支链的接枝共聚物.反应中不需要加入任何引发剂,以氯自由基引发接枝及氯代反应,得到羟基官能化CPE接枝聚合物.并用1H-NMR,FT-IR,GPC及X-射线衍射等对接枝共聚物的结构进行了表征.     

樟脑酸衍生物构筑的单一手性金属有机骨架化合物的合成、表征及荧光性质

设计合成了一个新的手性樟脑酸衍生物[D-H₂ctba, H₂ctba=4-(3-羧基-2,2,3-三甲基环戊烷酰胺)苯甲酸]. 将其作为配体与硝酸镉通过溶剂热反应得到了新的手性金属有机骨架化合物[Cd₃(ctba)₃·H₂O]_n(1). 通过单晶X射线衍射(XRD)、 粉末X射线衍射(PXRD)、 元素分析、 热重分析(TGA)和圆二色(CD)光谱对该化合物进行了表征. 单晶结构解析表明, 该化合物具有单一手性结构, 以1个六核的Cd羧基簇为基本单元, 簇与簇之间通过羧基相连形成(-Cd-O-C-)_∞棒状次级结构单元, 次级结构单元之间由配体相连, 拓展成为三维的骨架结构. 荧光光谱测试结果表明, 该化合物在室温下具有较强的荧光性质.     

Monitoring Humic Acid Photodegradation by CUPRAC Colorimetric and HPLC Determination of Dihydroxybenzoate Isomers Produced From a Salicylate Probe

Abstract

Novel analytical methods were designed for monitoring humic acid photodegradation in environmental waters. Modified CUPric Reducing Antioxidant Capacity (CUPRAC) spectrophotometric and chromatographic methods were used for the determination of dihydroxybenzoate isomers (DHBAs) produced from a salicylate probe, which was hydroxylated by hydroxyl radicals (^?OH) produced from the photodegradation of humic acid under ultraviolet A-radiation. The combined use of CUPRAC colorimetry and HPLC was shown to effectively monitor humic acid photodegradation and ^?OH generation for the first time. The formation of 2,5-dihydroxybenzoate and 2,3-dihydroxybenzoate, as major and minor products, respectively, from the hydroxylation of a salicylate probe was demonstrated by HPLC and confirmed by a modified CUPRAC method to indicate ^?OH formation from humic acid, which acted as both a generator and absorber of hydroxyl radicals. Salicylate hydroxylation showed an increase between 30 and 50?min of illumination, and was affected by the initial concentration of humic acid up to 0.01% but not by solution pH around the neutral values. Traces of Fe(III) and Mn(II) present in natural waters decreased the ^?OH production, but EDTA partly restored the probe hydroxylation by chelating these metal cations. Since humic acid-mediated ^?OH generation may aid in natural disinfection processes, this work may extend our comprehension of concentration- and time-dependent generation of ^?OH in environmental waters and of the possible effects of other antioxidants.     

Simple and sensitive determination of hydroxyl radical in atmosphere based on an electrochemically activated glassy carbon electrode

The hydroxyl radical (?OH) plays important roles in environment and health problems. However, the short life time and low concentrations of ?OH limited its detection. In this work, a simple method has been successfully performed for the sensitive detection of hydroxyl radical based on an activated glassy carbon electrode (AGCE).4-hydroxybenzoic acid (4-HBA) was used as a trapping agent for ?OH radicals, leading to the production of electroactive 3,4-dihydroxybenzoic acid (3,4-DHBA). Different procedures including polarisation and cyclic voltammetry in acid or base solutions have been used to activate the glassy carbon electrodes. The electrochemical behaviours of 3,4-DHBA on these activated electrodes were studied and compared. Experimental results showed that the glassy carbon electrode polarised in H₂SO₄ (AGCE-P/H₂SO₄) has the greatest sensitivity and reproducibility to 3,4-DHBA. 3,4-DHBA performed a linear relationship from 1.0 × 10^?7 to 1.0 × 10^?4 M on the AGCE-P/H₂SO₄. The detection limit was down to 6.2 × 10^?8 M. This method has been successfully applied for the detection of hydroxyl radical levels in atmosphere without separation and purification process.     

Degradation of n-butylparaben and 4-tert-octylphenol in H2O2/UV system

The degradation of two endocrine disrupting compounds: n-butylparaben (BP) and 4-tert-octylphenol (OP) in the H₂O₂/UV system was studied. The effect of operating variables: initial hydrogen peroxide concentration, initial substrate concentration, pH of the reaction solution and photon fluency rate of radiation at 254 nm on reaction rate was investigated. The influence of hydroxyl radical scavengers, humic acid and nitrate anion on reaction course was also studied. A very weak scavenging effect during BP degradation was observed indicating reactions different from hydroxyl radical oxidation. The second-order rate constants of BP and OP with OH radicals were estimated to be 4.8×10⁹ and 4.2×10⁹ M^?1 s^?1, respectively. For BP the rate constant equal to 2.0×10¹⁰ M^?1 s^?1was also determined using water radiolysis as a source of hydroxyl radicals.     

DNA damage induced via independent generation of the radical resulting from formal hydrogen atom abstraction from the C1′-position of a nucleotide

Background: Deoxyribonucleotide radicals resulting from formal C1′-hydrogen atom abstraction are important reactive intermediates in a variety of DNA-damage processes. The reactivity of these radicals can be affected by the agents that generate them and the environment in which they are produced. As an initial step in determining the factors that control the reactivity of these important radical species, we developed a mild method for their generation at a defined site within a biopolymer.Results: Irradiation of oligonucleotides containing a photolabile nucleotide produced C1'-DNA radicals. In the absence of potential reactants other than O₂, approximately 90% of the damage events involve formation of alkaline-labile lesions, with the remainder resulting in direct strand breaks. The ratio of alkaline-labile lesions to direct strand breaks (∼ 9:1) is independent of whether the radical is generated in single-stranded DNA or double-stranded DNA. Strand damage is almost completely quenched under anaerobic conditions in the presence of low thiol concentrations. Competition studies with 02 indicate that the trapping rate of C1′-DNA radicals by β-mercaptoethanol is ∼ 1.1 x 10⁷ M⁻¹s⁻¹Conclusions: The mild generation of the C1'-DNA radical in the absence of exogenous oxidants makes it possible to examine their intrinsic reactivity. In the absence of other reactants, the formation of direct strand breaks from C1′-radicals is, at most, a minor pathway. Competition studies between β-mercaptoethanol and 02 indicate that significantly higher thiol concentrations than those in vivo or some means of increasing the effective thiol concentration near DNA are needed for these reagents to prevent the formation of DNA lesions arising from the C1'-radical under aerobic conditions.     

Detection of active oxidative species in TiO2 photocatalysis using the fluorescence technique

The active oxidative species (mainly corresponding to hydroxyl radicals (· OH)) produced on TiO₂ film photocatalyst in aerated aqueous solution have been quantitatively investigated by measuring the fluorescence derived by the reaction with either coumarin or terephthalic acid. Upon UV light illumination, coumarin in aqueous solution and terephthalic acid in NaOH solution were converted on the TiO₂ film photocatalyst to highly fluorescent hydroxy products. Analysis of the resultant hydroxy compounds provides sensitive and specific monitoring of the generated active oxidative species. The rate of active species formation could be determined by the time dependence of the increase in concentration of the resultant hydroxy products. Using this fluorescence method, the effect of light intensity on the generation efficiency of active oxidative species was examined. The obtained results show that the efficiency of active oxidative species formation is constant at the UV intensity from 50 μW cm⁻² to 15 mW cm⁻², which is consistent with the results for · OH detection reported recently by the use of other techniques.     

Photoinduced degradation by iron(III): removal of triphenyltin chloride from water

The photoredox process taking place in iron(III) aquacomplexes was used to cause the complete degradation of triphenyltin (TPT). TPT elimination was proved to come only from attack by hydroxyl radicals generated upon irradiation at 365 nm of Fe(H₂O)₅OH²⁺, the iron(III) species present under the experimental conditions ([Fe(III)] in the range (3–6) × 10^?4 mol l^?1). The first step is the formation of an adduct between hydroxyl radicals and the benzene ring. The main process is a stepwise dephenylation of the starting TPT. Hydroxylated phenyltin derivatives were also formed, but only as minor photoproducts. The process was shown to be efficient with artificial light as well as with solar light. Copyright © 2001 John Wiley & Sons, Ltd.     

THE GENERATION OF HYDROXYL RADICALS IN BIOLOGIC SYSTEMS: TOXICOLOGICAL ASPECTS

Abstract— The formation of hydroxyl radicals in vitro was studied through their reaction with 2-keto-4-thiomethylbutyric acid to form ethylene gas. The autoxidation reaction of 6-aminodopamine served as a model source of hydroxyl radicals. Ethylene production was suppressed by catalase and by superoxide dismutase, indicating that both hydrogen peroxide and superoxide were involved in the reaction. Hydroxyl radical scavengers (thiourea > benzoate > ethanol) suppressed ethylene production in good agreement with their respective rate constants for reaction with hydroxyl radicals. Urea served as a negative control. Several substituted thiourea derivatives also suppressed ethylene production to a similar degree as thiourea itself. Biologic studies centered on several cytotoxic agents whose mechanisms of action are thought to involve hydroxyl radicals. These agents included alloxan, which destroys the beta cells of the pancreas, and 6-hydroxy- and 6-aminodopamine, which destroy sympathetic nerves. Damage to tissues in vivo was blocked to varying degrees by pretreatment of animals with hydroxyl radical scavengers such as ethanol or the thiourea derivatives. In addition, hydroxyl radical scavengers blocked the action of 5,7-dihydroxytryptamine, a neurotoxin whose effects on noradrenaline neurons were previously shown to be blocked by inhibitors of monoamine oxidase. The data indicate that these cell toxins produce their damaging actions on specific target cells through the intracellular generation of hydroxyl radicals.     

The roles of hydroxyl radicals, photo-generated holes and oxygen in the photocatalytic degradation of humic acid

This article is aimed at studying on the roles of the hydroxyl radicals, photo-generated holes, and oxygen in the photocatalytic degradation of humic acid (HA) in acid and alkaline conditions. The results indicate that hydroxyl radicals?? scavenger alone can inhibit the photocatalytic degradation process completely in alkaline condition, which implies that photo-generated holes cannot directly degrade the organic matter in alkaline condition. Moreover, the reaction sites between hydroxyl radicals and HA is on the TiO₂ surface in acid condition. But in alkaline condition, hydroxyl radicals diffuse and react with HA in the solution. The generation of hydroxyl radicals almost stops and the photocatalytic degradation is inhibited seriously without oxygen, which illustrates that oxygen plays an important role in the photocatalytic degradation of HA.     

A New CoII Complex as a Bulge-Specific Probe for DNA

Bulge cleavage of two or three bases occurs when a DNA substrate is specifically cleaved oxidatively by [Co^II(tfa)₂(happ)] (see picture). Hydrogen peroxide is necessary for the activation of this octahedral complex, which suggests that hydroxyl radicals are the reactive species. The complex has no significant reactivity towards the corresponding sequence in a single-stranded DNA region, and it exhibits only a low affinity towards double-stranded DNA. happ=macrocyclic ligand based on 1,10-phenanthroline, tfa=trifluoroacetate.