Bridging the Green Gap: Metal–Organic Framework Heteromultilayers Assembled from Porphyrinic Linkers Identified by Using Computational Screening

In organic photovoltaics, porphyrins (PPs) are among the most promising compounds owing to their large absorption cross-section, wide spectral range, and stability. Nevertheless, a precise adjustment of absorption band positions to reach a full coverage of the so-called green gap has not been achieved yet. We demonstrate that a tuning of the PP Q- and Soret bands can be carried out by using a computational approach for which substitution patterns are optimized in silico. The most promising candidate structures were then synthesized. The experimental UV/Vis data for the solvated compounds were in excellent agreement with the theoretical predictions. By attaching further functionalities, which allow the use of PP chromophores as linkers for the assembly of metal-organic frameworks (MOFs), we were able to exploit packing effects resulting in pronounced redshifts, which allowed further optimization of the photophysical properties of PP assemblies. Finally, we use a layer-by-layer method to assemble the PP linkers into surface-mounted MOFs (SURMOFs), thus obtaining high optical quality, homogeneous and crystalline multilayer films. Experimental results are in full accord with the calculations, demonstrating the huge potential of computational screening methods in tailoring MOF and SURMOF photophysical properties.     

高光学质量氮化碳薄膜的制备和表征

氮化碳(graphitic carbon nitride,g-CN)作为一种非金属半导体材料已被广泛应用于多种能源相关领域研究中。目前由于制备高质量g-CN薄膜的困难,大大限制了其在实际器件上的应用。本文中,我们报道了一种可制备高光学质量gCN薄膜的方法:即由三聚氰胺先通过热聚合制备本体g-CN粉末,再由本体g-CN粉末经过气相沉积在ITO导电玻璃或钠钙玻璃基底上制备g-CN薄膜。扫描电子显微镜和原子力显微镜的测量结果表明在ITO玻璃基底上形成的g-CN薄膜形貌结构均一且致密,厚度约为300nm。扫描电镜能量色散能谱和X射线光电子能谱测量结果表明在ITO玻璃基底上制备的g-CN薄膜的化学组成与本体g-CN粉末的化学组成基本一致。同时,我们发现制备的g-CN薄膜和本体g-CN粉末一样在光照射下可以有效降解亚甲基蓝染料。此外,我们还测量了制备的g-CN薄膜的稳态吸收光谱、稳态荧光光谱、荧光寿命和价带谱,并运用吸收光谱和价带谱数据确定了其能带结构。     

Mercury Speciation in Fish by High-Performance Liquid Chromatography (HPLC) and Post-Column Ultraviolet (UV)-Photochemical Vapor Generation (PVG): Comparison of Conventional Line-Source and High-Resolution Continuum Source (HR-CS) Atomic Absorption Spectrometry (AAS)

An ultraviolet-photochemical generator (UV-PVG) capable of post-column on-line transformation of both organic and inorganic mercury species to cold vapor (Hg⁰) with subsequent detection by quartz tube-atomic absorption spectrometry (QT-AAS) was developed. Mercury(II), methylmercury(I), ethylmercury(I), and phenylmercury(I) were successfully detected after separation by reversed-phase high-performance liquid chromatography (RP-HPLC). Two types of AAS detectors were compared. The first was a commonly used line-source instrument while the second was a high-resolution continuum source (HR-CS) AAS. The latter provided better limits of detection: 0.47?µg?L^?1 for Hg(II), 0.84?µg?L^?1 for methylmercury(I), 0.80?µg?L^?1 for ethylmercury(I), and 2.0?µg?L^?1 for phenylmercury(I). The repeatability at 30?μg?L^?1 was 3.6%, 4.1%, 6.2%, and 4.5% for these species (n?=?10). These figures of merit were comparable with those reported for more sensitive atomic fluorescence spectrometry. Nine sample extraction procedures were investigated. Extraction by tetramethylammonium hydroxide and HCl at 75?°C was selected as the only method compatible with the proposed separation and detection steps providing high extraction efficiency and no changes in mercury speciation. The applicability of the proposed high-performance liquid chromatography–ultraviolet-photochemical vapor generation–quartz tube-atomic absorption spectrometry method was demonstrated using fish samples and certified reference materials (CRM) DOLT-4 (dogfish liver) and ERM-CE464 (tuna fish). The results were comparable to those obtained by a reference method based on L-cysteine extraction and high-performance liquid chromatography–inductively coupled plasma-mass spectrometry (HPLC–ICP-MS) determination.     

Performance of Pleurotus ostreatus Mushrooms and Spent Substrate for the Biosorption of Cd(II) From Aqueous Solution

The capacities of Pleurotus ostreatus mushroom and spent substrate were evaluated for the biosorption of cadmium (II) from aqueous solution in order to select the most efficient material for bioremediation. The optimum sorption conditions were optimized, including the pH of the aqueous solution, contact time, biomass dosage, initial metal concentration, and temperature. The sorption of cadmium on both biosorbents was also evaluated by several kinetic, equilibrium, and thermodynamic models. The possible heavy metal biosorption mechanisms were evaluated through point of zero charge (pH_pzc), Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDX). Based on the results of column studies, the effectiveness of the P. ostreatus spent substrate was confirmed as a biosorbent for Cd(II) removal from aqueous solutions.     

表面增强红外吸收光谱——表面敏感的原位免标记光谱电化学技术

表面增强红外吸收光谱（尤其衰减全反射表面增强红外吸收光谱）是一种超灵敏的红外光谱技术,能够实现亚单层膜水平的表面选择性探测. 由于增强基底可同时作为工作电极实现电化学调制,衰减全反射表面增强红外吸收光谱是一种表面敏感的原位免标记光谱电化学技术. 本文首先简要介绍了表面增强红外吸收光谱的基本原理和技术特点,之后通过代表性研究工作着重介绍近年衰减全反射表面增强红外吸收光谱电化学的应用和发展,最后展望了表面增强红外光谱所面临的挑战和潜在的研究方向.     

克百威分子印迹聚合物的合成及其性能评价

以克百威为模板分子,甲基丙烯酸(MAA)为功能单体,二甲基丙烯酸乙二醇酯(EGDMA)为交联剂,采用沉淀聚合的方法制备了克百威分子印迹聚合物。通过红外光谱分析得到模板和功能单体的最佳配比为n(carbofuran)∶n(MAA)=1∶6。印迹聚合物的红外光谱测定结果表明,聚合物中存在与模板分子相互作用的特征基团;从印迹聚合物的扫描电镜图观察到分子印迹聚合物(MIP)与空白聚合物(NIP)的表面形态不同,可推论MIP存在与模板分子相互识别的结合位点。通过静态平衡结合法研究了模板分子聚合物的吸附能力、结合动力学和选择特性。结果表明,与非印迹聚合物相比,印迹聚合物对克百威具有较强的吸附特性和很好的专一选择性,3h后基本达到最大吸附量。采用固相萃取柱预处理样品,用高效液相色谱法测定自来水中10、50、100mg/L克百威的加标回收率为94%～117%,相对标准偏差(n=3)为2.5%～4.7%。     

凤仙花植株不同部位微量元素含量的比较分析

The samples of pueraria lobata ohwi were digested by HNO3 + HClO4 .contents of the next trace elements Fe,Zn,Cu,Mn,Ca,Mg,Co,Cr,Ni,Cd,Pb and Al in the bloom,base,stem,and leaf of Impatiens balsamina have been determined by Flame Atomic Absorption method.The result show that the recovery is about 97.5%-103.2%,and the RSD<2.7%,with good accuracy and precision.The order of the content of the trace elements of high to low is as follows:leaf>stem>bloom>base.The importance of essential trace elements Zn,Fe,Mn,Cu for human each has a higher content.In addition,toxic trace elements such as lead,arsenic and cadmium are also found.     

原子吸收光谱法测定苦藠中微量元素的含量

苦藠别名小野蒜是食用地下鳞茎及嫩茎叶的野生蔬菜,属药食同源的百合科多年生草本植物.有温中散结,宽胸通阳,祛湿止痢作用~([1,2]).在食疗方面有:(1)降脂作用,且性味辛温,能温阳散结,可用来治疗高胆固醇和高血脂症.(2)降低血压的奇妙作用,常食有通阳气、宽胸的效果.     

一种可溶性氯铟酞菁化合物的光限幅性能研究

本工作通过无中心金属酞菁合成了可溶性金属酞菁化合物--四-α-(2-乙基丁氧基)氯铟酞菁,用纳秒脉冲激光在532 nm处检测了它在四氢呋喃溶液中的光限幅过程,发现该化合物具有非常明显的光限幅性能.在很低的入射光能量下,输出能量即开始偏离Beer定律,透过率随着入射光能量的增加迅速下降.这一效应归因于酞菁分子的反饱和吸收.通过纳秒激光闪光光解实验测定了上述化合物在四氢呋喃溶液中的瞬态吸收光谱及三线态寿命,实验结果表明在很宽的波长范围内分子具有较强的激发态吸收性能.     

Dual mechanism of hydrogen desorption from palladium alloys postulated on the basis of cyclic voltammetric studies

The process of hydrogen absorption/desorption in Pd-Pt and Pd-Pt-Rh alloys has been investigated using cyclic voltammetry. Hydrogen absorbed at constant potential was electrooxidized at various scan rates. The charge of hydrogen oxidation has been found to be dependent on the scan rate. The decrease in the oxidation charge observed for low scan rates indicates that, under these conditions, some amount of hydrogen may be removed via a non-electrochemical recombination reaction. The results suggest that the dual mechanism of hydrogen desorption, involving electrochemical oxidation and non-electrochemical recombination, confirmed for pure palladium, is valid also for palladium alloys.Contribution to the 3rd Baltic Conference on Electrochemistry, GDASK-SOBIESZEWO, 23–26 APRIL 2003.Dedicated to the memory of Harry B. Mark, Jr. (February 28, 1934–March 3rd, 2003)