When Aggregation-Induced Emission Meets Perovskites: Efficient Defect-Passivation and Charge-Transfer for Ambient Fabrication of Perovskite Solar Cells

The intrinsic defects in perovskite film can serve as non-radiative recombination center to limit the performance and stability of metal halide perovskite solar cells (PSCs). The additive engineering in perovskite film is always applied to produce high-efficiency PSCs in recent years. Here, a typical donor-acceptor (D−A) structured aggregation-induced emission (AIE) molecule tetraphenylethene-2-dicyano-methylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TPE-TCF) was introduced into perovskite film. The D−A structure of TPE-TCF molecule provided additional charge transfer channels, contributing to transporting electron of TPE-TCF-based device. The cyano (C≡N) of TPE-TCF can interact with the uncoordinated Pb to from a relatively stable intermediate, PbI₂⋅TPE-TCF, resulting in the slower crystal growth, reduced the defects at the grain boundaries and suppressed carrier recombination. As a consequence, the power conversion efficiency (PCE) of TPE-TCF-modified PSCs achieved a remarkably enhanced from 15.63 to 19.66 % with negligible hysteresis, which was prominent in methylammonium lead iodide-based devices fabricated under ambient condition. Furthermore, the PSCs modified by AIE molecule possessed an outstanding stability and maintain about 86 % of the initial PCE after 300 h storage in air at 25–35 °C with a high relative humidity (RH) of ≈85 %. This work suggests that incorporating AIE molecule into perovskite is a promising strategy for facilitating high-performance PSCs commercialization in ambient environment without glovebox.     

A TD‐DFT study on the cyanide‐chemosensing mechanism of 8‐formyl‐7‐hydroxycoumarin

Proton transfer (PT) and excited‐state PT process are proposed to account for the fluorescent sensing mechanism of a cyanide chemosensor, 8‐formyl‐7‐hydroxycoumarin. The time‐dependent density functional theory method has been applied to investigate the ground and the first singlet excited electronic states of this chemosensor as well as its nucleophilic addition product with cyanide, with a view to monitoring their geometries and spectrophotometrical properties. The present theoretical study indicates that phenol proton of the chemosensor transfers to the formyl group along the intramolecular hydrogen bond in the first singlet excited state. Correspondingly, the nucleophilic addition product undergoes a PT process in the ground state, and shows a similar structure in the first singlet excited state. This could explain the observed strong fluorescence upon the addition of the cyanide anion in the relevant fluorescent sensing mechanism. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011     

A simple dual-channel sensor for detecting cyanide in water with high selectivity and sensitivity

Taking advantage of the special nucleophilicity of cyanide, a new simple colorimetric chemosensor has been synthesised. This allows a deprotonation reaction to monitoring the cyanide. With the addition of CN^? to the chemosensor aqueous solution, which could induce a change in the solution colour from yellowish to deep yellow, while no colour change could be observed in the presence of other hackneyed anions, by which CN^? can be distinguished from other anions immediate with the naked eye. At the same time, a fluorescence quenching was implemented upon adding cyanide into the chemosensor aqueous solution. The absorption spectra detection limits of the chemosensor for cyanide was 5.35 × 10^?8 M and the fluorescence spectra detection limit was 2.63 × 10^?8 M. The cyanide test strips based on the chemosensor could serve as a convenient cyanide test kits. Furthermore, the chemosensor was successfully applied to detect cyanide in sprouting potatoes.     

含硫氮螯合树脂对金、银及某些贱金属氰化物吸附性能的研究

用ＩＣＰ－ＡＥＳ研究了含硫氮螯合树脂对碱性氰化溶液中金、银、铜、铁、锌等金属离子的吸附行为。结果表明,该树脂除定量吸附金、银的氰化物外,也吸附铜、锌、铁的氰化物;吸附在树脂上的银及其它贱金属离子可以用２％ＮａＣＮ定量解吸,用硫脲－硫酸溶液可顺利地将金从树脂上洗脱下来,由此可实现金与银等元素的分离。树脂重复使用性能良好。对该树脂吸附金属氰化物的机理进行了初步探讨。     

Ratiometric fluorescence detection of cyanide based on a hybrid coumarin-hemicyanine dye: the large emission shift and the high selectivity

A new ratiometric fluorescent cyanide probe was developed based on the nucleophilic attack of CN(-) toward the indolium group of a hybrid coumarin-hemicyanine dye, by which high selectivity as well as large emission shift could be achieved.     

New methods for the detection of cyanide based on displacement of the glutathione ligand of glutathionylcobalamin by cyanide

Glutathionylcobalamin (GSCbl) is a vitamin B₁₂ derivative that contains glutathione as the upper axial ligand to cobalt via a Co–S bond. In the present study, we discovered that cyanide reacted with GSCbl, generating cyanocobalamin (CNCbl) and reduced glutathione (GSH) via dicyanocobalamin (diCNCbl) intermediate. This reaction was induced specifically by the nucleophilic attack of cyanide anion displacing the glutathione ligand of GSCbl. Based on the reaction of GSCbl with cyanide, we developed new methods for the detection of cyanide. The reaction intermediate, violet-coloured diCNCbl, could be applied for naked eye detection of cyanide and the detection limit was estimated to be as low as 520 μg L^?1 (20 μM) at pH = 10.0. The reaction product, CNCbl, could be applied for a spectrophotometric quantitative determination of cyanide with a detection limit of 26 μg L^?1 (1.0 μM) at pH = 9.0 and a linear range of 26–520 μg L^?1 (1.0–50 μM). In addition, the other reaction product, GSH, could be applied for a fluorometric quantitative determination of cyanide with a detection limit of 31 μg L^?1 (1.2 μM) at pH = 9.0 and a linear range of 31–520 μg L^?1 (1.2–20 μM). These new GSCbl-based methods are simple, highly specific and sensitive with great applicability for the detection of cyanide in biological and non-biological samples.     

Adsorption of Zinc and Cyanide from Cyanide Effluents on Anionic Ion-exchange Resin

The adsorption of zinc and cyanide from cyanide effluents onto strong and weak basic anion exchange resins was studied in a batch adsorption system. Factors influencing the adsorption rates such as resin selection, resin amounts, contact time and temperature were studied and scanning electron microscopy-energy disperse spectroscopy(SEM-EDS) was used in the analysis. The present study shows that the adsorption capacity of resin 201×7 is better than that of resin 301. The adsorption process was relatively fast and came to equilibrium after 60 min. The kinetic data were analyzed with three models and the pseudo-second-order kinetic model was found to agree with the experimental data well. The equilibrium data could also be described well by Langmuir isotherm model. Thermodynamic parameters such as enthalpy change(ΔH⁰), free energy change(ΔG⁰) and entropy change(ΔS⁰) were calculated and the adsorption process was spontaneous and endothermic.     

A rapid responsive and highly selective probe for cyanide in the aqueous environment

A colorimetric and fluorescent cyanide probe based on 7-(trifluoroacetamino)coumarin has been prepared. This structurally simple probe displays rapid response and high selectivity for cyanide over other common anions in the aqueous solution. The sensing of cyanide was performed via the nucleophilic attack of cyanide anion to carbonyl of the probe with a 1:1 binding stoichiometry, which could be confirmed by Job’s plot, ¹H NMR, and MS studies. DFT/TDDFT calculations support that the fluorescence enhancement of the probe is mainly due to the ICT process improvement. The detection limit of the fluorescent assay for cyanide is as low as 0.3 μM in a rapid response of less than 30 s. Thus, the present probe should be applicable as a practical system for the monitoring of cyanide concentrations in aqueous samples.     

氰化钠和醛及苦杏仁粗酶一锅法合成手性氰醇

直接使用固体氰化钠代替易挥发的HCN为氰源,用来源于苦杏仁的(R)-醇腈酶粗酶催化和醛的反应,并加入足量的HOAc来抑制非酶促反应和手性氰醇产物的外消旋化,一锅法合成了手性氰醇.考察了酸、(R)-醇腈酶粗酶、水、氰化钠和反应温度等因素对反应的影响.大部分反应底物的产物的产率及ee值都大于95%.该方法简单、安全、低成本、高对映选择性和收率,具有很好的应用价值.     

An Efficient Probe for Rapid Detection of Cyanide in Water at Parts per Billion Levels and Naked‐Eye Detection of Endogenous Cyanide

A new molecular probe based on an oxidized bis‐indolyl skeleton has been developed for rapid and sensitive visual detection of cyanide ions in water and also for the detection of endogenously bound cyanide. The probe allows the “naked‐eye” detection of cyanide ions in water with a visual color change from red to yellow (Δλ_max=80 nm) with the immediate addition of the probe. It shows high selectivity towards the cyanide ion without any interference from other anions. The detection of cyanide by the probe is ratiometric, thus making the detection quantitative. A Michael‐type addition reaction of the probe with the cyanide ion takes place during this chemodosimetric process. In water, the detection limit was found to be at the parts per million level, which improved drastically when a neutral micellar medium was employed, and it showed a parts‐per‐billion‐level detection, which is even 25‐fold lower than the permitted limits of cyanide in water. The probe could also efficiently detect the endogenously bound cyanide in cassava (a staple food) with a clear visual color change without requiring any sample pretreatment and/or any special reaction conditions such as pH or temperature. Thus the probe could serve as a practical naked‐eye probe for “in‐field” experiments without requiring any sophisticated instruments.     

Improved gas chromatography with electron-capture detection using a reaction pre-column for the determination of blood cyanide: a higher content in the left ventricle of fire victims

We developed a head-space method for the determination of blood cyanide by gas chromatography with electron-capture detection. In this technique, a reaction pre-column, packed with chloramine-T, was used for the conversion of hydrogen cyanide into cyanogen chloride. Since the reaction pre-column eliminated the necessity for trapping hydrogen cyanide from the biological samples, blood cyanide was quickly analysed by acidification only. The reaction pre-column was durable for at least several months. The calibration curve gave good linearity when dichloromethane was used as the internal standard, and the lower detection limit taken from this plot was ca. 0.05 micrograms/ml. The relative standard deviation of spiked blood samples was in the range 0.6-3.9%. We determined blood cyanide levels at autopsy in victims who had died from fire using this method. A significantly higher cyanide content was detected in the left ventricular blood than in the right. There was a positive correlation between blood cyanide and carboxylhaemoglobin contents. This simple and sensitive technique could be very useful for the determination of cyanide in various samples.     

双金属氰化物/稀土配合物催化二氧化碳和环氧丙烷的共聚合

使用双金属氰化物/稀土配合物复合催化剂催化二氧化碳和环氧丙烷共聚合,其催化效率比双金属氰化物催化剂有显著提高,得到了数均相对分子质量大于1.0×105的聚合物。研究了复合催化剂的组成(如稀土的种类、稀土与锌的比例(Ln/Zn)、稀土配合物中酸根离子的酸性等)对共聚反应的影响,同时研究了反应体系的压力及反应时间对催化活性的影响。采用Y(CCl3COO)3稀土金属配合物有利于共聚反应的进行。当n(Y)/n(Zn)=6、聚合4 h后,其催化活性比单纯的双金属氰化物提高了31.5%,聚合物的相对分子质量则没有太大变化,而副产物碳酸丙烯酯的质量分数低于2%,而在该温度下单独采用稀土三元催化剂时副产物碳酸丙烯酯的生成量通常在10%以上。聚合物中碳酸酯含量低于双金属氰化物的催化产物,说明稀土配合物只是起到活化金属与环氧丙烷配位的作用,没有提高共聚物的碳酸酯含量,整个共聚合反应依然遵循双金属氰化物催化的共聚反应机理。     

High performance liquid chromatography determination of cyanide in urine by pre-column fluorescence derivatization

A method for the determination of cyanide in human urine has been developed. The method is based on the reaction of cyanide with 2,3-naphthalenedialdehyde and taurine to give a fluorescent product for reversed-phase HPLC separation and fluorometric detection. After centrifugation followed by dilution of urine samples, the specimens could be analysed directly by this method. The recovery of cyanide added to urine at concentration levels of 50-1000 pmol/mL was 85-96%. The detection limit of cyanide was 30 pmol/mL in urine. The method was successfully applied to the analysis of urine from smokers and nonsmokers. The mean concentrations of cyanide were found to be 215 pmol/mL for the former and 84 pmol/mL for the latter.     

Analytical techniques for cyanide in blood and published blood cyanide concentrations from healthy subjects and fire victims

Hydrogen cyanide can be produced by the pyrolysis of man-made polymers. Cyanide has been measured in the blood of healthy adults as well as the blood of fire survivors and fatalities. In healthy subjects the blood cyanide concentration of smokers is higher than that of non-smokers. Fire survivors and fatalities have been found to have higher cyanide levels than of control groups and the levels from fire fatalities are often higher than survivors. Blood concentrations quoted as normal, toxic or fatal are highly variable in the literature. Many studies have been performed to measure the blood cyanide levels in control subjects as well as those who have been exposed to fire but the values found differ. The values for control subjects can vary from none detected to 19 μmol dm⁻³ while those for fire survivors range from not detected to 150 μmol dm⁻³ and fatalities range from not detected to 284 μmol dm⁻³. Analytical techniques and published data are critically reviewed.Many of the existing antidotes for cyanide poisoning are highly toxic themselves and should ideally be administered at doses proportional to the amount of cyanide a patient has received to avoid compounding damage done by cyanide intoxication. For this reason, a rapid, accurate bedside assay of blood cyanide concentration that differentiates between bound and free cyanide would represent a leap forward in the clinical management of cyanide poisoning.     

TDDFT Study on Different Sensing Mechanisms of Similar Cyanide Sensors Based on Michael Addition Reaction

The solvents and substituents of two similar fluorescent sensors for cyanide, 7-diethylamino-3-formylcoumarin (sensor a) and 7-diethylamino-3-(2-nitrovinyl)coumarin (sensor b), are proposed to account for their distinct sensing mechanisms and experimental phenomena. The time-dependent density functional theory has been applied to investigate the ground states and the first singlet excited electronic states of the sensor as well as their possible Michael reaction products with cyanide, with a view to monitoring their geometries and photophysical properties. The theoretical study indicates that the protic water solvent could lead to final Michael addition product of sensor a in the ground state, while the aprotic acetonitrile solvent could lead to carbanion as the final product of sensor b. Furthermore, the Michael reaction product of sensor a has been proved to have a torsion structure in its first singlet excited state. Correspondingly, sensor b also has a torsion structure around the nitrovinyl moiety in its first singlet excited state, while not in its carbanion structure. This could explain the observed strong fluorescence for sensor a and the quenching fluorescence for the sensor b upon the addition of the cyanide anions in the relevant sensing mechanisms.     

A novel fluorescent and chromogenic probe for cyanide detection in water based on the nucleophilic addition of cyanide to imine group

A fluorescent and colorimetric probe bearing salicylaldehyde hydrazone functionality has been prepared for cyanide sensing. The detection of cyanide was performed via the nucleophilic attack of cyanide anion on the imine group of the probe with a 1:1 binding stoichiometry, which could be confirmed by ¹H NMR and MS studies. The specific reaction results in a prominent fluorescence enhancement and a color change from colorless to yellow.     

New chemosensory materials based on disubstituted polyacetylene with strong green fluorescence

A new imidazole‐containing disubstituted polyacetylene ( P1 ) with strong green fluorescence was successfully prepared through polymer reaction, which was nearly impossible to be obtained from the direct polymerization of its corresponding monomer. The polymer was soluble in common organic solvents, and its strong green fluorescence could be quenched completely by the Cu²⁺ and Co²⁺ ions, at the concentrations as low as 1.33 and 1.67 × 10⁻⁵ mol/L (0.85 and 0.92 ppm), respectively. Because of the high stability of the complex formed by cyanide and copper ions, the quenched green fluorescence of P1 by copper ions could be turned on upon the addition of trace cyanide (as low as 2.70 × 10⁻⁵ mol/L, 0.70 ppm), making P1 a new sensitive cyanide chemosensor. The results thus provided a new opportunity to develop anion chemosensors based on good cation chemosensors. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8070–8080, 2008     

Cyanide reaction with ninhydrin: elucidation of reaction and interference mechanisms.

A new sensitive spectrophotometric method has recently been developed for the trace determination of cyanide with ninhydrin. Cyanide ion was supposed to act as a specific base catalyst. Nevertheless, this paper demonstrates that the reported assay is based on a novel reaction of cyanide with 2,2-dihydroxy-1,3-indanedione, which affords purple or blue colored salts of 2-cyano-1,2,3-trihydroxy-2H indene. Hydrindantin is merely an intermediary of the reaction. The formation of a stable and isolable ninhydrin-cyanide compound has been confirmed by its preparation in crystalline form. Also, it is thoroughly characterized by elemental as well as MS, IR, UV/VIS and 1H NMR analyses. The Ruhemann's sequence of reactions of cyanide with ninhydrin has been reconsidered and an adequate mechanism of the reaction is proposed. As a consequence, the interference of oxidizers as well as copper, silver and mercury ions with the cyanide determination has been elucidated.     

Determination of Cyanide in Blood for Forensic Toxicology Purposes—A Novel Nci Gc-Ms/Ms Technique

One of the recently evolving methods for cyanide determination in body fluids is GC-MS, following extractive alkylation with pentafluorobenzyl bromide or pentafluorobenzyl p-toluenesulfonate. The aim of this study was to improve previous GC methods by utilizing a triple quadrupole mass spectrometer, which could enhance selectivity and sensitivity allowing for the reliable confirmation of cyanide exposure in toxicological studies. Another purpose of this study was to facilitate a case investigation including a determination of cyanide in blood and to use the obtained data to confirm the ingestion of a substance, found together with a human corpse at the forensic scene. The blood samples were prepared following extractive alkylation with a phase transfer catalyst tetrabutylammonium sulfate and the PFB-Br derivatization agent. Optimal parameters for detection, including ionization type and multiple reaction monitoring (MRM) transitions had been investigated and then selected. The validation parameters for the above method were as follows—linear regression R² = 0.9997 in the range of 0.1 µg/mL to 10 µg/mL; LOD = 24 ng/mL; LOQ = 80 ng/mL and an average recovery of extraction of 98%. Our study demonstrates the first attempt of cyanide determination in blood with gas chromatography-tandem mass spectrometry. The established method could be applied in forensic studies due to MS/MS confirmation of organic cyanide derivative and low matrix interferences owning to utilizing negative chemical ionization.     

Direct determination of free cyanide in drinking water by ion chromatography with pulsed amperometric detection

Cyanide is a regulated contaminant in drinking water in the United States. This paper describes an ion chromatography method with pulsed amperometric detection (PAD) that directly determines free cyanide in drinking water. Samples are treated with sodium hydroxide to stabilize cyanide and with a cation-exchange cartridge to remove transition metals. Cyanide is separated by anion-exchange chromatography and detected by PAD with a waveform optimized for cyanide and used with a disposable silver working electrode. The recovery of cyanide spiked into five water samples was >80%. With an MDL of 1.0 microg/L, this method determines cyanide concentrations well below the reporting limits for free cyanide in drinking water.