A letter signed: the very beginnings of Dalton's atomic theory

This paper explores the provenance and content of a previously unknown personal letter by John Dalton (1766-1844), which is dated 12 April 1803. It relates to a startling breakthrough in Dalton's research, which pre-dates by five months the earliest date in his laboratory notebook, namely, 6 September 1803. The author acquired the letter about thirty years ago, and now offers it to the public. He makes no attempt to explain how it contributes to--or even changes--our understanding of Dalton, but leaves that privilege to Dalton scholars.     

Dalton’s Disputed Nitric Oxide Experiments and the Origins of his Atomic Theory

In 1808 John Dalton published his first general account of chemical atomic theory, a cornerstone of modern chemistry. The theory originated in his earlier studies of the properties of atmospheric gases. In 1803 Dalton discovered that oxygen combined with either one or two volumes of nitric oxide in closed vessels over water and this pioneering observation of integral multiple proportions provided important experimental evidence for his incipient atomic ideas. Previous attempts to reproduce Dalton’s experiments have been unsuccessful and some commentators have concluded the results were fraudulent. We report a successful reconstruction of Dalton’s experiments and provide an analysis exonerating him of any scientific misconduct. But we conclude that Dalton, already thinking atomistically, adjusted experimental conditions to obtain the integral combining proportions.     

Synthesis,DNA-binding,and cytotoxic studies on three copper(II) complexes of unsymmetrical synthetic analogues of curcumin

Copper(II) chelates of three unsymmetrical synthetic analogs of curcumin, namely (2E)-2-(4-hydroxy-3-methoxybenzylidene)-5-((E)-3-(4-hydroxy-3-methoxyphenyl)acryloyl)cyclopentanone(1), (2E)-2-(3,4-dihydroxybenzylidene)-5-((E)-3-(3,4-dihydroxyphenyl)acryloyl)cyclopentanone(2), and (2E)-2-(3,4-dimethoxybenzylidene)-5-((E)-3-(3,4-dimethoxyphenyl)acryloyl)cyclopeantanone(3) have been synthesized and characterized by physicochemical and spectroscopic methods. The ligands were in their enolic form and metal complexes have 1 : 2 metal:ligand stoichiometry. The DNA-binding properties of the ligands and their metal complexes were studied by absorption titrations, fluorescence quenching experiments, and viscosity measurements with calf-thymus DNA. The interactions of copper(II) complexes were higher than that of free ligands. The observed intrinsic binding constants reveal moderate interaction of copper(II) complexes with calf-thymus DNA. The binding involves intercalative mode through non-covalent interactions and produced conformational changes in the structure of DNA. The compounds were investigated for their possible cytotoxic and antitumor activities. All the compounds were cytotoxic towards Dalton’s lymphoma ascites cells. It was found that copper chelates are remarkably active compared to free curcumin analogs. Concentrations needed for 50% cell death were 10–22 μg mL^?1 for copper complexes and 27–52 μg mL^?1 for curcumin analogs. Copper complex of 2 with two hydroxyl groups in the phenyl ring was most active towards Dalton’s lymphoma ascites cells (increase in life span 77.91%). Copper(II) complex of 3, which possesses methoxy groups in the phenyl ring system, showed the lowest activity towards increase in lifespan of tumor-bearing mice (increase in lifespan 60.14%). Copper chelates of all curcuminoid analogs showed a significant reduction in solid tumor volume in mice.     

SYNTHESIS OF 1- AND 3-C-(AMINOMETHYL)-1,2,3,4,5-CYCLOHEXANEPENTOLS FROM (+)-epi-QUERCITOL[1]

Oxidation of three di-O-isopropylidene derivatives 2a—4a, newly derived from (+)-epi-quercitol (1), with acetic anhydride in DMSO gave the corresponding ketones 5—7, which underwent aldol-type condensation with nitromethane under basic conditions to give selectively the protected derivatives 8a—10a of C-nitromethyl-1,2,3,4,5-cyclohexanepentols, respectively. On treatment with diazomethane in DMSO, the ketones 6 and 7 gave single spiro epoxides 11 and 12, the structures of which were confirmed by converting them into new C-(azidomethyl)cyclohexanepentols 16 and 17. The nitro compounds were hydrogenated in the presence of Raney nickel to give the amines isolated as the N-acetyl derivatives. Deprotection gave three new 1- and 3-C-aminomethyldeoxyinositols 15c—17c. The aminocyclitols obtained and their N-acetyl derivatives were assayed for inhibitory activity against examples of glycosidases.     

Sustainable restoration: the contribution of algae

Abstract

The application of algae to the most meaningful fields of our life, such as food, environment and energy, finds a further confirmation in the extension of this application to cultural heritage protection. In this letter, we present the results of a preliminary study testing how a polysaccharide extracted from algal matrix can restore degraded paper giving back it mechanical strength and chemical structure.     

Mixed Chloro Bis[Alkylenedithiophosphato] Antimony(III) and Their Heterobinuclear Derivatives with Boron Tetraisopropoxide: Synthesis and Characterization

Chloro bis(alkylenedithiophosphato)antimony(III) complexes of the type [OGOP(S)S]₂SbCl (1–5) [where G = —C(Me)₂—CH₂—CH(Me)—1 —C(Me)₂—C(Me)₂—2, —CH₂—C(Me)₂—CH₂—3, —CH(Me)—CH(Me)—4 and –CH(Me)—CH₂—CH₂—5] have been synthesized by the reaction of SbCl₃ with sodium salts of alkylenedithiophosphoric acids in a 1:2 molar ratio in refluxing benzene. Reactions of chloro bis(alkylenedithiophosphato) antimony(III) compounds, [OGOP(S)S]₂SbCl with sodium tetraisopropoxoborate, NaB(OPrⁱ)₄, in a 1:1 molar ratio in refluxing benzene yielded some new heterobinuclear derivatives of antimony(III) and boron(III) of the type[OGOP(S)S]₂Sb(μ—OPrⁱ)₂B(OPrⁱ)₂. These newly synthesized complexes have been characterized by elemental analysis and molecular weight measurement, and their plausible structures have been proposed on the basis of IR, NMR (¹H, ¹³C,³¹P,¹¹B), and FAB-mass spectral studies. On the basis of the spectroscopic evidence, a pseudo octahedral geometry around antimony and tetrahedral geometry around boron atom has been proposed. Cyclic O,O′-alkylenedithiophosphate ligands and their corresponding chloro bis(alkylenedithiophosphato)antimony(III) compounds have been screened for microbial activities. These compounds showed significant antifungal activity against Fusarium and Trichoderma and antibacterial activity against E. Coli and Pseudomonas.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Activation of heterogeneous catalysts by organoaluminium compounds

The catalytic (benzene hydrogenation) and adsorption (O₂, CO) properties of NiO/Al₂O₃ and Ni(C₅H₇O₂)₂/Al₂O₃ reduced by trimethylaluminium and hydrogen have been studied. Significant differences in their catalytic and adsorption properties have been observed. The increased hydrogenation activity of catalysts reduced by trimethylaluminium is due to the increased reduction degree and dispersity of the active component.

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( ) (O₂, CO) NiO/Al₂O₃ Ni(C₅H₇O₂)₁/Al₂O₃, H₂. . , , .

     

The Vatican museum and the organic natural products. The Raphael’s frescoes and the “Last Judgment” by Nicolò and Giovanni

Abstract

In the second half of the 90s, alongside the restoration works of the Quattrocentisti (fifteenth century painters) in the Sistine Chapel, it also carried out the restoration of the frescoes of the Stanze di Raffaello. The results of scientific investigations conducted by the Scientific Research Laboratory of the Vatican Museums, previously presented in some assays of study, are summarised and presented in this letter to the Editor for the special issue of Natural Product Research: Natural Products in Cultural Heritage.     

Quality Information from the Grapevine

Abstract

A letter by Lucien Herr, a highly regarded leading French intellectual at the time of World War I, provides capsule portraits of chemists such as Gabriel Bertrand, Paul Lebeau, Charles Moureu, and Georges Urbain. It makes us better aware of who they were and of how their contemporaries saw their work, which had much to do with their personalities, whether congenial or abrasive. This article is concerned with the kind of information carried by the so-called grapevine. It can be invaluable to the historian, for the light it sheds on the character of a scientist. The document drawn upon, from World War I (1915), depicts graphically the personalities of some of the French chemists engaged in the rush to design and produce chemical weapons. It is a frank and even brutal appraisal of their strengths and weaknesses. This is the kind of evaluation that scientists routinely engage in, but devoid of the hyperbole, pro or con, which usually flavours it.     

Synthesis and characterization of a large bite angle iridium nixantphos complex

The complex (nixantphos)Ir(cod)Cl·CH₂Cl₂(0.5C₇H₈) 3 has been synthesized and structurally characterized by NMR, IR, and single crystal X-ray diffraction. The coordination around Ir is trigonal bipyramidal with both P groups of the nixantphos bound in a bis-equatorial mode. The bis-chelating cod (C₈H₁₂) occupies the remaining equatorial position and an axial position. This mode of bonding resulted in a large bite angle (P1—Ir—P2) of 106.49° (3) for 3. The IR and NMR data support the elucidated structure. Thermal analyses of 3 indicate that it is thermally stable up to decomposition greater than 400°C.     

Determination of Phenols Using Various Peroxidases

Abstract

Peroxidases of different origin — horseradish peroxidase isozyme C, alfalfa and peanut cationic peroxidases, tobacco leaves and novel fungal anionic peroxidases – were used to determine phenol and its analogues. Phenol and resorcinol were shown to be the inhibitors of the peroxidase activity towards o—dianisidine for all the enzymes tested, whereas pyrogallol and hydroquinone caused an appearance of a lag—period on a kinetic curve. The duration of a lag—period was proportional to the effector concentration and could be used to determine it. The novel fungal peroxidase from Phellinus igniarius exhibited the highest sensitivity towards phenols and they could be determined at the 10–6 – 10–7 M concentration levels.     

Ammonium Ion Optical Sensor Formation and Characterization of a Self‐Assembled Thiazole Containing Dibenzo‐18‐Crown‐6 Monolayer toward Developing Ammonium Ion‐Sensing Interface

Abstract

This letter demonstrates a selective NH₄ ⁺ detection using a synthesized thiazole benzo crownether ethylamine‐lipoic acid conjugate (1) monolayer. A self‐assembled monolayer (SAM) of 1 was formed on Au surface and well characterized by atomic‐force microscopy, Fourier transform infrared reflection absorption spectroscopy and cyclic voltammetry (CV). A good selectivity for NH₄ ⁺ sensing was observed in a range of 1.0×10^?1 to 1.0×10^?6 M by surface plasmon resonance.     

Complexes of [(iPrO)2P(O)NHC(S)NHCH2]2CH2 with Co(II), Ni(II), Zn(II), and Pd(II): Reaction of [(iPrO)2P(O)NHC(S)NHCH2]2 with KOH Leading to the Imidazolidine-2-Imine Derivative

Reaction of O,O′-diisopropylphosphoric acid isothiocyanate (iPrO)₂P(O)NCS with NH₂(CH₂)_nNH₂ (n = 3, 2) leads to the N-phosphorylated bis-thioureas [(iPrO)₂C(S)NHP(O) NH]₂Z (Z = —(CH₂)₃—, H₂L^I ; —(CH₂)₂—, H₂L^II ). Reaction of the potassium salt of H₂L^I with Co(II) and Zn(II) in aqueous EtOH leads to complexes of formula M₂(L-O,S)₂. The metal cation in both complexes is coordinated by two deprotonated ligands through the sulfur atoms of the thiocarbonyl groups and the oxygen atoms of the phosphoryl groups. Reaction of K₂L^I with Ni(II) and Pd(II) in the same conditions leads to M₂(L-N,S)₂ complexes. In both compounds, the metal center is found in a square-planar N₂S₂ environment formed by the C=S sulfur atoms and the P—N nitrogen atoms of two deprotonated ligands L^I . Reaction of H₂L^II with KOH leads to a product of heterocyclization, in which one of the thiourea fragments is retained. Compounds obtained were investigated by IR, UV-Vis, ¹H and ³¹P NMR spectroscopy, and microanalysis.     

N-(二茂铁酰胺基)硫脲类阴离子受体

我们将N-(苯甲酰胺基)硫脲类阴离子识别受体研究拓展至N-(二茂铁酰胺基)硫脲, 设计合成了N-(二茂铁甲酰胺基)-N'-(取代苯基)硫脲(3a～3e, 取代基X＝p-OCH₃, p-CH₃, H, m-Br, m-CF₃), 其中二茂铁基系芳香性的电化学活性基团、“—NH—”为连接臂．研究的目的是进一步理解 “—NH—”连接臂的特性和3a～3e作为阴离子的电化学响应受体的可行性. 我们发现, 3a～3e分子中的N'-苯环取代基不影响其半波电位(0.31V vs. Ag/AgNO₃); 二茂铁环芳香质子和酰胺基—NH质子的核磁化学位移不受取代基的影响, 而N'-苯基芳香质子和硫脲—NH质子的化学位移显著地受制于取代基; 说明受体3分子中酰肼基N—N单键高度扭曲, 阻碍了N'-苯环取代基电子效应传递至二茂铁基. 我们观察到乙腈中3的氧化电位因阴离子如CH₃CO₂^－和F^－的结合负移200 mV, 二茂铁基芳香质子的化学位移向高场移动, 意味着阴离子结合诱导了受体3分子中酰肼基N—N单键构型变化, 使阴离子结合信息得以传递至二茂铁环. 吸收光谱滴定实验表明, 乙腈中3a～3e与阴离子结合时在约315 nm处出现新的吸收峰, 光谱红移达5820 cm^－1, 阴离子如CH₃CO₂^－和F^－的结合常数在10⁶ mol^－1•L, 均远高于传统的二苯基硫脲类受体(1); 我们还发现, 尽管1和3a～3e分子中硫脲—NH质子酸性对取代基的依赖性相近, 3a～3e之阴离子结合常数的取代基效应强于1. 我们认为, 这是由于N—N键的变构作用导致3a～3e的吸收光谱红移、阴离子结合常数和阴离子结合常数的取代基效应远高于传统的N,N'-二苯基硫脲类受体, 因而体现了“—NH—”连接臂的独特性质.     

Ab Initio Study of Ring Flipping of the Overcrowded Peri-Substituted Naphthalenes

Ab inintio molecular orbital and density functional theory method were used to investigate the structural and dynamic behavior of 1,8-di-tert-butyl naphthalene (1), 1,8-bis(trimethylsilyl)naphthalene (2), 1,8-bis(trimethylgermyl)naphthalene (3), and 1,8-bis(trimethylstannyl)naphthalene (4). HF/3-21G//HF/3-21G results revealed that the ring flipping barrier height of compound 1–4 is 92.59, 32.13, 26.76, and 15.46 kJ mol^?1 respectively. The obtained results show that the transition state structure for ring flipping of the bulky-groups is in a planar form with naphthalene ring. Contrary to compound 1, the ring flipping of compounds 2–4 occurred easily at room temperature. Also, MP2/3-21G//HF/3-21G energy calculation, show that the enantiomerization energy of compounds 1–4 are 97.99, 33.24, 26.80, and 15.38 kJ·mol^?1 respectively. The required energy for ring inversion of compounds 1–4 are 85.09, 27.26, 21.54, and 10.21 kJ mol^?1 respectively, as calculated by B3LYP/3-21G//HF/3-21G method. It can be concluded that the lower energy barrier of the ring flipping of compounds 2–4 is related to the increasing of the bond lengths of Si—C, Ge—C, and Sn—C, in contrast to C—C bond.     

多叠氮基三唑类高氮化合物的合成与晶体结构

2,5,2'-三氯-1,1'-偶氮-1,3,4-三唑(1)与叠氮化钠反应首次合成含有多叠氮和四氮烯(N—N＝N—N)结构的高氮化合物2,5,2'-三叠氮-1,1'-偶氮-1,3,4-三唑(3). 在相同条件, 2,5,2',5'-四氯-1,1'-偶氮-1,3,4-三唑(2)与叠氮化钠反应没有得到2,5,2',5'-四叠氮-1,1'-偶氮-1,3,4-三唑(b), 而是得到其分解产物3,5-二叠氮基-1,2,4-三唑(4). 用X 射线单晶衍射测定了化合物3和4的晶体结构. 晶体2b通过分子间氢键的相互作用形成具有9元环的三聚体,并由于三唑环共轭体系使氮上的H原子具有酸性,从而导致互变现象发生.     

Detection of Al3+ and Hg2+ ions with anthracene appended Schiff base and its reduced analogue

Abstract

Chemosensor 1 has been synthesized via a one-pot synthetic route incorporating anthracene and azomethine (HC═N—) units acting as signaling and binding units, respectively. Chemosensor 1 offered selective colorimetric and fluorometric response towards Al³⁺ and Hg²⁺ ions among other cations in CH₃OH. Solution of 1 in methanol exhibited a naked eye color transition from yellow to colorless on addition of Al³⁺ and Hg²⁺ ions. In case of emission experiments, non-fluorescent solution of 1 showed major enhancement in intensity giving blue fluorescence for both metal ions. The limits of detection were calculated to be 1.04 and 0.8 µM for Al³⁺ and Hg²⁺, respectively, using fluorescence titrations. Further, reduced form of Schiff base 1 (2) has also been synthesized in order to compare the importance of azomethine (HC═N—) and (H₂C—NH—) moieties in selective coordination. However, the reduced analogue 2 did not exhibit selective detection towards any of the ions.     

Looking for an Order of Things: Textbooks and Chemical Classifications in Nineteenth Century France

Abstract

The purpose of this paper is to reconsider the issue of the creativity of textbook writing by exploring the links between nineteenth-century French textbooks and the quest for a classification of elements. The first section presents the elegant combination of didactic and chemical constraints invented by eighteenth-century chemists: the order of learning — from the known to the unknown — and the order of things — from the simple to the complex — were one and the same. In section two we argue that the alleged coincidence did not help the authors of elementary textbooks required for the new schools set up by the French revolution. Hence the variety of classifications adopted in the early nineteenth century. A debate between natural and artificial classifications raised a tension in the 1830s without really dividing the chemical community. Rather it ended up with the adoption of a hybrid classification, combining the rival natural and artificial systems.     

全氟烷基磺酸酯C—O键断裂的同面SN2反应

用密度泛函理论研究了CF₃SO₃CF₂CF₃＋F^－的碳氧键断裂反应的机理. 首先, 用DFT方法优化了反应物、中间体、过渡态、产物的平衡构型, 分析了碳氧键断裂反应的势能面变化. 发现在S_N2反应机理中, 除了S—O断裂S_N2反应外, 引起C—O键断裂的同面进攻也是一个可能的反应途径. 理论计算表明, 最终反应的产物是受热力学控制的, S—O键的断裂绝对地优于C—O的断裂. 因此, C—O断裂的同面机理虽然是可能的, 但却难以被实验观察到. 本文还讨论了端基 —F₃在同面S_N2反应中的邻位效应, 以及基组对这个效应的影响.     

The Analysis of Inorganic and Organic Pollutants in Soil with Special Regard to Their Bioavailability

Abstract

The most important inorganic pollutants in soil are the heavy metals. Problems related to the determination of the total and soluble content are discussed. Soluble contents are of interest in connection with studies about bioavailability. Because some of the heavy metals are essential for plant growth, most of the work about bioavailability has been done in the field of plant nutrition. Much less is known about the situation in polluted soils.

It was shown that neutral salt solutions which do not really change the pH of soil during the extraction procedure are best suited to define thresholds of excess. This is in contrast to much stronger extractants like EDTA or DTPA often proposed for the analysis of soils which are deficient in trace elements.

With three sets of experiments the correlation between the contents of cadmium, copper, nickel and zinc extracted by 0.1 M NaNO₃ (as an example of a neutral salt solution) and the plant response (phyto- or zootoxicity) are shown:

—pot experiments using soils which were contaminated by metal salt solutions

—pot experiments using soils from contaminated areas

—field studies in polluted areas. In these studies the aspect of heavy metal leaching was also considered.

The results were converted to indicative values in the Swiss Ordinance of Pollutants in the Soil. These indicative values derived from plant reactions were checked by the carbon mineralisation as an example of a soil microbiological process.

As it was found that organic pollutants are not easily taken up by plant roots the problem of bioavailability is much less important. However, the biodegradation and formation of metabolites has to be considered.