Louis Pasteur,Chemical Linguist: Founding the Language of Stereochemistry

Pasteur’s major discovery in chemistry was the recognition of molecular chirality, in 1848. He understood that his new science needed its own language, and introduced new terminology and nomenclature, thereby launching modern stereochemical language. He was eminently prepared for this task as a refined user of language, skills recognized by his election to the Académie française, the supreme institution for the protection and promotion of the French language. The terms chiral and chirality did not exist at the time and he adopted the French word dissymmétrie (dissymmetry) for the phenomenon of handedness. Although in his time almost nothing was known about molecular constitution and configuration, his insights allowed him to create useful language some of which is still used today in stereochemistry, e. g., racemic for the 1 : 1 mixture of the two enantiomers, and the use of the prefixes levo‐ and dextro‐ in the names of optically active substances. On the other hand, the limitations in the knowledge of organic chemistry at the time prevented him from creating some needed terms, e. g., for the phenomenon of diastereoisomerism. He also failed to adopt the enantio terminology introduced in the 1850s by German mineralogist Carl Friedrich Naumann. Analysis of Pasteur’s linguistic innovations is of interest from the point of view of the history of chemistry and is also useful in throwing light on the fundamental nature of the concepts of stereochemistry. Such understanding has acquired a new relevance due to the considerable misuse and misunderstanding of this language seen in the literature today.     

Mechanical and Chemical Explanations in Du Clos' Chemistry

Abstract

Samuel Cottereau Du Clos (1598–1685) appears as the first French chemist to combine in chemistry (for him, the science of substances, the physics of qualities) demonstrations using the laws of motion with demonstrations using the qualities of chemical principles. In this way, he brought to bear two different and complementary orders of explanation. According to Du Clos, the mechanical considerations represent a first approach, a stage towards the knowledge of “the truth of things” (la vérité des choses) in natural philosophy. He set out his chemistry at the Académie royale des sciences de Paris, especially through his criticism of Boyle's Certain Physiological Essays in 1668–1669.     

Niels Bohr (1885–1962): On the Wing of a Butterfly,Johann J. Balmer (1825–1898)

By the year 1913, a number of revolutionary events had begun to transform the landscape of physics. In 1900, Max Planck (1858–1947) had proposed that energy radiated in quanta or packets. The announcement of the photoelectric effect in 1905 by an unassuming Swiss patent worker by the name of Albert Einstein (1879–1955) clearly implicated that light energy, or the photon, later coined by Gilbert N. Lewis (1875–1946) in 1926, was also quantized and showed unprecedented particle‐like properties. More startling was the discovery by Ernest Rutherford (1871–1937) who demonstrated that the atom consisted of a hard positive center surrounded by electrons. Niels Bohr (1885–1962), then a young postgraduate, was deeply involved in understanding the structure of the atom. He needed physical or experimental evidence to substantiate his intuitive ideas. Ironically, that evidence had already been published in the year of his birth by Johann J. Balmer (1825–1898), a Swiss mathematics teacher at a secondary school for girls.     

Having Fun (and Commercial Success) with Josiphos and Related Chiral Ferrocene Based Ligands.

The Josiphos ligand family is arguably one of the most versatile classes of chiral ligands with a wide range of applications, including one of the two largest known enantioselective catalytic hydrogenations. In this personal account, we take a look back at the beginning and describe the role Antonio Togni has played to reach this point and the significance of his contributions for the commercial success, especially concerning today's ligand business of Solvias. This seems a fitting point in time in light of Antonio’s statement on his ETH home page that he ‘is working as a professor at this institution since 1992 (a few more months to go), not looking for a job’ and that the three authors have already retired for some time (H. U. B.) or are about to retire soon (B. P., F. S.).     

Stereoselectivity in Reactions of Metal Complexes. Part XIV.. Use of circular dichroism to determine the stereoselective formation of [M(his)2] and [M(PhEt-sal)2] (M = Ni2+, Cu2+, his = histidine,PhEt-sal = N-(1-phenylethyl)salicylaldimine)

The stereoselective formation of the 1:2 complexes [M(his)₂] and [M(PhEt-sal)₂] (M = Ni²⁺, Cu²⁺, PhEt-sal = N-(1-phenylethyl)salicylaldimine) has been determined by circular dichroism (CD) measurements. Stereoselectivity, defined as S = K_meso/2K_rac' has been found to be 2.48 for [Ni(his)₂], corresponding to a 21% excess of the mixed species relative to the statistical amount. This value is temperature-independent between 15 and 35°. Whereas the absence of stereoselectivity in the formation of [Cu(prol)₂] is confirmed, weak stereoselectivity is observed for [Cu(his)₂] (2% excess of the mixed species). The CD intensity of the latter complex strongly depends on temperature and decreases by 12%, when the temperature is increased from 15 to 35°. Small but significant stereoselectivity is found for the formation of the Schiff-base complexes [Ni(PhEt-sal)₂] and [Cu(PhEt-sal)₂] in acetone with 1.0% and 2.4% excess, respectively, of the mixed species over the statistical value.     

Synthesis of （p-Formylphenyl）azo Calix[4]arenes

Five novel azo calix[4]arenes were reported. The p-aminobenzaldehyde was diazotized with sodium nitrite in aqueous hydrochloride solution. Mono-, bis-, tris- and tetrakis(p-formylphenyl)azo calix[4]arenes (including proximal and distal isomers) were obtained respectively by diazo-coupling in different molar ratio to calix[4]arene(1) under pH=7.5--8.5 at 0-5℃. All (p-formylphenyl)azo calix[4]arenes were characterized by ^1H NMR, ^13C NMR, IR, MS (ESIMS) spectroscopies and elemental analysis.     

Interpretation and the Hieroglyphic Monad: John Dee's Reading of Pantheus's Voarchadumia

Abstract

John Dee's marginalia in his copy of Johannes Pantheus's Voarchadumia (now in the British Library) are an interesting source of information about the development of Dee's scientific ideas in the period between the Propaedeumata Aphoristica (1558) and the Monas Hieroglyphica (1564). In reading the book, Dee has systematically compared the text with Pantheus's earlier work, the Ars Metallicae, and noted any differences between the two largely identical works. Therefore, most of Dee's comments are not indications of his own interests, as has previously been assumed. Only the marginalia that are not concerned with comparing the two texts can be taken to express Dee's own views. These marginalia, probably written in 1559, provide evidence that Dee had already at this time a strong interest in cabbalistic methods as a means of gaining knowledge about natural substances. Cabbalistic speculation was to be central to Dee's thought in the Monas Hieroglyphica, and has previously been taken to indicate a dramatic change in Dee's scientific outlook, towards a spiritual quest. In his marginalia in the Voarchadumia, however, Dee appears to be using cabbalistic methods to gain information on wholly material, non-spiritual matters. The abundant use of the symbol of the hieroglyphic monad in the marginalia provides a further source of insight into the alchemical import of the symbol, five years before the publication of the Monas Hieroglyphica.     

Synthesis,characterization, thermal and redox behavior,and biological activity of Ni(II), Cu(II), and Zn(II) complexes containing pyridoxine and imidazole moieties

Several mixed ligand complexes [M(II)(PN)(B)] [M(II) = Ni(II), Cu(II), and Zn(II)] derived from pyridoxine (PN) and imidazoles (B), namely imidazole (him), benzimidazole (bim), histamine (hist), and L-histidine (his), were synthesized. The complexes are characterized by elemental analysis, IR, UV-Vis ¹H NMR, and ESR spectroscopy. In [M(II)(PN)B], the monovalent anion of PN is bidentate to M(II) (–O, –OH), him, bim monodentate (–N), hist bidentate (–N, –N), and his tridentate (–O, –N, –N). Magnetic moment studies showed that the Ni(II) complexes and Cu(II)–PN–his have octahedral configuration while the other Cu(II) complexes have distorted tetrahedral geometry. The g _∥/A _∥ values calculated from the X-band ESR spectra of Cu(II) complexes in DMSO at 300 and 77 K supports the geometry. The thermal behavior (TG/DTA) of the synthesized complexes indicates the presence of lattice as well as coordinated water in the complexes. The in vitro biological activity of the mixed ligand complexes was tested against common bacteria, yeast, and fungi. The results in comparison with the control indicate that most of the complexes exhibit higher biological activities. The oxidative DNA cleavage studies of the mixed ligand complexes were performed using gel electrophoresis.     

Phase transitions in A4Li(HSO4)3(SO4); A = Rb, K: Single crystal X-ray diffraction studies

The crystal structure of ferroelastic Rb₄Li(HSO₄)₃(SO₄) has been determined at two temperatures, which indicates a structural phase transition, tetragonal P4₃ witha = 7.629(1) ?,c = 29.497(2) ? at 293 K and monoclinic P2₁ witha = 7.583(3) ?,b = 29.230(19) ?,c = 7.536(5) ?,β = 90.14(1)° at 90 K. The crystal structure of K₄Li(HSO₄)₃(SO₄)₄ has also been determined at two temperatures, tetragonalP4₁ witha = 7.405(1) ?,c = 28.712(6) ? at 293 K and tetragonalP4₁ witha = 7.371(5) ?,c = 28.522(5) ? at 100 K. The overall coordination features in both the structures have been analysed in terms of bond valence sum calculations. Dedicated to Professor C N R Rao on his 70th birthday     

Serendipity: Werner's argument that the `two‐only forms' (green and violet) of [CoCl2(en)2]+ salts demanded his octahedral model was correct. True?

Chemists of the late 19th century, including Alfred Werner, prepared salts containing either green or violet cations of composition [CoCl₂(en)₂]⁺ (en is ethylenediamine, C₂H₈N₂); we now refer to these as trans‐dichloro and cis‐dichloro species. We have discovered a third salt, purple in color, containing cations of the same elemental composition and whose asymmetric unit composition is [CoCl₂(en)₂]₂Cl₂·3H₂O, in which the cobalt cations are a cis:trans dichloro pair. Such a discovery would undermine Werner's argument that if only two forms can be prepared, his octahedral theory was proven. Probably because his students never examined their crystals under a microscope, they failed to observe the `third' species, thereby ruining Werner's argument since he relied strictly on color to identify them. That was fortunate since our purple salt would have led him to abandon, or certainly delay, his momentous discovery. Our crystals consist of a 1:1 mixture of the cis and trans cations, thereby sharing the same elemental analysis and conductivity as the single salts, but not their crystal structure, inasmuch as X‐ray diffraction had not even been discovered then. Serendipitously, our discovery would have been a great boon to his theoretical acumen, while his `two‐color' argument may have doomed him.     

The Total Synthesis of Brevetoxin B: A Twelve-Year Odyssey in Organic Synthesis

The total synthesis of brevetoxin B has been achieved recently after a long search for a suitable pathway. This twelve-year odyssey

1 The Odyssey of Homer, translated by R. Lattimore, Harper Perenial, New York, 1975 . Homer's Odyssey, one of the western world's first two poems (the Iliad is the other), is the tale of the adventures, wanderings, and exploits of Odysseus, a Greek hero of the Trojan war, as he attempts to reach Ithaca, his home island where his wife Penelope awaits him. During his journey Odysseus has an incredible series of adventures and setbacks caused by the anger of the god Poseidon, whose son Odysseus had blinded. Finally, assisted by his patroness, the goddess Athene, Odysseus returns home to Ithaca to find and punish the suitors, evil men who tried to win his wife's hand and who squandered his wealth and corrupted his servants while he was away. Telemachus, Odysseus' son, who had his own share of adventures while growing up, facing the suitors and, looking for his father, joins him in glory and wisdom as they reestablish their throne on Ithaca. Besides Odysseus, other main characters of Odyssey are as follows: Telemachus: The son of Odysseus, who is just entering manhood, is highly conscious of his duties as a prince successor to the throne and protector of his mother as well as the need to live up to his father's reputation as a hero. His actions waver between the immature and the well-thought over as he searches for the truth about his father and desperately appeals to others for help. It is not until towards the end of the story that he exhibits great courage, skills, and confidence and one feels that he is, indeed, the son of Odysseus. Athene: She is the daughter of Zeus, goddess of wisdom, and patroness of arts and crafts. Odysseus is her favorite and protegé and she is his heroine, even though she is a goddess. She plays a leading role in all important events in the narrative, and her spirit and power always influence and assist Odysseus and Telemachus in their difficult moments. A friend and a confidant to Odysseus, she enjoys winning him over and her relationship with him, while the hero adores her and finds special comfort, companionship, and understanding in her. Poseidon: Younger brother to Zeus, god of the sea and of earthquakes, father of Polyphenus the one-eyed Cyclops whom Odysseus blinds. As a ruler of the sea and natural phenomena, Poseidon is able to place many obstacles in front of Odysseus, whom he despises. Poseidon, however, is unable to hold out against the combined pressure of the other gods, particularly Athene, of whom Odysseus is a favorite, and so eventually relents, but not before he repeatedly unleashes his anger. The Cyclops, Scylla, and The Sirens: Some of the superhuman and monstrous characters of the tale who inflicted tremendous tortures and blows at Odysseus and his men, before he finally overcame them. The Suitors: The evil noblemen of Ithaca who attempt to undermine Odysseus, win the hand of his queen, Penelope, and corrupt his palace servants. They succeed partly, wasting away a great deal of Odysseus fortune, but he eventually prevails and punishes them. Ithaca: The island kingdom of Odysseus, most likely located somewhere off the western coast of Greece and the destination of the hero in this adventure. It is interesting to compare places, events, and characters from the Odyssey to those of modern-day total synthesis, an excercise left to the imagination of the reader!

in synthetic organic chemistry was marked by several strategic and tactical routes, and resulted in numerous new synthetic methods. This article is a behind-thescenes account of the total synthesis of brevetoxin B, from its origins at the University of Pennsylvania to its completion at the University of California, San Diego, and The Scripps Research Institute, La Jolla, California.     

The Woodward Research Institute,Robert Burns Woodward (1917–1979) and Chemistry behind the Glass Door

Certainly a highlight in the career of Nobel Laureate Professor Robert Burns Woodward (1917–1979) was the foundation of the Woodward Research Institute (WRI) at Ciba AG in Basel, Switzerland, in 1963. Woodward's remarkable accomplishments in the development of organic chemistry altered not only our concepts of molecular structure, but also our comprehension of physico‐chemical properties. In his legacy, Woodward devised innovative strategies for natural product syntheses based on brilliant rationale of their properties and an uncanny sense of Nature. The chemistry community benefited not only at Harvard but especially in Basel and Zürich from Woodward's inspiring lectures and the opportunity to learn from the chemistry Meister. This article highlights parts of the chemistry and some personalities that contributed to forefront investigations at the Woodward Research Institute which began at the former Novartis legacy company, Ciba AG, Basel.     

Following the crystallisation of Bi2Mo2O9 catalyst by combined XRD/QuEXAFS

The formation ofβ-phase Bi₂Mo₂O₉ catalyst from a precursor precipitate has been studied using thein situ combined XRD/QuEXAFS technique and DSC during calcination. Accordingly the precursor was observed to undergo a number of changes in both the molybdenum (VI) coordination and long-range ordering during this heating. Initially the two other forms of bismuth molybdate (α-andγ-phases) were observed to form from the poorly crystalline precursor at about 230°C, however, theβ-phase eventually crystallised after prolonged heating at 560°C. Dedicated to Professor C N R Rao on his 70th birthday     

Establishing the Canon: George Ripley and his Alchemical Sources

Abstract

George Ripley, Canon of Bridlington (ca. 1415 to ca. 1490) was one of England's most famous alchemists, whose alchemical opera attracted study and commentary throughout the sixteenth and seventeenth centuries, and were printed and translated both in England and abroad. Yet Ripley's frequently baffling texts have proved resistant to scholarly interpretation. This paper attempts to unravel some of Ripley's alchemical theories and practice, firstly by identifying his major sources, and secondly by gauging his response to these texts. For instance, although Ripley's interest in the corpus of alchemical texts pseudonymously attributed to Ramon Lull is well documented, it transpires that his best known work, the Compound of Alchemy, or Twelve Gates, is actually based not on a Lullian work, but on a Latin treatise that Ripley attributed to the little-known alchemist, Guido de Montanor. Further clues to Ripley's alchemical thought can be obtained by considering his handling of a potential conflict between his two authorities, Lull and Guido. The resulting insights into Ripley's alchemy provide an instrument for assessing which of Ripley's pseudoepigraphic works can be truly called "canonical".     

Orientation fluctuations in concentrated solutions of hairy-rod polymers

Photon correlation spectroscopy in the depolarized geometry was employed to measure the orientation relaxation correlation functionC(q,t) in poly(p-2,5-dodecyl-1,4-phenylene)/toluene solutions at different scattering wavevectorsq. The large optical anisotropy of this hairy rod molecule with an average lengthL=117 nm allowed a detailed analysis of both amplitude and shape ofC(q,t) that revealed two mechanisms for relaxing the orientation fluctuations in the concentrated regime (10<cL ³<230). The comparison of the rotational diffusivity and the anisotropic scattering intensity with theoretical, simulation and experimental results of rigid rods indicated quantitatively different behavior for the present stiff-chain bearing two long side groups per repeating unit.Dedicated to Prof. E.W. Fischer on the occasion of his 65th Birthday. His intuitive judgment of results and interpretation based on his Welt Bild of Polymer Science is being proven to be correct so far     

In situ Ru K-edge X-ray absorption spectroscopy of a high-area ruthenium dioxide electrode in a Nafion-based supercapacitor environment

Changes in the state of charge of a high-area RuO_x electrode in an operating RuO_x|Nafion|IrO_x supercapacitor were monitored in situ by time-resolved, transmission Ru K-edge X-ray absorption spectroscopy (XAS). Linear and reversible variations in the intensity of the transmitted X-ray beam as a function of time were found by fixing the energy of the incident X-ray beam, E_i, at judiciously selected values within the Ru K-edge X-ray near edge structure (XANES), while the supercapacitor was charged and discharged at constant current. The sign of the slope of these temporal signals was found to vary, depending on the value of E_i. This behavior could be rationalized based on the spectral differences between the Ru K-edge XANES of RuO_x in the fully oxidized and fully reduced states, recorded in situ from films of the material electrodeposited on a gold substrate in the fluorescence mode.This paper is dedicated to Prof. Wolf Vielstich on the occasion of his 80th birthday for his outstanding contributions to electrochemistry     

New aspects of the protonation of biliverdins

Biliverdins undergo appreciable self association in acidic solutions especially if solvents like benzene or chloroform are employed. The population of aggregates further depends on the concentration of both the acid and the solute. In chloroform and benzene solutions at high acidity a doubly protonated species is formed. This is concluded from a combinatory evaluation of the CD and electronic absorption spectra of chiral optically active biliverdins (1–6) in benzene, chloroform, and ethanol solutions containing trifluoroacetic acid or hydrochloric acid. The aggregates formed at medium acid concentrations exhibit largeCotton effects in the long-wavelength absorption bands and thus dominate the CD spectra. Similarly, agrregates are the main contributors to theCotton effects of achiral, protonated biliverdins in (S)-(–)-ethyl lactate (SICD) at usual concentrations. The consequence and relevance of these findings with regard to the recent literature is briefly discussed.Dedicated to Prof. Dr.Karl Schlögl on occasion of his 60^th birthday.     

Solvent intercalation in cobalt dimethylglyoximato complexes: A miniature host-guest system

When crystallized from appropriate solvents, the complex aqua-bis(dimethylglyoximato)nitrocobalt (III) may incorporate solvent molecules, thus forming a variety of mixed crystals. In the resulting host-guest crystals, the space groupP2_l/m and the packing motif of the pure host compound are retained. Lattice constantsa andb remain essentially unaltered upon intercalation, whereasc and the monoclinic angle depend largely on the clathrated guest. Space filling and intermolecular contacts are discussed.Dedicated to Professor Peter Paetzold at the occasion of his 60th birthday. A preliminary account of this work has been given at the Spring Meeting of the British Crystallographic Association, Newcastle upon Tyne, 1994.