Impact of molecule-based magnetic materials: A critical outlook

A critical outlook of the field of molecular magnetic materials is presented. This article is inspired by an international symposium devoted to the “Design, Characterization and Modelling of Molecule-Based Magnetic Materials (DCM4-II)” that took place at Strasbourg (France), from May 28th to June 1st, within the E-MRS 2007 Spring Meeting (Symposium R) organized by the European Materials Research Society in collaboration with the European Science Foundation. A series of papers linked to this symposium are published in this issue and in the previous issue (Volume 11, Issue 4) of Solid State Sciences.     

Alkali Metal Arenides as a Universal Synthetic Tool for Layered 2D Germanene Modification

The rediscovery of graphene in 2004 has started an enormous chase in the research of 2D materials. A new family of layered 2D materials consisting of the 14th group elements beyond carbon has already been reported. Here, a new methodology in germanene chemistry is presented using germanane (Ge₆H₆) as a stable and easily accessible starting material for effective synthesis of novel germanene derivatives. The modification procedure utilizing strong bases—alkali metal arenides—for deprotonation of germanane and its subsequent functionalization with p‐nitrobenzyl bromide is described. Functionalization of germanene is confirmed by FT‐IR, Raman, and XPS spectroscopy as well as by X‐ray diffraction analysis.     

Paramagnetic pyrrole-based semiconductor molecular material

The electrochemical oxidation of hexa-N-pyrrolylbenzene in organic media leads, via intramolecular coupling of the pyrrole residues, to the deposition of a molecular semiconductor film on an electrode surface. In situ electron spin resonance–electrochemical experiments reveal that the semiconductor is endowed with both properties of conducting polymers (i.e., reversible oxidation) and polyaromatic molecular materials (i.e., highly paramagnetic). The material, which is easy to process as soft homogeneous thin film, shows a tunable 0 to 1 spin concentration per molecule at room temperature by controlling the electrochemical potential. Contribution to the Fall Meeting of the European Materials Research Society, Symposium D: 9th International Symposium on the Electrochemical–Chemical Reactivity of Metastable Materials, Warsaw, 17th–21st September, 2007. An erratum to this article can be found at     

Mechanochemical synthesis and electrochemical properties of nanostructured electrode materials for Li ion batteries

We focus on the synthesis by ball milling and on the electrochemical characterization of nanocrystalline bimetallic and composite materials to be employed as anodes in Li ion batteries. Ni₃Sn₄ and Ni₃Sn₂ based compounds were obtained by ball milling of three different Ni–Sn mixtures. The properties of the resulting anodes for Li ion batteries were evaluated as a function of composition. Moreover, a biphasic system is presented, with CoSn₂ and CoSn type structures, arising from the synthesis of the Sn₃₁Co₂₈C₄₁ composition. When cycled in a Li cell, this material showed a high reversible specific capacity, about 450 mA h g⁻¹, and a very good electrochemical and structural stability, making it of interest for application purposes. Contribution to the Fall Meeting of the European Materials Research Society, Symposium D: 9th International Symposium on Electrochemical–Chemical Reactivity of Metastable Materials, Warsaw, 17th–21st September, 2007.     

Correction: Enzyme-powered micro- and nano-motors: key parameters for an application-oriented design

Correction for ‘Enzyme-powered micro- and nano-motors: key parameters for an application-oriented design’ by Xavier Arqué et al., Chem. Sci., 2022, https://doi.org/10.1039/d2sc01806c.

The authors regret that several references were cited in incorrect locations in the figure captions. The correct captions are reproduced below. Fig. 1 Chassis materials of enzyme-powered micro- and nano-motors. (A) Representation of each chassis material in the publications of the field. Examples of enzymatic motors made of (B) polymers,^27,37,66 (C) metals,^49,67,104 (D) silica,^70,96 (E) carbon,^107,108 (F) lipid vesicles,^117,118 (G) MOFs^112,115 and (H) bio-inspired materials.^120–122 Panel (B) adapted with permission from (1) ref. 27 Copyright 2019 Springer Nature, (2) ref. 37 Copyright 2017 AAAS, and (3) ref. 66 Copyright 2021 Royal Society of Chemistry. Panel (C) adapted with permission from (1) ref. 104 Copyright 2021 American Chemical Society, (2) ref. 49 Copyright 2019 American Chemical Society, and (3) ref. 67 Copyright 2019 Wiley. Panel (D) adapted with permission from (1) ref. 70 Copyright 2015 American Chemical Society and (2) ref. 96 Copyright 2021 AAAS. Panel (E) adapted with permission from (1) ref. 108 Copyright 2021 Wiley and (2) ref. 107 Copyright 2019 American Chemical Society. Panel (F) adapted with permission from (1) ref. 117 Copyright 2020 Wiley and (2) ref. 118 Copyright 2019 American Chemical Society. Panel (G) adapted with permission from (1) ref. 115 Copyright 2020 American Chemical Society and (2) ref. 112 Copyright 2019 Wiley. Panel (H) adapted with permission from (1) ref. 122 Copyright 2016 Wiley, (2) ref. 121 Copyright 2020 AAAS, and (3) ref. 120 Copyright 2022 American Chemical Society. Fig. 2 Chassis shape and product release distribution of enzyme-powered micro- and nano-motors. (A) Representation of each chassis shape in the publications of the field. Inset: representation of each configuration of product release in the publications of the field. Examples of enzymatic motors with shapes of (B) spheres,^{15,29,62,69,89} (C) tubes,^30,86 (D) rods,^17,20,122 (E) vesicles,^37,118 (F) stomatocytes,^23,24,27 (G) crystals,¹¹² (H) bottles^35,98 and (I) shells.⁴⁷ Panel (B) adapted with permission from (1) ref. 15 Copyright 2019 Elsevier, (2) ref. 89 Copyright 2018 American Chemical Society, (3) ref. 29 Copyright 2019 Wiley, (4) ref. 69 Copyright 2017 Elsevier and (5) ref. 62 Copyright 2017 Royal Society of Chemistry. Panel (C) adapted with permission from (1) ref. 86 Copyright 2016 American Chemical Society and (2) ref. 30 Copyright 2016 Wiley. Panel (D) adapted with permission from (1) ref. 17 Copyright 2020 Elsevier, (2) ref. 122 Copyright 2016 Wiley, and (3) ref. 20 Copyright 2021 Elsevier. Panel (E) adapted with permission from (1) ref. 37 Copyright 2017 AAAS and (2) ref. 118 Copyright 2019 American Chemical Society. Panel (F) adapted with permission from (1) ref. 24 Copyright 2016 American Chemical Society, (2) ref. 27 Copyright 2019 Springer Nature and (3) ref. 23 Copyright 2016 American Chemical Society. Panel (G) adapted with permission from (1) ref. 112 Copyright 2019 Wiley. Panel (H) adapted with permission from (1) ref. 98 Copyright 2021 American Chemical Society and (2) ref. 35 Copyright 2022 Wiley. Panel (I) adapted with permission from (1) ref. 47 Copyright 2019 Wiley. Fig. 3 Enzyme incorporation method of enzyme-powered micro- and nano-motors. (A) Representation of each enzyme incorporation method in the publications of the field. Examples of enzymatic motors with enzymes attached by using covalent attachment like (B) EDC/NHS,^13,40,58,104 (C) glutaraldehyde,^60,74,100 (D) biotin/streptavidin^44,118,120 or (E) other covalent methods,^21,27 and non-covalent incorporation methods like (F) encapsulation^32,37,59,117 and (G) non-covalent interaction.^{30,35,65,74,76} Panel (B) adapted with permission from (1) ref. 13 Copyright 2021 American Chemical Society, (2) ref. 58 Copyright 2017 Elsevier, (3) ref. 40 Copyright 2019 American Chemical Society, and (4) ref. 104 Copyright 2021 American Chemical Society. Panel (C) adapted with permission from (1) ref. 74 Copyright 2019 American Chemical Society, (2) ref. 100 Copyright 2021 American Institute of Physics and (3) ref. 60 Copyright 2021 American Chemical Society. Panel (D) adapted with permission from (1) ref. 120 Copyright 2020 AAAS, (2) ref. 118 Copyright 2019 American Chemical Society, and (3) ref. 44 Copyright 2020 American Chemical Society. Panel (E) adapted with permission from (1) ref. 27 Copyright 2019 Springer Nature and (2) ref. 21 Copyright 2022 Elsevier. Panel (F) adapted with permission from (1) ref. 59 Copyright 2015 American Chemical Society, (2) ref. 32 Copyright 2021 Multidisciplinary Digital Publishing Institute, (3) ref. 37 Copyright 2017 AAAS and (4) ref. 117 Copyright 2020 Wiley. Panel (G) adapted with permission from (1) ref. 76 Copyright 2020 Wiley, (2) ref. 30 Copyright 2016 Wiley, (3) ref. 65 Copyright 2019 American Chemical Society, (4) ref. 35 Copyright 2022 Wiley, and (5) ref. 74 Copyright 2019 American Chemical Society. Fig. 4 Enzyme type and motion mechanism of enzyme-powered micro- and nano-motors. (A) Representation of each enzyme type in the publications of the field. Inset: representation of each motion mechanism in the publications of the field. Examples of enzymatic motors powered with the enzymes (B) catalase,^{38,43,45,54,61,98} (C) urease,^{20,22,39,44,82,100,120} (D) glucose oxidase,^67,68 (E) glucose oxidase and catalase,^{27,35,37,91,95} (F) lipase,^75,76 (G) acetylcholinesterase,⁸³ (H) trypsin,¹⁰³ (I) enzyme combinations^52,105 and (J) enzymatic pathway.²³ Panel (B) adapted with permission from (1) ref. 54 Copyright 2013 American Chemical Society, (2) ref. 98 Copyright 2021 American Chemical Society, (3) ref. 61 Copyright 2019 American Chemical Society, (4) ref. 45 Copyright 2010 American Chemical Society, (5) ref. 38 Copyright 2018 American Chemical Society, and (6) ref. 43 Copyright 2019 Elsevier. Panel (C) adapted with permission from (1) ref. 120 Copyright 2020 AAAS, (2) ref. 22 Copyright 2020 American Chemical Society, (3) ref. 82 Copyright 2020 American Physical Society, (4) ref. 20 Copyright 2021 Elsevier, (5) ref. 39 Copyright 2019 Wiley, (6) ref. 44 Copyright 2020 American Chemical Society, and (7) ref. 100 Copyright 2021 American Institute of Physics. Panel (D) adapted with permission from (1) ref. 67 Copyright 2019 Wiley and (2) ref. 68 Copyright 2021 American Chemical Society. Panel (E) adapted with permission from (1) ref. 27 Copyright 2019 Springer Nature, (2) ref. 37 Copyright 2017 AAAS, (3) ref. 95 Copyright 2022 American Chemical Society, (4) ref. 91 Copyright 2015 American Chemical Society, and (5) ref. 35 Copyright 2022 Wiley. Panel (F) adapted with permission from (1) ref. 76 Copyright 2020 Wiley and (2) ref. 75 Copyright 2019 Wiley. Panel (G) adapted with permission from (1) ref. 83 Copyright 2019 Springer Nature and (2) ref. 70 Copyright 2015 American Chemical Society. Panel (H) adapted with permission from (1) ref. 103 Copyright 2017 American Chemical Society. Panel (I) adapted with permission from (1) ref. 52 Copyright 2014 Wiley and (2) ref. 105 Copyright 2005 American Chemical Society. Panel (J) adapted with permission from ref. 23 Copyright 2016 American Chemical Society. Fig. 5 (A) Sizes of enzyme-powered micro- and nano-motors and motion detection technique. Representation of the different motor sizes in the publications of the field. Inset: representation of each motion detection technique in the publications of the field. Examples of enzymatic motors powered with sizes of (B) <0.3 (ref. 69, 25, 104, 42, 37 and 98), (C) 0.3–1 (ref. 96, 31, 76, 79 and 107), (D and E) 1–10 (ref. 112, 111, 100, 84, 120, 62, 86, 17 and 54) and (F) >10 μm.^30,39,66,123 Panel (B) <0.3 μm adapted with permission from ref. 69 Copyright 2017 Elsevier, ref. 25 Copyright 2019 American Chemical Society, ref. 104 Copyright 2021 American Chemical Society, ref. 42 Copyright 2021 Elsevier, ref. 37 Copyright 2017 AAAS, and ref. 98 Copyright 2021 American Chemical Society. Panel (C) 0.3–1 μm adapted with permission from ref. 96 Copyright 2021 AAAS, ref. 31 Copyright 2021 American Chemical Society, ref. 76 Copyright 2020 Wiley, ref. 79 Copyright 2021 American Chemical Society, and ref. 107 Copyright 2019 American Chemical Society. Panels (D and E) 1–10 μm adapted with permission from ref. 112 Copyright 2019 Wiley, ref. 111 Copyright 2021 American Chemical Society, ref. 100 Copyright 2021 American Institute of Physics, ref. 84 Copyright 2020 AAAS, ref. 120 Copyright 2020 AAAS, ref. 62 Copyright 2017 Royal Society of Chemistry, ref. 86 Copyright 2016 American Chemical Society, ref. 17 Copyright 2020 Elsevier, and ref. 54 Copyright 2013 American Chemical Society. Panel (F) >10 μm adapted with permission from ref. 66 Copyright 2021 Royal Society of Chemistry, ref. 39 Copyright 2019 Wiley, ref. 30 Copyright 2016 Wiley, and ref. 123 Copyright 2019 Wiley. Fig. 6 (A) Applications of enzyme-powered micro- and nano-motors and motion detection technique. Representation of the different motor applications in the publications of the field. Inset: representation of each motion media in the publications of the field. Examples of enzymatic motors applied in (B) drug delivery treatment,^{20,21,42,59,111,121} (C) visualization inside organisms exploiting enhanced targeting and penetration,^{25,40,62,73,96,104} (D) photo- and magnetic thermal treatment,^65,113 (E) cell and compound sensing,^{17,43,49,58,81} (F) contaminant compound removal^13,75,115 and (G) bacteria capture or elimination.^60,66,72,78 Panel (B) adapted with permission from (1) ref. 121 Copyright 2022 American Chemical Society, (2) ref. 42 Copyright 2021 Elsevier, (3) ref. 21 Copyright 2022 Elsevier, (4) ref. 20 Copyright 2021 Elsevier, (5) ref. 59 Copyright 2015 American Chemical Society, and (6) ref. 111 Copyright 2021 American Chemical Society. Panel (C) adapted with permission from (1) ref. 104 Copyright 2021 American Chemical Society, (2) ref. 73 Copyright 2019 American Chemical Society, (3) ref. 40 Copyright 2019 American Chemical Society, (4) ref. 96 Copyright 2021 AAAS, (5) ref. 62 Copyright 2017 Royal Society of Chemistry, and (6) ref. 25 Copyright 2019 American Chemical Society. Panel (D) adapted with permission from (1) ref. 113 Copyright 2019 Elsevier and (2) ref. 65 Copyright 2019 American Chemical Society. Panel (E) adapted with permission from (1) ref. 43 Copyright 2019 Elsevier, (2) ref. 49 Copyright 2019 American Chemical Society, (3) ref. 17 Copyright 2020 Elsevier, (4) ref. 58 Copyright 2017 Elsevier, and (5) ref. 81 Copyright 2019 American Chemical Society. Panel (F) adapted with permission from (1) ref. 13 Copyright 2021 American Chemical Society, (2) ref. 75 Copyright 2019 Wiley, and (3) ref. 115 Copyright 2020 American Chemical Society. Panel (G) adapted with permission from (1) ref. 60 Copyright 2021 American Chemical Society, (2) ref. 66 Copyright 2021 Royal Society of Chemistry, (3) ref. 72 Copyright 2021 American Chemical Society, and (4) ref. 78 Copyright 2022 American Chemical Society.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

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.     

An ab initio molecular dynamics study on the dissociative recombination reaction of HD2O+ + e−

An ab initio molecular dynamics simulations have been carried out for the dissociative recombination reaction of the deuterium-substituted hydronium cation, HD₂O⁺ + e ⁻, at the state-averaged multiconfigurational self-consistent field level. In the present simulations, five electronic states of HD₂O were included explicitly, and nonadiabatic transitions among adiabatic electronic states were taken into account by the Tully’s fewest switches algorithm. It is shown that the dominant products, OD + D + H, were generated in 63% of trajectories, while the products, OH + 2D, were generated in only 11% of trajectories, indicating that the release of a light fragment H is favored over the release of a heavy fragment D. This result is in conformity with the observation that there is a larger amount of deuterium substituted species than the non-substituted species in the interstellar space. Contribution to the Mark S. Gordon 65th Birthday Festschrift Issue.     

1997 in Review and What to Expect From The Chemical Educator in 1998

Happy Holidays! This issue closes the second volume of The Chemical Educator. The release of Volume 2, Issue 5 in November and this, Issue 6, in December allows us to have a calendar-year schedule starting with Volume 3 (1998) and henceforth. We will have six bimonthly issues in 1998 and will move our release date to near the first of the month beginning in February 1998.     

Local monitoring of surface chemistry with Raman spectroscopy

The efficiency of Raman scattering from molecules in some nano-resonators can increase by many orders of magnitude. Sometimes, in Raman measurements carried out with such resonators, it is possible to record a spectrum from only a few (or even a single) molecules. In this contribution, we show that resonator-enhanced Raman scattering is very useful for analysis of the electrochemically formed carbon. Carbon material has been formed on the surface of the copper-modified silver electrode during the electrochemical reduction of CO₂. The Raman spectra measured were often from only a few carbon clusters. By the analysis of a large series of such spectra, we managed to identify large graphite-like rings and polyenes with various lengths. Some other applications of resonator-enhanced Raman scattering to local characterisation of electrode surfaces (e.g. studies of CO adsorption on gold) are also presented. Contribution to the Fall Meeting of the European Materials Research Society, Symposium D: 9th International Symposium on Electrochemical/Chemical Reactivity of Metastable Materials, Warsaw, 17th–21st September, 2007     

Secondary metabolites produced by Sardiniella urbana,a new emerging pathogen on European hackberry

In this study the production of secondary metabolites by a virulent strain of Sardiniella urbana, a recently described pathogen originally found on declining European hackberry trees in Italy, was investigated for the first time. Chemical analysis of the culture filtrate extracts led to the isolation of three well known compounds as R-(?)-mellein and (3R,4R)-and (3R,4S)-4-hydroxy melleins which were identified by spectroscopic methods (essentially NMR and ESIMS). The isolated compounds were tested for their phytotoxic, antifungal and zootoxic activities. Among them, only R-(?)-mellein was found to be active.     

Radiolysis of Aqueous Solutions of Benzoate Ion: A Radiation Chemistry Experiment for Undergraduates

This investigation describes the chemical effects of ionizing radiation on dilute aqueous solutions of benzoate ion. We have composed an experimental procedure that allows undergraduate chemistry students to identify and to quantitatively determine the amount of the products that are produced. The student investigators determine the absorbed dose that a sample receives when exposed to a ⁶⁰Co source, irradiate dilute aqueous solutions of benzoate ion, and analyze the resulting mixture of hydroxybenzoate ions using high-performance liquid chromatography. The radiolysis of dilute solutions of benzoate ion results in the formation of a mixture of ortho-, meta-, and para-hydroxybenzoate ions that are readily separated on a C₁₈ -Bondapak column. By the use of appropriate calibration curves, the yield (G values) of each of the isomers may be determined and compared.This paper was presented at the 15th Biennial Conference on Chemical Education, Waterloo, Ontario, Canada, August 1998 by N. Zevos and at the 26th Northeast Regional Meeting of the American Chemical Society by Evon Powell.     

Surface chemistry and electronics of semiconductor–nanosystem junctions I: metal-nanoemitter-based solar cells

Photoelectrochemically prepared nanotopographies on semiconductors are used for realization of nanoemitter solar devices that are active in the photovoltaic and the photoelectrocatalytic mode. The development of solar devices by a nonlinear electrochemical process and combined chemical/electrochemical metal deposition is described. Based on this low-temperature scalable approach, first efficiencies of 7.3% in the photovoltaic mode are reported for the photoelectrochemical solar cell n-Si/SiO₂/Pt/I₃ ⁻–I⁻. With p-Si/Pt nanocomposite structures, light-induced H₂ evolution is achieved. The surface chemistry and morphology is analyzed by photoelectron spectroscopy (PES), Fourier transform infrared spectroscopy, and high-resolution scanning electron microscopy. The operational principle of Pt-based nanoemitter solar devices that use silicon single crystal absorbers is analyzed by Mott–Schottky plots, chronoamperometric profiles, and PES. Related to simultaneous oxide formation during Pt deposition, evidence for the formation of a metal–oxide–semiconductor junction is obtained that explains the observed electronic behavior. Contribution to the Fall Meeting of the European Materials Research Society, Symposium D: 9th International Symposium on Electrochemical/Chemical Reactivity of Metastable Materials, Warsaw, 17th–21st September 2007.     

A modification of the heteropoly blue method for the microgram determination of arsenic in biological materials

Summary A sensitive method has been developed for analysis of trace amounts of arsenic in biological materials using the heteropoly blue method. The method employs a closed apparatus and a nitrogen atmosphere, and allows the detection of arsenic in ppm concentration using samples of 100 mg.

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Zusammenfassung Eine empfindliche Methode zur Bestimmung von Arsenspuren in biologischem Material im Wege der Molybdänblaumethode wurde ausgearbeitet. Man arbeitet dabei in einer geschlossenen Apparatur in Stickstoffatmosphäre und kann so in 100-mg-Proben Arsenkonzentrationen in der Größenordnung von ppm bestimmen.

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Presented at the 6th Annual Northeast Regional Meeting of the American Chemical Society, Burlington, Vermont, August 19, 1974.     

Kinetics of the dimerization of silylenes to disilenes

The activation parameters of the dimerization of t-butylmesitylsilylene (2a), dimesitylsilylene (2b) and bis(2,4,6-triisopropylphenyl)silylene (2c) to the corresponding disilenes were estimated by monitoring the time-dependent changes in their UV-Vis absorption spectra. The activation energy increased in the order: 2a < 2b < 2c. This article is part of a Special Issue dedicated to M. Kira.     

Thermodynamics of sodium chloride solutions at high temperatures

Osmotic coefficients are reported from vapor-pressure-lowering measurements on sodium chloride solutions at concentrations from approximately 4m to saturation and at temperatures from 75° C to 300° C. In combination with previously reported measurements at lower concentrations, these results allow a correlation of free energies for the system NaCl–H₂O over a range of concentrations and temperatures that is unprecedented for any aqueous electrolyte. Activity coefficients and other thermodynamic quantities for both salt and water have been calculated for the complete range of concentrations and temperatures. Calculated heats of solution and standard partial molal entropies agree well with calorimetric determinations where comparison is possible. The excess partial molal entropy of the salt is informative concerning structural effects and their changes with temperature and concentration.Presented in part at the 160th National Meeting of the American Chemical Society, Chicago, Illinois, September 1970.     

Mono-, Bis- und Tris(trimethylsilyl)hydroxylamin

Ohne ZusammenfassungMit 1 Abbildung77. Mitt.:U. Wannagat undM. Schulze, Z. Chem.8, 255 (1968).Vorläufige Mitt.:U. Wannagat, Angew. Chem.78, 648 (1966).Auszugsweise vorgetragen auf dem 155th National Meeting der American Chemical Society, San Francisco, April 1968.Sonderdrucke überU. W., D-33 Braunschweig, Pockelsstr. 4, Inst. für Anorg. Chem. der Techn. Universität.Mit Auszügen aus der DissertationO. Smrekar, Techn. Hochschule Graz 1969.     

Total synthesis of 7-ethyl-10-hydroxycamptothecin (SN38) and its application to the development of C18-functionalized camptothecin derivatives

A new chemical synthesis of SN38, the active metabolite of the camptothecin prodrug irinotecan, has been achieved in 12 steps from simple, commercially available starting materials. A mild and efficient FeCl₃‐catalyzed Friedländer condensation was successfully applied to construct the AB ring system. Functionalization of the C ring was accomplished by a vinylogous Mukaiyama reaction of an in situ generated N‐acyliminium intermediate with a silyl enol ether. An intramolecular oxa Diels–Alder reaction efficiently constructed the D and E rings in one step. Successive asymmetric dihydroxylation and I₂‐based hemiacetal oxidation furnished the stereochemistry of SN38 with high enantiopurity. Utilizing the ABC‐ring intermediate and a functionalized silyl enol ether permitted the synthesis of a number of new C18‐functionalized SN38 derivatives. Several of the novel SN38 derivatives that bore a C10 methoxy group were found to exhibit comparable or more potent inhibitory activity against the proliferation of cancer cells relative to SN38.     

Retracted: Nanobubbles influence on BSA adsorption on mica surface

Retraction: The following article from the Surface and Interface Anlysis, 'Nanobubbles influence on BSA adsorption on mica surface' by Wu ZH, Zhang XH, Zhang XD, Li G, Sun J, Zhang Y, Li M and Hu J, published online on 1 September 2005 in Wiley InterScience ( www.interscience.com ) and in print Volume 37 Issue 10 pages 797‐801, 2005, has been retracted by agreement between the authors, the journal's Editor‐in‐Chief Professor John F. Watts and John Wiley & Sons, Ltd. The retraction has been agreed due to the article being subsequently published in Volume 38 Issue 6, pages 990‐995 of the journal as part of a Special Issue entitled 'Chinese‐German Forum on Fundamentals and Technological Perspectives of Nanoscience 26‐30 September 2004, Beijing, China.'     

Rethinking Chemistry

The German Chemical Society (GDCh) Board of Directors chose the motto “Rethinking Chemistry” last year to address challenges connected to climate change, loss of natural resources, and geopolitical conflicts as the guiding principle of all our endeavors and actions. Rethinking Chemistry indicates the Board's desire to encourage scientists to approach chemistry in a new way, with a focus on reconsidering the field from many different angles. By taking a holistic approach, the Board intends to foster innovative, sustainable, and effective ways to use chemistry. Rethinking Chemistry is also the motto of the GDCh Science Forum Chemistry (WiFo) 2023, and a Special Collection on the homepage of Angewandte Chemie is dedicated to this event and its motto. Rethinking Chemistry means something different in each area of chemistry, and the WiFo 2023 as well as this Special Collection of Angewandte Chemie showcase its many facets.     

Stereoselective Synthesis of D‐ and L‐Carbocyclic Nucleosides by Enzymatically Catalyzed Kinetic Resolution

An efficient synthesis of (S)‐ or (R)‐3‐(benzyloxy‐methyl)‐cyclopent‐3‐enol was developed by appling an enzyme‐catalyzed kinetic‐resolution approach. This procedure allowed the syntheses of the enantiomeric building blocks (S)‐ and (R)‐cyclopentenol with high optical purity (>98 % ee). In contrast to previous approaches, the key advantage of this procedure is that the resolution is done on the level of enantiomers that only contain one stereogenic center. Owing to this feature, it was possible to chemically convert the enantiomers into each other. By using this route, the starting materials for the syntheses of carbocyclic D ‐ and L ‐nucleoside analogues were readily accessible. 3′,4′‐Unsaturated D ‐ or L ‐carbocyclic nucleosides were obtained from the condensation of various nucleobases with (S)‐ or (R)‐cyclopentenol. Functionalization of the double bond in 3′‐deoxy‐3′,4′‐didehydro‐carba‐D ‐thymidine led to a variety of new nucleoside analogues. By using the cycloSal approach, their corresponding phosphorylated metabolites were readily accessable. Moreover, a new synthetic route to carbocyclic 2′‐deoxy‐nucleosides was developed, thereby leading to D ‐ and L ‐carba‐dT. D ‐Carba‐dT was tested for antiviral activity against multidrug‐resistance HIV‐1 strain E2‐2 and compared to the known antiviral agent d4T, as well as L ‐carba‐dT. Whilst L ‐carba‐dT was found to be inactive, its D ‐analogue showed remarkably high activity against the resistant virus and significantly better than that of d4T. However, against the wild‐type virus strain NL4/3, d4T was found to be more‐active than D ‐carba‐dT.