bluuebunny/crossref_metadata_2025 huggingface dataset:
Strategi Branding Peningkatan Skala Usaha Badan Usaha Milik Desa (BUMDes) Darussalam, Desa Burai, Tanjung Batu, Ogan Ilir, Sumatra Selatan
Authors: Viatra Aji Windu , Putra M. Edo Pratama
Published: January 2024

Pandemi yang sangat membebani sistem kesehatan, mendisrupsi ekonomi dan menimbulkan kekhawatiran yang meluas serta ketidakpastian situasi membuat kelesuan dalam bidang ekonomi keluarga. Penelitian ini memiliki tujuan untuk mengetahui dan mengidentifikasi kendala yang dihadapi BUMDes Darussalam Desa Burai dalam membangun strategi branding. Strategi branding yang dilakukan dipengaruhi oleh faktor internal yakni pemahaman dan kemampuan akan membangun branding yang kuat dan faktor eksternal yakni kemampuan dalam membangun jaringan usaha dengan pihak-pihak yang terkait. Strategi yang digunakan BUMDes Darussalam dalam membangun branding ini menggunakan beberapa teori melalui metode deskriptif. Perencanaan membangun branding BUMDes Darussalam dilakukan dengan melakukan survei data, wawancara, kuesioner, diskusi, brainstorming gagasan branding, perancangan identity branding. Solusi yang dilaksanakan berupa kegiatan analisis ekuitas brand dalam menghasilkan rumusan strategi yang tepat, baik dan benar untuk BUMDes Darussalam, dan perancangan identity branding berupa corporate identity. Kajian ini menjadi salah satu aspek tolok ukur bagi BUMDes Darussalam dalam melakukan strategi pengembangan brand peningkatan skala usaha. Program pengembangan strategi branding BUMDes Darussalam diharapkan menghasilkan produk unggulan daerah dalam menghadapi persaingan pasar yang dinamis di era saat ini.
Perancangan Board Game Journey of Bengok Craft sebagai Media Promosi dalam Memperkenalkan Proses Bisnis Bengok Craft
Authors: Kristianti Catarina Mutiara Reva , Prasida T. Arie Setiawan , Prestiliano Jasson
Published: January 2024

Bengok Craft adalah usaha mikro, kecil, dan menengah (UMKM) tentang kerajinan eceng gondok di Tuntang, Kabupaten Semarang, Jawa Tengah. Bengok Craft mengalami kesulitan serius di mana tidak adanya media promosi yang mendekatkan calon konsumen atau masyarakat terhadap Bengok Craft. Media yang digunakan sama dengan kompetitor sehingga tidak memiliki nilai lebih dan media yang ada saat ini tidak efektif, masyarakat jarang memperhatikan ketika dijelaskan mengenai proses bisnis Bengok Craft. Dilakukan inovasi media promosi untuk menyelesaikan permasalahan Bengok Craft, melalui media board game. Dengan media board game, Bengok Craft bisa menyelesaikan masalah yang dihadapi karena board game digunakan sebagai media edukasi menarik yang melibatkan pemain sehingga menimbulkan interaksi antar pemain. Metode penelitian yang digunakan adalah deskriptif, pendekatan kualitatif, dan strategi linear. Hasil penelitian board game Journey of Bengok Craft bisa menggambarkan proses bisnis dari Bengok Craft secara baik dan menarik bahkan sangat membantu mendekatkan Bengok Craft kepada masyarakat dan calon konsumen secara menyenangkan.
Presentation of Traditional Folktale Through 3-Dimensional Animation Film in Gromore Studio YouTube Channel, A Study Case
Authors: Budi Hutomo Setia , Adnyana I Wayan , Swandi I Wayan , Suardina I Nyoman
Published: January 2024

This research aimed to discover audience responses toward animation content that tells about folklore and is uploaded onto the Gromore Studio YouTube platform. It is designed based on interview data as well as observation of the view count, comments, and literature study. This research included cultural studies which studied social culture phenomena by using descriptive quantitative analysis methods with emphasis on discovering the comparison of positive and negative comments, and the comparison between like and dislike counts from the folklore video which was uploaded by Gromore Studio. The results of this research showed that the presentation of legendary folktales received outstanding responses from the audience with Indonesians as the majority. Comments given by the audience mostly showed positive feedback and support toward animation content produced by Gromore Studio which lifted the local cultures and stories, packed into interesting visual media. Through the positive responses in the comments, it can be concluded that the animations by Gromore Studio in traditional folktales became very welcomed by Indonesian audiences.
Biomimetische organische Synthesen: Anmerkungen zu jüngeren Ergebnissen
Authors: de la Torre María C. , Sierra Miguel A.
Published: December 2003

Die Synthesewege, auf die die Natur zum Aufbau von Naturstoffen zurückgreift, sind in ihrer Ausgereiftheit atemberaubend, und schon sehr früh wurde nach Laborsynthesen gesucht, die diese Wege nachahmen. Das Konzept der biomimetischen Synthese, 1917 von Robinson eingeführt, löste sehr bald eine lang anhaltende Diskussion darüber aus, ob an jedem einzelnen Schritt in der Biogenese einer jeden Naturstoffklasse ein spezifisches Enzym beteiligt ist. Erfolgreiche Naturstoffsynthesen folgen oft natürlichen Prozessen, die mit einer minimalen Enzymteilnahme ablaufen, allerdings sollte daraus nicht geschlossen werden, dass nur solche biogenetischen Prozesse nachgeahmt werden könnten, an denen keine Enzyme beteiligt sind. Der vielleicht attraktivste Aspekt einer biomimetischen Strategie ist, dass sie die Entwicklung einer Synthesemethode nach biogenetischem Vorbild verfolgt, auch wenn der imitierte Biosyntheseweg nur hypothetisch ist. Zukünftige Verbesserungen sind durch künstliche Enzyme zu erwarten, die spezifische Umwandlungen katalysieren.
Bioinspiriertes Molekulardesign von lichtsammelnden Multiporphyrinsystemen
Authors: Choi Myung‐Seok , Yamazaki Tomoko , Yamazaki Iwao , Aida Takuzo
Published: December 2003

Jüngste Fortschritte bei Grundlagenstudien zu Multiporphyrinsystemen geben Aufschluss über die maßgeblichen Strukturparameter für das Molekulardesign von künstlichen Lichtsammelantennen, die die radähnlichen Antennenkomplexe photosynthetischer Purpurbakterien imitieren. “Kovalente” und “nichtkovalente” Ansätze kamen für den Aufbau von künstlichen lichtsammelnden Multiporphyrinsystemen zum Einsatz. Diese lassen sich in die Kategorien ring‐, windmühlen‐, sternförmig und dendritisch einteilen, wobei insbesondere die dendritischen Multiporphyrinsysteme als vielversprechende Kandidaten gelten. Sie verfügen über einen hohen Absorptionsquerschnitt und ermöglichen einen zielgerichteten vektoriellen Energietransfer über große Entfernungen. Erwartet wird, dass sich solche molekularen und supramolekularen Systeme als leistungsstarke Komponenten für die molekulare Elektronik und in photonischen Bauelementen eignen.
Titelbild: Zur Entwicklung der Dip‐Pen‐Nanolithographie (Angew. Chem. 1/2004)
Authors: Ginger David S. , Zhang Hua , Mirkin Chad A.
Published: December 2003

Dip‐Pen‐Nanolithographie ermöglicht die schnelle Musterbildung auf Oberflächen auf der Nanometerskala. Das Titelbild verdeutlicht das Prinzip dieser Technik, die Abscheidung von Tintenmolekülen von einer Kraftmikroskopspitze auf ein Substrat. Feynmans 1960 formuliertes Diktum zur Miniaturisierung, in nanometergroßen Lettern im Hintergrund, erweist sich erneut als zutreffend. C. A. Mirkin et al. fassen in einem Aufsatz auf S. 30 ff. den gegenwärtigen Stand der Din‐Pen‐Methode zusammen und geben einen Ausblick auf zukünftige Entwicklungen.
Titelbild: Supramolecular Construction of Molecular Ladders in the Solid State (Angew. Chem. 2/2003)
Authors: Gao Xiuchun , Friščić Tomislav , MacGillivray Leonard R.
Published: December 2003

Ein Templat dirigiert die Knüpfung kovalenter Bindungen bei der quantitativen photochemischen Dimerisierung von Polyenen zu Ladderanen. X. Gao, T. Friščić und L. R. MacGillivray beschreiben in ihrer Zuschrift auf S. 234 ff., wie diese auf andere Weise schwer zugänglichen Verbindungen durch eine templatgesteuerte Festphasenreaktion im Grammmaßstab erhalten werden können. Ladderane findet man als Bestandteil der Lipidmembranen von Anammox‐Bakterien, die am Stickstoffhaushalt im Ozean beteiligt sind.
Comments on Recent Achievements in Biomimetic Organic Synthesis
Authors: de la Torre María C. , Sierra Miguel A.
Published: December 2003

The appealing beauty of the routes that Nature uses to build natural products is breathtaking and the quest for laboratory syntheses that mimic these routes is longstanding. Since Robert Robinson introduced the concept of biomimetic synthesis in 1917, debates have been conducted about the participation of specific enzymes in every step of the biogenesis of every class of natural product. The successful synthesis of many natural products often follows routes analogous to processes that occur in the living cell with minimum enzyme participation. It should not be concluded, however, that we are only able to imitate biogenetic processes in which enzymes are not involved. Perhaps the most appealing facet of a biomimetic strategy is that it pursues the development of synthetic methodology inspired by biogenesis, even if the mimicked biogenetic route is only hypothetical. Improved biogenetic syntheses could be brought about by artificial enzymes that catalyze specific transformations.
The Evolution of Dip‐Pen Nanolithography
Authors: Ginger David S. , Zhang Hua , Mirkin Chad A.
Published: December 2003

The ability to tailor the chemical composition and structure of a surface on the 1–100 nm length scale is important to researchers studying topics ranging from electronic conduction, to catalysis, to biological recognition in nanoscale systems. Dip‐pen nanolithography (DPN) is a new scanning‐probe based direct‐write tool for generating such surface‐patterned chemical functionality on the sub‐100 nm length‐scale, and it is a technique that is accessible to any researcher who can use an atomic force microscope. This article introduces DPN and reviews the rapid growth of the field of DPN‐related research over the past few years. Topics covered range from the development of new classes of DPN‐compatible chemistry, to experimental and theoretical advances in the understanding of the processes controlling tip–substrate ink transport, to the implementation of micro‐electro‐mechanical system (MEMS) based strategies for parallel DPN applications.
Cover Picture: Supramolecular Construction of Molecular Ladders in the Solid State (Angew. Chem. Int. Ed. 2/2003)
Authors: Gao Xiuchun , Friščić Tomislav , MacGillivray Leonard R.
Published: December 2003

A supramolecular approach to covalent synthesis allows the photoconversion of polyenes into ladderanes, which are challenging synthetic targets discovered in the lipid membranes of the anammox bacteria that participate in the oceanic nitrogen cycle. In their Communication on page 232 ff. X. Gao, T. Friščić, and L. R. MacGillivray explain how solid‐state synthesis directed by molecular templates can provide gram quantities of the ladderanes in quantitative yield. Thus, ladderanes bridge a gap between conventional synthesis, supramolecular chemistry, and biology.
A novel chemiluminescent method for determination of phloroglucinol
Authors: Cui Hua , Xie Cheng‐gen , Lai Chun‐ze
Published: December 2003

It was found that the inhibition and enhancement by phloroglucinol of the chemiluminescence from the luminol–K3Fe(CN)6 system were dependent on the pH of luminol solution and the concentration of phloroglucinol. In Na2CO3–NaHCO3 buffer, phloroglucinol exhibited strong chemiluminescent enhancement at pH 9.4. On this basis, a flow injection method was developed for the determination of phloroglucinol. The method was simple, rapid, convenient and sensitive, with a detection limit of 2.0 × 10−9 mol/L. It is effective for determining phloroglucinol in the range of 1.0 × 10−5–5.0 × 10−9 mol/L. The relative standard deviation is 1.3% within one day and 3.2% between days for the determination of 5.0 × 10−7 mol/L phloroglucinol. The method has been successfully used to determine phloroglucinol in environmental water, with satisfactory results. Copyright © 2003 John Wiley & Sons, Ltd.
Comparison of oxidative stress induced by ciprofloxacin and pyoverdin in bacteria and in leukocytes to evaluate toxicity
Authors: Becerra M. C. , Eraso A. J. , Albesa I.
Published: December 2003

Oxidative stress induced by ciprofloxacin and pyoverdin, a leukotoxic pigment, was studied by comparing their effect in bacteria and leukocytes. Chemiluminescence (CL) assays with lucigenin or luminol were adapted to measure the stimuli of superoxide anion (O2−) and other reactive species of oxygen (ROS) in bacteria. Ciprofloxacin principally induced the production of O2− in the three species studied: Staphylococcus aureus, Enterococcus faecalis and Escherichia coli. Lucigenin CL assay showed high oxidative stress in S. aureus due to its low superoxide dismutase (SOD) activity, whereas E. coli exhibited important SOD activity, responsible for little production of O2− in absence or presence of ciprofloxacin. Reduction of nitroblue of tetrazolium (NBT) was applied. This assay indicated that there was higher oxidative stress in S. aureus and E. faecalis than in E. coli. The comparison of oxidative stress generated in bacteria and leukocytes was used to check the selective toxicity of ciprofloxacin in comparison with pyoverdin. Ciprofloxacin did not generate significant stimuli of O2− in neutrophils, while pyoverdin duplicated the production of O2−. CL and NBT were useful to study the leukotoxicity of ciprofloxacin. Oxidative stress caused by the antibiotic and the leukotoxic pigment was similar in bacteria. Copyright © 2003 John Wiley & Sons, Ltd.
Chemiluminescence behaviour of alkaline earth metal ions in the potassium permanganate–fluorescein reaction
Authors: Du Jianxiu , Liu Wenxia , Lu Jiuru
Published: December 2003

A chemiluminescence (CL) signal was observed when alkaline earth metal ion solution, Mg2+ or Ca2+ or Ba2+, was injected into a reaction mixture of fluorescein and potassium permanganate. A possible CL mechanism is proposed based upon the CL, fluorescence and UV‐visible spectra. Furthermore, the feasibility of the application of these reactions to the analysis of these alkaline earth metal ions was evaluated and the analytical parameters of the methods were determined. Copyright © 2003 John Wiley & Sons, Ltd.
Spatial and temporal distribution of a bioluminescent‐marked Pseudomonas putida on soybean root
Authors: Beauchamp Chantal J. , Kloepper Joseph W.
Published: December 2003

The ability of rhizobacteria to compete with other microorganisms for root colonization may be critical for its establishment on a root. Over a 6 day period, visualization of the spatial and temporal rhizosphere distribution of a bioluminescent‐marked rhizobacterium, Pseudomonas putida, strain GR7.4lux, was examined on soybean grown in non‐sterile soil conditions. Luminometry technologies showed a rapid root distribution of rhizobacteria where bioluminescence was particularly intense on the seed and upper root parts. The results provide new information on rhizobial root distribution, where, using enrichment broth, 50% of the root tips were still colonized by rhizobacteria up to 6 days after sowing. This suggests that rhizobial enrichment is required to detect low populations at the root tip. Bioluminescent technology represents a promising alternative to previous methods for studying rhizobial growth and distribution on roots. Copyright © 2003 John Wiley & Sons, Ltd.
The Activation of Fibroblast Growth Factors (FGFs) by Glycosaminoglycans: Influence of the Sulfation Pattern on the Biological Activity of FGF‐1
Authors: Angulo Jesús , Ojeda Rafael , de Paz José‐Luis , Lucas Ricardo , Nieto Pedro M. , Lozano Rosa M. , Redondo‐Horcajo Mariano , Giménez‐Gallego Guillermo , Martín‐Lomas Manuel
Published: December 2003

Six synthetic heparin‐like oligosaccharides have been used to investigate the effect of the oligosaccharide sulfation pattern on the stimulation of acidic fibroblast growth factor (FGF‐1) induced mitogenesis signaling and the biological significance of FGF‐1 trans dimerization in the FGF‐1 activation process. It has been found that some molecules with a sulfation pattern that does not contain the internal trisaccharide motif, which has been proposed for high affinity for FGF‐1, stimulate FGF‐1 more efficiently than those with the structure of the regular region of heparin. In contrast to regular region oligosaccharides, in which the sulfate groups are distributed on both sides of their helical three‐dimensional structures, the molecules containing this particular sulfation pattern display the sulfate groups only on one side of the helix. These results and the fact that these oligosaccharides do not promote FGF‐1 dimerization according to sedimentation‐equilibrium analysis, confirm the importance of negative‐charge distribution in the activation process and strongly suggest that FGF dimerization is not a general and absolute requirement for biological activity.
A (4R)‐ or a (4S)‐Fluoroproline Residue in Position Xaa of the (Xaa‐Yaa‐Gly) Collagen Repeat Severely Affects Triple‐Helix Formation
Authors: Barth Dirk , Milbradt Alexander G. , Renner Christian , Moroder Luis
Published: December 2003

The triple‐helical fold of collagen requires the presence of a glycine residue at every third position in the peptide sequence and is stabilized by proline and (4R)‐4‐hydroxyproline residues in positions Xaa and Yaa of the (Xaa‐Yaa‐Gly) triplets, respectively. Regular down/up puckering of these Xaa/Yaa residues is possibly responsible for the tight packing of the three peptide strands, which have a polyproline‐II‐like structure, into the supercoiled helix. (4R)‐Configured electronegative substituents such as a hydroxy group or a fluorine substituent on the pyrrolidine ring of the residue in the Yaa position favor the up pucker and thus significantly stabilize the triple helix. A similar effect was expected from the corresponding (4S)‐isomers in the Xaa positions, but the opposite effect has been observed with (4S)‐hydroxyproline, a result that has been speculatively attributed to steric effects. In this study, (4R)‐ and (4S)‐fluoroproline residues were introduced into the Xaa position and potential steric effects were thus avoided. Contrary to expectations, (4S)‐fluoroproline prevents triple‐helix formation, whereas (4R)‐fluoroproline stabilizes the polyPro II conformation, but without supercoiling of the three strands. The latter observation suggests that folding of the single chains into a polyproline II helix is not directly associated with triple helix formation and that fine tuning of van der Waals contacts, electrostatic interactions, and stereoelectronic effects is required for optimal packing into a triple helix.
Chemical Strategies for Activity‐Based Proteomics
Authors: Speers Anna E. , Cravatt Benjamin F.
Published: December 2003

The assignment of molecular and cellular functions to the numerous protein products encoded by prokaryotic and eukaryotic genomes presents a major challenge for the field of proteomics. To address this problem, chemical approaches have been introduced that utilize small‐molecule probes to profile dynamics in enzyme activity in complex proteomes. These strategies for activity‐based protein profiling enable both the discovery and functional analysis of enzymes associated with human disease.
Identification of Luciferyl Adenylate and Luciferyl Coenzyme A Synthesized by Firefly Luciferase
Authors: Fraga Hugo , Esteves da Silva Joaquim C. G. , Fontes Rui
Published: December 2003

The firefly luciferase reaction intermediate luciferyl adenylate was detected by RP‐HPLC analysis when the luciferase reaction was performed under a nitrogen atmosphere. Although this compound is always specified as an intermediate in the light‐production reaction, this is the first report of its identification by HPLC in a luciferase assay medium. Under a low‐oxygen atmosphere, luciferase can catalyze the synthesis of luciferyl coenzyme A from luciferin, ATP, and coenzyme A, but in air dehydroluciferyl coenzyme A was produced. The luciferase‐catalyzed synthesis of these coenzyme A derivatives may be a consequence of the postulated recent evolutionary origin of firefly luciferases from an ancestral acyl‐coenzyme A synthetase.
Intraribosomal Regulation of Expression and Fate of Proteins
Authors: Nakatogawa Hitoshi , Ito Koreaki
Published: December 2003

Our studies of SecM (secretion monitor) in E. coli have revealed that some amino acid sequences can interact with ribosomal interior components, particularly with gate components of the exit tunnel, thereby interfering with their own translation elongation. Such translation arrest can be regulated by interaction of the N‐terminal portion of the nascent polypeptide with other cellular components outside the ribosome. These properties of nascent proteins can in turn provide regulatory mechanisms by which the expression of genetic information at different levels is regulated.
Proline‐Directed Random‐Coil Chemical Shift Values as a Tool for the NMR Assignment of the Tau Phosphorylation Sites
Authors: Lippens Guy , Wieruszeski Jean‐Michel , Leroy Arnaud , Smet Caroline , Sillen Alain , Buée Luc , Landrieu Isabelle
Published: December 2003

NMR spectroscopy of the full‐length neuronal Tau protein has proved to be difficult due to the length of the protein and the unfavorable amino acid composition. We show that the random‐coil chemical shift values and their dependence on the presence of a proline residue in the (i+1) position can successfully be exploited to assign all proline‐directed phosphorylation sites. This is a first step toward the study of the phosphorylation of Tau by NMR spectroscopy.
Identification of a Phosphopantetheinyl Transferase for Erythromycin Biosynthesis in Saccharopolyspora erythraea
Authors: Weissman Kira J. , Hong Hui , Oliynyk Markiyan , Siskos Alexis P. , Leadlay Peter F.
Published: December 2003

Phosphopantetheinyl transferases (PPTases) catalyze the essential post‐translational activation of carrier proteins (CPs) from fatty acid synthases (FASs) (primary metabolism), polyketide synthases (PKSs), and non‐ribosomal polypeptide synthetases (NRPSs) (secondary metabolism). Bacteria typically harbor one PPTase specific for CPs of primary metabolism (“ACPS‐type” PPTases) and at least one capable of modifying carrier proteins involved in secondary metabolism (“Sfp‐type” PPTases). In order to identify the PPTase(s) associated with erythromycin biosynthesis in Saccharopolyspora erythraea, we have used the genome sequence of this organism to identify, clone, and express (in Escherichia coli) three candidate PPTases: an ACPS‐type PPTase (S. erythraea ACPS) and two Sfp‐type PPTases (a discrete enzyme (SePptII) and another that is integrated into a modular PKS subunit (SePptI)). In vitro analysis of these recombinant PPTases, with an acyl carrier protein‐thioesterase (ACP‐TE) didomain from the erythromycin PKS as substrate, revealed that only SePptII is active in phosphopantetheinyl transfer with this substrate. SePptII was also shown to provide complete modification of ACP‐TE and of an entire multienzyme subunit from the erythromycin PKS in E. coli. The efficiency of the SePptII in phosphopantetheinyl transfer in E. coli makes it an attractive alternative to other Sfp‐type PPTases for co‐expression experiments with PKS proteins.
Unprecedented Diversity of Catalytic Domains in the First Four Modules of the Putative Pederin Polyketide Synthase
Authors: Piel Jörn , Wen Gaiping , Platzer Matthias , Hui Dequan
Published: December 2003

Polyketides of the pederin group are highly potent antitumor compounds found in terrestrial beetles and marine sponges. Pederin is used by beetles of the genera Paederus and Paederidus as a chemical defense. We have recently identified a group of putative pederin biosynthesis genes and localized them to the genome of an as yet unculturable Pseudomonas sp. symbiont, the likely true pederin producer. However, this polyketide synthase cluster lacks several genes expected for pederin production. Here we report an additional polyketide synthase encoded on a separate region of the symbiont genome. It contains at least three novel catalytic domains that are predicted to be involved in pederin chain initiation and the formation of an unusual exomethylene bond. The region is bordered by mobility pseudogenes; this suggests that gene transposition led to the disjointed cluster organization. With this work, all putative pederin genes have been identified. Their heterologous expression in a culturable bacterium will provide important insights into how sustainable sources of invertebrate‐derived drug candidates can be created.
Cover Picture: The Activation of Fibroblast Growth Factors (FGFs) by Glycosaminoglycans: Influence of the Sulfation Pattern on the Biological Activity of FGF‐1 (ChemBioChem 1/2004)
Authors: Angulo Jesús , Ojeda Rafael , de Paz José‐Luis , Lucas Ricardo , Nieto Pedro M. , Lozano Rosa M. , Redondo‐Horcajo Mariano , Giménez‐Gallego Guillermo , Martín‐Lomas Manuel
Published: December 2003

The cover picture shows a comparison of the effect of increasing concentrations of heparin and two synthetic heparin‐like hexasaccharides, with specifically designed different sulfation patterns, on the mitogenic activity of acidic fibroblast growth factor (FGF‐1). These two hexasaccharides, members of a series of six synthetic oligosaccharides with the same monosaccharide sequence but differing size and charge distribution, either have different negative charge orientations on both sides, like heparin itself, or on one side of their three dimensional helical structures. This alternative arrangement induces differences in the electrostatic potential, as is shown in the surface maps. The hexasaccharide with sulfate groups on only one side of the helix stimulates FGF‐1 more efficiently than that with the sulfate groups distributed on both sides as in the regular region of heparin. This result and the fact that, according to sedimentation‐equilibrium analysis, these oligosaccharides do not promote FGF‐1 dimerization, strongly suggest that FGF oligomerization is not a general and absolute requirement for biological activity. Further details can be found in the article by M. Martín‐Lomas and co‐workers on p. 55 ff.
Promises and Problems of Mesoscale Materials Chemistry or Why Meso?
Authors: Antonietti Markus , Ozin Geoffrey A.
Published: December 2003

Manipulation and control of chemical structures on the mesoscale has recently developed to a very promising and also aesthetically appealing area of chemistry. This concept article tries to integrate the views of two experts to delineate the specific principles, approaches, and the novel opportunities for chemistry that arise from the rational control of matter and functionality on that scale.
Mapping the Stereochemistry and Symmetry of Tetracoordinate Transition‐Metal Complexes
Authors: Cirera Jordi , Alemany Pere , Alvarez Santiago
Published: December 2003

A continuous shape and symmetry study of tetracoordinate transition‐metal complexes is presented, in an attempt to provide a systematic description of the stereochemistry of the metal coordination sphere in this important family of compounds. A tetrahedron/square‐planar symmetry map has been developed, the main distortion paths of the ideal geometries are presented, and the applicability of a sawhorse shape measure is discussed. More than 13,000 structural data sets have been analyzed and the corresponding stereochemistries assigned from the values of their tetrahedral and square‐planar symmetry measures. A good number of structures that are quite distant from the two ideal geometries can be adequately described as snapshots along the spread pathway for their interconversion, making use of the corresponding path deviation function. Further analysis of the structural data by metal electron configuration or by the denticity and conformation of the ligands provide general rules to describe the stereochemical preferences of tetracoordinate transition metal centers.
Synthesis of Novel Chiral and Acentric Coordination Polymers by the Reaction of Zinc or Cadmium Salts with Racemic 3‐Pyridyl‐3‐aminopropionic Acid
Authors: Qu Zhi‐Rong , Zhao Hong , Wang Yi‐Ping , Wang Xi‐Sen , Ye Qiong , Li Yong‐Hua , Xiong Ren‐Gen , Abrahams Brendan F. , Liu Zhi‐Guo , Xue Zi‐Ling , You Xiao‐Zeng
Published: December 2003

Under hydrothermal (solvothermal) reaction conditions chiral compounds 1, 2, and 3 and one acentric compound 4 were obtained by the reaction of Zn2+ or Cd2+ with racemic 3‐(3‐pyridyl)‐3‐aminopropionic acid (rac‐HPAPA). Compounds 1 and 2 crystallized in chiral space group P212121. At 105 °C, racemic 3‐pyridyl‐3‐aminopropionic acid (rac‐HPAPA) reacted with Zn(ClO4)2⋅6 H2O and dehydrogenated in situ to form the first chiral coordination polymer [Zn{(E)‐3‐C5H4NC(NH2)CHCOO}]ClO4 (1) with a β‐dehydroamino acid. Beyond 120 °C, the reaction of rac‐HPAPA with Zn(ClO4)2⋅6 H2O deaminates in situ to form chiral coordination polymer [Zn{(E)‐3‐C5H4NCHCHCOO}(OH)] (2). At relatively low temperatures (70 °C), the solvothermal reaction of Zn(NO3)2⋅6 H2O with rac‐HPAPA in methanol does not lead to any change in the ligand and results in the formation of a chiral (P212121) coordination polymer [Zn(papa)(NO3)] (3). The same reaction of Cd(ClO4)2⋅6 H2O with HPAPA also does not lead to any change in ligand and results in the formation of noncentric (Cc) coordination polymer [Cd(papa)(Hpapa)]ClO4⋅H2O (4). The network topology of both 1 and 3 is 10,3a, while 2 has a diamondoid‐like (KDP‐like, KDP=potassium dideuterophosphate) network. Particularly interesting from a topological perspective is that 4 has an unprecedented three‐dimensional network. Compounds 1, 2, 3, and 4 are all second harmonic generation (SHG) active with 1 exhibiting the strongest response, while only 4 also displays good ferroelectric properties.
Crystal, Molecular and Electronic Structure of N,N′‐Diphenyl‐N,N′‐bis(2,4‐dimethylphenyl)‐(1,1′‐biphenyl)‐4,4′‐diamine and the Corresponding Radical Cation
Authors: Low Paul J. , Paterson Michael A. J. , Puschmann Horst , Goeta Andrés E. , Howard Judith A. K. , Lambert Christoph , Cherryman Julian C. , Tackley Daniel R. , Leeming Stephen , Brown Bev
Published: December 2003

Oxidation of N,N′‐diphenyl‐N,N′‐bis(3‐methylphenyl)‐(1,1′‐biphenyl)‐4,4′‐diamine (TPD, 1 a) and N,N′‐diphenyl‐N,N′‐bis(2,4‐dimethylphenyl)‐(1,1′‐biphenyl)‐4,4′‐diamine (1 b) with SbCl5 affords the corresponding radical cations quantitatively. The crystal and molecular structure of 1 b and [1 b]SbCl6, the first tetraphenyl benzidene derivatives to be characterised crystallographically in both the neutral and radical cation states, reveal molecular parameters in agreement with the predictions made on the basis of DFT studies. Analysis of the NIR transition in the radical cations [1]+. allows an estimate of the electronic coupling parameter V (1 a+. 3200 cm−1; 1 b+. 3300 cm−1), the reorganisation energy λ(1 a+. 7500 cm−1; 1 b+. 7800 cm−1), and the linear coupling constant l (1 a+. 3100 cm−1; 1 b+. 2700 cm−1) of the symmetric mode.
Quantitative Evaluation of d–π Interaction in Copper(i) Complexes and Control of Copper(i)–Dioxygen Reactivity
Authors: Osako Takao , Tachi Yoshimitsu , Doe Matsumi , Shiro Motoo , Ohkubo Kei , Fukuzumi Shunichi , Itoh Shinobu
Published: December 2003

Crystal structures of the copper(i) complexes 1X, 2, and 3 of a series of tridentate ligands L1X, L2, and L3, respectively (L1X: p‐substituted derivatives of N,N‐bis[2‐(2‐pyridyl)ethyl]‐2‐phenylethylamine; X=H, Me, OMe, Cl, NO2; L2: N,N‐bis[2‐(2‐pyridyl)ethyl]‐2‐methyl‐2‐phenylethylamine; L3: N,N‐bis[2‐(2‐pyridyl)ethyl]‐2,2‐diphenylethylamine) were solved to demonstrate that all the copper(i) complexes involve an η2 copper–arene interaction with the phenyl ring of the ligand sidearm. The CuI ion in each complex has a distorted tetrahedral geometry consisting of the three nitrogen atoms (one tertiary amine nitrogen atom and two pyridine nitrogen atoms) and C1C2 of the phenyl ring of ligand sidearm, whereby the CuC distances of the copper–arene interaction significantly depend on the para substituents. The existence of the copper–arene interaction in a nonpolar organic solvent (CH2Cl2) was demonstrated by the observation of an intense MLCT band around 290 nm, and the magnitude of the interaction was evaluated by detailed analysis of the 1H and 13C NMR spectra and the redox potentials E1/2 of the copper ion, as well as by means of the ligand‐exchange reaction between the phenyl ring and CH3CN as an external ligand. The thermodynamic parameters ΔHo and ΔSo for the ligand‐exchange reaction with CH3CN afforded a quantitative measure for the energy difference of the copper–arene interaction in the series of copper(i) complexes. Density functional studies indicated that the copper(i)–arene interaction mainly consists of the interaction between the d orbital of CuI and a π orbital of the phenyl ring. The copper(i) complexes 1X reacted with O2 at −80 °C in CH2Cl2 to give the corresponding (μ‐η2:η2‐peroxo)dicopper(II) complexes 4, the formation rates kobs of which were significantly retarded by stronger d–π interaction, while complexes 2 and 3, which exhibit the strongest d–π interaction showed significantly lower reactivity toward O2 under the same experimental conditions. Thus, the d–π interaction has been demonstrated for the first time to affect the copper(i)–dioxygen reactivity, and represents a new aspect of ligand effects in copper(i)–dioxygen chemistry.
A Chiroptical Molecular Switch with Distinct Chiral and Photochromic Entities and Its Application in Optical Switching of a Cholesteric Liquid Crystal
Authors: Delden Richard A. van , Mecca Tommaso , Rosini Carlo , Feringa Ben L.
Published: December 2003

Two new structurally related photoswitches are described, in which azobenzene photochromism is combined with the chirality of a 2,2′‐dihydroxy‐1,1′‐binaphthyl unit. In system 1 the chiral binaphthyl moiety is bridged by a methylene tether, locking the biaryl chirality while in system 2 the biaryl core is unbridged and has considerable conformational flexibility. Both compound are capable of inducing cholesteric liquid crystalline phases and proved to be good photoswitches both in solution and in a liquid crystalline matrix. Compound 2 is capable of completely reversing the liquid crystalline chirality which is unique for a chiroptical molecular switch where the switching unit and the chiral moiety are separate entities.
Detection and Amplification of Chirality by Helical Polymers
Authors: Yashima Eiji , Maeda Katsuhiro , Nishimura Tatsuya
Published: December 2003

A unique feature of synthetic helical polymers for the detection and amplification of chirality is briefly described in this article. In sharp contrast to host–guest and supramolecular systems that use small synthetic receptor molecules, chirality can be significantly amplified in a helical polymer, such as poly(phenylacetylene)s with functional pendants, which enable the detection of a tiny imbalance in biologically important chiral molecules through a noncovalent bonding interaction with high cooperativity. The rational design of polymeric receptors can be possible by using chromophoric helical polymers combined with functional groups as the pendants, which target particular chiral guest molecules for developing a highly efficient chirality‐sensing system. The chirality sensing of other small molecular and supramolecular systems is also briefly described for comparison.
Zirconium‐Mediated Cross‐Coupling of Terminal Alkynes and Vinyl Bromides: Selective Synthesis of Cyclobutene and 1,3‐Diene Derivatives
Authors: Barluenga José , Rodríguez Félix , Álvarez‐Rodrigo Lucía , Fañanás Francisco J.
Published: December 2003

A diastereoselective synthesis of 1,3‐butadiene or cyclobutene derivatives by a zirconium‐mediated reaction of alkenyllithium compounds and vinyl bromides is reported. The key steps involve the generation of zirconocene–alkyne complexes from haloalkenes and subsequent coupling with alkenyl bromides. Thus, formally the process supposes the cross‐coupling reaction between a terminal alkyne and an alkenyl bromide. Moreover, the use of butyl vinyl ether instead of vinyl bromide as the unsaturated system allows an alternative access to different 1,3‐butadiene regioisomers.
A Concave Fluorescent Sensor for Anions Based on 6‐Methoxy‐1‐methylquinolinium
Authors: Amendola Valeria , Fabbrizzi Luigi , Monzani Enrico
Published: December 2003

The ligand 2, in which three fluorogenic 6‐methoxy‐1‐methylquinolinium fragments are appended to a mesityl platform, in MeCN forms 1:1 adducts with halides and other inorganic anions. 1H NMR studies and molecular modelling indicate that 2 provides a cavity for anion inclusion and establishes electrostatic interactions with the guest. Anion inclusion induces quenching of the fluorogenic fragments with an efficiency decreasing along the series Br−≫I−>NCS−≫Cl−>NO3−>HSO4−. The fluorimetric response of 2 to anions is orders of magnitude more sensitive than that of just 6‐methoxy‐1‐methylquinolinium, ligand 1.
Theoretical Insights into the Mechanism for Thiol/Disulfide Exchange
Authors: Fernandes Pedro Alexandrino , Ramos Maria João
Published: December 2003

The mechanism for thiol/disulfide exchange has been studied with high‐level theoretical calculations. Free energies, transition structures, charge densities, and solvent effects along the reaction pathway have been determined for the first time. Mechanistic results agree with experimental data, and support the idea that the thiolate is the reacting species and that the reaction indeed proceeds through an uncomplicated SN2 transition state. The transition structures have the charge density evenly concentrated in the attacking and leaving sulfur atoms. The charge densities allow us to rationalize the solvent effects. As transition structures have the charge density more widely distributed than reactants, hydrophobic environments catalyze the reaction. The effect can be so dramatic that disulfide exchange inside the active site of ribonucleotide reductase is estimated to be catalyzed 103 times faster than the reaction in water. It was also found that attack by thiol is much faster than previously assumed, if mediated through water chains. Although the present results, as well as experimental data, still suggest that thiolate is the main reaction species, water‐mediated thiol attack is almost kinetically competitive, and can eventually become competitive under specific experimental conditions.
Synthesis and Spectroscopic and Electrochemical Studies of Novel Benzo‐ or 2,3‐Naphtho‐Fused Tetraazachlorins, Bacteriochlorins, and Isobacteriochlorins
Authors: Fukuda Takamitsu , Makarova Elena A. , Luk′yanets Evgeny A. , Kobayashi Nagao
Published: December 2003

Benzene‐ or 2,3‐naphthalene‐ring‐expanded tetraazachlorins (TACs), tetraazabacteriochlorins (TABCs), and tetraazaisobacteriochlorins (TAiBCs) have been synthesized by using tetramethylsuccinonitrile as a source of hydrogenated sites. The derived compounds were characterized by using NMR spectroscopy, X‐ray crystallography, electronic and magnetic circular dichroism (MCD) spectroscopy, and electrochemical and spectroelectrochemical methods. X‐ray analysis revealed that the benzene‐fused TAiBC deviates slightly from planarity at the hydrogenated sites as a result of the presence of sp3 carbons, which prefer a nonplanar tetrahedral conformation. The spectral data were analyzed by using a band deconvolution technique. In the electronic absorption spectra of TAC and TABC species, the Q band splits into two intense components and smaller splittings were observed for the 2,3‐naphthalene‐fused derivatives relative to the benzo‐fused species. In contrast, in the case of TAiBCs, the Q band splitting was apparently not observed in absorption spectra, as expected from the C2v molecular symmetry. However, MCD signals of the Q band in TAiBCs showed Faraday B terms, implying that the accidental degeneracy of the LUMO and LUMO+1 was broken even for adjacently ring‐fused species. Relative molecular orbital energies were estimated by using cyclic and differential pulse voltammetry. The first reduction potentials were close for TACs and TABCs, although those of TAiBCs shifted to more negative potentials. In contrast, although TABCs and TAiBCs exhibited similar first oxidation potentials, those of TACs appeared at more positive potentials. These properties were reproduced and rationalized by molecular orbital and configuration interaction calculations within the framework of the ZINDO/S Hamiltonian. DFT‐level frequency calculations have succeeded in reproducing the IR spectra for low‐symmetry tetraazaporphyrin (TAP) derivatives for the first time. The relationship between structures and spectral features is discussed.
Zirconium‐Mediated Coupling Reactions of Amines and Enol or Allyl Ethers: Synthesis of Allyl‐ and Homoallylamines
Authors: Barluenga José , Rodríguez Félix , Álvarez‐Rodrigo Lucía , Zapico José M. , Fañanás Francisco J.
Published: December 2003

An easy and efficient zirconium‐mediated synthesis of allylamines from simple amines and enol ethers is described. This strategy also allows the synthesis of amino alcohol derivatives containing a Z double bond in their structure when 2,3‐dihydrofuran is used. Simple conventional modification of these amino alcohols leads to 2‐substituted piperidine derivatives. By applying this approach, a formal total synthesis of the alkaloid coniine is easily achieved from a protected butylamine. Finally, the zirconium‐mediated reaction of amines and allyl phenyl ether furnishes homoallylamines or amino ethers depending on the structure of the starting amine.
Framework Fluxionality of Organometallic Oxides: Synthesis, Crystal Structure, EXAFS, and DFT Studies on [{Ru(η6‐arene)}4Mo4O16] Complexes
Authors: Laurencin Danielle , Garcia Fidalgo Eva , Villanneau Richard , Villain Françoise , Herson Patrick , Pacifico Jessica , Stoeckli‐Evans Helen , Bénard Marc , Rohmer Marie‐Madeleine , Süss‐Fink Georg , Proust Anna
Published: December 2003

Reactions of the molybdates Na2MoO4⋅2 H2O and (nBu4N)2[Mo2O7] with [{Ru(arene)Cl2}2] (arene=C6H5CH3, 1,3,5‐C6H3(CH3)3, 1,2,4,5‐C6H2(CH3)4) in water or organic solvents led to formation of the triple‐cubane organometallic oxides [{Ru(η6‐arene)}4Mo4O16], whose crystal and molecular structures were determined. Refluxing triple cubane [{Ru(η6‐C6H5CH3)}4Mo4O16] in methanol caused partial isomerization to the windmill form. The two isomers of [{Ru(η6‐C6H5CH3)}4Mo4O16] were characterized by Raman and Mo K‐edge X‐ray absorption spectroscopy (XAS), both in the solid‐state and in solution. This triple‐cubane isomer was also used as a spectroscopic model to account for isomerization of the p‐cymene windmill [{Ru(η6‐1,4‐CH3C6H4CH(CH3)2)}4Mo4O16] in solution. Using both Raman and XAS techniques, we were then able to determine the ratio between the windmill and triple‐cubane isomers in dichloromethane and in chloroform. Density functional calculations on [{Ru(η6‐arene)}4Mo4O16] (arene=C6H6, C6H5CH3, 1,3,5‐C6H3(CH3)3, 1,4‐CH3C6H4CH(CH3)2, C6(CH3)6) suggest that the windmill form is intrinsically more stable, provided the complexes are assumed to be isolated. Intramolecular electrostatic interactions and steric bulk induced by substituted arenes were found to modulate but not to reverse the energy difference between the isomers. The stability of the triple‐cubane isomers should therefore be accounted for by effects of the surroundings that induce a shift in the energy balance between both forms.
Solid‐Phase Synthesis and Screening of Macrocyclic Nucleotide‐Hybrid Compounds Targeted to Hepatitis C NS5B
Authors: Smietana Michael , Johnson Robert B. , Wang Q. May , Kool Eric T.
Published: December 2003

A convergent strategy for the synthesis of cyclic nucleotide‐hybrid molecules on controlled pore glass is reported. A major advantage of the approach is the lack of restrictions on the sequence and structural variation, allowing the incorporation of modified ribonucleosides (such as 2′‐OMe‐ribonucleotides), as well as threoninol derivatives. This methodology allows a fully automated assembly by means of standard phosphoramidite chemistry and is based on a recently published procedure for the preparation of cyclic oligodinucleotides in the DNA series (M. Smietana, E. T. Kool, Angew. Chem. 2002, 114, 3856–3859; Angew. Chem. Int. Ed. Engl. 2002, 41, 3704–3707). A library of potential cyclic hybrid inhibitor compounds targeting hepatitis C virus NS5B enzyme (the replicating polymerase of HCV) was generated by means of the parallel‐pool strategy. Screening of the library revealed that cyclic hybrid c(COMEEthenodA) was a significant inhibitor of NS5B, with an IC50 of 40 μM. Preliminary structure–activity studies of this lead compound are described.
Selective Adsorption of Polychlorinated Dibenzo‐p‐dioxins and Dibenzofurans by the Zeosils UTD‐1, SSZ‐24, and ITQ‐4
Authors: Jäger Ralph , Schneider Andreas M. , Behrens Peter , Henkelmann Bernhard , Schramm Karl‐Werner , Lenoir Dieter
Published: December 2003

Zeosils are microporous solids with a pure silica framework. Due to their hydrophobic properties, zeosils are ideal host materials for the adsorption of hydrophobic guest molecules. We tested zeosils with different pore diameters (UTD‐1, SSZ‐24 and ITQ‐4 as well as CIT‐5) for the selective adsorption of the polychlorinated dibenzo‐p‐dioxins and dibenzofurans. This group of highly toxic substances contains 210 congeners that possess similar chemical properties, but differ in their size and shape. In the experiment, polychlorinated dibenzo‐p‐dioxins and dibenzofurans were extracted from fly ash of a waste incinerator, adsorbed on amorphous silica, then thermally desorbed and flushed over a sequential arrangement of the zeosils at elevated temperature by a stream of nitrogen. ITQ‐4 with the smallest pore diameter was placed first, followed by SSZ‐24 and, finally, by UTD‐1 with the largest pore diameter. After the experiment, the zeosils were analysed for their contents of the different congeners. The results show that the sorption of the congeners occurs selectively and that it is governed by the size and the shape of the dioxin molecules, which in turn depend on the number of chlorine atoms and the pattern of chlorine substitution (regioisomers). Geometrical reasoning as well as molecular dynamics calculations on the zeosil structures and on the dioxin molecules were helpful in rationalising the results. This work represents an especially complex case of the molecular sieving effect and may lead to a selective on‐line monitoring of the concentrations of dioxin molecules in waste gases of industrial combustion processes. The size‐ and shape‐selective sorption of dioxin molecules may also bear some resemblance to the molecular recognition process that occurs in nature at the aryl hydrocarbon receptor.
Highly Enantioselective Ruthenium‐Catalyzed Reduction of Ketones Employing Readily Available Peptide Ligands
Authors: Bøgevig Anders , Pastor Isidro M. , Adolfsson Hans
Published: December 2003

Highly efficient and selective catalysts for the asymmetric reduction of aryl alkyl ketones under hydrogen‐transfer conditions (2‐propanol) were obtained by combining a novel class of pseudo‐dipeptide ligands with [{RuCl2(p‐cymene)}2]. A library of 36 dipeptide‐like ligands was prepared from N‐Boc‐protected α‐amino acids and the enantiomers of 2‐amino‐1‐phenylethanol and 1‐amino‐2‐propanol. The catalyst library was evaluated with the reduction of acetophenone and excellent enantioselectivity of 1‐phenylethanol was obtained with several of the novel catalysts. A ligand based on the combination of N‐Boc‐L‐alanine and (S)‐1‐amino‐2‐propanol (ligand A‐(S)‐4) was found to be particular effective. When the situ formed ruthenium complex of this ligand was employed as the catalyst in the hydrogen‐transfer reaction of various aryl alkyl ketones, the corresponding alcohol products were achieved in excellent enantioselectivity (up to 98 % ee).