Search

Bis(imino)pyridine cobalt(I) alkyl complexes react with 1-alkenes by β-hydrogen transfer, providing a model reaction for the study of a commonly encountered chain transfer process in polymerization and oligomerization catalysis. The influence of steric effects on reaction rates is described. The theoretical models largely agree with the experimentally determined structures, provide a more detailed view of the species involved, and are consistent with the observed reactivities. Both experiment and theory support a stepwise pathway involving a cobalt-hydride intermediate.

We describe how a collection of documents expressed in XML-conforming languages such as CML and XHTML can be authenticated and validated against digital signatures which make use of established X.509 certificate technology. These can be associated either with specific nodes in the XML document or with the entire document. We illustrate this with two examples. An entire journal article expressed in XML has its individual components digitally signed by separate authors, and the collection is placed in an envelope and again signed. The second example involves using a software robot agent to acquire a collection of documents from a specified URL, to perform various operations and transformations on the content, including expressing molecules in CML, and to automatically sign the various components and deposit the result in a repository. We argue that these operations can used as components for building what we term an authenticated and semantic chemical web of trust.

We describe the development of a structured method of representing chemistry on the World-Wide Web using an object-oriented approach to information objects. We show how a document object model (DOM) for chemistry can be constructed using as its basis Chemical Markup Language (CML). Application of the CMLDOM to the development of chemical tools is described.

A robot-based procedure is described for traversing a collection of hyperlinked documents written in HTML and converting these to the XML-compliant and well-formed XHTML representation. Transcluded chemical content invoked using <embed> or <applet> HTML calls are converted to the XHTML recommended <object> form. Additional attributes such as title or derived chemical attributes such as a SMILES descriptor are added to improve the indexing of the resulting document collection. Conformance tests for the popular Web browsers are reported.

Chemical markup language (CML) is an application of XML, the extensible markup language, developed for containing chemical information components within documents. Its design supports interoperability with the XML family of tools and protocols. It provides a base functionality for atomic, molecular, and crystallographic information and allows extensibility for other chemical applications. Legacy files can be imported into CML without information loss and can carry any desired chemical ontology. Some applications of CML (Markush structures, chemical searching) will be discussed in later articles. An XML document type declaration (DTD) for CML is included as a Chart.

The evolution of the World Wide Web from a model allowing only the public and open exchange of information on the global Internet via simple HTML-based pages to one involving the additional development of Intranets or Extranets with secure interactive client-server processes is discussed. These client-server processes can be customized on the client browser by the use of embedded applications such as Java Applets that allow the client to communicate with other remote applications or databases via a distributed computing architecture. We show¹ how software authentication using digital object signing procedures in conjunction with X.509 certificates was used to develop three authenticated distributed chemical applications. COS (Chemical Object Store) is a database application based on Java Remote Method Invocation, MoldaNet invokes Java3D to create a molecular visualization tool, and JSpec delivers analytical spectral data. We argue that such authentication of chemical resources on the Internet provides one mechanism for increasing the perception of quality and integrity of molecular information disseminated within the chemical community and creates an architecture for electronic commerce to develop in the molecular science community.

The design and implementation of two interactive Internet-based applications for the storage, retrieval, and display of molecular structures, spectra, and physicochemical properties is described. The first, suitable for small-scale laboratory or teaching applications, uses a JavaScript-controlled structure to load data from discrete files located on a server or a CD-ROM into a local Web browser. The second, developed for scaling to larger commercial-sized applications, uses a Java-based Distributed Object Computing architecture to allow a local client applet to have persistent access to a remote object database, in which information for the different chemical classes has been stored. Both browser applications have a dynamically created page structure and use readily available Plugins and Java applets for the active display of three-dimensional molecular structures and their experimental spectra.

The proposal and subsequent global use of an Internet standard based on chemical primary Multipurpose Internet Mail Extensions (chemical MIME) media type is reviewed. Examples of the configuration of this standard for use with Internet-based electronic mail and World Wide Web clients are shown. The long-term objectives of the integration and interoperability of chemical information across the boundaries of Internet-based electronic journals, conferences, virtual courses, databases, modeling, and newly emerging information handling and modeling tools are set out. We believe that one way forward is by concentrating on more finely grained chemical information components, using generic tools based on XML (eXtensible markup language) and its support in chemistry via CML (chemical markup language).

B3LYP and KMLYP/6-31G(d) calculations predict a double-helical and chiral conformation of [14]annulene with the topological properties of a double-twist Möbius band as highly aromatic; its energy with respect to the known Hückel-aromatic conformation is predicted to be stabilized by suitable ring substitution.