Getting it together, virtually - Part 2 - Weaving the molecular Web
by David Bradley
Riding high on the success of BioMedNet, the Current Science group launched a second Web community officially in April 1997 in collaboration with software house MDL Information Systems Inc; this time for chemists - under the banner 'The World Wide Club for the Chemical Community'. ChemWeb.com like its sibling, has a thriving membership of well over
150,000.
One might cynically suggest that members of any of these virtual communities might be rather transient, as is the fickle nature of the average Web surfer, but Bill Town head of ChemWeb has reported that the browser statistics stack up to show this is not true. Most members join and keep coming back to reap the benefits, and are, in a sense, even more active than most members of the old-style learned societies. Indeed, there is often a greater incentive to maintain a loyalty to a virtual community because membership numbers are so high so diversity is often greater.
At the time of writing ChemWeb.com, had just launched two new
forums for its members - an analytical forum and an electrochemistry
forum, which have been designed as new virtual communities under the ChemWeb umbrella for
specialists in these fields. In addition, in a collaboration with ACD/Labs ChemWeb members can now access a virtual laboratory to allow
them to carry out spectral analyses and chemical structure drawing and molecular
prediction and naming.
Virtuality will never replace face to face contact and
scientists will continue to attend conferences and chat in the coffee room until
the last fact is filed. But, given limited money and time budgets, the online
community will provide individuals with the chance to shake hands virtually with
far more colleagues than they could ever hope to in a single scientific career
and that can be no bad thing. Virtuality knows no political or international
borders and membership is open to all who care to join.
Communal notes
ChemConnect's World Chemical Exchange was created to satisfy chemical industry demands for access to materials through a single interface, rather than trawling company catalogues, to find a bargain. 'Members can now buy products with a few mouse clicks', says Vice-President Online Patrick van der Valk. With more than 10,000 regular users ChemConnect forms a strong community of traders, manufacturers, and distributors. An active bidding system, provides true market prices making the market highly efficient with the San Francisco based company taking a 0.1-1% cut on transactions.
chemsoc is a shared resource for all the European chemical societies hosted by the UK's Royal Society of Chemistry. The site is searchable and provides 'instant' access to educational resources, such as discussion forums, searchable journals from the RSC and others, table of contents are readily accessible and subscribers can download PDF versions of the papers days before they appear in print. Access to the societies other than the RSC is critical to its sense of community.
The American Institute of Physics perhaps has a lot more resources to invest in its site than its UK counterpart and is applying these to developing new content at However, at the time of writing, the interactivity of the site is really minimal, so whereas PhysicsWeb is offering community, the AIP is still perhaps in the portal stage of Web evolution.
Roster
Membership in some of these virtual communities far exceeds the roster of some of the learned societies themselves. But like any club, members have to sign up to feel the benefits, for much of PhysicsWeb, ChemWeb and BioMedNet the services are given free in exchange for your registration data, which might include some brief details about qualifications and interests. The non-gratis parts of these virtual communities are the commercial databases and journals repositories, although even then there are often sub-sections available without charge. So, while it does seem possible to get a free lunch in cyberspace, you might have to pay for your own dessert. Highly targeted advertising and payment for sub-sections of any of these virtual communities seems to, if not cover the costs, provide a major incentive for the creators to maintain them. Profits might be the ultimate goal but they are not the only motive at this point in the Web's life...
A shorter version of this article appears in the November issue of
Scientific Computing World
for which DBSW is a Specialist Reporter.
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Fullerene skeletons
Skeletal hydrocarbon chains with embedded nitrogens could be the key to building azafullerenes, chemical cousins of the buckyball, with potentially more interesting electrical and physical properties.
Yoshito Tobe, Tomonari Wakabayashi and colleagues at Osaka and Tokyo Metropolitan Universities reasoned that if they could build a fullerene skeleton into which they had inserted nitrogen atoms at appropriate points they might then be able to add the flesh with some chemical tinkering and produce a hollow carbon sphere with its nitrogen atoms in place.
They first tested the approach on fullerene itself by building a hydrocarbon skeleton from a 1,3,5-cyclophane and converting it into a poly-yne in which a loop of alternating carbon-carbon triple bonds is bridged by a second loop. When they subjected this molecule to laser-desorption mass spectrometry they observed various fullerenes including C60H6 and the positive and negative ions of C60.
The next step was to prepare a pyridinophane in which nitrogen atoms are swapped for two carbons in the cyclophane and convert this to the loop form. Mass spectrum revealed the fleeting presence of C58N2 - the target azafullerene (Chem. Commun., 1999, 1625). The fact the team have generated azafullerene by design bodes well for a total synthesis, but Tobe will not speculate on a timescale, although he says that hexaazafullerene will be the most interesting target.
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To dye for
Catching a hydrophilic dye in the branches of a dendritic polymer, UK chemists can prepare tuneable optical materials without having to synthesise a complex spherical dendrimer. The approach could be used to make better behaved printers inks, optoelectronics materials and for creating novel catalysts and pharmaceuticals.
Starburst dendrimers are polymers where the chains emerge and branch repeatedly from a focal point. According to York University's
David Smith chemists worldwide have been investigating the possibility of using the unique microenvironment within the branching structures to alter the properties of smaller molecules.
The trouble with the spherical starburst dendrimers, first prepared by IBM scientist Donald Tomalia in the 1980s, is that they are hard to make so tailoring the microenvironment is no simple task. Smith, writing in Chem. Commun. (1999, 1685), describes how he has built much simpler versions of dendrimers that still provide the microenvironment by using individual branches rather than the whole tree.
Inspired by Denkewalter's work, Smith used the amino acid lysine as a building block, Smith produced a first generation branched polymer, then added another layer and another to make a third generation branch. To make a starburst dendrimer the initial starting point would require more initial branches and many more generations to produce a sphere.
The twist came when Smith tested the branches to see whether they could catch the intensely orange dye proflavine through a non-covalent interaction with the focal caboxylic acid group. UV-visible spectroscopy quickly revealed that dye had been taken up in the branches. 'Each dendritic branch solubilised a small but significant quantity of the solid dye into dichloromethane solution,' explains Smith. The branches shield the water-soluble dye from the organic solvent and as the branches grow, more and more dye dissolves.
The trapped dye's fluorescence changes depending on branch depth demonstrating the tunability of its optical properties. 'As well as optoelectronic applications, this approach could be used in making better printing inks, as well as catalysts and pharmaceuticals,' Smith says.
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