ChemSpider is a free online chemical database that has been serving the chemistry community since 2007. It provides a vast collection of molecular structures and associated properties, and includes crowdsourcing features for adding data, and improving its quality and reliability.
There are many ways to search ChemSpider, the most direct method being to enter a search term on the main website. The website is optimised for all device form factors (desktop/laptop/mobile), but when it comes to drawing a chemical structure to use for searching the database, the sketching tools are not available for mobile devices.
The Royal Society of Chemistry, owner of ChemSpider, commissioned Molecular Materials Informatics to construct iOS and Android apps, to make structure searching on a mobile device as simple as possible. The resulting app, ChemSpider Mobile, is available to download for free on the iTunes AppStore and Google Play. The app has a very straightforward design layout, and provides structure drawing capabilities via the embedded version of the powerful MMDSLib structure editor.
Interface for iPhone, iPod and iPad
The ChemSpider Mobile app has three tab panels, which are shown along the bottom of the screen:
The Structure and Text panels are used to setup these two types of search operations, while the Results panel is used to display the list of hits from the most recent search.
The structure search panel shows the current molecular structure, and additional search parameters:
The current structure can be modified by activating the New, Edit or Recent buttons. There are presently three types of structure searches that can be performed: Exact, Skeleton and Substructure. An exact search attempts to match the drawn structure precisely, i.e. atoms, bonds, charge, stereochemistry, isotope, etc., are all required to complete the match, and a result will typically contain one hit, or none at all. A skeleton search, on the other hand, matches the core sigma framework only, and so often results in multiple hits. This is an effective way to search for tautomers, stereomers and materials with different nuclear isotopes. Substructure searches match any structure that contains the given fragment.
To modify the current structure, use the Edit button.
The first time the editor is invoked, a dialog is presented asking you what sketcher mode you want to use. The options are:
If you are familiar with drawing chemical structures on a desktop platform, and want to get started with mobile apps without having to learn a new interface, you should choose the Casual mode. The molecular structure drawing interface is simple and familiar. If you are already proficient with the powerful drawing interface pioneered by the Mobile Molecular DataSheet app, among others, you should select the Expert mode. If want to learn the more powerful interface with the benefit of tool tips and training banks, select the Novice mode.
Once the editing is complete, either Accept or Reject the changes.
To draw a new structure from scratch, use the New button. The editor will be invoked. In Novice mode, a list of starting templates will be presented:
A list of recently used structures is maintained, which can be recalled by activating the Recent button:
Selecting any of these structures will replace the current structure.
The text search panel shows a single text entry box, for which a chemical identifier should be provided, typically the name of the molecule:
When a structure or name has been specified, the Search button is used, from either of the panels. It will initiate a request to the ChemSpider online database, and when the request is complete, a list of results will be shown, with a structure and name for each.
An exact structure search for aspirin shows a single result:
A skeleton structure search for aspirin shows multiple results, including the conjugate base form, and isomerically enriched substances:
A substructure search locates structures that match the given structure, or contain it as a sub-unit:
For more information on any of the search results, double-tap on an entry, or select and tap the Open in Browser button. This will launch the mobile browser and direct it to the ChemSpider page, which provides a wealth of information for the molecule:
Interface for Android
A wide variety of Android phones and tablets are supported. Any device that has access to the Google Play storefront and runs at least version 2.3.3 of the operating system can use it.
The app supplies 4 tabs, which are presented on the left hand side of the screen when oriented in landscape mode, or along the bottom of the screen when the device is in portrait mode:
Text searches can be initiated by typing into the search box:
Setting up a structure search involves providing a structure and selecting a search type:
The New and Edit buttons bring up the molecular structure editor:
The structure editor is the same as the sketcher used in expert mode for the iOS version of the app. The first time the New button is pressed, the app will offer to guide you through a tutorial. The tutorial will take you through the most important functionality of the sketcher, in which each step is guided by instruction, and must be passed successfully to get to the end of the tutorial. It is highly recommended that new users go through the entire tutorial before attempting to draw structures.
When a text or structure search is initiated, ChemSpider will be contacted, and results will be made available as they arrive:
Results are shown by structure and name. Tapping on any of the rows allows the entry to be opened by launching the mobile browser and pointing it to the corresponding ChemSpider page:
Each time a search is issued, it is stored in a list of recent searches:
Selecting any of them will recall the search for reuse.
The ChemSpider Mobile app makes searching the ChemSpider online database from an iPhone, iPod, iPad or Android device simple and convenient. It is the easiest and most effective way to search by structure on a mobile device. Once results are obtained, detailed information is provided via the standard ChemSpider web page, which provides all of the available chemical information.