3. Accessing and Searching Chemical Information Databases

Access to chemical information databases has been primarily subscription-based due to the large amount of manual labor needed for curating high-value chemical data and information as well as their often proprietary nature. In recent years, some open access databases such as PubChem and ChemSpider have emerged with the advance of cheminformatics techniques. However, chemists still need to rely on subscription-based databases for accurate and efficient searches. The table below summarizes some major databases we often use in chemistry research, their scopes, and major functionalities. Please choose the ones available through your institution to explore. The tutorials linked in the last column will help you get started with using these databases. For more information on databases covering chemical substance data, please consult Ben Wagner’s book chapter³ and the poster presented by Ye Li and Leena Lalwani.⁴

Please note: most of these databases index the citation and abstracts of articles; fulltext of the articles are often linked with the database records through your institutional citation link resolver to journals your institution have access to. Occasionally, you may discover articles that your institution does not have access to online. You can consult with your institution’s library for access to the print source or through interlibrary loan service.

3.1 Search Techniques for Databases in Chemistry

Most of the databases, especially the subscription based ones, provide useful tools to refine your search. You may use the advanced search features and/or filter options in these databases to optimize your search strategy. Here are a few useful tips in general for searching databases in Chemistry.

• Use Boolean logic ( AND, OR, NOT) to connect your search terms instead of typing in a full sentence ⁵
• Pay attention to subject terms (standard terms a database used to index literature) and use them for more accurate search ⁵
• Track down publications by a specific author through author name search or author ID such as ORCID ⁵
• Search for references cited in a chosen article and search for other publications cited a chosen article to expand your findings⁵
• Learn structure, substructure⁶, and reaction⁷ searching through practice and understanding how chemical structures are indexed (covered more in later modules)

3.2 Search Techniques for Physical Properties and Spectra of Chemical Substance

Searching for physical properties and spectra of chemical substances is an important skill for chemists to master. Physical property data and spectra data are often indexed around chemical substances in databases and handbooks with referencing to the primary literature published the data.³

• Databases such as SciFinder, Reaxys, PubChem, and ChemSpider listed in the above table index physical properties, spectra, and bioactivities and can be searched through chemical substances. When you locate the interested substance in these databases, you can navigate to the particular physical property data or spectra under various sections in the substance record. Please note: you may need to go to the linked primary literature from the database to obtain the actual spectra or the conditions of how a piece of physical property was measured. There is another type of databases which function as repositories of spectra, such as the Spectral Database for Organic Compounds, SDBS. In SDBS, you can download the spectral data directly.
• Handbook examples include CRC Handbook of Chemistry and Physics and ASM Handbooks. You may either browse the handbook by property categories or use the index to search for a specific substance. Online versions for many of these handbooks are available and will allow you to search for property data and spectra with keyword searching. Some handbooks available through the Knovel platform may even allow you to download and interact with individual tables and graphs containing substance property data.

Depending on the database and handbooks available for you, you can explore more of the search techniques specific to the resource using their guide or help. Also, you may learn more about them from Ben Wagner’s book chapter. ³

When you use physical properties and spectra discovered from literature in your own writing or presentation, the condition of how the data were measured are often important to include; because different conditions can generate very different data from the same substance. Without the original context, the audience of your writings will not be able to interpret the data you cited and evaluate your research based on the data.

3.3 Learning to Become a Power Searcher While Doing Research

You can always consult publications and learning materials from chemical information professionals for advanced search skills like those can be found in XCITR.¹ It takes practice and patience to become a power searcher in the chemical information world. In reality, you may need to balance the comprehensiveness of results and the time spent to seek for them. Please never hesitate to consult with your librarians and experienced researchers around you for suggestions and tips. Further more, with what you will learn in this class, you will be able to see the chemical information world from an insider point of view. For example, in module 5 of this class: Comparing and Searching Chemical Entities, you will learn more about how databases like PubChem and ChemSpider are organized and updated in order to understand the advanced methods to retrieve chemical information from them.

Nowadays, search engines like Google and Google Scholar and collaborative references online like Wikipedia can often provide quick and easy access to chemical data and literature online. They can be used to get started with a topic as long as you pay attention to the true source of the data and information discovered and evaluate the sources carefully as described in the next section. For comprehensive research on a topic and finding credible sources, these quick tools are usually not sufficient. Using the databases mentioned above will ensure you perform effective and efficient searches to identify data and information for your research.