Featured Research

from universities, journals, and other organizations

How Does Aspirin Crystallize?

Date:
December 23, 2006
Source:
John Wiley & Sons, Inc.
Summary:
"The two crystalline forms of aspirin are so closely related," explain Andrew D. Bond, Roland Boese and Gautam R. Desiraju in Angewandte Chemie, "that they form structures containing domains of both crystal types."

When you get a headache, you probably reach for aspirin. What is giving researchers a headache is the question of the crystal structure of aspirin. Is there another form on top of the long-known one? A team of scientists from Denmark, Germany, and India seems to have solved this controversial puzzle: yes, there is a second structure—but it does not exist as a pure form. “The two crystalline forms of aspirin are so closely related,” explains the research team of Andrew D. Bond, Roland Boese and Gautam R. Desiraju in Angewandte Chemie, “that they form structures containing domains of both crystal types.”

Related Articles


In 2004, computer calculations had indicated that while the long-known crystal structure of aspirin (form I) is definitely one of the most stable forms, another version might exist that is just as stable, though it had not yet been discovered—a clear challenge to researchers in the field. The difference between the proposed structures is slight: both have identical layers containing molecules grouped into pairs, but these layers are arranged differently in the two different structures. In 2005, researchers in the USA announced the discovery of the predicted structure (form II). But was this merely an artifact?

“We can now clear this matter up,” say Bond, Boese and Desiraju, after very careful examination of aspirin crystals. “Aspirin has a tendency to crystallize with an unusual intergrown structure. The same single crystal contains domains with both arrangements lying side by side.” The distribution and ratio of the domains are variable but limited. Whereas a pure form I exists, it has so far only been possible to obtain crystals containing a maximum of 85 % form II. The ratio of the two domains within crystals produced under identical conditions seems to be roughly constant.

This discovery upends fundamental principles and requires new concepts: chemists previously understood “polymorphism” to mean that a molecule can take on one or another packing arrangement in the crystalline state; a single crystal of a specific chemical substance is either one polymorph or the other. Aspirin is the first case in which two different “polymorphic” structures exist in one single crystal. So is aspirin polymorphic or not? Should the definition of polymorphism be updated? Such questions are not just philosophical in nature, but could have tangible implications in patent law, because each polymorph of a compound is viewed as a separate patentable substance.


Story Source:

The above story is based on materials provided by John Wiley & Sons, Inc.. Note: Materials may be edited for content and length.


Cite This Page:

John Wiley & Sons, Inc.. "How Does Aspirin Crystallize?." ScienceDaily. ScienceDaily, 23 December 2006. <www.sciencedaily.com/releases/2006/12/061223092859.htm>.
John Wiley & Sons, Inc.. (2006, December 23). How Does Aspirin Crystallize?. ScienceDaily. Retrieved January 28, 2015 from www.sciencedaily.com/releases/2006/12/061223092859.htm
John Wiley & Sons, Inc.. "How Does Aspirin Crystallize?." ScienceDaily. www.sciencedaily.com/releases/2006/12/061223092859.htm (accessed January 28, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Wednesday, January 28, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Amplifying Tiny Movements to Visualize the Invisible

Amplifying Tiny Movements to Visualize the Invisible

Reuters - Innovations Video Online (Jan. 28, 2015) A new video recording method that amplifies seemingly invisible motion could lead to a touch-free vital signs monitor, and offer a new tool for engineers to gauge stresses on bridges and tunnels in real time. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Boeing's Profit Soars

Boeing's Profit Soars

Reuters - Business Video Online (Jan. 28, 2015) Boeing delivered more commercial planes, especially 737s and 787s, fueling profit. But it issued a mixed outlook. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Robot Replacements for Foxconn's Workers

Robot Replacements for Foxconn's Workers

Reuters - Business Video Online (Jan. 28, 2015) Foxconn parent Hon Hai Precision Industry is looking to automation to keep productivity up without the rising costs of human labor. Meg Teckman reports. Video provided by Reuters
Powered by NewsLook.com
More Guns Found in Carry-on Bags at US Airports

More Guns Found in Carry-on Bags at US Airports

AP (Jan. 27, 2015) The Transportation Security Administration says officers discovered 2,212 firearms during safety screenings last year, a 22 percent jump over 2013. (Jan. 27) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins