Facile Isolation of Functionalized Spiropyran Mechanophores without Recrystallization
Abstract
The use of spiropyrans in the fields of photoswitches, metal chelation, and dyes has been reported extensively in the literature. However, only within the last decade, as the field of mechanochemistry has evolved, have spiropyrans found use as force-sensing molecules. Through this use of spiropyrans as force-sensing molecules, observation of molecular-level bond breakage occurring in a sample is possible and can provide information about material failure before micro or macro cracks are formed in samples being impacted at ballistic velocities. To capture the onset of mechanophore activation due to impact at ballistic speeds, mechanophore purity is critical because it can influence the color of the polymer samples being tested, therefore influencing the accuracy of the observation being made. However, functionalized spiropyran isolation has proven to be challenging, and to date, recrystallization of the open form merocyanine in a nonpolar solvent has been the only way of obtaining the spiropyran form in acceptable purity. This method of purification can be very time consuming and difficult to reproduce for obtaining material useful for mechanochemical studies. This report describes new methods recently developed at the US Army Research Laboratory to isolate two different functionalized spiropyran molecules in high purity without recrystallization. These newly developed methods can provide hundreds of milligrams of functionalized spiropyrans a few hours after reaction completion, as opposed to several days to greater than a week for recrystallization.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2018
- Accession Number
- AD1060417
Entities
People
- James F. Berry