In by admin

Name Mrs. Arwa Alharbi
Organization or Institution Florida Institute of Techology
Presentation Type Poster
Topic Physical Chemistry

The equilibrium of merocyanin photoacid and spiropyran


Arwa Alharbi, Thaaer  Khalil, Yi Liao, Clayton Baum

Author Institution(s)

Florida Institue of Technology


The recently discovered metastable-state photoacids (mPAH) can produce a large proton concentration with high efficiency and good reversibility. Most metastable-state photoacids are protonated merocyanines (MEH). Under irradiation, an MEH is converted to acidic spiropyran (SP). However, conversion between MEH and SP occurs thermally at different pH. A series of molecules have been synthesized to study the thermal equilibrium between MEH and SP. The effective pkas of these molecules in the dark were determined using a range of pH buffers (pH=4.5-7.5). The effective pKais determined by the equilibrium between SP and ME as well as the acidity of ME. By correlating the structural difference with that of the pKas, the two factors can be isolated. The results of this study explain the reason that the merocyanine photoacid has a stable MEH state while the well-known spiropyran has a stable SP state