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AAPS PharmSciTech. 2005 September; 6(3): E444–E448.
Published online 2005 October 22. doi:  10.1208/pt060355
PMCID: PMC2750389

Solid-state fluorescence of the trihydrate phases of ampicillin and amoxicillin


The purpose of this work was to study the effects of crystal structure on the solid-state photoluminescence of the trihydrate phases of ampicillin and amoxicillin, and to contrast these spectra with analogous spectra obtained on the molecules dissolved in a solution phase. The polymorphic identity of the analytes was established using x-ray powder diffraction and Fourier transform infrared absorption spectroscopy, and the solid-state luminescence spectra obtained under ambient conditions. It was found that the solid-state excitation and emission spectra of ampicillin trihydrate and amoxicillin trihydrate were dominated by energy transfer and exciton effects, which were manifested as decreases in the energy of the excitation and emission bands of the solid-state systems relative to those of the free molecule in solution. The photoluminescence data revealed that in spite of the known structural similarity of ampicillin trihydrate and amoxicillin trihydrate, the magnitude of the Davydov splitting, and the degree of band energy shifting differed between the 2 systems. This finding indicates that the small differences in crystal structure existing between the 2 compounds leads to measurable differences in the patterns of energy transfer.

Keywords: polymorphism, fluorescence spectroscopy, energy transfer, exciton splitting

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
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