Photophysical properties of poly(3,4-ethylenedioxythiophene)/permethylated β- and γ- cyclodextrin polyrotaxanes

Poly(3,4-ethylenedioxythiophene) (PEDOT) is known as an interesting material for optoelectronic applications. Since the solubility of PEDOT compound is a critical element for the application, a lot of synthetic procedures such as the encapsulation of PEDOT backbone into the macrocyclic cavities via noncovalent interactions have been applied.

Herein, we continue to provide extensive insights into the excited state dynamics of absorption and emission (fluorescence and phosphorescence) in water and acetonitrile (ACN) solutions of two PEDOT∙TMe-βCD and PEDOT∙TMe-γCD polyrotaxanes. The transient absorption map revealed ground state bleaching bands (GSB) in the range 270- 315 nm, whereas an absorption band in excited state (ESA) occurs at shorter wavelengths from 210 to 250 nm and more than one excited state (S_n > 1). At longer wavelength, from 390 to 455 nm negative bands appeared which can be assigned to the stimulated emissions (SE). Also, the quantum yields measurements and time resolved fluorescence experiments were performed in both water and ACN in solutions. The quantum yields with absolute values from 0.0005 to 0.76 were found depending on the solvent nature, and lifetimes from 0.4 ns to 29 ns were obtained for fluorescence and phosphorescence lifetime with values ​​in the range 0.8 to 9 μs.

ACKNOWLEDGMENTS

This presentation was supported by a grant from the Romanian Ministry of Research, Innovation, and Digitization, CNCS-UEFISCDI, project number PN-III-P4-PCE-2021-0906