High-Throughput Single-Molecule Spectroscopy Resolves the Conformational Isomers of BODIPY Chromophores

Lorenzo Sansalone, Yang Zhang, Mercedes M.A. Mazza, Janel L. Davis, Ki Hee Song, Burjor Captain, Hao F. Zhang, Françisco M. Raymo

Research output: Contribution to journalArticle

Abstract

A borondipyrromethene (BODIPY) chromophore is connected to a benzoxazole, benzothiazole, or nitrobenzothiazole heterocycle through an olefinic bridge with trans configuration. Rotation about the two [C-C] bonds flanking the olefinic bridge occurs with fast kinetics in solution, leading to the equilibration of four conformational isomers for each compound. Ensemble spectroscopic measurements in solutions fail to distinguish the coexisting isomers. They reveal instead averaged absorption and emission bands with dependence of the latter on the excitation wavelength. Using high-throughput single-molecule spectroscopy, two main populations of single molecules with distinct spectral centroids are observed for each compound on glass substrates. Computational analyses suggest the two populations of molecules to be conformational isomers with antiperiplanar and periplanar arrangements of the BODIPY chromophores about its [C-C] bond to the olefinic bridge. Thus, statistical analysis of multiple single-molecule emission spectra can discriminate stereoisomers that would otherwise be impossible to distinguish by ensemble measurements alone.

Original languageEnglish (US)
Pages (from-to)6807-6812
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume10
Issue number21
DOIs
StatePublished - Nov 7 2019

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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