Chapter 12
Circularly Polarized Luminescence
from Intramolecular Excimers
Francesco Zinna, Elodie Brun, Alexandre Homberg, and Jérôme Lacour
Abstract In this chapter, examples of circularly polarized luminescence (CPL)
stemming from intramolecularly formed excimers will be reviewed. Emission from
excimers has peculiar photophysical properties with respect to fluorescence of
regular monomers. In addition, if the fluorophoric couple forming the excimer in
the excited state is mounted on a chiral scaffold, a strong CPL can be usually
observed. Examples of chiral scaffolds include oligopeptides, macrocycles,
binaphthyl, and diaminocyclohexane derivatives. CPL from excimers has mainly
been observed from pyrenes but other molecules are also able to give rise to such
phenomenon, e.g., perylenes and 1,8-naphthalene monoimide. Excimer CPL can
provide important information about the conformation of a molecule in the excited
state and how it evolves depending on the environment (e.g., solvent and temperature) or external stimuli (e.g., light irradiation and cation addition). Moreover, thanks
to the peculiar photophysical nature of excimers, the degree of circular polarization
associated with excimer emission is usually much larger than the one associated with
the absorption (electronic circular dichroism, ECD) for the same molecule. This
allows to study chiroptical emission properties of molecules which are ECD-silent
(ground state cryptochirality). As a whole, excimer CPL is an interesting and useful
strategy to develop organic molecular systems endowed with bright and highly
polarized luminescence.
F. Zinna (*)
Department of Organic Chemistry, University of Geneva, Geneva, Switzerland
Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Pisa, Italy
e-mail: francesco.zinna@unipi.it
E. Brun · A. Homberg · J. Lacour (*)
Department of Organic Chemistry, University of Geneva, Geneva, Switzerland
e-mail: jerome.lacour@unige.ch
© Springer Nature Singapore Pte Ltd. 2020
T. Mori (ed.), Circularly Polarized Luminescence of Isolated Small Organic
Molecules, https://doi.org/10.1007/978-981-15-2309-0_12
273
Circularly Polarized Luminescence
from Intramolecular Excimers
Francesco Zinna, Elodie Brun, Alexandre Homberg, and Jérôme Lacour
Abstract In this chapter, examples of circularly polarized luminescence (CPL)
stemming from intramolecularly formed excimers will be reviewed. Emission from
excimers has peculiar photophysical properties with respect to fluorescence of
regular monomers. In addition, if the fluorophoric couple forming the excimer in
the excited state is mounted on a chiral scaffold, a strong CPL can be usually
observed. Examples of chiral scaffolds include oligopeptides, macrocycles,
binaphthyl, and diaminocyclohexane derivatives. CPL from excimers has mainly
been observed from pyrenes but other molecules are also able to give rise to such
phenomenon, e.g., perylenes and 1,8-naphthalene monoimide. Excimer CPL can
provide important information about the conformation of a molecule in the excited
state and how it evolves depending on the environment (e.g., solvent and temperature) or external stimuli (e.g., light irradiation and cation addition). Moreover, thanks
to the peculiar photophysical nature of excimers, the degree of circular polarization
associated with excimer emission is usually much larger than the one associated with
the absorption (electronic circular dichroism, ECD) for the same molecule. This
allows to study chiroptical emission properties of molecules which are ECD-silent
(ground state cryptochirality). As a whole, excimer CPL is an interesting and useful
strategy to develop organic molecular systems endowed with bright and highly
polarized luminescence.
F. Zinna (*)
Department of Organic Chemistry, University of Geneva, Geneva, Switzerland
Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Pisa, Italy
e-mail: francesco.zinna@unipi.it
E. Brun · A. Homberg · J. Lacour (*)
Department of Organic Chemistry, University of Geneva, Geneva, Switzerland
e-mail: jerome.lacour@unige.ch
© Springer Nature Singapore Pte Ltd. 2020
T. Mori (ed.), Circularly Polarized Luminescence of Isolated Small Organic
Molecules, https://doi.org/10.1007/978-981-15-2309-0_12
273