Chapter 10
Structural and Electronic Information
Drawn from the Circularly Polarized
Luminescence Spectra: Many Questions
and Some Answers for Simple Organic
Molecules, Polymers, and Molecular
Aggregates
Giovanna Longhi and Sergio Abbate
Abstract In the last ten years, circularly polarized luminescence (CPL) has greatly
advanced: lots of data have been collected and many compounds have been synthesized with the aim of enhancing this chiroptical response. We review here a few
aspects with illustrative examples. After examination of the relation of circular
dichroism (CD) and CPL signals, we investigate how CPL can be used to probe
environment: aggregation phenomena or the presence of metal ions or pH variations.
We also study the CPL of inherently dissymmetric chromophores and of metal
complexes. We finally touch upon whether CPL originates from molecules or
from aggregated inhomogeneous systems.
10.1 Introduction
Circularly polarized luminescence (CPL) has a long history, which, schematically,
may be divided, with some degree of arbitrariness, into three stages: we may define
the seminal work by Emeis and Osterhoof [1] as the starting point of CPL history for
organic compounds. They concentrated on the systematic investigation of ketones,
which exhibit large circular dichroism (CD), associated with n ! πà transitions, the
latter being electric dipole moment-forbidden/magnetic dipole moment-allowed, as
of the definition of the rotational strength:
G. Longhi (*) · S. Abbate
Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Brescia, Italy
e-mail: giovanna.longhi@unibs.it; sergio.abbate@unibs.it
© 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_10
219
Structural and Electronic Information
Drawn from the Circularly Polarized
Luminescence Spectra: Many Questions
and Some Answers for Simple Organic
Molecules, Polymers, and Molecular
Aggregates
Giovanna Longhi and Sergio Abbate
Abstract In the last ten years, circularly polarized luminescence (CPL) has greatly
advanced: lots of data have been collected and many compounds have been synthesized with the aim of enhancing this chiroptical response. We review here a few
aspects with illustrative examples. After examination of the relation of circular
dichroism (CD) and CPL signals, we investigate how CPL can be used to probe
environment: aggregation phenomena or the presence of metal ions or pH variations.
We also study the CPL of inherently dissymmetric chromophores and of metal
complexes. We finally touch upon whether CPL originates from molecules or
from aggregated inhomogeneous systems.
10.1 Introduction
Circularly polarized luminescence (CPL) has a long history, which, schematically,
may be divided, with some degree of arbitrariness, into three stages: we may define
the seminal work by Emeis and Osterhoof [1] as the starting point of CPL history for
organic compounds. They concentrated on the systematic investigation of ketones,
which exhibit large circular dichroism (CD), associated with n ! πà transitions, the
latter being electric dipole moment-forbidden/magnetic dipole moment-allowed, as
of the definition of the rotational strength:
G. Longhi (*) · S. Abbate
Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Brescia, Italy
e-mail: giovanna.longhi@unibs.it; sergio.abbate@unibs.it
© 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_10
219