future CPL materials is also provided, demonstrating the rapid evolution of SOMsbased CPL chemistry in the last 5 years.
1.2 Background
Circularly polarized luminescence (CPL) represents a difference of incidental emission of left- and right-handed circularly polarized light from chiral materials
(Fig. 1.1). The phenomenon can be observed, in principle, at the atomic, molecular,
as well as supramolecular levels, necessarily involving chiral substances and/or
surroundings. Such a polarized luminescence may be induced even for achiral
systems by the external applied field (such as magnetic field), but we only focus
on in this book the “natural” CPL that occurs through the electronic transition in the
absence of external field. As a whole, emissions from both singlet and triplet (as well
as other) electronically excited states are similarly treated without distinction
between fluorescence and phosphorescence, unless the cases when a particular
emphasis is placed. First of all, the CPL measurement is attractive and powerful
means to elucidate the chiral information in their emissive excited states, complemental to its ground-state analog, circular dichroism (CD). Recently, the materials
with strong CPL intensity (usually defined by a dissymmetry factor, vide infra) has
been attracting great attention due to their promising applications in advanced
photonic materials for chiral devices, enantioselective sensing systems, and biomedical applications, more specifically 3D displays, OLED materials, optoelectronic
devices, spintronics devices, security painting, information storage, and so forth.
More recently, functional CPL materials responsive to various stimuli such as pH,
chemicals, temperature changes, mechanical forces, or light have been also developed as smarter chiroptical switching devices.
At the early stage of CPL chemistry, the CPL spectrum was only measured on a
custom-made instrument, limiting such measurement only to the spectroscopist. This
instrumental limitation unquestionably hampered the progress of CPL chemistry for
a certain period. Now, the instrument becomes commercially available, facilitating
to obtain reliable and reproducible CPL spectra expanding into other relevant fields
Fig. 1.1 Circularly polarized luminescence (CPL) obtained from or with chiral substances
2
T. Mori
1.2 Background
Circularly polarized luminescence (CPL) represents a difference of incidental emission of left- and right-handed circularly polarized light from chiral materials
(Fig. 1.1). The phenomenon can be observed, in principle, at the atomic, molecular,
as well as supramolecular levels, necessarily involving chiral substances and/or
surroundings. Such a polarized luminescence may be induced even for achiral
systems by the external applied field (such as magnetic field), but we only focus
on in this book the “natural” CPL that occurs through the electronic transition in the
absence of external field. As a whole, emissions from both singlet and triplet (as well
as other) electronically excited states are similarly treated without distinction
between fluorescence and phosphorescence, unless the cases when a particular
emphasis is placed. First of all, the CPL measurement is attractive and powerful
means to elucidate the chiral information in their emissive excited states, complemental to its ground-state analog, circular dichroism (CD). Recently, the materials
with strong CPL intensity (usually defined by a dissymmetry factor, vide infra) has
been attracting great attention due to their promising applications in advanced
photonic materials for chiral devices, enantioselective sensing systems, and biomedical applications, more specifically 3D displays, OLED materials, optoelectronic
devices, spintronics devices, security painting, information storage, and so forth.
More recently, functional CPL materials responsive to various stimuli such as pH,
chemicals, temperature changes, mechanical forces, or light have been also developed as smarter chiroptical switching devices.
At the early stage of CPL chemistry, the CPL spectrum was only measured on a
custom-made instrument, limiting such measurement only to the spectroscopist. This
instrumental limitation unquestionably hampered the progress of CPL chemistry for
a certain period. Now, the instrument becomes commercially available, facilitating
to obtain reliable and reproducible CPL spectra expanding into other relevant fields
Fig. 1.1 Circularly polarized luminescence (CPL) obtained from or with chiral substances
2
T. Mori