12.5 Conclusions
Chiral molecules bearing two or more fluorophores able to interact in the excited
state and generate an emitting excimer induce fluorescence often with high quantum
yield allied with highly polarized emission. Through this strategy, it is thus possible
to maximize polarization output not only in terms of dissymmetry factor, but also in
terms of circular polarization brightness [6], to an extent which is generally
unsurpassed by most single organic molecule (i.e., non-aggregated) emitters. This
field will benefit from further experimental efforts to produce and investigate new
compounds. Moreover, computational analysis of excimer allied CPL could provide
in the future better insight into the mechanism behind such phenomenon and help to
design tailored systems. Unfortunately, to the best of our knowledge, no computational work has been reported so far on the topic. A possible difficulty lies in the
optimization of excimer geometry, considering that such geometry exists only in the
excited state, therefore no direct experimental structure is available for a straightforward check of the calculated one. In such cases, in fact, a correct geometry is
necessary to reproduce emission [37, 38], and even more CPL [39], in a
trustable way.
References
1. IUPAC, Compendium of chemical terminology, 2nd ed. the “Gold Book”
2. Birks J (1975) Excimers. Rep Prog Phys 38:903
3. Pucci A, Ruggeri G (2011) Mechanochromic polymer blends. J Mater Chem 21:8282–8291
4. Sánchez-Carnerero EM, Agarrabeitia AR, Moreno F, Maroto BL, Muller G, Ortiz MJ, de la
Moya S (2015) Circularly polarized luminescence from simple organic molecules. Chemistry
21:13488–13500
5. Tanaka H, Inoue Y, Mori T (2018) Circularly polarized luminescence and circular dichroisms in
small organic molecules: correlation between excitation and emission dissymmetry factors.
ChemPhotoChem 2:386–402
6. Zinna F, Di Bari L (2018) Emerging field of chiral Ln(III) complexes for OLEDs. In: MartínRamos P, Ramos Silva M (eds) Lanthanide-based multifunctional materials. Elsevier, Amsterdam, pp 171–194
7. Lunkley JL, Shirotani D, Yamanari K, Kaizaki S, Muller G (2011) Chiroptical spectra of a
series of tetrakis ((+)-3-heptafluorobutylyrylcamphorato) lanthanide (III) with an encapsulated
alkali metal ion: circularly polarized luminescence and absolute chiral structures for the Eu (III)
and Sm (III) complexes. Inorg Chem 50:12724–12732
8. Zinna F, Di Bari L (2015) Lanthanide circularly polarized luminescence: bases and applications.
Chirality 27:1–13
9. Kumar J, Nakashima T, Kawai T (2015) Circularly polarized luminescence in chiral molecules
and supramolecular assemblies. J Phys Chem Lett 6:3445–3452
10. Duhamel J (2012) New insights in the study of pyrene excimer fluorescence to characterize
macromolecules and their supramolecular assemblies in solution. Langmuir 28:6527–6538
11. Kano K, Matsumoto H, Hashimoto S, Sisido M, Imanishi Y (1985) A chiral pyrene excimer in
γ-cyclodextrin cavity. J Am Chem Soc 107:6117–6118
290
F. Zinna et al.
Chiral molecules bearing two or more fluorophores able to interact in the excited
state and generate an emitting excimer induce fluorescence often with high quantum
yield allied with highly polarized emission. Through this strategy, it is thus possible
to maximize polarization output not only in terms of dissymmetry factor, but also in
terms of circular polarization brightness [6], to an extent which is generally
unsurpassed by most single organic molecule (i.e., non-aggregated) emitters. This
field will benefit from further experimental efforts to produce and investigate new
compounds. Moreover, computational analysis of excimer allied CPL could provide
in the future better insight into the mechanism behind such phenomenon and help to
design tailored systems. Unfortunately, to the best of our knowledge, no computational work has been reported so far on the topic. A possible difficulty lies in the
optimization of excimer geometry, considering that such geometry exists only in the
excited state, therefore no direct experimental structure is available for a straightforward check of the calculated one. In such cases, in fact, a correct geometry is
necessary to reproduce emission [37, 38], and even more CPL [39], in a
trustable way.
References
1. IUPAC, Compendium of chemical terminology, 2nd ed. the “Gold Book”
2. Birks J (1975) Excimers. Rep Prog Phys 38:903
3. Pucci A, Ruggeri G (2011) Mechanochromic polymer blends. J Mater Chem 21:8282–8291
4. Sánchez-Carnerero EM, Agarrabeitia AR, Moreno F, Maroto BL, Muller G, Ortiz MJ, de la
Moya S (2015) Circularly polarized luminescence from simple organic molecules. Chemistry
21:13488–13500
5. Tanaka H, Inoue Y, Mori T (2018) Circularly polarized luminescence and circular dichroisms in
small organic molecules: correlation between excitation and emission dissymmetry factors.
ChemPhotoChem 2:386–402
6. Zinna F, Di Bari L (2018) Emerging field of chiral Ln(III) complexes for OLEDs. In: MartínRamos P, Ramos Silva M (eds) Lanthanide-based multifunctional materials. Elsevier, Amsterdam, pp 171–194
7. Lunkley JL, Shirotani D, Yamanari K, Kaizaki S, Muller G (2011) Chiroptical spectra of a
series of tetrakis ((+)-3-heptafluorobutylyrylcamphorato) lanthanide (III) with an encapsulated
alkali metal ion: circularly polarized luminescence and absolute chiral structures for the Eu (III)
and Sm (III) complexes. Inorg Chem 50:12724–12732
8. Zinna F, Di Bari L (2015) Lanthanide circularly polarized luminescence: bases and applications.
Chirality 27:1–13
9. Kumar J, Nakashima T, Kawai T (2015) Circularly polarized luminescence in chiral molecules
and supramolecular assemblies. J Phys Chem Lett 6:3445–3452
10. Duhamel J (2012) New insights in the study of pyrene excimer fluorescence to characterize
macromolecules and their supramolecular assemblies in solution. Langmuir 28:6527–6538
11. Kano K, Matsumoto H, Hashimoto S, Sisido M, Imanishi Y (1985) A chiral pyrene excimer in
γ-cyclodextrin cavity. J Am Chem Soc 107:6117–6118
290
F. Zinna et al.