Configuration of Charge Waves
in Polymethine Linear Dye Systems
S. V. Vasylyuk, A. D. Suprun, L. V. Shmeleva, and O. D. Kachkovsky
In the middle of the essential particular properties of linear conjugate systems 1, it
is an ability to exhibit quasimetallic conductivity. The basis polymers 1 looks like
[R—(CH) m —R]
n , where n = 0, ±1, ±2. This discovery, awarded with the Nobel
Prize in 2000, led to the revision of many theoretical models based on representations of the action of π-electrons in the conjugated molecules, primarily in anions
and cations of polymethine dyes, in cation or anion radicals of polyenes, and thus
inspired the improvement of original theoretical model of the electronic structure of
similar special type of systems, taking into account the features of charge distribution and molecular geometry [1–4]. In addition to the use of conjugated systems as
molecular conductors [1], they find numerous applications in nonlinear optics: as a
result, polymethine dyes with uneven number of carbon group CH (system 1, where
m = 2 k + 1, n = ±1, and R—various heterocyclic residues) are capable to intensively
absorb and emanate a quant of light in visible part of spectrum and near-infrared part
of the spectrum [5, 6]. Such unique spectral properties are suitable to the definite
charge distribution in a main and in the excited state, as well as an arrangement of
the lengths of carbon–carbon bonds [1–8]. According to modern notions, the carbon
atom in the conjugate system is in the sp
3 -hybridized state and accordingly, forms
three σ-bonds, resulting in the molecules 1 being flat, as can be seen in Fig. 1, which
shows an example of polymethine ion at 5, n = + 1, R = CH 2 . The last 2p z -electron
together with the same electrons of other carbon atoms forms a common collective π-electron system. The transition from a neutral conjugate molecule to ions
that is the injection of an electron or a hole into a high polarizable common collective π-electronic system is accompanied by the manifestation of supposed soliton
level (level of impurity) in the energy gap in addition to significant shift in both the
conduction band base and the valence band top [2–4]. The injection charge is not
S. V. Vasylyuk (B) · A. D. Suprun · L. V. Shmeleva · O. D. Kachkovsky
Physics Faculty of Kyiv National Taras Shevchenko University, Volodymirska 64, Kiev, Ukraine
e-mail: svetlanafvasylyuk@gmail.com; bladewalker@ukr.net
© Springer Nature Switzerland AG 2021
O. Fesenko and L. Yatsenko (eds.), Nanomaterials and Nanocomposites,
Nanostructure Surfaces, and Their Applications, Springer Proceedings
in Physics 246, https://doi.org/10.1007/978-3-030-51905-6_15
189
in Polymethine Linear Dye Systems
S. V. Vasylyuk, A. D. Suprun, L. V. Shmeleva, and O. D. Kachkovsky
In the middle of the essential particular properties of linear conjugate systems 1, it
is an ability to exhibit quasimetallic conductivity. The basis polymers 1 looks like
[R—(CH) m —R]
n , where n = 0, ±1, ±2. This discovery, awarded with the Nobel
Prize in 2000, led to the revision of many theoretical models based on representations of the action of π-electrons in the conjugated molecules, primarily in anions
and cations of polymethine dyes, in cation or anion radicals of polyenes, and thus
inspired the improvement of original theoretical model of the electronic structure of
similar special type of systems, taking into account the features of charge distribution and molecular geometry [1–4]. In addition to the use of conjugated systems as
molecular conductors [1], they find numerous applications in nonlinear optics: as a
result, polymethine dyes with uneven number of carbon group CH (system 1, where
m = 2 k + 1, n = ±1, and R—various heterocyclic residues) are capable to intensively
absorb and emanate a quant of light in visible part of spectrum and near-infrared part
of the spectrum [5, 6]. Such unique spectral properties are suitable to the definite
charge distribution in a main and in the excited state, as well as an arrangement of
the lengths of carbon–carbon bonds [1–8]. According to modern notions, the carbon
atom in the conjugate system is in the sp
3 -hybridized state and accordingly, forms
three σ-bonds, resulting in the molecules 1 being flat, as can be seen in Fig. 1, which
shows an example of polymethine ion at 5, n = + 1, R = CH 2 . The last 2p z -electron
together with the same electrons of other carbon atoms forms a common collective π-electron system. The transition from a neutral conjugate molecule to ions
that is the injection of an electron or a hole into a high polarizable common collective π-electronic system is accompanied by the manifestation of supposed soliton
level (level of impurity) in the energy gap in addition to significant shift in both the
conduction band base and the valence band top [2–4]. The injection charge is not
S. V. Vasylyuk (B) · A. D. Suprun · L. V. Shmeleva · O. D. Kachkovsky
Physics Faculty of Kyiv National Taras Shevchenko University, Volodymirska 64, Kiev, Ukraine
e-mail: svetlanafvasylyuk@gmail.com; bladewalker@ukr.net
© Springer Nature Switzerland AG 2021
O. Fesenko and L. Yatsenko (eds.), Nanomaterials and Nanocomposites,
Nanostructure Surfaces, and Their Applications, Springer Proceedings
in Physics 246, https://doi.org/10.1007/978-3-030-51905-6_15
189