Molecular chirality and spontaneous symmetry breaking (report on the occasion of awarding of V.I. Vernadsky Gold Medal of NAS of Ukraine)
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| Цитувати: | Molecular chirality and spontaneous symmetry breaking (report on the occasion of awarding of V.I. Vernadsky Gold Medal of NAS of Ukraine) / M. Larsson // Вісник Національної академії наук України. — 2022. — № 7. — С. 50-53. — Бібліогр.: 4 назв. — англ. |
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Larsson, M. 2022-09-09T15:34:53Z 2022-09-09T15:34:53Z 2022 Molecular chirality and spontaneous symmetry breaking (report on the occasion of awarding of V.I. Vernadsky Gold Medal of NAS of Ukraine) / M. Larsson // Вісник Національної академії наук України. — 2022. — № 7. — С. 50-53. — Бібліогр.: 4 назв. — англ. 0372-6436 https://nasplib.isofts.kiev.ua/handle/123456789/185286 en Видавничий дім "Академперіодика" НАН України Вісник НАН України Загальні збори НАН України Molecular chirality and spontaneous symmetry breaking (report on the occasion of awarding of V.I. Vernadsky Gold Medal of NAS of Ukraine) Article published earlier |
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Molecular chirality and spontaneous symmetry breaking (report on the occasion of awarding of V.I. Vernadsky Gold Medal of NAS of Ukraine) |
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Molecular chirality and spontaneous symmetry breaking (report on the occasion of awarding of V.I. Vernadsky Gold Medal of NAS of Ukraine) Larsson, M. Загальні збори НАН України |
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Molecular chirality and spontaneous symmetry breaking (report on the occasion of awarding of V.I. Vernadsky Gold Medal of NAS of Ukraine) |
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Molecular chirality and spontaneous symmetry breaking (report on the occasion of awarding of V.I. Vernadsky Gold Medal of NAS of Ukraine) |
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Molecular chirality and spontaneous symmetry breaking (report on the occasion of awarding of V.I. Vernadsky Gold Medal of NAS of Ukraine) |
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Molecular chirality and spontaneous symmetry breaking (report on the occasion of awarding of V.I. Vernadsky Gold Medal of NAS of Ukraine) |
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molecular chirality and spontaneous symmetry breaking (report on the occasion of awarding of v.i. vernadsky gold medal of nas of ukraine) |
| author |
Larsson, M. |
| author_facet |
Larsson, M. |
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Загальні збори НАН України |
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Загальні збори НАН України |
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2022 |
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English |
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Вісник НАН України |
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Видавничий дім "Академперіодика" НАН України |
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Article |
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0372-6436 |
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https://nasplib.isofts.kiev.ua/handle/123456789/185286 |
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Molecular chirality and spontaneous symmetry breaking (report on the occasion of awarding of V.I. Vernadsky Gold Medal of NAS of Ukraine) / M. Larsson // Вісник Національної академії наук України. — 2022. — № 7. — С. 50-53. — Бібліогр.: 4 назв. — англ. |
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2025-11-26T20:36:43Z |
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50 ISSN 1027-3239. Visn. Nac. Acad. Nauk Ukr. 2022. (7)
MOLECULAR CHIRALITY
AND SPONTANEOUS
SYMMETRY BREAKING
Report on the occasion of awarding of
V.I. Vernadsky Gold Medal of NAS of Ukraine
Introduction
A molecule that is not superimposable on its mirror image is found
in two different enantiomeric forms, which we denote left- and
right-handed. What is so striking is that life on Earth is homochi-
ral; proteins occur in L-form and sugars in D-form. We do not know
the origin of homochirality.
Molecular chirality was discovered in 1848 by Louis Pasteur.
It was a young Pasteur who made the leap from crystal chirality,
known since several decades, to molecular chirality. The concept of
chirality was instrumental in establishing the tetrahedral valencies
of the carbon atom, and has continued to play a key role in chemis-
try and molecular biology ever since.
Homochirality is an example of spontaneous symmetry break-
ing. Every sugar molecule made in a living organism is spiral in the
same way, and quantum mechanical tunneling between the two en-
antiomeric forms is extremely slow, in fact non-existing. The parity
symmetry can be ignored and the symmetry laws have been not
repealed, but broken. There are several other examples of sponta-
neous symmetry breaking in physics and chemistry, of which one
famous example is Bogolyubov’s treatment of a Bose condensate
[1]. This is a subtle and much less geometric symmetry breaking, as
compared with chirality. Another famous example from physics is
the introduction of order parameters to treat superconductivity by
Ginzburg and Landau [2].
A chiral molecule is a source of optical activity. A linearly polar-
ized light beam passing through an optically active medium will ex-
perience a rotation of the electric field vector. The direction of the
rotation depends on the chirality of the active medium. An optical
method that can differentiate between the two enantiomers of a chi-
ral molecule is referred to as a chiroptical technique. Linear and cir-
cular dichroism, and light scattering techniques have been developed
MATS LARSSON —
Department of Physics,
AlbaNova University Center,
Stockholm University
ISSN 1027-3239. Вісн. НАН України, 2022, № 7 51
ЗАГАЛЬНІ ЗБОРИ НАН УКРАЇНИ
to study molecules in gas and solution phase. The
increasing demand for enantiomeric pure pharma-
ceuticals causes a need for efficient enantioselec-
tive analytical methods. Drugs that contain only
one type of enantiomer are now the most common
type of drugs. This is because different biological
responses are obtained from different enantiomers
of the same drug; one enantiomer produces the de-
sired effect (eutomer) whereas the other has little
effect or a serious adverse effect (distomer).
Chiral recognition in biology is based on the
phenomenological three-point model, which
states that at least three configuration-dependent
interactions are required for a chiral selector to
recognize enantiomers. Figure 1 shows the three-
point model schematically.
Together with two young Ukrainian scientists,
Kostiantyn Kulyk and Oleksii Rebrov, we decid-
ed to test the three-point model experimentally.
Experiment and results
Enantiomers of Methionine (Met), Phenylala-
nine (Phe) and Tryptophan (Trp) of 98 % op-
Figure 1. The chiral selector is represented by the plane.
In order for the chiral selector to recognize the chiral mol-
ecule ABCD, three configuration-dependent points are
required. This is fulfilled to the left, but not to the right
Figure 2. Molecular structure of analytes and target gases
that were used in experiment
Figure 3. The Q-TOF instrument at the Department of
Chemistry, University of Oslo. The ion source is of elec-
trospray type. The ions are mass-selected and steered into
the collision cell. Collision products, either as formed
charged complexes or fragment ions, are analysed by the
reflectron
tical purity were purchased from Sigma Aldrich
and used in experiments without further purifi-
cation. R-2-butanol (RB), S-2-butanol (SB), ra-
cemic 2-butanol, and 1-S-Phenylethanol (SP) of
99 % purity were purchased from Sigma Aldrich
and used as target gases. Amino acids were dis-
solved in water/methanol/formic acid mixture
(49:49:2 v/v/v) at a concentration of 0.04 mM.
Molecular structure of amino acids and alcohols
used in experiment are shown on Figure 2.
Experiments were carried out in MS/MS mode
on the hybrid quadrupole time of flight (Q-ToF)
mass spectrometer (Q-ToF 2, Micromass®) at the
Department of Chemistry, University of Oslo
(see Figure 3). Ions were produced by electro-
spray ionization source in positive mode of opera-
tion with 3 kV needle voltage and 100 °C source
temperature. Precursor ions of studied amino
acid were isolated by the quadrupole analyzer
and transferred to a hexapole collision cell. After
reaction with target gas ion products were trans-
ferred to ToF analyzer and detected with micro-
channel plate detector. Target gas was introduced
to the collision cell via a needle valve. The gas
52 ISSN 1027-3239. Visn. Nac. Acad. Nauk Ukr. 2022. (7)
ЗАГАЛЬНІ ЗБОРИ НАН УКРАЇНИ
pressure in collision cell remained in a range of
7.02—8.2510–4 mBar during experiments with
2-butanol. The low pressure mode was used in
order to study the basic mechanism of projectile-
target complex formation in single collision mode.
Collision energy range used in measurements was
0.1—4 eV in the laboratory frame of reference.
The procedure of electrospray source cleaning
with water : methanol solution (50:50 v/v) was
performed after each measurement by spray-
ing the solution through the system for several
minutes.
The main product of an ion-molecule interac-
tion for all amino acids used in the experiment
was an adduct formation of analyte and target
gas. Figure 4 shows the mass spectra recorded by
the reflectron.
Based on the three-point model, one would
anticipate that the combination of projectile and
target chirality would affect the efficiency in
complex formation, but as seen in Figure 5, this
is not the case.
The results of the study of complex formation
was published in ref. [3]. The study does not nec-
Figure 4. Mass spectra obtained from collisions of L-form of Trp (a), Met (b), Phe (c) with (S)-(+)-2-butanol at 0.1 eV
collision energy. The parent ion (charged amino acids) is more abundant than the complex (diastereomer), but complex
formation is clearly a very likely outcome of the interaction between projectile and target in the collision cell
Figure 6. The amino acid Trp and butanol forms a
charged complex which is introduced into the gas phase
by the electrospray source. This diastereomer is now the
projectile and the target is achiral argon atoms. In the
collision process, butanol is lost and charged Trp detected
Figure 5. The abundance of complexes of L- and D-Met,
L- and D-Phe, and L- and D-Trp with (S)-2-butanol
as a function of collision energy. Within error bars, no
difference in formation efficiency between the L- and
D-forms are observed
ISSN 1027-3239. Вісн. НАН України, 2022, № 7 53
ЗАГАЛЬНІ ЗБОРИ НАН УКРАЇНИ
essarily invalidate the three-point model since we
were unable to control the orientation of neither
projectile nor target, which can lead to multiple
hydrogen-bonded complexes with similar struc-
ture and energy.
We therefore tried another strategy, explained
in Figure 6.
The results are shown in Figure 7, and taken
from ref. [4]. It is clear from Fig. 7 that S-Trp
is more stable when forming a complex with R-
butanol, since it is destroyed less frequently as
compared with R-Trp (Fig. 7b). The stability is
reversed when S-butanol is used, and now the R-
Trp + S-butanol complex is more stable than S-
Trp + S-butanol complex.
Conclusions
The results presented here are the first of their
type. It is the cleanest experiment ever carried out
for chiral molecules; mass-selected ions at con-
trolled energies in single collisions with a target
gas. The fact that we did not see any effect of chi-
rality in the experiments when we used charged
amino acids as projectiles [3] does not invalidate
the three-point model. It is quite possible that an
experiment with orientation-controlled projectile
and target would give a different outcome. Such
experiments would be extremely difficult and
have never been attempted. Instead we formed
complexes of chiral molecules, so called diastereo-
mers, and now clearly visible effects were noted
[4]. These experiments give some qualitative sup-
port of the three-point model.
Acknowledgement
I am extremely honored and thankful to the Na-
tional Academy of Sciences of Ukraine for award-
ing me the Vernadsky Gold Medal.
Figure 7. Relative abundance of protonated S- and R-Trp
fragment generated in dissociation of proton-bound
complex of S/R-Trp and S-2-butanol (a); R-2-butanol (b)
as a function of collision energy. Here we used the S/R
formalism instead of the L/D formalism for Trp, where S
equals L and R equals D. The higher the abundance, the
less stable is the complex
REFERENCES
1. Bogolyubov N. On the theory of superfluidity. Journal of Physics. 1947. 11: 23.
2. Ginzburg V.L., Landau L.D. K Teorii Sverkhprovodimosti (On the theory of superconductivity). Zh. Eksp. Teor. Fiz.
1950. 20: 1064.
3. Kulyk K., Rebrov O., Ryding M., Thomas R.D., Uggerud E., Larsson M. Low-energy collisions of enantiopure amino
acids with chiral target gases. J. Am. Soc. Mass Spectrom. 2017. 28(12): 2686. https://doi.org/10.1007/s13361-017-
1796-7
4. Rebrov O., Ryding M., Thomas R.D., Thorin M., Uggerud E., Larsson M. Non-covalently Bonded Diastereomeric
Adducts of Amino Acids and (S)-1-Phenylethanol in Low-energy Dissociative Collisions. Mol. Phys. 2020. 118(4):
e1615145. https://doi.org/10.1080/00268976.2019.1615145
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