Influence of Hydrogen/Fluorine Substitution on Structure, Thermal Phase Transitions, and Internal Molecular Motion of Aromatic Residues in the Crystal Lattice of Steroidal Rotors
Por:
Pawlak, Tomasz, Czajkowska-Szczykowska, Dorota, Jastrzebska, Izabella, Santillan, Rosa, Seroka, Barbara, Maj, Jadwiga, Morzycki, Jacek W., Labra-Vazquez, Pablo, Farfan, Norberto, Bujacz, Grzegorz D., Potrzebowski, Marek J.
Publicada:
1 abr 2020
Resumen:
Two, acyclic (1) and cyclic (2), steroidal molecular rotors containing
1,4-diethynyl-2,3-difluoro-phenylene units as rotators were investigated
by means of single crystal X-ray diffraction, high resolution solid
state NMR spectroscopy, and computer methods. The aim of this study was
to understand and search for a correlation between the size of
difluoro-phenylene units and free space in the crystal lattice required
for molecular reorientation as well as the topology and time scale of
dynamic processes. As a primary tool for analysis of molecular motions
in the solid state, H-1-C-13 PISEMA, a technique which allows following
the dynamics in the range of 10(-3)-10(-6) s, was employed. The PISEMA
data defining the H-1-C-13 dipolar couplings, whose values are sensitive
to local motion, were confronted with C-13 CSA parameters. Our studies
revealed that replacing hydrogen by fluorine in acyclic rotors has
significant consequences for dynamic processes. In the case of
hydrogen-substituted species, free rotation around the 1-4 axis of the
benzene ring was proven. For fluorine derivatives 1, only small
amplitude wobbling of aromatic residues was observed. The only large
amplitude reorientation, a so-called pi-jump around the 1-4 axis, was
observed during the phase transition related with solvent migration from
the crystal lattice. For cyclic rotors (2) two crystallographic forms 2A
(triclinic, P1 space group) and 2B (monoclinic, P2(1) space group) are
established. The form 2B containing a heptane molecule in the crystal
lattice undergoes a thermal transition with large amplitude motion of
building units of the steroidal frame. The high dynamics of the
fluorinated rotator for 2A is proven.
Filiaciones:
Pawlak, Tomasz:
Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, Lodz, 90-363, Poland
Polish Acad Sci, Ctr Mol & Macromol Studies, PL-90363 Lodz, Poland
Czajkowska-Szczykowska, Dorota:
Faculty of Chemistry, University of Bialystok, Ciolkowskiego 1K, Bialystok, 15-245, Poland
Univ Bialystok, Fac Chem, PL-15245 Bialystok, Poland
Jastrzebska, Izabella:
Faculty of Chemistry, University of Bialystok, Ciolkowskiego 1K, Bialystok, 15-245, Poland
Univ Bialystok, Fac Chem, PL-15245 Bialystok, Poland
Santillan, Rosa:
Departamento de Qulmica, Centro de Investigación y de Estudios Avanzados Del IPN, Apdo. Postal 14-740, Ciudad de México, 07000, Mexico
Ctr Invest & Estudios Avanzados IPN, Dept Quim, Ciudad De Mexico 07000, Mexico
Seroka, Barbara:
Faculty of Chemistry, University of Bialystok, Ciolkowskiego 1K, Bialystok, 15-245, Poland
Univ Bialystok, Fac Chem, PL-15245 Bialystok, Poland
Maj, Jadwiga:
Faculty of Chemistry, University of Bialystok, Ciolkowskiego 1K, Bialystok, 15-245, Poland
Univ Bialystok, Fac Chem, PL-15245 Bialystok, Poland
Morzycki, Jacek W.:
Faculty of Chemistry, University of Bialystok, Ciolkowskiego 1K, Bialystok, 15-245, Poland
Univ Bialystok, Fac Chem, PL-15245 Bialystok, Poland
Labra-Vazquez, Pablo:
Facultad de Qulmica, Departamento de Qulmica Orgánica, Universidad Nacional Autónoma de México, Ciudad de México, 04510, Mexico
Univ Nacl Autonoma Mexico, Fac Quim, Dept Quim Organ, Ciudad De Mexico 04510, Mexico
Farfan, Norberto:
Facultad de Qulmica, Departamento de Qulmica Orgánica, Universidad Nacional Autónoma de México, Ciudad de México, 04510, Mexico
Univ Nacl Autonoma Mexico, Fac Quim, Dept Quim Organ, Ciudad De Mexico 04510, Mexico
Bujacz, Grzegorz D.:
Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 4/10, Lodz, 90-924, Poland
Lodz Univ Technol, Fac Biotechnol & Food Sci, Inst Tech Biochem, PL-90924 Lodz, Poland
Potrzebowski, Marek J.:
Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, Lodz, 90-363, Poland
Polish Acad Sci, Ctr Mol & Macromol Studies, PL-90363 Lodz, Poland
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