Paramagnetic Properties and Moderately RapidConformational Dynamics in the Cobalt(II) Calix[4]arene Complex by NMR

Eugeny Nikolaevich Zapolotsky; Sergey Pavlovich Babailov; Gennadiy Alexandrovich Kostin

doi:10.3390/molecules27144668

Paramagnetic Properties and Moderately RapidConformational Dynamics in the Cobalt(II) Calix[4]arene Complex by NMR

Molecules. 2022 Jul 21;27(14):4668. doi: 10.3390/molecules27144668.

Authors

Eugeny Nikolaevich Zapolotsky¹, Sergey Pavlovich Babailov¹, Gennadiy Alexandrovich Kostin¹

Affiliation

¹ Nikolayev Institute of Inorganic Chemistry SB RAS, 630090 Novosibirsk, Russia.

Abstract

¹H NMR measurements are reported for the CD₂Cl₂/CDCl₃ solutions of the Co(II) calix[4]arenetetraphosphineoxide complex (I). Temperature dependences of the ¹H NMR spectra of I have been analyzed using the line shape analysis, taking into account the temperature variation of paramagnetic chemical shifts, within the frame of the dynamic NMR method. Conformational dynamics of the 2:1 Co(II) calix[4]arene complexes was conditioned by the pinched cone ↔pinched cone interconversion of I (with activation Gibbs energy ΔG^≠(298K) = 40 ± 3 kJ/mol. Due to substantial temperature dependence of paramagnetic shifts, complex I can be used as model compound for designing an NMR thermosensor reagent for local temperature monitoring.

Keywords: Gibbs free energy of activation; calix[4]arene; complexes of lanthanides; dynamic NMR; molecular dynamics; tetraphosphineoxide substituent.

MeSH terms

Calixarenes* / chemistry
Cobalt*
Magnetic Resonance Spectroscopy / methods
Phenols / chemistry

Substances

Phenols
calix(4)arene
Calixarenes
Cobalt

Grants and funding

20-63-46026/Russian Science Foundation