Relaxing Time: a T1 study for heteronuclei

Longitudinal relaxation (T1) is a NMR phenomenon that implies the return of the bulk magnetization to the equilibrium state (MZ). This process occurs by the fluctuations on the magnetic field in the Larmor frequency of the nucleus, which allows the energetic changes in the excited states of the spins and the lattice. Knowing these times can bring information about the dynamics of the molecules [1] and is associated with the experimental time of quantitative analyses.
To measure the T1, pulse sequences such as the Saturation-Recovery (SR) [2] and Inversion-Recovery (IR) are used [3]. T1 values can vary for each nuclei due to the difference in Larmor frequency between them [4].
This work has the aim to analyze T1 values for the most important nuclei (1H, 13C and 19F) in organic compounds, as well as how a Paramagnetic Agent (P.A), which enhances the relaxation process [5], affects each nuclei. The decrease in the relaxation time T1 by the P.A will be compared. To measure T1 values the saturation time was optimized in SR sequence. This parameter was also compared for different nuclei.

References
1. Gkoura, Lydia, et. al. Int. J, Mol. Sci. 24(7), 6739 (2023)
2. Percival, Paul W.; Hyde, James S. J. Magn. Reason. 23(2), 249-257 (1976).
3. Allegretti, Chiara, et. al. RSC Adv. 13, 3004-3007 (2023).
4. Peng, Jeffrey W.; Wagner Gerhard. J. Magn. Reson. 98(2), 308-332 (1992).
5. Mulder, Frans AA; Tenori, Leonardo; Luchinat, Claudio. Angew. Chem. Int. Ed. 131, 15427-15430 (2019).

Acknowledgment
We thank CAPES and FAPESP for financial support (grants #2020/10246-0) and the IQ-UNICAMP for the infrastructure and NMR facilities.