Application of polarization transfer algorithm in organic molecules with three nonequivalent coupled spins

Polarization transfer between three $1/2$ nuclear spins in a specially prepared isotopically enriched molecule diethylphthalimide malonate-2-$^{13}$C,$^{15}$N molecule was obtained using the nuclear magnetic resonance (NMR) method. The polarization transfer was performed by implementing a sequence of radio frequency pulses and waiting intervals. Relaxation times and NMR spectrum for the studied nuclei were measured in samples of molecules with natural and enriched isotopes $^{13}$C and $^{15}$N. Measurements of the proton relaxation rate for diethylphthalimidomalonate and diethylpthalimidomalonate-2-$^{13}$C,$^{15}$N showed an increase in relaxation rate by a factor of 4 for protons bound to $^{13}$C,$^{15}$N nuclei. The use of the quantum polarization transfer method made it possible to reduce the measurement time of the relaxation rate of spin polarization $^{15}$N by about 500 times. In addition, the possibility of implementing three-qubit quantum gates using this molecule was shown.