Understand, elucidate and rationalize the coordination mode of pyrimidylmethylamines: an intertwined study combining NMR and DFT methods †

International audiencea Conception of new pyrimidylmethylamine (pyrma) ligands and their corresponding Pd(II) complexes has been described. Both symmetrical and non-symmetrical ligands were prepared and subjected to complexation. Two different coordination modes, Pd(N,N)– or Pd(C,N,N)–pyrma, have been evidenced depending on the substitution of the pyrimidine ring and the nature or the shape of the additional pendant arm. In a non-symmetrical pyrimidine series, the substituent-induced discrimination of each heterocyclic nitrogen atom provoked regio-controlled coordination to the metal center. The molecular structure of pyrma–Pd(II) complexes in the solution state has been elucidated thanks to combined NMR experiments and DFT calculations. This study highlights the potency of 15 N and 13 C NMR spectroscopy for the elucidation of the regio-selective coordination to the Pd(II) in the pyrma-based complex series. DFT calculations were highly relevant to the identification of crucial factors that govern the regio-selectivity and the complexation modes. Close predicted and experimental chemical shift values put into relief the reliability of coordination modes for the most stable complexes in solution, depicted by DFT approaches

Large-Scale Production of Microcrystals and Precipitates of Proteins and Their Complexes

International audienceThe optimum conditions for the formation of plate-like and urchin-like microcrystals of biomolecules and their transfer to rotors for solid-state NMR spectroscopy depend on a variety of factors, of which minimizing the manipulation of the microcrystals and storing the sample for several months at 277 K (4 degrees C) play an important role. Three biological systems were investigated: Hen Egg-White (HEW) lysozyme (129 residues), the lengthened C-terminal domain (LCter) of Human centrin 2 (89 residues), and the complex between the C-terminal domain (Cter) of Human centrin 2 (79 residues) and the P17-XPC peptide (17 residues)