L-selenomethionine 1 crystallizes in P2(1) space group with two molecules in the asymmetric unit. Solid-state NMR spectroscopy is used for searching of structure and dynamics of 1 in the crystal lattice. The distinct molecular motion of side chains for A and B molecules of 1 is apparent from measurements of relaxation parameters (1H 1rho, 13C T1) and analysis of CSA data (2D-PASS experiment). The 13C delta(ii) and 77Se delta(ii) parameters are correlated with theoretical shielding parameters obtained by means DFT GIAO calculations. Attempt to explain the mechanism of phase transition of crystals of 1 at 313K is presented.
In this work, we report the structural studies on the solid state of two benzodiazacoronads that form chiral and achiral crystals. Crystals have to be considered as a two-component system consisting of an organic unit and a water molecule in 1:1 ratio. Both components play an important role in the crystal structure. The strong (O-H...O, N-H...O) and weak (C-H...O) intermolecular hydrogen bonds are responsible for phase organization and, in consequence, formation of chiral or achiral crystals. The alignment of the water molecule with respect to the macrocycle is different for samples 1 and 2. Removal of water from the crystal lattice of 1 is reversible. Formation of chiral cocrystals from two different achiral molecules by self-assembly is well-known. However, in this paper, we show that the water molecule can be an important achiral cofactor responsible for chiral crystallization.
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