L-Leucinium perchlorate

Crystals of L-leucinium perchlorate, C₆H₁₄NO₂⁺·ClO₄⁻, are built up from protonated L-leucinium cations and perchlorate anions. L-Leucinium cations related by a twofold screw axis are inter­connected by N—H...O hydrogen bonds into zigzag chains parallel to [010]. The O atoms of the perchlorate anions act as acceptors of hydrogen bonds that link the L-leucinium chains into separated but inter­acting two-dimensional layers parallel to (001). Since the title compound crystallizes in a non-centrosymmetric space group, it can be useful as a material for non-linear optics. The efficiency of second harmonic generation is about twice that of K₂[HPO₄].

2,4-Diamino-6-methyl-1,3,5-triazin-1-ium trifluoro­acetate

Crystals of the title compound, C₄H₈N₅⁺·C₂F₃O₂⁻, are built up of singly protonated 2,4-diamino-6-methyl-1,3,5-triazin-1-ium cations and trifluoro­acetate anions. The CF₃ group of the anion is disordered. The oppositely charged ions inter­act via almost linear N—H...O hydrogen bonds, forming a CF₃COO⁻...C₄H₈N₅⁺ unit. Two units related by an inversion centre inter­act through a pair of N—H...N hydrogen bonds, forming planar (CF₃COO⁻...C₄H₈N₅⁺...C₄H₈N₅⁺·CF₃COO⁻) aggregates that are linked by a pair of N—H...O hydrogen bonds into chains running along the c axis.

2,4,6-Triamino-1,3,5-triazine–1H-isoindole-1,3(2H)-dione (1/3)

The asymmetric unit of the title compound, C₃H₆N₆·3C₈H₅NO₂, contains a melamine and a phthalimide [1H-isoindole-1,3(2H)-dione] mol­ecule, both residing on a mirror plane, and a second phthalimide mol­ecule residing on a general position. The two components are linked by almost linear N—H...O and N—H...N hydrogen bonds, forming an essentially planar superstructure. These aggregates, related by a twofold screw axis, inter­act through weak C—H...O contacts, forming chains parallel to the b axis, while those related by translation along the c axis inter­act via π–π inter­actions between the π clouds of the aromatic triazine and phthalimide rings to form a stacked structure.