Piperazine-1,4-diium bis­(perchlorate) dihydrate

The asymmetric unit of the title compound, C4H12N2 2+·2ClO4 −·2H2O, contains half of a piperazinediium cation, one perchlorate anion and one water mol­ecule. The diprotonated piperazine ring, which is completed by crystallographic inversion symmetry, adopts a chair conformation. In the crystal structure, the cations and anions are linked by inter­molecular N—H⋯O and O—H⋯O hydrogen bonds into a three-dimensional network

(±)-2-Methyl­piperazin-1-ium perchlorate

In the title compound, C5H13N2 +·ClO4 −, the monoprotonated piperazine ring adopts a chair conformation. In the crystal structure, cations and anions are linked by inter­molecular N—H⋯O and N—H⋯N hydrogen bonds into layers parallel to (01)

4-(N-Propan-2-ylcarbamo­yl)pyridinium perchlorate

In the title compound, C9H13N2O+·ClO4 −, the dihedral angle between the planes of the amide group and the pyridinium fragment is 34.11 (14)°. In the crystal, the cations are connected by N—H⋯O hydrogen bonds between the amide groups into chains extended along the a axis. Hydrogen bonds between the pyridinium N—H group and the perchlorate anions organize the chains into a two-dimensional network

On the giant deformation and ferroelectricity of guanidinium nitrate

The extraordinary properties of materials accompanying their phase transitions are exciting from the perspectives of scientific research and new applications. Most recently, Karothu et al.1 described guanidinium nitrate, [C(NH2)3]+[NO3]-, hereafter GN, as a ferroelectric semiconducting organic crystal with exceptional actuating properties. However, the ferroelectric and semiconducting properties of this hybrid organic-inorganic material were not confirmed by the experimental results, and the reproducibility of the large stroke associated with the first-order transition is questionable, because the GN crystals are inherently susceptible to the formation of defects. Besides, previous extensive studies on GN were not acknowledged

Negative linear compression and expanding NH N bonds in an imidazoline compound.

The 3-dimensional network of NHN hydrogen bonds and ClCl hydrogen contacts in the crystal structure of 2-(3′-chlorophenyl)imidazoline exhibits an anomalous hydrostatic compression. The lengthening of hydrogen bonds NHN and some CHN contacts as well as their supramolecular architecture lead to anomalous expansion of the crystal along [x] and [y] on increasing pressure to 0.1 GPa. The mechanism of this phenomenon is due to the ‘stiffness’ of the NHN and ClCl interactions and ‘softness’ of other van der Waals contacts. Above 0.1 GPa all crystal directions become compressed. However, up to 1.20 GPa, the crystal remains in the same orthorhombic phase of polar space group Fdd2

Supramolecular structure of the 1:2 complex of 1,4-dimethylpiperazine mono-betaine with squaric acid

The 1: 2 complex of 1,4-dimethylpiperazine mono-betaine (MBPZ) with squaric acid (H(2)SQ) has been characterised by single-crystal X-ray analysis, FTIR and NMR spectroscopies, and by DFT calculations. The crystals are monoclinic, space group P2(1)/c. Two MBPZ cations and four hydrogen squarate anions (HSQ(-)) are linked by strong O(1)=H center dot center dot center dot O(13) (2.525(4) angstrom), O(14)-H center dot center dot center dot O(21) (2.511(4) angstrom) and N(4)-H center dot center dot center dot O(23) (2.607(3)angstrom) hydrogen bonds into a cyclamer R-6(6)(38). In turn, the cyclamers are linked into a helix C-4(4)(20) through two O(24)-H center dot center dot center dot O(11) hydrogen bonds of 2.516(4)angstrom. The piperazinium ring has a chair conformation with N(4)-CH3 and N(1)-CH2COOH substituents in the equatorial positions, and N(1)-CH3 in the axial position. The FTIR spectrum is consistent with the crystal data. Two models of the 1: 2 complex of MBPZ with H(2)SQ have been optimised at the B3LYP/6-311++G(d,p) level of theory and have been used to calculate harmonic IR frequencies. One of the models (2) is dominated by electrostatic attraction between NH(4)(+) and HSQ(-), whereas in the other (3) squaric acid interacts with a zwitterionic MBPZ through the O-H center dot center dot center dot O and O-H center dot center dot center dot N hydrogen bonds