The asymmetric unit of the title compound, C(5)H(6)N(3)O(2) (+)·HSeO(4) (-), contains two monoprotonated 2-amino-3-nitro-pyridinium cations and two hydrogen selenate anions which are connected through N-H⋯O and O-H⋯O hydrogen bonds, building chains parallel to the a direction. These chains are further connected to each other by weaker C-H⋯O hydrogen-bonding inter-actions, leading to the formati...

In the title compound, C(7)H(16)NO(2) (+)·Cl(-), the asymmetric unit consists of two cation-anion pairs, in which the ion pairs are inter-connected by weak C-H⋯Cl hydrogen bonds. Each cation forms a network of weak C-H⋯Cl hydrogen bonds to surrounding chloride ions. The morpholine ring is in a chair conformation. The crystal structure is consolidated by O-H⋯Cl, C-H⋯Cl and C-H⋯O inter-molecular ...

The non-H atoms in the structure of the title mol-ecule, C7H7N3, are almost coplanar (r.m.s. deviation = 0.018 Å). The two amine groups each donate two and accept one weak N-H⋯N hydrogen bonds. N-H⋯N hydrogen bonding between the amine and nitrile groups results in chains parallel to [101] in the crystal structure. The chains are cross-linked by N-H⋯N hydrogen bonds between amine groups, giving ...

In the title compound, C(23)H(19)N(8)O(+)·BF(4) (-), one pyridine N atom is protonated. Two intra-molecular N-H⋯N hydrogen bonds occur. In the crystal, inter-molecular N-H⋯N hydrogen bond links neighboring C(23)H(19)N(8)O(+) units into cyclic supra-molecular dimers while C-H⋯O hydrogen bonds link the C(23)H(19)N(8)O(+) units into a two-dimensional supra-molecular network structure.

In the title salt, C(8)H(16)N(2)O(4) (2+)·2H(2)PO(4) (-)·2H(2)O, the piperazine ring is located around an inversion center and adopts a chair conformation. The dihydrogen phosphate anions and free water mol-ecules are linked via O-H⋯O hydrogen bonds into two-dimensional hydrogen-bonding layers, which are further connected through O-H⋯O and N-H⋯O hydrogen bonds involving the protonated piperazin...

The mechanism of the denaturing effects of urea and the guanidinium ion on proteins is still an unsolved and important problem in protein chemistry. Changes in the hydrogen bond network of water in the first hydration shell of urea and guanidinium were analyzed in terms of the random network model using Monte Carlo simulations. Bulk water consists of two populations of hydrogen bonds: a predomi...

In the title salt, C2H10N2 (2+)·2C14H10NO3 (-), the ethyl-ene-diaminium dication lies on an inversion centre. In the anion, the benzene rings make a dihedral angle of 33.87 (9)° and intramolecular N-H⋯O and C-H⋯O hydrogen bonds occur. All the amino H atoms are involved in N-H⋯O hydrogen bonds. These hydrogen bonds link the ionic units into a three-dimensional network. In addition, the crystal s...

In the title compound, C(15)H(21)NO(5)S, two crystallographically independent mol-ecules are linked into a dimer by a pair of N-H⋯O hydrogen bonds, forming an R(2) (2)(8) ring motif. In the crystal, mol-ecules are further linked by inter-molecular O-H⋯O hydrogen bonds into a two-dimensional network parallel to (012). Additional stabilization is provided by weak inter-molecular C-H⋯O hydrogen bo...

In the crystal structure of the title compound, C(15)H(13)BrN(2)O(5)·CH(3)OH, the methanol solvent mol-ecule links symmetry-related mol-ecules through O-H⋯O and N-H⋯O hydrogen bonds. Further inter-molecular O-H⋯O hydrogen bonds link symmetry-related mol-ecules, leading to the formation of a three-dimensional network. Two of the H atoms involved in hydrogen bonding are disordered. The dihedral a...

The asymmetric unit of the title compound, 2C6H9N2 (+)·HPO4 (2-), comprises two 2-amino-anilinium cations and one hydrogen phosphate dianion. In the crystal, the HPO4 (2-) dianions are linked by O-H⋯O hydrogen bonds into chains along [100]. The inorganic anionic chains and organic cations are linked by N-H⋯O and N-H⋯N hydrogen bonds, forming a two-dimensional supra-molecular network extending p...