Bis(4-aminopyridinium) dichromate(VI)

Bis(2-aminopyridinium) tetra­chloridozincate(II)

In the title compound, (C(5)H(7)N(2))(2)[ZnCl(4)], the pyridine N atoms are protonated and the [ZnCl(4)](2-) anions adopt a slightly distorted tetra-hedral configuration. In the crystal, weak N-H⋯Cl hydrogen bonds link the mol-ecules into layers, while weak π-π inter-actions [centroid-centroid distance = 4.2758 (18) Å] also help to stabilize the packing.

2-aminopyridinium benzoate.

Cyclic eight-membered hydrogen-bonded rings exist in the title compound, C(5)H(7)N(2)(+).C(7)H(5)O(2)(-), involving the 2-aminopyridinium and benzoate ions. Each benzoate ion has two intramolecular hydrogen bonds. 2-Aminopyridinium benzoate ion pairs are linked by N-H...O hydrogen bonds, with an N...O distance of 2.8619 (14) A.

A second polymorph of 2-aminopyridinium dihydrogenphosphate.

In the title compound, beta-C5H7N2+.H2PO4-, the tetrahedral dihydrogenphosphate moieties are linked into double chains by O-H...O hydrogen bonds, and the organic species crosslink the chains into sheets by way of N-H...O bonds. The resulting structure is quite different from that of the previously described alpha polymorph of this stoichiometry [Czapla, Dacko & Waskowska (2003). J. Phys. Conden...

Synthesis, Growth and Characterization of Nonlinear Optical Bis(2-aminopyridinium) Sulfate Single Crystals

Helical chiral 2-aminopyridinium ions: a new class of hydrogen bond donor catalysts.

Helical chiral 2-aminopyridinium ions were designed as a significantly more acidic (active) dual hydrogen-bonding catalyst than commonly used (thio)urea-based systems. The helicene framework was specifically utilized to position an inherently chiral barrier on the hydrogen-bonding side of the catalyst. The catalyst reactivity and enantioselectivity were successfully demonstrated in additions of...