The asymmetric unit of the title salt, C(4)H(12)N(2) (2+)·2C(7)H(4)NO(4) (-) or pipzH(2) (2+)·2(py-2,3-dcH(-)), prepared by a reaction between pyridine-2,3-dicarboxylic acid (py-2,3-dcH(2)) and piperazine (pipz), contains a monoanion and half of a centrosymmetric dication. The anionic fragment individually has two intra-molecular hydrogen bonds, an almost linear O-H⋯O bond between two carboxyl-...

The complete mol-ecule of the title compound, C(8)H(12)N(4), is generated by a crystallographic inversion centre. The piperazine ring adopts a chair conformation with the N-bonded substituents in equatorial positions. In the crystal, mol-ecules are linked by C-H⋯N(c) (c = cyanide) hydrogen bonds.

In the title compound, C(27)H(26)Br(2)N(2)O, the piperazine ring adopts a chair conformation with the N-C bonds in equatorial orientations. The C=C double bond has an E configuration. The dihedral angle between the bromo-benzene rings is 83.0 (4)°. In the crystal, inversion dimers linked through pairs of C-H⋯O hydrogen bonds generate R(2) (2)(10) loops.

In the title compound, C15H23N3O3, the piperazine ring is in a slightly distorted chair conformation and is twisted from the mean plane of the benzene ring making a dihedral angle of 14.94 (6)°. The 4-meth-oxy substituent is almost co-planar with the benzene ring [C-C-O-C torsion angle = 5.4 (1)°], while the meth-oxy groups at positions 2 and 3 [C-C-O-C torsion angles of 122.6 (4) and -66.1 (4)...

In the title compound, C(11)H(17)N(2)O(+)·Cl(-), the dihedral angle between the benzene ring and the basal plane of piperazine ring is 39.20 (8)°. In the crystal, intermolecular N-H⋯Cl hydrogen bonds occur. There is also a C-H⋯π inter-action between the benzene rings.

In the title mol-ecule, C(26)H(23)Br(3)N(2)O, the piperazine ring adopts a chair conformation and the C=C double bond has an E configuration. In the crystal, mol-ecules are linked through weak inter-molecular C-H⋯O hydrogen bonds.

In the title compound, C(13)H(14)ClN(5), the piperazine ring adopts a chair conformation and the dihedral angle between the aromatic rings is 13.91 (7)°. The crystal structure is stabilized by weak inter-molecular C-H⋯N hydrogen-bond inter-actions.

In a search for new bactericidal and fungicidal agents some new piperazine-TV, TV'-bis-substituted derivatives have been prepared and characterized by their elemental analysis, IR, *H N M R , and mass spectral d a t a . T h e ant ibacter ia l and antifungal activities of all p repared c o m p o u n d s have been determined using Gentamycin as s t a n d a r d antibiotic. Some c o m p o u n d s s...