Structure and serotonin 5-HT2C receptor activity of ortho- and meta-substituted phenylpiperazines

Syntheses and crystal structures of 4-(4-meth-oxy-phen-yl)piperazin-1-ium 4-methyl-benzoate monohydrate and bis-[4-(4-meth-oxy-phen-yl)piperazin-1-ium] benzene-1,2-di-carboxyl-ate

Co-crystallization of N-(4-meth-oxy-phen-yl)piperazine with 4-methyl-benzoic acid and with benzene-1,2-di-carb-oxy-lic acid yields the salts 4-(4-meth-oxy-phen-yl)piperazin-1-ium 4-methyl-benzoate monohydrate, C11H17N2O+·C8H7O2 -·H2O (I), and bis-[4-(4-meth-oxy-phen-yl)piperazin-1-ium] benzene-1,2-di-carboxyl-ate, 2C11H17N2O+·C8H4O4 2- (II). These salts both crystallize with Z' = 2, in space groups P and Pna21, respectively. In compound (I), a combination of four O-H⋯O, four N-H⋯O, one C-H⋯O and one C-H⋯π(arene) hydrogen bonds link the six independent components into complex sheets, within which the two piperazine rings, the two anions, and the two water mol-ecules are related by an approximate, non-crystallographic translation along the b-axis direction. In compound (II), sheets containing R 4 4(18) and R 10 12(38) rings are formed by the combined action of eight independent N-H⋯O hydrogen bonds. Comparisons are made with the structures of some related compounds.

Crystal structure of 4-(2-meth-oxy-phen-yl)piper-azin-1-ium 3,5-dintrosalicylate

The title salt [systematic name: 4-(2-methoxyphenyl)piperazin-1-ium 2-carboxy-4,6-dinitrophenolate], C11H17N2O+·C7H3N2O7 -, exhibits secondary nitro-gen atoms (N-H) in the 2-meth-oxy-phenyl-piperazine (2MeOPP) cation, which is protonated with a phenolic hydrogen atom of 3,5-di-nitro-salicylic acid (DNSA). One of the oxygen atoms of the nitro group in the 3,5-di-nitro-salicylate anion is disordered over two orientations with occupancy factors of 0.65 (7) and 0.35 (7) . The 2-meth--oxy-phenyl-piperazinium cation and 3,5-di-nitro-salicylate anion are linked in the asymmetric unit by a bifurcated N-H⋯O hydrogen bond, which formed is between the H atom in the protonated piperazinium unit of the cation and the carb-oxy-lic acid group in the anion. The piperazine ring adopts a chair conformation. The crystal structure features N-H⋯O and C-H⋯O hydrogen bonds inter-actions, which lead to the formation of a sandwich-like arrangement. Hirshfeld surface analysis was used to determine the relative contributions of various inter-molecular inter-actions, indicating that that H⋯O/O⋯H (38. 3%) and H⋯H (31. 8%) contacts are the major contributors.

Fifteen 4-(2-meth-oxy-phen-yl)piperazin-1-ium salts containing organic anions: supra-molecular assembly in zero, one, two and three dimensions

Fifteen 4-(2-meth-oxy-phen-yl)piperazin-1-ium salts containing organic anions have been prepared and structurally characterized. In the isostructural 4-chloro-benzoate and 4-bromo-benzoate salts, C11H17N2O+·C7H4ClO2 - (I) and C11H17N2O+·C7H4BrO2 - (II), and the 4-iodo-benzoate salt C11H17N2O+·C7H4IO2 - (III), the ions are linked by N-H⋯O hydrogen bonds, forming centrosymmetric R 4 4(12) four-ion aggregates; a similar aggregate is formed in the 2-chloro-benzoate salt (V), isomeric with (I). In the 2-fluoro-benzoate salt C11H17N2O+·C7H4FO2 - (IV), and the isomorphous pair of salts, the 2-bromo-benzoate (VI), isomeric with (II) and 2-iodo-benzoate (VII), isomeric with (III), N-H⋯O and C-H⋯π(arene) interactions link the components into three-dimensional arrays. Four-ion R 4 4(12) aggregates are also found in the 2-methyl-benzoate, 4-amino-benzoate and 4-nitro-benzoate salts, C11H17N2O+·C8H7O2 - (VIII), C11H17N2O+·C7H6NO2 - (IX) and C11H17N2O+·C7H4NO4 - (X), but those in (IX) are linked into complex sheets by an additional N-H⋯O hydrogen bond. In the 3,5-dinitrobenzoate salt, C11H17N2O+·C7H3N2O6 -·2H2O (XI), N-H⋯O and O-H⋯O hydrogen bonds link the components into a complex ribbon structure. In the picrate salt, C11H17N2O+·C6H2N3O7 - (XII), the four-ion aggregates are linked into chains of rings by C-H⋯O hydrogen bonds. In the hydrogen maleate salt, C11H17N2O+·C4H3O4 - (XIII), two- and three-centre hydrogen bonds link the ions into a ribbon structure while both anions contain very short but asymmetric O-H⋯O hydrogen bonds, having O⋯O distances of 2.4447 (16) and 2.4707 (17) Å. O-H⋯O Hydrogen bonds link the anions in the hydrogen fumarate salt (XIV), isomeric with (XIII), into chains that are linked into sheets via N-H⋯O hydrogen bonds. In the hydrogen (2R,3R)-tartrate salt, C11H17N2O+·C4H5O6 -·1.698H2O (XV), the anions are linked into sheets by O-H⋯O hydrogen bonds. Comparisons are made with the structures of some related compounds.

Twelve 4-(4-meth-oxy-phen-yl)piperazin-1-ium salts containing organic anions: supra-molecular assembly in one, two and three dimensions

Twelve 4-(4-meth-oxy-phen-yl)piperazin-1-ium salts containing organic anions have been prepared and structurally characterized. The monohydrated benzoate, 4-fluoro-benzoate, 4-chloro-benzoate and 4-bromo-benzoate salts, C11H17N2O+·C7H5O2 -·H2O (I), C11H17N2O+·C7H4FO2 -·H2O (II), C11H17N2O+·C7H4ClO2 -·H2O (III), and C11H17N2O+·C7H4BrO2 -·H2O (IV), respectively, are isomorphous and all exhibit disorder in the 4-meth-oxy-phenyl unit: the components are linked by N-H⋯O and O-H⋯O hydrogen bond to form chains of rings. The unsolvated 2-hy-droxy-benzoate, pyridine-3-carboxyl-ate and 2-hy-droxy-3,5-di-nitro-benzoate salts, C11H17N2O+·C7H5O3 - (V), C11H17N2O+·C6H4NO2 - (VI) and C11H17N2O+·C7H3N2O7 - (VII), respectively, are all fully ordered: the components of (V) are linked by multiple N-H⋯O hydrogen bonds to form a chain of rings; those of (VI) are linked into a three-dimensional framework by a combination of N-H⋯O, C-H⋯O and C-H⋯N hydrogen bonds and those of (VII), where the anion has a structure reminiscent of the picrate anion, are linked into a three-dimensional array by N-H⋯O and C-H⋯O hydrogen bonds. The hydrogensuccinate and hydrogenfumarate salts, C11H17N2O+·C4H5O4 - (VIII) and C11H17N2O+·C4H3O3 - (IX), respectively, are isomorphous, and both exhibit disorder in the anionic component: N-H⋯O and O-H⋯O hydrogen bonds link the ions into sheets, which are further linked by C-H⋯π(arene) inter-actions. The anion of the hydrogenmaleate salt, C11H17N2O+·C4H3O3 - (X), contains a very short and nearly symmetrical O⋯H⋯O hydrogen bond, and N-H⋯O hydrogen bonds link the anions into chains of rings. The ions in the tri-chloro-acetate salt, C11H17N2O+·C2Cl3O2 - (XI), are linked into simple chains by N-H⋯O hydrogen bonds. In the hydrated chloranilate salt, 2C11H17N2O+·C6Cl2O4 2-·2H2O (XII), which crystallizes as a non-merohedral twin, the anion lies across a centre of inversion in space group P21/n, and a combination of N-H⋯O and O-H⋯O hydrogen bonds generates complex sheets. Comparisons are made with the structures of some related compounds.

1-Methyl-piperazine-1,4-diium dipicrate

IN THE CRYSTAL STRUCTURE OF THE TITLE COMPOUND [SYSTEMATIC NAME: 1-methyl-piperazine-1,4-diium bis-(2,4,6-trinitro-phen-ol-ate)], C(5)H(14)N(2) (2+)·2C(6)H(2)N(3)O(7) (-), the ionic components are connected by relatively strong N-H⋯O hydrogen bonds into centrosymmetric six-membered conglomerates, which comprise two dications and four anions. Besides Coulombic inter-actions, only weak C-H⋯O inter-actions and some stacking between picrates (separation between the planes of ca. 3.4 Å but only a small overlapping) can be identified between these 'building blocks' of the crystal structure. The piperazine ring adopts a chair conformation with the methyl substituent in the equatorial position. In the picrate anions, the twist angles of the nitro groups depend on their positions relative to the phenolate O atom: it is much smaller for the NO(2) groups para to the C-O(-) group [15.23 (9)and 3.92 (14)°] than for the groups in the ortho positions [28.76 (13)-39.84 (11)°].

Investigations on the synthesis and pharmacological properties of 4-alkoxy-2-[2-hydroxy-3-(4-aryl-1-piperazinyl)propyl]-6-methyl-1H-pyrrolo[3,4-c]pyridine-1,3(2H)-diones

Synthesis of 2-[2-hydroxy-3-(4-aryl-1-piperazinyl)propyl] derivatives of 4-alkoxy-6-methyl-1H-pyrrolo[3,4-c]pyridine-1,3(2H)-diones (8-12) is described. The chlorides used in the above synthesis can exist in two isomeric forms: chain (18-20) and cyclic (19a, 20a). The compounds 8-12 exhibited potent analgesic activity which was superior than that of acetylsalicylic acid in two different tests. Most of the investigated imides suppressed significantly spontaneous locomotor activity in mice.