Synthesis of novel p-tert-butylcalix[4]arene Schiff bases and their complexes with C60, potential HIV-Protease inhibitors.

Some p-tert-butylcalix[4]arene Schiff base crown ethers were synthesized, characterized using (1)H, (13)C-NMR, DEPT 135 and Mass spectrometry. Their complexes with C60 were isolated and characterized. The inhibition effect of these complexes on HIVP was studied and found that complexes of 9 and 10 have comparable Ki values to Pepstatine which is known as HIVP inhibitor and used as a control. The synthesis of the ligands, complexes and the inhibition behavior are discussed in this article.

Selective phytotoxic activity of 2,3,11ß,13-tetrahydroaromaticin and ilicic acid isolated from Inula graveolens.

Inula graveolens is a poisonous annual plant of Mediterranean origin. The invasive nature of the plant suggests that it may possess phytotoxic activity. The aim of this study was to assess the ability of I. graveolens to inhibit the growth of different plants in Petri dish and to identify the main bioactive compounds. Bio-guided fractionation of the plant extracts led to the isolation of 2,3,11ß,13-tetrahydroaromaticin (THA) and ilicic acid. Both compounds showed selective and significant phytotoxic activity at 25 ppm. Root length of barley, oat, millet, tuberous canary grass and lentils were significantly reduced by 25 ppm of THA, while the root of cauliflower, cress and radish were similarly reduced by ilicic acid at 25 ppm. The structure of each compound was elucidated by using NMR and HR-MS. X-ray crystallography of THA is reported for the first time to confirm the relative stereochemistry of the compound.

One step synthesis of NiO nanoparticles via solid-state thermal decomposition at low-temperature of novel aqua(2,9-dimethyl-1,10-phenanthroline)NiCl2 complex.

[NiCl2(C14H12N2)(H2O)] complex has been synthesized from nickel chloride hexahydrate (NiCl2·6H2O) and 2,9-dimethyl-1,10-phenanthroline (dmphen) as N,N-bidentate ligand. The synthesized complex was characterized by elemental analysis, infrared (IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy and differential thermal/thermogravimetric analysis (TG/DTA). The complex was further confirmed by single crystal X-ray diffraction (XRD) as triclinic with space group P-1. The desired complex, subjected to thermal decomposition at low temperature of 400 °C in an open atmosphere, revealed a novel and facile synthesis of pure NiO nanoparticles with uniform spherical particle; the structure of the NiO nanoparticles product was elucidated on the basis of Fourier transform infrared (FT-IR), UV-vis spectroscopy, TG/DTA, XRD, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDXS) and transmission electron microscopy (TEM).

4-Chloro-butyl 7-chloro-1-cyclo-propyl-4-(1,3-diethyl-4,6-dioxo-2-sulfanyl-idene-1,3-diazinan-5-yl-idene)-6-fluoro-1,4-di-hydro-quinoline-3-carboxyl-ate.

The title compound, C25H26Cl2FN3O4S, contains two bio-active moieties (thio-barbituric acid and fluoro-quinolone). In the crystal, mol-ecules are linked via C-H⋯O and C-H⋯F hydrogen bonds, forming two-dimensional slab-like networks lying parallel to the bc plane. The benzene ring substituted by F and Cl atoms and the 4-chloro-butyl group seem to be partly disordered, however attempts to model the disorder were unsuccessful.

rac-(E,E)-N,N'-Bis(2-chloro-benzyl-idene)cyclo-hexane-1,2-di-amine.

In the title racemic Schiff base ligand, C20H20Cl2N2, which was prepared by the condensation of 2-chloro-benzaldehyde and cyclo-hexane-1,2-di-amine, the cyclo-hexane ring adopts a chair conformation and the dihedral angle between the aromatic rings of the 2-chloro-phenyl substituent groups is 62.52 (8)°. In the structure, there are two short intra-molecular methine C-H⋯Cl inter-actions [C⋯Cl = 3.066 (2) and 3.076 (3) Å], and in the crystal there are also weak inter-molecular aromatic C-H⋯Cl [3.464 (3), 3.553 (3) and 3.600 (3) Å] and Cl⋯Cl [3.557 (3) and 3.891 (3) Å] contacts.

2-Phen-oxy-ethyl benzoate.

In the title compound, C15H14O3, the dihedral angle between the benzene rings is 75.85 (7)°. In the crystal, centrosymmetrically related mol-ecules are weakly associated through pairs of inter-actions between a benzene ring and an O atom of the ester group [ring centroid⋯O = 3.952 (7) Å], and through pairs of inter-actions between the other benzene ring and an O atom of the phen-oxy group [ring centroid⋯O = 3.912 (7) Å], giving chains extending along [110].

2,2-Bis(pyridin-2-yl)-1,3-diazinane.

In the title compound, C14H16N4, the six-membered hexa-hydro-pyrimidine ring adopts a chair conformation. In the crystal, one of the two pyrimidine N atoms engages in N-H⋯N hydrogen bonding with one of the pyridine N atoms, generating a helical chain running along the c axis. The helical pitch is the length of the c axis.

Dichlorido(2,9-dimethyl-1,10-phenanthroline-κ(2)N,N')mercury(II).

The title compound, [HgCl(2)(C(14)H(12)N(2))], consists of one 2,9-dimethyl-1,10-phenanthroline (dmphen) ligand chelating the Hg(II) ion and two chloride ligands coordinating to the Hg(II) ion, forming a distorted tetra-hedral environment. The dmphen ligand is nearly planar (r.m.s. deviation = 0.0225 Å). The dihedral angle between the normal to the plane defined by the Hg(II) atom and the two Cl atoms and the normal to the plane of the dmphen ring is 81.8 (1)°.

N'-[(E)-2-Chloro-benzyl-idene]thio-phene-2-carbohydrazide.

There are two independent mol-ecules in the asymmetric unit of the title compound, C12H9ClN2OS, a Schiff base derived from hydrazide, in which the dihedral angles between the thio-phene and benzene rings are 3.6 (3) and 7.3 (3)°. In the crystal, the two independent mol-ecules are arranged about an approximate non-crystallographic inversion center and are connected by two N-H⋯O hydrogen bonds. Weak C-H⋯Cl contacts are also present. Conversely, there are neither significant aromatic stacking inter-actions nor contacts involving S atoms.

(2,9-Dimethyl-1,10-phenanthroline-κ(2)N,N')bis-(thio-cyanato-κS)mercury(II).

The asymmetric unit of the title compound, [Hg(SCN)(2)(C(14)H(12)N(2))], contains two complex mol-ecules in which the Hg(II) atoms are both four-coordinated in a distorted tetra-hedral configuration by two N atoms from a chelating 2,9-dimethyl-1,10-phenanthroline ligand and by two S atoms from two thio-cyanate anions. The 1,10-phenanthroline ligand is slightly folded for one complex, the dihedral angle between the pyridine planes being 5.3 (1)°. In contrast it is nearly planar [0.5 (1)°] as it complexes with the other Hg(II) atom. The thio-cyanate ligands are virtually linear and the S atom is bonded to Hg(II) with N⋯S-Hg angles ranging from 99.3 (1) to 103.5 (1)°. Despite the presence of six aromatic rings in the asymmetric unit, there are no significant inter-molecular π-π contacts between phenanthroline ligands as the centroid-centroid distance of the closest contact between six-membered rings is 4.11 (1) A°.

2,6-Dimethyl-pyridinium bromide.

The asymmetric unit of the title salt, C(7)H(10)N(+)·Br(-), comprises two 2,6-dimethyl-pyridinium cations and two bromide anions. One cation and one anion are situated in general positions, while the other cation and the other anion lie on a crystallographic mirror plane parallel to (010). Each pair of ions inter-act via N-H⋯Br and C-H⋯Br hydrogen bonding, generating motifs depending on the cation and anion involved. Thus, the cation and the anion on the mirror plane generate infinite chains along the c axis, while the other ionic pair leads to sheets parallel to the ac plane. In the overall crystal packing, both motifs alternate along the b axis, with a single layer of the chain motif sandwiched between two double layers of the sheet motif. The sheets and chains are further connected via aryl π-π inter-actions [centroid-centroid distances = 3.690 (2) and 3.714 (2) Å], giving a three-dimensional network.

Redetermination of 2,2'-bipyridine-1,1'-diium dibromide.

In the title mol-ecular salt, C(10)H(10)N(2) (2+)·2Br(-), the dihedral angle between the aromatic rings is 20.83 (14)° and the N-H groups have a transoid conformaton [N-C-C-N = 158.5 (3)°]. In the crystal, the cations are linked to the anions by two N-H⋯Br and five C-H⋯Br hydrogen bonds, generating corrugated sheets incorporating R(2) (1)(7), R(4) (2)(10), R(4) (2)(11) and two different R(4) (2)(12) loops. This structure was originally reported by Nakatsu et al. [Acta Cryst (1972), A28, S24], but no atomic coordinates are available.

Bis(2,6-dimethyl-pyridinium) dibromo-iodate bromide.

In the title salt, 2C(7)H(10)N(+)·IBr(2) (-)·Br(-), each of the anions, viz. [IBr(2)](-) and Br(-), lie on a twofold axis. The IBr(2) (-) anion is almost linear, with a Br-I-Br angle of 178.25 (3)°. The cation is essentially planar (r.m.s. deviation = 0.0067 Å). In the crystal, each Br(-) anion links two cations via N-H⋯Br⋯H-N hydrogen-bonding inter-actions.

2-Amino-5-methyl-pyridinium dibromo-iodate.

In the title salt, C(6)H(9)N(2) (+)·Br(2)I(-), the cation is essentially planar (r.m.s. deviation = 0.0062 Šfor the non-H atoms) while the anion is almost linear with a Br-I-Br angle of 177.67 (2)°. The crystal packing shows two anions and two cations connected via N-H⋯Br and (pyridine)N-H⋯Br hydrogen-bonding inter-actions, forming centrosymmetric tetra-mers with R(4) (4)(16) ring motifs. Very weak offset aromatic π-π stacking interactions [centroid-centroid separation = 4.038 (4), slippage = 1.773 Å] also occur.

Bis(2,4-dimethyl-pyridinium) tetra-bromido-mercurate(II).

The asymmetric unit of the title compound, (C7H10N)2[HgBr4], consists of one cation and one half-anion, bis-ected by a twofold rotation axis passing through the metal atom. The anion exhibits a distorted tetra-hedral arrangement about the Hg(II) atom. In the crystal, the cations and anions are linked by N-H⋯Br hydrogen-bonding inter-actions along [010]. Cation-cation π-π stacking and Br⋯Br inter-molecular inter-actions are absent.

Bis{(E)-3-[(2-hy-droxy-benzyl-idene)amino]-prop-yl}ammonium chloride.

The title salt, C20H26N3O2(+)·Cl(-), lies across a twofold crystallographic axis with the central N atom of the cation and the chloride anion sitting on this axis, Z' = 0.5. There is an intra-molecular hydrogen bond between the hy-droxy H atom and the imino N atom. The chloride anion and the cation are connected into chains along the a axis by an N-H⋯Cl hydrogen bond. In the crystal, the chains are linked via C-H⋯Cl interactions forming two-dimensional networks lying parallel to (101).

Bis(2,4,6-trimethyl-pyridinium) tetra-bromidozincate.

In the title compound, (C(8)H(12)N)(2)[ZnBr(4)], the coordination geometry of the anion is approximately tetra-hedral. The Zn-Br bond lengths range from 2.3901 (19) to 2.449 (2) Šand the Br-Zn-Br angles range from 107.09 (8) to 112.48 (8)°. In the crystal, each [ZnBr(4)](2-) anion is connected to four cations through two N-H⋯Br and two C-H⋯Br hydrogen bonds, forming two-dimensional ⋯(cation)(2)⋯anion⋯(cation(2))⋯ sheets parallel to the bc plane. Within each sheet, the anions are arranged in stacks with no significant inter-anion Br⋯Br inter-actions [the shortest being > 4.3 Å], while the cations are in chains, with weak π-π stacking inter-actions [centroid-centroid distance = 3.991 Å] between cations inter-acting with the same anion.

3-(Ammonio-meth-yl)pyridinium dibromide.

In the title salt, C(6)H(10)N(2) (2+)·2Br(-), the non-H atoms of the 3-methyl-pyridinium unit of the cation are almost coplanar (r.m.s. deviation = 0.0052 Å). In the crystal, the dications and Br anions are linked by a combination of six hydrogen bonds, viz. one N(py)-H⋯Br, two C-H⋯Br and three H(2)N-H⋯Br, into supra-molecular layers, parallel to the bc plane, composed of alternating R(2) (4)(10) and R(2) (4)(8) loops. Weak π-π inter-actions between cationic rings with centroid-centroid distances of 3.891 (2) Šare also observed.

Three isomorphous 2,6-dibromopyridinium tetrabromidometallates: (C(5)H(4)Br(2)N)(2)[MBr(4)].2H(2)O (M = Cu, Cd and Hg).

The structures of three isomorphous compounds, namely bis(2,6-dibromopyridinium) tetrabromidocuprate(II) dihydrate, (C(5)H(4)Br(2)N)(2)[CuBr(4)].2H(2)O, bis(2,6-dibromopyridinium) tetrabromidocadmate(II) dihydrate, (C(5)H(4)Br(2)N)(2)[CdBr(4)].2H(2)O, and bis(2,6-dibromopyridinium) tetrabromidomercurate(II) dihydrate, (C(5)H(4)Br(2)N)(2)[HgBr(4)].2H(2)O, show a crystal supramolecularity represented by M-Br...H-O-H...Br-M intermolecular interactions along with (pi)N-H...OH(2) hydrogen-bonding interactions forming layers connected via aryl-aryl face-to-face stacking of cations, leading to a three-dimensional network. The anions have significantly distorted tetrahedral geometry and crystallographic C(2) symmetry. The stability of this crystal lattice is evidenced by the crystallization of a whole series of isomorphous compounds.

Three-dimensional framework structures: isomorphous bis(2,6-diamino-3,5-dibromopyridinium) tetrabromidometallate(II) salts with Cd(II) and Mn(II).

In the structural motifs of two isomorphous triclinic salts, (C5H6Br2N3)2[MBr4] (M = Cd(II) and Mn(II)), each [MBr4]2- anion interacts with eight surrounding 2,6-diamino-3,5-dibromopyridinium cations through intermolecular C/N-H...Br and Br...Br interactions, leading to a three-dimensional framework structure. The cations show a minor degree of pi-pi stacking, adding extra stability to the three-dimensional architecture.