Novel Schiff base compounds containing calix[4]arene

New cyclic and acyclic Schiff bases have been prepared by condensation reaction of 5,17-diamino-25,26,27,28-tetrapropoxycalix [4] arene (L(B)) with 2,6-diformyl-4-chlorophenol and 1,5-diamino-3-aza(methyl)pentane or with 2,3-dihydroxybenzaldehyde. The related complexes containing d- or f-metal ions have been obtained by reaction of the preformed ligands with the appropriate metal salt or by a template macrocyclic synthesis. The hetero-polynuclear complexes have been synthesized by a step by step procedure. Condensation of 5,17-diformyl-25,27-dipropoxycalix [4]arene (L(A)) with tris(2-aminoethyl) amine affords a macrobicyclic ligand containing three calixarene units. The ligands and the related complexes have been characterized by elemental analyses, IR or NMR spectroscopy and mass spectrometry. The stoicheiometries of the complexes have been assigned by SEM and EDX investigations

Alkaline Earth and Uranyl Cation Complexes of a Calix[4]arene-tetramide: MD and FEP Simulations in Aqueous and Acetonitrile Solutions and X-Ray Structure of Its Sr(Picrate)2 Complex

We report the X-ray structure of the L . Sr(Picrate)(2) (L = tert-butyl-calix[4] arene-tetrakis(diethylamide)dagger and MD simulations on the L . M(2+) complexes in vacuo, in water and in acetonitrile solutions (M(2+) = Mg2+, Ca2+, Sr2+, Ba2+), with a comparison of 'converging' L(C) and 'diverging' L(D) conformers. Ln the simulated and solid-state structures of the L . Sr2+ complex, the cation is completely encapsulated within the polar pseudo-cavity of L, without coordination to its counterion in the crystal, or to solvent molecules in solution. Computations show that the L . M(2+) complexes are of converging type in water and in acetonitrile, This contrasts with the L . M(+) alkali cation complexes, which display conformational flexibility in solution. Subtle structural changes from Mg2+ to Ba2+ are compared in the gas phase and in solution. In the L . UO22+ hypothetical complex, simulated for comparison, the UO22+ cation is calculated to be less bound by L than the alkaline earth cations, The solvent content of the cone is shown to depend on the size of the complexed cation and modulated by the top-bottom mechanical coupling in the calixarene. Based on free energy perturbation calculations, we calculate a binding sequence of alkaline earth cations (Ca2+ > Sr2+ > Ba2+ > Mg2+) in agreement with experiment

Synthesis And Antiviral Activity Of Dihydroxycyclohexyl Pirimidine And Purine Carbocyclic Nucleosides

Some novel dihydroxycyclohexyl pyrimidine and purine carbocyclic nucleosides I (B = uracil, adenine, guanine), were prepd. and tested for inhibitory activity against Cytomegalovirus and Herpes virus-1 and 2

Synthesis and dopaminergic properties of the two enantiomers of 3-(3,4-dimethylphenyl)-1-propylpiperidine, a potent and selective dopamine D4 receptor ligand

The synthesis of the two enantiomers of 3-(3,4-dimethylphenyl)-1-propylpiperidine 1, a potent and selective D4 dopaminergic ligand, was performed. The 3-(3,4-dimethylphenyl)- 1-propylpiperidine with the R configuration showed an affinity for the D4 receptors 6-fold higher than the corresponding enantiomer with the S configuration. Furthermore, the (R)-1 enantiomer proved to be highly selective for D4 receptors with respect to D2-D3 receptors, with a Ki ratio higher than 25,000, while the (S)-1 enantiomer was about 100-fold less selective than the (R)-1 one