Synthesis and characterisation of macromolecules containing multiple tetrazole functionalities

The synthesis of tetra-tetrazole macromolecules, containing various aromatic cores including benzene, pyridine and pyrazine directly attached to the tetrazole moieties, is described. This variation allowed for the generation of ligands with greater potential for metal ion complexation. Metal ion complexation reactions of the tetra-tetrazole macromolecules with the chelating pyridyl-tetrazole arms result in the formation of metal complexes where the metal ion was bound at the pendant arms rather than at the central core.     

Heterodimerization studies of calix[4]arene derivatives in polar solvents

[reaction: see text] Several calix[4]arene derivatives propylated on the lower rim and substituted on the upper rim with amino or carboxyl groups have been synthesized. Examples include calixarenes substituted with alanino (C- and N-linked), amino, carboxy, carboxyphenyl, and amidino groups. The self-assembly of these derivatized calixarenes into heterodimers has been studied by NMR in DMSO-d(6) or CD(3)OD with 5% aqueous phosphate buffer.     

The time scale for electronic reorganization upon sudden ionization of the water and water-methanol hydrogen bonded dimers and of the weakly bound NO dimer

When the valence molecular orbital is localized sudden ionization can cause the nascent hole to move rapidly even before any relaxation of the geometry occurs. Hydrogen bonded clusters offer suitable test systems where the hole is initially localized on one moiety. Computational studies are reported for the water dimer and water-methanol bimer. The local ionization potential of water is different in the methanol-water and water-methanol conformers and this difference is very clearly reflected in the dynamics of charge migration. For the NO dimer the results are that its structure is symmetric so that the two NO molecules are equivalent and do not exhibit the required localization. The role of symmetry is also evident in the charge propagation for holes created in different orbitals. Localization of the initial hole distribution even if absent in the bare molecule can still be induced by the intense electric field of a sudden photoionization. This effect is computationally studied for the NO dimer in the presence of a static electric field.     

Efficient synthesis of achiral seco-cyclopropylbenz[2,3-e]indoline analogues: [4-amino-2-(5,6,7-trimethoxyindole-2-carboxamido)naphthalen-1-yl]ethyl chloride and [4-hydroxy-2-(5,6,7-trimethoxyindole-2-carboxamido)naphthalen-1-yl]ethyl chloride

Achiral seco-aminocyclopropylbenz[2,3-e]indoline and seco-hydroxycyclopropylbenz[2,3-e]indoline (seco-CBI) analogues of the duocarmycins and CC-1065, e.g., 7 and 8, are potent anticancer agents. This paper describes significantly improved synthetic strategies for preparing these compounds. Starting from Martius acid (9), the new strategy gave a 13-fold increase in the overall yield of 7, and the use of di-tert-butyl malonate was economically beneficial. For compound 8, the new strategy employed an Emmons-Horner reaction, followed by a Stobbe condensation, and the overall yield was improved 15-fold.