Synthesis of Linear Oligo(catechol) Ligands for the Metal Directed Self-Assembling of Helicates
作者:Markus Albrecht
DOI:10.1055/s-1996-4188
日期:1996.2
The synthesis of the oligo(catechol) systems 1-4 with different substituents, length of the connecting spacer, and number of catechol units is achieved by the use of various coupling reactions (e.g. Wurtz, Glaser-Eglinton, Stephens-Castro). In order to do this methods of preparing the building blocks, 2,3-dimethoxybenzyl bromides 5, 2,3-dimethoxyphenylacetylene (17), or 1,4-dibromo-2,3-dimethoxybenzene (23) have been developed starting with simple catechol (benzene-1,2-diol) derivatives.
meso-helicate-type dinucleartitanium(IV) complexes Mn[(ligand)3Ti2] (n = 4: M = Li, Na, K, Cs; n = 2: M = Ca, Sr), which are formed by metal-directed self-assembly of alkyl-bridged bis(catecholate) ligands in the presence of basic alkali-metal or alkaline-earth metal salts, can be monitored by dynamic NMR spectroscopy. The free-energy barrier (ΔG‡) of this process is influenced by the nature of the ligand, the