Synthesis and Binding Properties of Dendritic Oxybathophenanthroline Ligands towards Copper(II)

Abstract

Dendritic oxybathophenanthroline ligands (generation 0 to 3) have been synthesized by treatment of 4,7‐bis(4′‐hydroxyphenyl)‐1,10‐phenanthroline with the corresponding Fréchet‐type dendrons carrying a benzylic bromide function at the focal point. The complexation of copper(II) has been studied by liquid–liquid extraction using the radioisotope 64Cu and time‐resolved laser‐induced fluorescence spectroscopy (TRLFS) in organic media indicating the formation of 1:3 complexes (Cu:dendritic ligand). Electronic and EPR spectroscopy were used to characterize the copper(II) chromophore, which is shown to have the expected distorted square‐planar geometry with two phenanthroline donors coordinated to the copper(II) center. The third dendritic ligand therefore is proposed to be bound by secondary interactions. The stability constants of the 1:3 complexes were found to be in the order of log K ≈ 16 in CHCl3. On the other hand, increasing generation of the dendritic Fréchet‐type branches leads to enhanced shielding of the copper ion from the environment. Additional information about this behaviour was obtained by the fluorescence lifetimes, which are much less influenced upon addition of copper(II) salt to solutions of the higher generation ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Mn-Enabled Radical-Based Alkyl–Alkyl Cross-Coupling Reaction from 4-Alkyl-1,4-dihydropyridines

“…The resulting residue was purified by column chromatography (PE/EA = 10/1) on silica gel to give the product. 1b , 1c , 1e , 1i , and 1m are known compounds.…”

Fifty Shades of Phenanthroline: Synthesis Strategies to Functionalize 1,10-Phenanthroline in All Positions

“…758 Finally, Stephan et al have obtained the 4,7-oxybathophen 859 through convergent methods. 198 Then the hydroxy group is deprotonated with sodium hydride and reacted with dendrons that are highly branched (the corresponding Frećhet-type dendrons carrying a benzylic bromide function, Scheme 155) 198 or have ethylene glycol units. 759 Those new dendritic phen ligands were shown to be able to extract Cu(II) ions from water.…”

Hydrophilic oxybathophenanthroline ligands: synthesis and copper(ii) complexation

“…The phenanthroline ligand 1 with two peripheral hydroxy groups was obtained in five steps, according to a previously reported procedure. 7 The dendritic precursors 2-4 with terminal hydrophilic ethylene glycol chains and a benzylic bromide functional group (generation 1-3) have also been prepared following synthetic routes described in literature. 9 The dendritic diphenylphenanthroline ligands L G1 -L G3 were synthesized as shown in Scheme 1.…”

“…1), which are able to rapidly form stable copper(II) complexes in trichloromethane. 7 In view of biomedical applications such as the design of novel diagnostic and therapeutic agents, it was of interest to develop the corresponding hydrophilic systems. 8 In this paper, we report the synthesis and the copper(II) complexation of dendritic 4,7-diphenyl-1,10-phenanthroline (dpp) ligands with attached Fre´chet-type dendrons, containing triethylene glycol monomethyl ether end groups (Fig.…”