Synthesis of tris(β-diketones) and study of their complexation with some transition metals

Abstract

New chelating ligands consisting of three β diketone fragments, viz., 1,3,5 tris[(acetyl aceton 3 yl)methyl]benzene, 1,3,5 tris[(benzoylaceton 3 yl)methyl]benzene, and 1,3,5 tris[(dibenzoylmethan 1 yl)methyl]benzene, linked to each other through the mesitylene spacer were synthesized by the reaction of 1,3,5 tris(bromomethyl)benzene with the corre sponding β diketone sodium salt. The acidity of these compounds and their complexation properties were studied by pH potentiometry in aqueous ethanol solutions. Tris(β diketones) form mononuclear complexes with lanthanide ions, whose stability increases in the series La 3+ < Gd 3+ < Lu 3+ . 1,3,5 Tris[(acetylaceton 3 yl)methyl]benzene forms both mononuclear and polynuclear complexes with the Ni 2+ and Cu 2+ ions. The stability constants and selectivity of complex formation increase substantially with an increase in the degree of deprotonation of the ligands, thus indicating that all deprotonated chelate groups are involved in coordination with the metal ion. The replacement of the methyl groups by the phenyl substituents in the β diketone fragments of the molecules affects substantially the composition and stability of the complexes formed.

A facile synthetic route to convert Tb(iii) complexes of novel tetra-1,3-diketone calix[4]resorcinarene into hydrophilic luminescent colloids

“…33 The nucleophilic substitution of 1,3,5-tris(bromomethyl)benzene with 1,3-diketone sodium salts was successfully applied in our previous work introducing the synthesis of the mesitylene derivative substituted by three 1,3-diketone moieties. 34 A similar approach to incorporate four 1,3-diketone groups into the upper rim of the calix [4]resorcinarene cavitand is introduced herein. Scheme 1 presents the synthetic route for 4 with the introduction of the synthesis of some earlier reported intermediates.…”

1,3,5-Tris(bromomethyl)benzene

“…The title compound, (I), is an important starting material for the synthesis of branched ligands (Reger et al, 2010;Podyachev et al, 2006;Spiccia et al, 1997) or dendrimeric molecules (Newkome et al, 1986;Berl et al, 2002) which have a mesitylene unit at their core. Given the synthetic possibilities of this molecule, our research group is now using it for the preparation of new ligands which may be employed in the selfassembly of coordination polymers (Rocha et al, 2011;Klinowski et al, 2011;Shi et al, 2008;Cunha-Silva et al, 2007).…”

1,1′-[(5-Hydroxymethyl-1,3-phenylene)bis(methylene)]dipyridin-4(1H)-one monohydrate

“…For previous reports on the design and synthesis of molecules based on a mesitylene core, see: Reger et al (2010); Podyachev et al (2006); Spiccia et al(1997); Newkome et al (1986); Berl et al, (2002). For the crystal structure and vibrational features of the precursor, 1,3,5-tris(bromomethyl)benzene, see: Fernandes et al (2011).…”

“…Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT-Plus (Bruker, 2005); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: DIAMOND (Brandenburg, 2009); software used to prepare material for publication: SHELXTL. 1,3,5-Tris(bromomethyl)benzene has been systematically employed in the preparation of many branched (Reger et al, 2010;Podyachev et al, 2006;Spiccia et al, 1997) or dendritic molecules (Newkome et al, 1986;Berl et al, 2002) with a mesitylene unit comprising the core. Our research groups have also been using this molecule as a versatile template and recently we reported its crystal structure and detailed vibrational features (Fernandes et al, 2011).…”