Lower rim calix[4]arene derivatives: complexation with silver in non-aqueous media and extraction of this cation in the water–nitrobenzene solvent system

Transition metal cations extraction by ester and ketone derivatives of chromogenic azocalix[4]arenes

“…Equal volumes (10 mL) of aqueous solutions of metal picrates 2 × 10 −5 M and solutions of derivatives of azocalix [4]arene (1 × 10 −3 M) in chloroform were vigorously shaken at 25 • C for 1 h contact time. After the complete phase separation, the concentration of picrate ion in the aqueous phase was determined spectrophotometrically (λ max = 354 nm) and the absorbance measurements were repeated three times.…”

“…Despite the complexation of transition metal cations being favoured by the introduction of softer donor atoms, such as nitrogen [4,5], sulphur [6], or phosphorus [7], ligands with harder oxygen atoms also bind those cations. These calix[n]arenes bear phenoxy and carbonyl oxygens as the ligating sites, and include vic-dioximes [8,9], hydroxamates [10], amides [11], carboxylic acids [12], esters [13], and ketones [14].…”

“…In the course of the studies of synthesis of new chromogenic azocalix [4]arene derivatives containing the bithiazole group at lower rim [22], we have extended our research into transition metal cations.…”

“…We report in this paper the extraction ability of ligands L1-L12 derived from azocalix [4]arenes, the alkaline earth (Sr 2+ ) and the transition (Ag + , Hg 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Cr 3+ ) metal cations. This has been assessed by extraction studies with metal picrates from aqueous solution into chloroform.…”

“…Over the last decade, calix [4]arene applications in the field of host-guest chemistry have been the focus of an intense research [1,2]. Many of these studies deal with lower rim functionalized calixarenes and cationic guests, in particular alkali and alkaline earth metal cations.…”