In situ complexation versus complex isolation in synthesis of ion imprinted polymers

authors

• Laatikainen Katri
• Branger Catherine
• Coulomb Bruno
• Lenoble Véronique
• Sainio Tuomo

keywords

• Vbamp
• Nickel
• Distribution of complexes
• Ion imprinted polymers IIP
• N-4-vinylbenzyl-2-aminomethylpyridine
• Isolation of complexes

document type

abstract

In this study, the object is to prove that isolation of complexes made by varying the metal/ligand ratio (in situ complexation) yields similar polymer characteristics, metal binding and selectivity results as polymers synthesized by isolating the complex by precipitation. Complexation between nickel and the N-(4-vinylbenzyl)-2-(aminomethyl)pyridine (Vbamp) monomer was studied in dimethyl sulfoxide (DMSO) and in a DMSO-methanol mixture (50:50, v/v) at 80 °C using a Ni(NO 3) 2 ·6H 2 O salt as the nickel source. According to the results, the three nickel/Vbamp complexes could be selectively obtained using specific conditions: for [Ni(Vbamp)] 2 + the Ni/ Vbamp ratio in DMSO was 1.08, for [Ni(Vbamp) 2 ] 2 + the Ni/Vbamp ratio DMSO-methanol (50:50, v/v) was 0.49 and for [Ni(Vbamp) 3 ] 2 + the Ni/Vbamp ratio in DMSO was 0.3. Ion-imprinted polymers (IIPs) were prepared either with [Ni(Vbamp)](NO 3) 2 , [Ni(Vbamp) 2 ](NO 3) 2 , or [Ni(Vbamp) 3 ](NO 3) 2 complexes as the template. IIP with a [Ni(Vbamp) 3 ] 2 + complex, isolated by precipitation prior to polymerization, was also prepared. The results demonstrated that surface properties, nickel binding and selectivity properties were similar for both kind of IIPs – prepared by in situ complexation or isolation of the complex prior to polymer synthesis. Selectivity coefficients of nickel toward zinc for IIPs with [Ni(Vbamp)] 2 + , [Ni(Vbamp) 2 ] 2 + and [Ni(Vbamp) 3 ] 2 + templates were close to 1038, 1441 and 1463, respectively.

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