Synthesis and Characterization of Trivalent Cerium Complexes of p-tert-Butylcalix[4,6,8]Arenes: Effect of Organic Solvents

Md Hasan Zahir

doi:10.1155/2013/494392

Abstract

Reaction of Ce3+with p-tert-butylcalix[n]arene (n=4,6,8) yields purple crystalline complexes structurally as [Ce(p-tert-butylcalix[4]arene-3H)2(NO3)(DMF)x](2 −x)DMF (1), [Ce(p-tert-butylcalix[6]arene-4H)2(NO3)(DMF)x](3 −x)DMF (2), and [Ce(p-tert-butylcalix[8]arene-7H)2(NO3)(DMF)6] (3), whereDMF=N,N-dimethylformamide. The properties and coordination characteristics of the three calixarene complexes were determined by elemental analyses, electronic absorption, X-ray absorption spectroscopy (EXAFS), TG-DTA, FT-IR, SEM, and1H-NMR spectroscopy. The effect of various organic solvents on complexes1,2, and3has been discussed based on results from electronic absorption spectra. The polar protic solvents showed the most significant molar extinction coefficients in comparison with those of nonpolar and polar aprotic solvents. The Ce3+ions in the complexes are proved to combine with the ligand phenolic groups, oxygen atoms of DMF molecules, and/or OH−ions.

Highlights

Calixarenes are macrocyclic compounds built of n phenol linked via alkylidene groups in such a way that large cavities of molecular dimensions are formed [1]
The large calixarene p-t-butylcalix[8]arene is a ligand which can act as a ditopic receptor for the lanthanide and other [7] ions and in principle may bind in various ways to a single metal ion
Furphy et al [10] reported that the europium(III) complex of p-t-butylcalix[4]arene does contain the ligand in its “cup” conformation and does form an inclusion complex with dimethylformamide

Summary

Introduction

Calixarenes are macrocyclic compounds built of n phenol linked via alkylidene groups in such a way that large cavities of molecular dimensions are formed [1]. These molecules, and their various substituted derivatives, make up one of the most important families of supramolecular chemistry [2]. The large calixarene p-t-butylcalix[8]arene is a ligand which can act as a ditopic receptor for the lanthanide and other [7] ions and in principle may bind in various ways to a single metal ion. The effects of polar protic, polar aprotic, and nonpolar solvents on the synthesized three Ce3+-calixarene complexes were studied

Experimental Section

Results and Discussion

Conclusions