ELECTRON-SPIN-RESONANCE AND ELECTRON-SPIN ECHO MODULATION STUDIES OF THE INCORPORATION OF MACROCYCLIC-COMPLEXED CUPRIC IONS INTO SILICEOUS MCM-41

A novel complexation method to control the incorporation of Cu(II) wit hin silica tubes of siliceous MCM-41 is developed. Complexation of the cupric ions with a surfactant macrobicyclic cage compound in the reac tion gel has been used for this purpose. Electron spin resonance and e lectron spin echo modulation techniques are used to monitor the coordi nation of Cu(II) in as-synthesized, calcined, and dehydrated MCM-41 as well as its interaction with polar absorbates such as NH3, and D2O. C upric ions are found to be coordinated to four framework oxygens in de hydrated CuMCM-41. Adsorption of ammonia and water results in the form ation of [CU(NH3)(4)](2+) and [CU(H2O)(6)](2+) complexes. The results of this complexation method are compared with experiments on CuMCM-41 where uncomplexed Cu(II) is directly added to the reaction gel. No maj or differences in the dehydration behavior and adsorbate interaction w ere found. Therefore, both complexed and uncomplexed Cu(II) ions intro duced during synthesis are incorporated inside the silica tubes of the MCM-41 structure.