Nanodiamonds functionalized with different organic moieties carrying terminal amino groups have been synthesized. These include conjugates generated by Diels-Alder reactions of ortho-quinodimethanes formed in situ from pyrazine and 5,6-dihydrocyclobuta[d]pyrimidine derivatives. For the quantification of primary amino groups a modified photometric assay based on the Kaiser test has been developed and validated for different types of aminated nanodiamond. The results correspond well to values obtained by thermogravimetry. The method represents an alternative wet-chemical quantification method in cases where other techniques like elemental analysis fail due to unfavourable combustion behaviour of the analyte or other impediments.
Keywords: Diels–Alder reaction; Kaiser test; amino groups; carbon nanomaterials; nanodiamond; pyrazine.