A major step towards reliable reading of information coded in the sequence of long poly(phosphodiester)s was previously achieved by introducing an alkoxyamine spacer between information sub-segments. However, MS/MS decoding had to be performed manually to safely identify useful fragments of low abundance compared to side-products from the amide-based alkoxyamine used. Here, alternative alkoxyamines were designed to prevent side-reactions and enable automated MS/MS sequencing. Different styryl-TEMPO spacers were prepared to increase radical delocalization and stiffness of the structure. Their dissociation behavior was investigated by EPR and best results were obtained with spacers containing in-chain benzyl ring, with no side-reaction during synthesis or sequencing. Automated decoding of these polymers was performed using the MS-DECODER software, which interprets fragmentation data recorded for each sub-segment and re-align them in their original order based on location tags.
Keywords: alkoxyamine synthesis; digital information; mass spectrometry; sequence-defined synthetic polymers; structural design.
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