Carbazole-based molecular tweezers as platforms for the discrimination of heavy metal ions

Eight carbazole-based molecular tweezers (CMTs) were designed and synthesized for application in the discrimination of heavy metal ions. All CMT solutions in MeCN were transparent, but exhibited strong deep blue or sky blue fluorescence emission upon UV irradiation. The electronic absorptions of CMTs appeared mainly in the UV region. The CMTs exhibited different fluorescence response patterns upon the addition of various transition metal ions. The principal component analysis (PCA) and linear discriminant analysis (LDA) exhibited clear clustering of data points within the same metal ions and successful dispersion of data clusters. The influence of anionic species on the fluorescence emission of CMTs was almost negligible. Therefore, the chemometric analysis allowed for successful discrimination of 18 heavy metal ions.