D-π-A based Diaminomalenonitrile Imine Compounds as Sensors: From Ion Recognition to Logic Arithmetic Applications

In this review article, exciting highlights on highly π-conjugated (π-D-A) 2,3-diaminomaleonitrile (DAMN) based imines or Schiff base chemosensors have been reviewed and discussed. Owing to the typical free -NH2 anion recognition site and 1,2-ethylenediamine based chelating structure, both anion and cation sensing has been achieved with such designed molecules. It has been found that ion interactions strongly alter the electronic push-pull and hence intramolecular charge transfer (ICT) properties across the molecular system. So far such molecular recognition strategy has successfully detected ions like F–, CN– and Cu+2 in aqueous as well as non-aqueous media. Importantly, recognition is usually reversible and changes are clearly perceived through naked eyes. In this work, various sensing aspects like mechanism of interaction, type of recognition, sensitivity, reversibility, binding constants and spectral changes (absorption and emission) have been thoroughly discussed. Herein, the designed and fabricated sensor reports have been arranged in systematic order since 2010 so that the reader gets complete and trending picture of how the developments have taken place in the area of this research. In last, essential shortcomings and future challenges existing with the current approaches have also been highlighted.