Polymorphism Induced Gas Adsorption on Naphthalic Imide Appended Phenothiazine for the Detection of Volatile Organic Compounds

In this work, we have developed a new polymorphic phase of 2-(4-(10H-phenothiazin-10-yl)phenyl)-1H-benzo [de]isoquinoline-1,3(2H)-dione(NIPTZ-DM) and compared it with the reported polymeric phase (NIPTZ-C). Single crystal XRD analysis revealed that NIPTZ-C existed in herringbone molecular arrangement and NIPTZ-DM showed a zigzag pattern. The photophysical properties of the two phases in the solid state were explored. The unique crystalline phases were investigated for photo- response behaviour with saturated vapours of volatile organic compounds (VOCs). The gas interaction study was carried with Scanning Kelvin Probe (SKP) system with different VOCs such as acetone, triethylamine (TEA), ethanol, and n-hexane. NIPTZ-DM demonstrated excellent gas response towards acetone vapours and showed a high photo response behaviour. NIPTZ-C exhibits both ptype and n-type behaviour, whereas NIPTZ-DM exhibits only n-type behaviour under UV-light illumination.