Fluorene‐Functionalized, Dendrimer‐Modified SBA‐15: Detection of Iron(III) and Mercury (II) in Aqueous Media and Logic Gate Studies

Abstract

AbstractA novel silica‐based fluorescent sensor, (S‐DPP), was prepared via grafting of dimethyl 3,3′‐(propylazanediyl)(1Z,1′Z)‐bis(N‐(9H‐fluoren‐2‐yl)propanimidate) (DPP), onto the pore walls of SBA‐15 channels. DPP was prepared by growing of dendrimer (G= 0.5) onto the amino functionalized surface of SBA‐15, followed by anchoring of 2‐aminflourene via imine condensation. Synthesized materials were characterized using FT‐IR, PXRD, SEM, TEM, BET and TGA techniques. Fluorescence properties of the sensor were investigated in aqueous solution towards various metal ions. The signal quenching of sensor at λ=380 nm is based on complex formation between the S‐DPP and Fe3+ or Hg2+ ions, leading to the inhibition of reverse intramolecular charge transitions at the probe and appearance of new transitions at Mn+—S‐DPP complex. Furthermore, the limit of detection of both ions were calculated as 2.4 × 10−8 M and 6.3 × 10−8 M, respectively. A reversibility in fluorescence behavior of the probe was found in the presence of Cl−, and was demonstrated a circuit logic system with the Fe3+, Hg2+ and Cl− ions. Finally, density functional theory (DFT) and time‐dependent density functional theory (TDDFT) computational studies were performed in order to obtain a detailed electronic description of the quenching mechanism by Hg2+ and Fe3+ as well as studying the structure and bonding in the complexes.