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Author: Islam, Muhammad × Type: Text ×

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    Novel acridine-based thiosemicarbazones as ‘turn-on' chemosensors for selective recognition of fluoride anion: a spectroscopic and theoretical study
    (London : Royal Soc. Publ., 2018-7-4) Isaac, Ibanga Okon; Munir, Iqra; al-Rashida, Mariya; Ali, Syed Abid; Shafiq, Zahid; Islam, Muhammad; Ludwig, Ralf; Ayub, Khurshid; Khan, Khalid Mohammed; Hameed, Abdul
    New thiosemicarbazide-linked acridines 3a–c were prepared and investigated as chemosensors for the detection of biologically and environmentally important anions. The compounds 3a–c were found selective for fluoride (F−) with no affinity for other anions, i.e. −OAc, Br−, I−, HSO4−, SO42−, PO43−, ClO3−, ClO4−, CN− and SCN−. Further, upon the gradual addition of a fluoride anion (F−) source (tetrabutylammonium fluoride), a well-defined change in colour of the solution of probes 3a–c was observed. The anion-sensing process was studied in detail via UV–visible absorption, fluorescence and 1H-NMR experiments. Moreover, during the synthesis of acridine probes 3a–c nickel fluoride (NiF2), a rarely explored transition metal fluoride salt, was used as the catalyst. Theoretical studies via density functional theory were also carried out to further investigate the sensing and anion (F−) selectivity pattern of these probes.
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    Acridinedione as selective flouride ion chemosensor: A detailed spectroscopic and quantum mechanical investigation
    (London : RSC Publishing, 2018) Iqbal, Nafees; Ali, Syed Abid; Munir, Iqra; Khan, Saima; Ayub, Khurshid; al-Rashida, Mariya; Islam, Muhammad; Shafiq, Zahid; Ludwig, Ralf; Hameed, Abdul
    The use of small molecules as chemosensors for ion detection is rapidly gaining popularity by virtue of the advantages it offers over traditional ion sensing methods. Herein we have synthesized a series of acridine(1,8)diones (7a-7l) and explored them for their potential to act as chemosensors for the detection of various anions such as fluoride (F-), acetate (OAc-), bromide (Br-), iodide (I-), bisulfate (HSO4-), chlorate (ClO3-), perchlorate (ClO4-), cyanide (CN-), and thiocyanate (SCN-). Acridinediones were found to be highly selective chemosensors for fluoride ions only. To investigate in detail the mechanism of selective fluoride ion sensing, detailed spectroscopic studies were carried out using UV-visible, fluorescence and 1H NMR spectroscopy. Fluoride mediated (NH) proton abstraction of acridinedione was found to be responsible for the observed selective fluoride ion sensing. Quantum mechanical computational studies, using time dependent density functional theory (TDDFT) were also carried out, whereupon comparison of acridinedione interaction with fluoride and acetate ions explained the acridinedione selectivity for the detection of fluoride anions. Our results provide ample evidence and rationale for further modulation and exploration of acridinediones as non-invasive chemosensors for fluoride ion detection in a variety of sample types.