Synthesis and crystal structure of the 6-oxyquinoline derivative cyclotriphosphazene chemosensor with high selectivity and immediate sensitivity for Fe(III) ion and TNT detection

Abstract

New flexible hexapodal cyclotriphosphazene molecule, named 2,2,4,4,6,6-hexakis(quinoline-6-yloxy)cyclotriphosphazene (QCP) was designed and synthesized. The isolated compound was characterized by elemental analysis, NMR (proton decoupled P-31{H}, H-1, C-13, and COSY H-1) and FT-IR spectroscopy, mass analysis and single crystal X-ray crystallography. X-ray crystal structure analysis revealed that QCP crystallize in monoclinic crystal system with P2/c space group. According to TGA analysis, compound exhibited high thermal stability up to similar to 355 degrees C. The photophysical and chemosensor properties of the QCP against a series of analytes (various metal ions and nitro compounds) were investigated by UV-Vis and Fluorescence spectrophotometer. A significant increase in UV-Vis absorption signals were observed with the addition of Fe(III) ions and TNT(trinitrotoluene), and the detection limits for these analytes were calculated as 1.40 and 0.42 mu M, respectively. In addition, the complex stoichiometry of QCP and selective analytes was determined as 1:2 (L/M) by UV-Vis absorption titrations (Job's plot). This study showed that the donor N atoms on the QCP interact selectively with Fe(III) ion. It also showed that the oxyquinoline rings in QCP interact with the TNT ring through intermolecular pi-pi and CH-pi stacking interactions.