화학공학소재연구정보센터
Langmuir, Vol.33, No.17, 4291-4300, 2017
Pt(II)(CNN)-N-boolean AND-N-boolean AND-Based Luminophore-Micelle Adducts for Sensing Nitroaromatic Explosives
Two luminescent cyclometalated Pt(II)-complexes, 1 center dot Pt and 2 center dot Pt, respectively, were synthesized by using unsymmetrical C<^>N<^>N ligands having different alkyl substituents. These pi-electron-rich complexes are used for sensing various electron deficient nitroaromatic explosives, e.g., 4-nitrotoluene (NT), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), and 2,4,6-trinitrophenol (TNP), in aqueous, nonaqueous, as well as in the solid state as a paper strip with maximum detection limit of ca. 10(-9) M. It was demonstrated that the sparingly soluble 2 center dot Pt complex becomes water-soluble in the presence of all kinds of surfactants, viz., cationic (e.g., cetyltrimethylammonium bromide, CTAB), anionic (e.g., sodium dodecyl sulfate, SDS), and neutral (e.g., Triton X-100). This may be due to the incorporation of its long lyophilic tail group (-C12H25) inside the micellar core, exposing planar Pt(II)C<^>N<^>N headgroup to the aqueous bulk phase. It was also observed that the extent of solubility of these Pt(II)-complexes in micellar media strongly depends on the length of the existing alkyl chain. For instance, the presence of longer dodecyl chain makes 2 center dot Pt complex ca. 1000-fold more soluble than the complex 1 center dot Pt, which contains a shorter propyl chain. Their sensing behavior essentially arises by the quenching of Pt(II)-based intense luminescence due to the supramolecular charge transfer (CT) process originating from Pt(II)C<^>N<^>N-antenna to the electron deficient nitroaromatic explosives. Our present work shows that the micellar adducts formed by highly luminophoric material and surfactant molecules could effectively detect such explosives in aqueous medium with better sensitivity compared to what were observed in other media.