<span style="font-size:15.0pt;mso-bidi-font-size:12.0pt;mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB;mso-fareast-language:EN-US;mso-bidi-language:HI" lang="EN-GB">Pyrene-appended Schiff base as a turn-on fluorescence sensor for Al³⁺ detection and interaction with DNA</span>

Abstract

1446-1450Pyrene appended Schiff base, 1,3-bis-((E)-pyrene-1-ylmethyleneamino)propan-2-ol (HL) fluoresces at 419 nm and 508 nm in DMF solution upon excitation at 344 nm. The addition of Al3+ results in a significant 100 fold increase of its fluorescent intensity with the emission maximum red shifted from 421 nm to 508 nm with intense green emission. This phenomenon may be attributed to the formation of a 1:2 stoichiometric [Al2Cl5(L)] complex, which has been supported by Jobs, NMR titration and mass spectral data. The complexation inhibits the photo-induced electron transfer process and the cheletropic enhancement of fluorescence mechanism is responsible for the turn-on fluorescence sensitivity. The limit of detection of Al3+ (7.42×10-8 M) is the second lowest in the series of pyrene functionalized chemosensor. Both HL and its Al3+ complex, [Al2Cl5(L)], show DNA stacking interaction (binding constant Kb 9.8×104 M-1 (of HL) and 3.8×104 M-1 (of [Al2Cl5(L)]).</span