Naphthalene-Grafted Mof as a Unique Fluorescent Sensor for “Turn-Off” Detection for Fe3+ and “Turn-On” Detection for Clo4- in Different Solvents with High Selectivity and Sensitivity

Abstract

Naphthalene-grafted zirconium-organic framework UiO-66 (HNA@UiO-66-NH 2 ) was synthesized via the Schiff base reaction and its structure and morphology were well characterized. HNA@UiO-66-NH 2 retained the original crystal structure of UiO-66 and high thermal stability. HNA@UiO-66-NH 2 exhibited selective fluorescence sensing ability in two modes, “turn-off” response to Fe 3+ in methanol and “turn-on” response to ClO 4 - in ethanol with high selectivity and sensitivity accompanied by obvious changes of fluorescence photographs. Its fluorescence intensity presented linear changes with the concentrations of Fe 3+ and ClO 4 - with high sensitivity, the low detection limits (LOD) were 0.911 μM for Fe 3+ and 1.44 μM for ClO 4 - . In addition, HNA@UiO-66-NH 2 can simply identified Fe 3+ and ClO 4 - in the test paper mode with naked eyes. The photoinduced electron transfer (PET) from excited HNA@UiO-66-NH 2 to Fe 3+ ion and the absorption competition quenching (ACQ) were responsible for the fluorescence quenching of HNA@UiO-66-NH 2 , the fluorescence enhancement of HNA@UiO-66-NH 2 induced by ClO 4 - was attributed to the hydrogen bond formation between HNA@UiO-66-NH 2 and ClO 4 - . The good recovery of HNA@UiO-66-NH 2 in detection of Fe 3+ in water samples confirmed the practical application capability. HNA@UiO-66-NH 2 can also recognize Fe 3+ and ClO 4 - in the test paper mode. This work paved a way to fabricate the fluorescent sensing materials for the simple, accurate and instantaneous detection and recognition of the different analytes.

Keywords: metal organic framework, Fluorescence sensor, Fe3+ ion, ClO4- ion, High selectivity