This study has developed
a simple and innovative approach to design
a metal–organic framework (MOF) with tunable conductivity.
The in situ amine functionalized TMU-60 [Zn(OBA)(L*)·DMF] has
the potential of converting to a conductor due to the selective and
fast sorption of cadmium ion. In order to precisely monitor the cadmium
penetration to the framework pores, in addition to full kinetic and
thermodynamic studies of sorption, the time-dependent effects of Cd(II)
penetration to MOF pores was taken by fluorescence and electrochemical
methods. The results obviously prove that the conductivity of the
structure can be adjusted by changing the Cd exposure time and the
quantity of ion sorption. The presence of cadmium ions can enhance
the ability of the framework to pass electrons through its constituents.
Even though the porosity of the structure remains to a certain extent,
the achieved tunable and highly stable electrical conductivity is
provided by sorption of metal ions. More importantly, the conductivity
has been improved from 53 × 10–6 to 1.8 ×
10–2 S·cm–1 for TMU-60 and
TMU-60-Cd compressed pellet (room temperature), respectively. The
mechanism of charge transport through the pellet is proposed to be
a hopping mechanism between metal nodes and localized Cd(II) after
sorption, which is supported by chronoamperometry measurement. A fit
of the time-dependent data to the Cottrell equation gave a charge-transport
diffusion coefficient of 1.6 × 10–10 cm2/s throughout the structure. This novel approach not only
enhances the conductivity of the MOF but also allows adjusting the
conductivity according to the desired applications.
Correction for ‘Selective sacrificial metal–organic frameworks: a highly quantitative colorimetric naked-eye detector for aluminum ions in aqueous solutions’ by Farzaneh Rouhani et al., J. Mater. Chem. A, 2019, 7, 18634–18641, https://doi.org/10.1039/C9TA03647D.
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