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.

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Fast and effective adsorbents for the selective removal of Hg and Pb ions were prepared by the reaction of Zn(NO ) ⋅6H O, H BDC, and N ,N -bis(pyridin-4-ylmethylene) ethane-1,2-diamine (L) that yields an unprecedented two-dimensional layer-based supramolecular framework, {Zn(BDC)(L*)}⋅DMF (TMU-40), by solvothermal reaction. The formation of this framework involved an in situ C=C coupling of L to L* [L*=5,6-di(pyridin-4-yl)-1,2,3,4-tetrahydropyrazine]. As L* contains free nitrogen atoms, direct reaction of L* and metals led to metallated products. Post-synthetic modification of this novel MOF (TMU-40) with H O gives a new framework (O-TMU-40) by same structure and different ligand, which also bears free nitrogen atoms. FTIR spectra, TGA analysis, X-ray diffraction, Zeta Potential analysis and H NMR spectroscopy were used to characterize the prepared frameworks. The TMU-40 and O-TMU-40 frameworks were used for heavy-metal removal from aqueous solutions. Maximum adsorption values of 269 mg g for Hg with TMU-40 and 215 mg g for Pb with O-TMU-40 were achieved in 10 min at 298 Kwithout changes in the pH of the adsorption medium with pseudo-second order kinetics based on the Langmuir model. The extremely fast kinetics of TMU-40 means this adsorbent can reduce heavily contaminated water containing Hg concentrations of 40 ppm down to the acceptable limit of 2 ppb.

Luminogenic materials, particularly those that have turn-on response by sensing the analytes, are highly regarded as optical instruments, sensing material, fluorescent probes, etc. However, most of these materials are only usable in dilute form and often show the self-quenching effect at high concentrations. The use of light-emitting AIE-based materials (aggregation-induced emission) is the solution of this problem. The rigid structure of these active fluorescence ligands, which contains several aromatic rings attached to each other, does not lose its fluorescence properties by increasing the concentration. Unlike other AIE ligands, which have a complex or multistep synthetic route, here, we present a simple one-pot method for in situ synthesis of the AIE ligand and the metal–organic framework (MOF) contained therein. Presence of metal nodes having varied outer-shell electron configurations affects the fluorescence intensity of these materials and, thus, both high and low emissive “turn on” MOFs were readily acquired. Based on the possible interactions between the free nitrogens on the ligand and the phenolic compounds, the MOFs enable highly selective and sensitive detection of phenol derivatives in several seconds with low detection limits (less than 65 nM for 4-aminophenol and 120 nM for phenol) through turn-on emission fluorescence.