Evaluating the relationship between structure and function of metal–organic frameworks (MOFs) is an interesting issue that is discussed in this work. Here, four isoreticular 3D porous zinc(II) MOFs with pcu topology, including [Zn(oba)(4-bpmb)_0.5]·(DMF)_1.5 (TMU-6), [Zn(oba)(bpmn)_0.5]·(DMF)_1.5 (TMU-21), [Zn₂(oba)₂(bpfb)]·(DMF)₅ (TMU-23) and [Zn₂(oba)₂(bpfn)]·(DMF)₂ (TMU-24), H₂oba = 4,4′-oxybisbenzoic acid, bpmb = N,N′-bis-(4-pyridylmethylene)-1,4-benzenediamine, bpmn = N,N′-bis-(4-pyridylmethylene)-1,5-naphthalenediamine, bpfb = N,N′-bis-(4-pyridylformamide)-1,4-benzenediamine and bpfn = N,N′-bis(4-pyridylformamide)-1,5-naphthalenediamine, containing imine- (TMU-6 and TMU-21) and amide- (TMU-23 and TMU-24) decorated pores, were successfully synthesized by a mechanochemical method. Then, adsorption efficiency of these four MOFs for some heavy metal ions was studied to evaluate effects of the types of functional groups of the pillars in different MOFs on the adsorption process. The results indicated that amide-decorated MOFs show a better adsorption efficiency toward metal ions than the imine-decorated MOFs. In the following, TMU-23 was used as an efficient sorbent for extraction and removal of some heavy metal ions (Co²⁺, Cd²⁺, Cu²⁺, Cr³⁺, Fe²⁺, and Pb²⁺) and its analytical performance was evaluated and determined. In addition, DFT calculations were performed on possible coordination modes between cations and simplified functional groups of the related pillars in each MOF and a probable interaction mechanism of the MOFs and the metal ions was evaluated.

A theoretical study was performed to examine intermolecular halogen bond properties in one-dimensional NCX chains (X=Cl and Br). Geometries, binding energies, and charge-transfer of linear (NCCl)_2–10 and (NCBr)_2–10 chains were investigated by means of second-order Møller–Plesset perturbation theory (MP2) and DFT methods. All MP2, B3LYP and M06/aug-cc-pVTZ results indicate that the magnitudes of the interaction energies increase with increasing halogen size. Considering MP2/aug-cc-pVTZ results, it can be seen that the (NCBr)₁₀ cluster is bound −12.72 kcal/mol more strongly than (NCCl)₁₀. The n-dependent trend of charge-transfer is reasonably correlated with cooperative effects in halogen bond energies. According to the quantum theory of atoms in molecules, the capability of the (NCX)_2–10 clusters for electron localization, at the C–X ··· N bond critical point (BCPs), depends on the cluster size and thereby leads to cooperative changes in the C–X ··· N strength, and charge-transfer. It is also revealed that for all intermolecular C–X ··· N interactions, total electronic energy densities are all greater than zero, suggesting that the interactions are significantly electrostatic in nature.