Selective and Reversible Solvent Uptake in Tetra‐4‐(4‐pyridyl)phenylmethane‐based Supramolecular Organic Frameworks

Abstract

The dynamic behavior of supramolecular organic frameworks (SOFs) based on the rigid tetra‐4‐(4‐pyridyl)phenylmethane (TPPM) organic tecton has been elucidated through 3D electron diffraction, X‐ray powder diffraction and differential scanning calorimetry (DSC) analysis. The SOF undergoes a reversible single‐crystal‐to‐single‐crystal transformation when exposed to vapours of selected organic solvents, moving from a closed structure with isolated small voids to an expanded structure with solvated channels along the b axis. The observed selectivity is dictated by the fitting of the guest in the expanded SOF, following the degree of packing coefficient. The effect of solvent uptake on TPPM solid‐state fluorescence was investigated, evidencing a significant variation in the emission profile only in the presence of chloroform.

3D electron diffraction analysis of a novel, mechanochemically synthesized supramolecular organic framework based on tetrakis-4-(4-pyridyl)phenylmethane

“…with the measured intensity considered proportional to the square modulus of the structure factor. The kinematically refined model revealed the formation of a supramolecular network characteristic of the SOF expanded form (Marchetti et al, 2022), in which the TPPM molecules are mainly involved in CHÁ Á ÁN interactions (Figs. S8 and S9).…”

“…It is well known that porous materials, like MOFs (metalorganic frameworks) and SOFs, have the capability to release the guest molecules held inside their pores, and this process is accelerated by vacuum and heat. Indeed, under the previously mentioned stimuli, the expanded, solvated form of the TPPMbased SOF could easily release guest molecules, such as CHCl 3 , EtOH, C 6 H 6 and CH 3 CN (Marchetti et al, 2022). However, the fact that the unit-cell volume remains significantly larger than that of the empty phase (Table S4) indicates that the BnOH release is only partial and the molecules remaining in the pores can stabilize the expanded form of the TPPM-based SOF also under high vacuum [$10 À7 mbar [1 mbar = 0.1 kPa)] conditions.…”

“…We have recently reported the selective and reversible solvent uptake by an SOF based on tetrakis-4-(4pyridyl)phenylmethane (TPPM), a rigid, aromatic tecton [Fig. 1(a)] which undergoes a single-crystal-to-single-crystal transformation when exposed to vapours of selected organic solvents and heat (Marchetti et al, 2022). As represented in Fig.…”

Stimuli‐Responsive, Dynamic Supramolecular Organic Frameworks

“…Our group recently reported a dynamic responsive SOF obtained through the self-assembly of the tetra-4-(4-pyridyl)phenylmethane (T15) via van der Waals interactions and hydrogen bonds. [76] This tecton crystallizes from different solvents (DMF, DMSO, chloroform, ethanol, benzene) as 1 : 1 solvate in the space group C2/c with marginal structural variations. All these supramolecular networks are held together by multiple CÀ H•••N interactions between tectons and contain channels parallel to the b axis direction filled by the disordered solvent molecules (Figure 5a).…”

“…Our group recently reported a dynamic responsive SOF obtained through the self‐assembly of the tetra‐4‐(4‐pyridyl)phenylmethane ( T15 ) via van der Waals interactions and hydrogen bonds [76] . This tecton crystallizes from different solvents (DMF, DMSO, chloroform, ethanol, benzene) as 1 : 1 solvate in the space group C 2/c with marginal structural variations.…”