A Hydrogen-Bonded Organic Framework Based on Pyrazinopyrazine

Abstract

Hydrogen-bonded organic frameworks (HOFs) composed of high-nitrogen-content π-conjugated molecules are expected to show multifunctionality. In this study, we studied on a HOF based on pyrazinopyrazine (PP), which is one of the simplest and the most essential structural motifs of high-nitrogen-content polycyclic aromatic hydrocarbons. We describe synthesis of a PPbased building block molecule with four carboxyphenyl groups (CP-PP), spectroscopic and electronic properties of CP-PP and its ester precursor, structures of CP-PP-based HOFs, and thermal behaviors of the HOFs. Interestingly, the initial framework with hydrogen-bonded rhombic two-dimesnional (2D) network rapidly undergoes a guest release-induced three-step structural transformation into other frameworks, including a semiopening framework with small void, through rearrangement of hydrogen bonds. These results provide insight into design new functional Nπ-HOFs and contribute to solid-state chemistry on porous molecular crystalline materials.

Design Rules of Hydrogen-Bonded Organic Frameworks with High Chemical and Thermal Stabilities

“…Through the rational design of organic building blocks with geometric symmetry, planar molecules with diverse π-conjugated systems can coordinate to each other through intermolecular H-bonding interactions to form a single layer, and multiple layers pack together through strong π–π-stacking interactions to form a 3D framework with one-dimensional (1D) channels throughout the structure. HOFs that contain large, π-conjugated aromatic molecules as building blocks exhibit significantly enhanced thermal stabilities and increased chemical resistance to organic solvents and acidic or basic aqueous solutions due to the inert reactivity of the tectons (Figure ) (see refs , , , , , , − , − , − , , , , , , , − , , , , , − , , , − ). Several groups have independently demonstrated that HOFs with shape-fitted π–π-stacking interactions not only show type III stability upon desolvation but also become even more stable as the effective π–π-stacking areas become larger (Table ).…”

Multifunctional Porous Hydrogen-Bonded Organic Frameworks: Current Status and Future Perspectives

“…The 2D square lattice ( sql net) is the most common platform used for the construction of stable HOFs. − For example, Liu and Cao et al isolated a crystalline PFC-1 based on 1,3,6,8-tetrakis­( p -benzoic acid)­pyrene (H 4 TBAPy) that comprises a large π-conjugated planar scaffold pyrene and four benzoic acid arms (Figure a) . In PFC-1, each H 4 TBAPy is connected by four adjacent ones by carboxyl dimers, forming 2D hydrogen-bonded layers with sql topology.…”

Isomeric effect of naphthyl spacers on structures and properties of isostructural porous crystalline frameworks

“…Removal of guest molecules from the pores of HOFs results in pore shrinkage and/or structural transitions of the framework associated with recombination or dissociation. [48][49][50][51] The molecular conformation, stacking manner, and hydrogen bonds of C1N4DBC-1 were perturbed, resulting in shrinkage of the pore aperture along the shorter direction. However, structurally hindered 1-naphthyl spacers as well as the shapefitted docking of DBC cores prevented a drastic transition that would have led to collapse of the framework into an amorphous state.…”