An Ultrastable π–π Stacked Porous Organic Molecular Framework as a Crystalline Sponge for Rapid Molecular Structure Determination

Abstract

The crystalline sponge method is a pragmatic and promising strategy for molecular structure determination.However, the dominant metal-organic framework crystal sponge platforms are always facing poor chemical stability, especially solvent instability, which has hampered their application in vaster domain. Herein we report an ultra-stable π-π stacked porous organic molecular framework which exhibits permanent porosity, high thermal stability, and good chemical resistance. It can efficiently implement an approach to molecular structure determination via a single-crystal-to-single-crystal transformation. This is the first example utilizing π-π stacked porous organic molecular framework as "crystalline sponge" to determine a wide variety of guests, ranging from hydrophilic to hydrophobic, and from aliphatic to aromatic, which complements the crystalline sponges based on the famous metal-organic frameworks. More importantly, it can achieve rapid structure determination of small molecules within three hours.

Hybrid interaction network of guanidinium–biphenyldisulfonic acid for the structure determination of liquid molecules

“…1 However, spectroscopic methods have some limitations. A major disadvantage of NMR spectroscopy has been its low sensitivity and narrow spectrum (0-10 ppm for 1 H-NMR and 0-200 ppm for 13 C-NMR); MS provided information about molecular weight and fragment ions, and IR and UV can only give a rough idea about the functional groups in the molecules. Furthermore, spectroscopic methods only suggest speculative molecular structures that are sometimes incorrect.…”

“…Recently, Chen et al have reported an ultrastable π-π stacked porous organic molecular framework as a "crystalline sponge" to determine guests, but the solvent-accessible volume was only 10.6% and only small volume guests can enter the sponge. 13 (iii) Yaghi et al developed a coordinative alignment of molecules in chiral metal-organic frameworks, 14 in which guest molecules including liquid compounds coordinate with aluminum ions. However, the framework still needs a tedious solvent exchange and activation process.…”

Luminescent organic porous crystals from non-cyclic molecules and their applications

“…As we know, the luminescence of organic molecules in the aggregated state depends not only on their intrinsic molecular structure, but also on the aggregation types, 61 so the relation between intermolecular stacking and luminescent behavior is clear because precise atom locations may be obtained from single-crystal structure analysis. It facilitates further understanding of the luminescence properties of porous crystals.…”

A Noncovalent π‐Stacked Porous Organic Molecular Framework for Selective Separation of Aromatics and Cyclic Aliphatics

“…developed a distinctive noncovalent π⋅⋅⋅π interaction‐stacked organic framework (πOF) with permanent porous and remarkable conductive properties [8] . We employed an organic molecule carrying three identical propeller‐like wedges to construct a durable πOF, which can be used as a new crystalline sponge for rapid molecular structure determination [9] . In general, use of an organic molecule with multiple branches of large π‐conjugate planes to enhance intermolecular π⋅⋅⋅π interactions is a promising strategy to construct stable molecular frameworks.…”