Crystalline Sponge Method

Single-crystal X-ray analysis is one of the most reliable methods for determining molecular structure. The analysis requires access to diffraction-ready single crystals, but the preparation of crystals sufficient for analysis can be a serious bottleneck. The crystalline sponge method makes the crystallization step in it unnecessary and promises to revolutionize the determination of molecular structure.

The crystalline sponge method does not require the sample to undergo a crystallization process. As the sample solvent evaporates, the target molecules automatically penetrate the interior of the crystal sponge-like water is drawn inside the sponge and is arranged in the pores of the crystal sponge in a long-range orderly manner. Thus, the molecular structure can be analyzed using X-ray diffraction.

Figure 1. (a) Preparation of the most potent crystalline sponge [(ZnI₂)₃(tpt)₂·x(solvent)]_n. (b, c) Packing views of 1 in the (b) [010] and (c) [101] directions. (Hoshino, M., et al., 2016)

Technical features

• No crystallization process is required. With the evaporation of the sample solvent, the target molecules automatically penetrate inside the crystalline sponge and arrange themselves in the pores of the crystalline sponge in a long-range orderly manner.
• Crystal structure analysis of nanogram-level compounds can be realized. Theoretically, a single (80 × 80 × 80 μm³) crystalline sponge can achieve the structural analysis of 26 ng of target molecules.
• It can be used in conjunction with high-performance liquid chromatography (HPLC) to achieve direct structural analysis of small amounts of mixed products.
• The absolute conformation of the molecule can be determined.

Applications

• From central chirality to axial chirality and face chirality

The crystalline sponge method has been used to determine the absolute configuration of molecules (mainly central chirality).

• Determination of chemical reaction sites

Using the unique advantages of the crystalline sponge method, the exact reaction sites of molecules with multiple similar reactive sites can be determined when chemical reactions occur.

• Application to organic synthesis research

The crystalline sponge method can be applied to all aspects of organic synthesis and can be of great help in determining the structure of complex intermediates and final products in terms of stereochemistry.

The crystalline sponge method has an unlimited future. First, the metal-organic framework has a rich database of structures, and it can be envisioned that new crystalline sponges can be discovered from existing structures in the future and that crystalline sponges can be redesigned to specifically identify certain types of target molecules (e.g., amino acid crystalline sponges, sugar crystalline sponges, etc.). Secondly, the synthesis of crystalline sponges with extra-large pores will help to solve the crystal structure resolution of biological macromolecules. Again, it will be of great help to determine the structure of intermediate molecules in the drug development process. Creative Biostructure can provide you with more project support solutions for the crystalline sponge method, please feel free to contact our staff for more information.

Ordering Process

Reference

1. Hoshino M, et al. The crystalline sponge method updated. IUCrJ. 2016, 3(2): 139-151.