The Ward Group in the Molecular Design Institute has reported a substantial number of molecular frameworks, built from two-dimensional hydrogen-bonded networks, that are capable of encapsulating a wide range of guests, developing a toolkit for synthetic chemists. The article, entitled "Hydrogen-Bonded Frameworks for Molecular Structure Determination," appears in Nature Communications, authored by graduate students Yuantao Li and Anna Yusov, NYU undergraduate Shishuang Tang, visiting students James Rose and Andre Nyberg Borrfors, and NYU Chemistry X-Ray Crystallographer Chunhua "Tony" Hu.
Abstract: Single crystal X-ray diffraction is arguably the most definitive method for molecular structure determination, but the inability to grow suitable single crystals can frustrate conventional X-ray diffraction analysis. We report herein an approach to molecular structure determination that relies on a versatile toolkit of guanidinium organosulfonate hydrogen-bonded host frameworks that form crystalline inclusion compounds with target molecules in a single-step crystallization, complementing the crystalline sponge method that relies on diffusion of the target into the cages of a metal-organic framework. The peculiar properties of the host frameworks enable rapid stoichiometric inclusion of a wide range of target molecules with full occupancy, typically without disorder and accompanying solvent, affording well-refined structures. Moreover, anomalous scattering by the framework sulfur atoms enables reliable assignment of absolute configuration of stereogenic centers. An ever-expanding library of organosulfonates provides a toolkit of frameworks for capturing specific target molecules for their structure determination.
This research was supported by the National Science Foundation, including the Materials Research Science and Engineering Center (MRSEC) Program, the Chemistry Research Instrumentation and Facilities Program and other grants.