Tuning Proton Behavior in a Ternary Molecular Complex

The multicomponent ternary complex of 4-dimethylaminobenzoic acid (4-DABA), 3,5-dinitrobenzoic acid (3,5-DNBA), and 4,4′-bipyridine (BIPY) has been studied by variable temperature X-ray and neutron diffraction. Proton disorder is observed within the 4-DABA homodimers present and quantitatively evaluated from neutron data. The effect of the crystal environment and in particular the pyramidalization of the nitrogen atom within the 4-DABA molecule and the consequential effect on the presence of hydrogen atom disorder are discussed with reference to the previously determined pure 4-DABA structure and the binary cocrystal with 3,5-DNBA.

本研究通过变温X射线衍射与中子衍射技术，对由4-二甲氨基苯甲酸（4-dimethylaminobenzoic acid, 4-DABA）、3,5-二硝基苯甲酸（3,5-dinitrobenzoic acid, 3,5-DNBA）与4,4′-联吡啶（4,4′-bipyridine, BIPY）组成的多组分三元复合物展开了研究。研究中观测到体系中存在的4-DABA同二聚体内部存在质子无序现象，并通过中子衍射数据对该现象完成了定量表征。此外，本研究结合此前已解析的纯相4-DABA晶体结构，以及其与3,5-DNBA形成的二元共晶结构，探讨了晶体环境尤其是4-DABA分子内氮原子的锥型化畸变，及其对氢原子无序现象产生的连带影响。