当前位置: X-MOL 学术Chem. Mater. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
A Mechanism for Reversible Solid-State Transitions Involving Nitro Torsion
Chemistry of Materials ( IF 8.6 ) Pub Date : 2020-09-08 , DOI: 10.1021/acs.chemmater.0c02209
Yue Gui , Xin Yao , Ilia A. Guzei , Michael M. Aristov , Junguang Yu , Lian Yu

Reversible solid-state transformations are important in stimuli-responsive materials. The current understanding is limited on what kind of structure enables reversible transitions. We report that for molecular solids containing nitro groups, reversible phase transitions can occur if the nitro group is a hydrogen bond (HB) acceptor and has torsional freedom. We use the polymorphs of nifedipine (NIF) to illustrate this phenomenon taking advantage of their different molecular packing but identical chemical structure. NIF has six known polymorphs with four being kinetically stable at 100 K. Upon heating, two polymorphs undergo reversible phase transitions with large volume change, while the others do not. In the transforming structures, the nitro group is an HB acceptor and rotates to optimize HBs to offset loss of close packing, while in the inactive structures, the nitro group has similar torsional freedom but is not engaged in HBs. We test the generality of this phenomenon using all available systems in the Cambridge Structural Database, including NIF’s derivative nisoldipine, and suggest possible applications in designing materials with controlled mechanical response.

中文翻译:

涉及硝基扭转的可逆固态转变的机制

可逆的固态转变在刺激反应性材料中很重要。当前的理解仅限于哪种类型的结构可逆转换。我们报告说,对于含有硝基的分子固体,如果硝基是氢键(HB)受体并且具有扭转自由度,则会发生可逆相变。我们利用硝苯地平的多晶型物(NIF)来说明这种现象,因为它们具有不同的分子堆积但具有相同的化学结构。NIF有6种已知的多晶型物,其中4种在100 K时具有动力学稳定性。加热后,两种多晶型物发生可逆的相变,体积变化大,而其他的则没有。在转化结构中,硝基是HB受体,可旋转以优化HBs,以抵消紧密堆积的损失,在非活性结构中,硝基具有类似的扭转自由度,但不参与HBs。我们使用剑桥结构数据库中的所有可用系统(包括NIF的衍生尼索地平)测试了这种现象的普遍性,并建议了在设计具有受控机械响应的材料中的可能应用。
更新日期:2020-09-22
down
wechat
bug