A novel series of pure organic ferroelectrics R¹-DABOO-R² (substituted 3,5-diazabicyclo[2.2.2]octane-2,6-diones) were newly designed by us, serving as analogues and exhibiting the amelioration of experimentally well investigated organometallic ferroelectrics/ferroelastics, R-DABCO-[M(H₂O)Cl₃] (substituted 1,4-diazabicyclo[2.2.2]octonium trichloroaquo-metal(II)). Combining our first-principles calculations with previous experimental observations, the R-DABCO-[M(H₂O)Cl₃] model systems were well investigated to demonstrate the structure–property relationship for realizing their ferroelectricity/ferroelasticity. We found that tuning the ferroelectricity/ferroelasticity of the model systems significantly depended on subtle weak intermolecular interactions changing with the substituent R groups within each crystal. Thus, the design principle that the rotator–stator-type assemblies should hold rotational dynamics and characteristic space groups to easily switch ferroelectricity/ferroelasticity and get rid of weak metal coordinate bonds to increase their thermostability was proposed to conduct an effective symmetry/structure-limited structure search from the existing crystallographic structure database. The ferroelectric/ferroelastic R¹-DABOO-R² series were located, and the further delicate chemical modification of their substituent R¹ and R² groups was performed to reserve specific weak intermolecular interactions in these molecular crystals to finally realize their ferroelectricity. Three new ferroelectrics, namely, 1-benzyl-4-phenyl-3,5-diazabicyclo[2.2.2]octane-2,6-dione, 1-pyrrol-1-yl-methyl-4-(4-bromophenyl)-3,5-diaza-bicyclo[2.2.2]octane-2,6-dione, and 1-piperazin-1-yl-methyl-4-(4-oxo-4H-pyridin-1-yl)-3,5-diaza-bicyclo[2.2.2]octane-2,6-dione with their spontaneous polarizations of about 1 μC cm⁻² were designed, and we are waiting for their future experimental confirmation. Our developed novel design methodology of organic ferroelectrics/ferroelastics from the model system study (building the structure–property relationship) and structure search (following symmetrical and structural principles) to delicate chemical modification (tuning weak intermolecular interactions) would surely inspire the experimental and theoretical exploration of new ferroelectrics/ferroelastics with specific molecular dynamics to switch the phase transitions.

中文翻译：

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通过对称/结构受限结构搜索设计的纯有机转子-定子型组件的弱分子间相互作用调节铁电/铁弹性的计算发现

我们新设计了一系列新颖的纯有机铁电体R ¹ -DABOO-R ²（取代的3,5-二氮杂双环[2.2.2]辛烷-2,6-二酮），作为类似物并表现出良好的实验性能研究了有机金属铁电体/铁弹性体R-DABCO- [M（H ₂ O）Cl ₃ ]（取代的1,4-二氮杂双环[2.2.2] oc三氯水合金属（II））。R-DABCO- [M（H ₂ O）Cl ₃对模型系统进行了充分的研究，以证明结构与属性之间的关系，以实现其铁电/铁弹性。我们发现，调节模型系统的铁电/铁弹性很大程度上取决于随着每个晶体中取代基R的变化而变化的微弱的分子间相互作用。因此，提出了转子-定子型组件应具有旋转动力学和特征空间群以易于切换铁电/铁弹性并摆脱弱金属配位键以增加其热稳定性的设计原理，以进行有效的对称性/结构限制。从现有的晶体学结构数据库中进行结构搜索。铁电/铁弹性R ¹ -DABOO-R ²找到一系列的分子，并对它们的取代基R ¹和R ²进行进一步的精细化学修饰，以保留这些分子晶体中特定的弱分子间相互作用，从而最终实现其铁电性。三种新的铁电体，即1-苄基-4-苯基-3,5-二氮杂双环[2.2.2]辛烷-2,6-二酮，1-吡咯-1-基甲基-4-（4-溴苯基）- 3,5-二氮杂双环[2.2.2]辛烷-2,6-二酮和1-哌嗪-1-基-甲基-4-（4-氧代-4 H-吡啶-1-基）-3， 5-二氮杂双环[2.2.2]辛烷-2,6-二酮，其自发极化约为1μCcm ^-2设计，我们正在等待他们未来的实验确认。我们从模型系统研究（建立结构与属性的关系）和结构搜索（遵循对称和结构原理）到精细的化学修饰（调整弱的分子间相互作用）开发的新颖的有机铁电/铁弹性设计方法论，一定会激发实验和理论上的灵感探索具有特定分子动力学的新铁电/铁弹性体，以切换相变。