当前位置：
X-MOL 学术
›
Faraday Discuss.
›
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.)
Adventures in boron chemistry – the prediction of novel ultra-flexible boron oxide frameworks
Faraday Discussions ( IF 3.3 ) Pub Date : 2018-05-16 , DOI: 10.1039/c8fd00052b Neil L. Allan 1, 2, 3, 4 , Harvey J. A. Dale 1, 2, 3, 4 , Judy N. Hart 5, 6, 7 , Frederik Claeyssens 4, 8, 9, 10, 11
Faraday Discussions ( IF 3.3 ) Pub Date : 2018-05-16 , DOI: 10.1039/c8fd00052b Neil L. Allan 1, 2, 3, 4 , Harvey J. A. Dale 1, 2, 3, 4 , Judy N. Hart 5, 6, 7 , Frederik Claeyssens 4, 8, 9, 10, 11
Affiliation
|
Recent periodic density functional calculations have predicted the existence of ultra-flexible low-energy forms of boron oxides in which rigid boron–oxygen heterocycles are linked by flexible B–O–B bridges. The minima in the energy landscapes of these frameworks are remarkably broad, with widths in excess of those of many hybrid metal–organic frameworks. Enormous changes in cell volume, which can exceed a factor of two, are accompanied by negligible changes in energy. Here we explore the underlying reasons for this behaviour using molecular electronic-structure calculations, periodic density functional theory and template-based geometric simulations. The angular flexibility of the B–O–B bridge depends only upon the geometry of the local B2O5 unit, independent of the configuration of neighbouring bridges. Unique cooperativity between the bending and twisting motions of the bridges leads to considerable anisotropy in framework flexibility. Exceptional flexibility is conferred not only by the intrinsic bending flexibility of the bridges but by topological factors, crucially the relaxation of torsional constraints when B3O3 rings are present. We test these conclusions by showing how the flexibility of the frameworks can be tuned by decoration with isoelectronic rings. The new nanoporous boron oxides presented in this work are predicted to be potential novel guest–host materials because of their flat energy landscapes. Furthermore, such structures can be generated systematically from silicates by the substitution of B2O54− for SiO44−. A borate analogue of β-cristobalite is shown to be isoenergetic with the known B2O3-I polymorph. We raise the possibility of new families of frameworks and zeolite analogues.
中文翻译：
硼化学历险记–新型超柔性氧化硼骨架的预测
最近的周期性密度泛函计算已经预测了超柔和的低能形式的氧化硼，其中刚性的硼-氧杂环通过挠性的B-O-B桥连接。这些框架在能量方面的最小值非常宽，其宽度超过许多金属-有机杂化框架的宽度。细胞体积的巨大变化（可能超过两倍）伴随着能量的微不足道的变化。在这里，我们使用分子电子结构计算，周期密度泛函理论和基于模板的几何模拟来探索这种行为的根本原因。B–OB–B桥的角度灵活性仅取决于本地B 2 O 5的几何形状单元，与相邻桥的配置无关。桥的弯曲和扭转运动之间的独特协作性导致框架柔韧性方面的相当大的各向异性。桥的固有弯曲柔韧性和拓扑因素都赋予了出色的柔韧性，而当存在B 3 O 3环时，拓扑因素也至关重要。我们通过显示如何通过用等电子环装饰来调整框架的灵活性来测试这些结论。由于其平坦的能量分布，预计这项工作中出现的新型纳米多孔氧化硼是潜在的新型客体-宿主材料。此外，可以通过取代B由硅酸盐系统地生成此类结构2 ø 5 4-对的SiO 4 4-。已知β-方英石的硼酸盐类似物与已知的B 2 O 3 -I多晶型物是同能的。我们提出了新的骨架和沸石类似物家族的可能性。
更新日期：2018-10-26
中文翻译：
硼化学历险记–新型超柔性氧化硼骨架的预测
最近的周期性密度泛函计算已经预测了超柔和的低能形式的氧化硼，其中刚性的硼-氧杂环通过挠性的B-O-B桥连接。这些框架在能量方面的最小值非常宽，其宽度超过许多金属-有机杂化框架的宽度。细胞体积的巨大变化（可能超过两倍）伴随着能量的微不足道的变化。在这里，我们使用分子电子结构计算，周期密度泛函理论和基于模板的几何模拟来探索这种行为的根本原因。B–OB–B桥的角度灵活性仅取决于本地B 2 O 5的几何形状单元，与相邻桥的配置无关。桥的弯曲和扭转运动之间的独特协作性导致框架柔韧性方面的相当大的各向异性。桥的固有弯曲柔韧性和拓扑因素都赋予了出色的柔韧性，而当存在B 3 O 3环时，拓扑因素也至关重要。我们通过显示如何通过用等电子环装饰来调整框架的灵活性来测试这些结论。由于其平坦的能量分布，预计这项工作中出现的新型纳米多孔氧化硼是潜在的新型客体-宿主材料。此外，可以通过取代B由硅酸盐系统地生成此类结构2 ø 5 4-对的SiO 4 4-。已知β-方英石的硼酸盐类似物与已知的B 2 O 3 -I多晶型物是同能的。我们提出了新的骨架和沸石类似物家族的可能性。
京公网安备 11010802027423号