Merging Constitutional and Motional Covalent Dynamics in Reversible Imine Formation and Exchange Processes
Merging Constitutional and Motional Covalent Dynamics in Reversible Imine Formation and Exchange Processes
复制标题
DOI：
10.1021/ja302793c
复制
发表时间：
2012-06-06
影响因子：
15
通讯作者：
Lehn, Jean-Marie
中科院分区：
文献类型：
--
作者：
Kovaricek, Petr;Lehn, Jean-Marie
研究了苯甲醛亚胺的形成和交换过程，表明前者具有动态共价化学的特点，表现出高效率和快速率。与脂肪族α，α，ω-二胺形成的单亚胺显示出自传递型的内部交换过程，通过键交换引起“原地步进”或“单步”型的局部运动，其速率随末端氨基的距离迅速降低。通过取代基、溶剂组成和温度可以在宽范围内控制该过程的速度。这些单亚胺也进行分子间交换，从而合并同一分子内的运动和结构共价行为。与多胺，单亚胺形成执行内部运动，其特征在于广泛的一维，二维和EXSY质子NMR研究。特别地，对于线性多胺，通过醛残基沿着充当分子轨道的多胺链移动而发生非定向置换。因此，亚胺表现为显示分子部分的相对运动的系统的简单原型，这是合成和生物分子马达研究中当前高度感兴趣的主题。所描述的运动过程是动态共价性质的，并且在分子构成没有变化的情况下发生。因此，它们代表一类动态共价运动，由可逆共价键形成和解离引起。他们将动态共价化学扩展到分子运动领域。进一步的一个主要步骤将是实现方向性控制。这里报道的结果为亚胺开辟了广阔的前景，与其他化学基团一起，在多功能分子中实现这些功能，以设计分子器件，呈现出复杂的运动和结构动态行为的组合。
The formation and exchange processes of imines of benzaldehyde have been studied, showing that the former has features of for dynamic covalent chemistry, displaying high efficiency and fast rates. The monoimines formed with aliphatic a,alpha,omega-diamines display an internal exchange process of self-transimination type, inducing a local motion of either "stepping-in-place" or "single-step" type by bond interchange, whose rate decreases rapidly with the distance of the terminal amino groups. Control of the speed of the process over a wide range may be achieved by substituents, solvent composition, and temperature. These monoimines also undergo intermolecular exchange, thus merging motional and constitutional covalent behavior within the same molecule. With polyamines, the monoimines formed execute internal motions that have been characterized by extensive one-dimensional, two-dimensional, and EXSY proton NMR studies. In particular, with linear polyamines, nondirectional displacement occurs by shifting of the aldehyde residue along the polyamine chain serving as molecular track. lmines thus behave as simple prototypes of systems displaying relative motions of molecular moieties, a subject of high current interest in the investigation of synthetic and biological molecular motors. The motional processes described are of dynamic covalent nature and take place without change in molecular constitution. They thus represent a category of dynamic covalent motions, resulting from reversible covalent bond formation and dissociation. They extend dynamic covalent chemistry into the area of molecular motions. A major further step will be to achieve control of directionality. The results reported here for imines open wide perspectives, together with other chemical groups, for the implementation of such features in multifunctional molecules toward the design of molecular devices presenting a complex combination of motional and constitutional dynamic behaviors.