Dynamic vapochromic behaviors of organic crystals based on the open-close motions of S-shaped donor-acceptor folding units.
Dynamic vapochromic behaviors of organic crystals based on the open-close motions of S-shaped donor-acceptor folding units.
复制标题
DOI：
10.1002/chem.200903403
复制
发表时间：
2010-04
期刊：
影响因子：
--
通讯作者：
E. Takahashi;H. Takaya;T. Naota
中科院分区：
文献类型：
--
作者：
E. Takahashi;H. Takaya;T. Naota
介绍了第一批气致变色有机晶体的制备、变色、吸附/脱附性能、晶体结构和变色机理。带有两个吡咯亚胺（PI）系链的非溶剂化变色的1，4，5，8-萘-四羧酸二酰亚胺（NDI）衍生物Ia已被用作晶体堆积模板的基序。通过抽空橙子晶体2（相当于1a 2 MeOH）来制备红紫色汽致变色固体3，所述晶体2通过从MeOH中重结晶1a获得。固体3在暴露于各种有机蒸气时显示出高吸附能力和前所未有的蒸气依赖性颜色变化，而浅棕色无定形固体Ia没有显示出对任何有机溶剂的蒸气变色或溶剂化变色行为。TGA实验和吸附/脱附等温线证实了3的强吸附能力。对固态UV/维斯分析的分析表明，3的蒸气依赖性颜色变化归因于溶剂蒸气对其在λ =450-650 nm处的宽CT吸光度的特定干扰。通过单晶和同步辐射粉末X射线衍射分别明确地建立了1 a在橙子晶体2、红紫色固体3和再生橙子固体2中的堆积结构。分子结构和排列表明：（1）在2和3中，单元1a通过NDI与两个PI单元之间的分子内给体-受体相互作用而形成S型折叠构象：（2）在S型模板中引入客体蒸气，降低了分子内PI-NDI相互作用，同时增加了分子间NDI-NDI和PI-PI相互作用;和3）在可逆吸附/脱附过程中，S形模板的这种柔性的开-闭运动可以重复，而不会使晶体堆积降解。结合实验结果、晶体学数据和理论计算，讨论了3的吸附性质和分子形状依赖的汽致变色行为的机理。
The first vapochromic organic crystals are described with respect to their preparation, color change, adsorption/desorption properties, crystal structures, and color-change mechanism. Non-solvatochromic, 1,4,5,8-naphthalene-tetracarboxylic diimide (NDI) derivatives 1 a bearing two pyrrole imine (PI) tethers have been used as a motif for the crystal packing template. Red-purple vapochromic solid 3 was prepared by evacuation of orange crystals 2 (equivalent to 1 a2 MeOH), obtained by recrystallization of 1 a from MeOH. Solid 3 showed high-adsorption ability and unprecedented vapor-dependent color changes upon exposure to a variety of organic vapors, whereas light brown amorphous solid 1 a, did not show vapo- or solvatochromic behavior toward any organic solvent. The strong adsorption capability of 3 was confirmed by TGA experiments and adsorption/desorption isotherms. Analysis of the solid-state UV/Vis analysis revealed that the vapor-dependent color changes of 3 were owed to the specific interference of solvent vapors with its broad CT absorbance at lambda=450-650 nm. Packing structures of 1 a in orange crystals 2, red-purple solid 3, and regenerated orange solid 2 were unequivocally established by single crystal and synchrotron powder X-ray diffraction, respectively. Molecular structures and arrays of 1 a in these materials indicated that 1) unit 1 a had an S-shaped folded conformation in 2 and 3 by intramolecular donor-acceptor interactions between NDI and two PI units; 2) inclusion of the guest vapor into the S-shaped template decreased the intramolecular PI-NDI interactions, accompanied by increasing intermolecular NDI-NDI and PI-PI interactions; and 3) such flexible, open-close motions of the S-shaped template could be repeated during reversible adsorption/desorption processes without degradation of crystal packing. The adsorption properties and mechanism of molecular shape-dependent vapochromic behavior of 3 are discussed with reference to experimental results, crystallographic data, and theoretical calculations.