Thomas Brijith, Rombouts Jeroen, Oostergetel Gert T, Gupta Karthick B S S, Buda Francesco, Lammertsma Koop, Orru Romano, de Groot Huub J M
Leiden Institute of Chemistry, Einsteinweg 55, 2333CC, Leiden, The Netherlands.
Vrije University Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands.
Chemistry. 2017 Mar 8;23(14):3280-3284. doi: 10.1002/chem.201700324. Epub 2017 Feb 16.
Hybrid magic-angle spinning (MAS) NMR spectroscopy and TEM were demonstrated for de novo structure determination of para-crystalline materials with a bioinspired fused naphthalene diimide (NDI)-salphen-phenazine prototype light-harvesting compound. Starting from chiral building blocks with C molecular symmetry, the asymmetric unit was determined by MAS NMR spectroscopy, index low-resolution TEM diffraction data, and resolve reflection conditions, and for the first time the ability to determine the space group from reciprocal space data using this hybrid approach was shown. Transfer of molecular C symmetry into P2/c packing symmetry provided a connection across length scales to overcome both lack of long-range order and missing diffraction-phase information. Refinement with heteronuclear distance constraints confirmed the racemic P2/c packing that was scaffolded by molecular recognition of salphen zinc in a pseudo-octahedral environment with bromide and with alkyl chains folding along the phenazine. The NDI light-harvesting stacks ran orthogonal to the intermolecular electric dipole moment present in the solid. Finally, the orientation of flexible lamellae on an electrode surface was determined.
利用混合魔角旋转（MAS）核磁共振光谱和透射电子显微镜（TEM）对具有仿生稠合萘二酰亚胺（NDI）-水杨醛缩邻苯二胺-吩嗪原型光捕获化合物的准晶材料进行了从头结构测定。从具有C分子对称性的手性结构单元出发，通过MAS核磁共振光谱、低分辨率TEM衍射数据索引和解析反射条件确定了不对称单元，并且首次展示了使用这种混合方法从倒易空间数据确定空间群的能力。分子C对称性向P2/c堆积对称性的转变提供了跨越长度尺度的联系，以克服缺乏长程有序和缺少衍射相位信息的问题。用异核距离约束进行精修证实了外消旋P2/c堆积，其由在具有溴化物的伪八面体环境中水杨醛缩邻苯二胺锌的分子识别以及烷基链沿吩嗪折叠所支撑。NDI光捕获堆叠与固体中存在的分子间电偶极矩正交。最后，确定了柔性薄片在电极表面的取向。
