Abstract:
The ditopic halogen-bond (X-bond) donors 1,2-, 1,3-, and 1,4-diiodotetrafluorobenzene (1,2-, 1,3-, and 1,4-di-I-tFb, respectively) form binary cocrystals with the unsymmetrical ditopic X-bond acceptor trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene (2,4-bpe). The components of each cocrystal (1,2-di-I-tFb)·(2,4-bpe), (1,3-di-I-tFb)·(2,4-bpe), and (1,4-di-I-tFb)·(2,4-bpe) assemble via N···I X-bonds. For (1,2-di-I-tFb)·(2,4-bpe) and (1,3-di-I-tFb)·(2,4-bpe), the X-bond donor supports the C=C bonds of 2,4-bpe to undergo a topochemical [2+2] photodimerization in the solid state: UV-irradiation of each solid resulted in stereospecific, regiospecific, and quantitative photodimerization of 2,4-bpe to the corresponding head-to-tail (ht) or head-to-head (hh) cyclobutane photoproduct, respectively.
摘要:
同位素卤素键(X键)供体1,2-,1,3-,和1,4-二碘四氟苯(1,2-,1,3-,和1,4-di-I-tFb,分别)与不对称双位X键受体反式-1-(2-吡啶基)-2-(4-吡啶基)乙烯(2,4-bpe)形成二元共晶体。每个共晶的成分(1,2-di-I-tFb)·(2,4-bpe),(1,3-di-I-tFb)·(2,4-bpe),和(1,4-di-I-tFb)·(2,4-bpe)通过N···IX-键组装。对于(1,2-di-I-tFb)·(2,4-bpe)和(1,3-di-I-tFb)·(2,4-bpe),X键供体支持2,4-bpe的C=C键,以在固态下进行拓扑化学[22]光二聚:每种固体的紫外线照射导致立体定向,区域特异性,并将2,4-bpe定量光二聚化为相应的头对尾(ht)或头对头(hh)环丁烷光产物,分别。