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。
