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首页> 外文期刊>Chemistry: A European journal >Modification of Supramolecular Binding Motifs Induced By Substrate Registry: Formation of Self-Assembled Macrocycles and Chain-Like Patterns
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Modification of Supramolecular Binding Motifs Induced By Substrate Registry: Formation of Self-Assembled Macrocycles and Chain-Like Patterns

机译：底物登记处诱导的超分子结合基序的修饰：自组装大环和链状模式的形成。

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The self-assembly properties of two ZnII porphyrin isomers on Cu- ACHTUNGTRENUNG(111) are studied at different coverage by means of scanning tunneling microscopy (STM). Both isomers are substituted in their meso-positions by two voluminous 3,5-di(tert-butyl)phenyl and two rod-like 4’-cyanobiphenyl groups, respectively. In the trans-isomer, the two 4’-cyanobiphenyl groups are opposite to each other, whereas they are located at right angle in the cis-isomer. For coverage up to one monolayer, the cis-substituted porphyrins self-assemble to form oligomeric macrocycles held together by antiparallel CN···CN dipolar interactions and CN···H-CACHTUNGTRENUNG(sp2) hydrogen bonding. Cyclic trimers and tetramers occur most frequently but everything from cyclic dimers to hexa- ACHTUNGTRENUNGmers can be observed. Upon annealing of the samples at temperatures >150 8C, dimeric macrocyclic structures are observed, in which the two porphyrins are bridged by Cu atoms, originating from the surface, under formation of two CN···Cu···NC coordination bonds. The trans-isomer builds up linear chains on CuACHTUNGTRENUNG(111) at low coverage, whereas for higher coverage the molecules assemble in a periodic, densely packed structure. Both cis- and trans-bis(4’-cyanobiphenyl)-substituted ZnII porphyrins behave very differently on CuACHTUNGTRENUNG(111) compared to similar porphyrins in literature on less reactive surfaces such as AuACHTUNGTRENUNG(111) and AgACHTUNGTRENUNG(111). On the latter surfaces, there is no signal visible between molecular orientation and the crystal directions of the substrate, whereas on CuACHTUNGTRENUNG(111), very strong adsorbate–substrate interactions have a dominating influence on all observed structures. This strong porphyrin– substrate interaction enables a much broader variety of structures, including also less favorable intermolecular bonding motifs and geometries.
机译：通过扫描隧道显微镜（STM）研究了两种ZnII卟啉异构体在Cu-ACTHUNGTRENUNG（111）上的自组装特性。两种异构体的内消旋位分别被两个庞大的3,5-二（叔丁基）苯基和两个棒状4'-氰基联苯基取代。在反式异构体中，两个4′-氰基联苯基彼此相反，而在顺式异构体中它们成直角。为了覆盖多达一个单层，顺式取代的卟啉通过反平行的CN··CN双极相互作用和CN··H-CACHTUNGTRENUNG（sp2）氢键结合而自组装形成寡聚大环。环状三聚体和四聚体最常出现，但从环状二聚体到六乙酰基肾上腺素均可以观察到。在> 150 8C的温度下对样品进行退火时，观察到二聚体大环结构，其中两个卟啉被源自表面的Cu原子桥接，形成了两个CN··Cu··NC配位键。反式异构体在CuACHTUNGTRENUNG（111）上以低覆盖率建立线性链，而对于较高覆盖率，分子以周期性，密集堆积的结构组装。与文献中类似的卟啉相比，在AuACHTUNGTRENUNG（111）和AgACHTUNGTRENUNG（111）等反应性较低的表面上，顺式和反式双（4'-氰基联苯）取代的ZnII卟啉在CuACHTUNGTRENUNG（111）上的行为都非常不同。在后者的表面上，分子取向与底物的晶体方向之间没有可见的信号，而在CuACHTUNGTRENUNG（111）上，很强的吸附物-底物相互作用对所有观察到的结构都起主要作用。卟啉与底物之间的强相互作用使结构更加广泛，包括分子间键合基序和几何形状较差。

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