Square molecular units, self-assembly

Examples of ditopic and tetratopic macrocycles have been described by Stang and coworkers by combining the calixarene chemistry with the metal-directed self-assembly of molecular squares [61]. In this case the calixarene units coordinate to the Pt through their P(Ph)2 ligands at the lower rim and assume a diverging spatial orientation in the macrocycle. These calixarene metallamacrocycles are used in transport experiments to carry sulfonate salts from one aqueous phase into another through chloroform. 

The self-assembly of a molecular square consisting of four [Pt(ethane-1,2-diamine)] " corner units and four singly deprotonated uracil nucleobases 26 has... 

Hess JL, Hsieh CH et al (2011) Self-assembly of dinitrosyl iron units into imidazolate-edge-bridged molecular squares characterization including Mossbauer spectroscopy. J Am Chem Soc 133 20426-20434... 

Lo Schiavo, S., G. Pocsfalvi, S. Serroni, P. Cardiano, and P. Piraino (2000). Self-assembly of square molecular boxes containing dirhodium(II,II) units. Eur. J. Inorg. Chem. 6, 1371-1375. 

The cavity of [BBIPYBIBTCY] " was found to be almost square with inner dimensions of approximately 11 x 10.5 A, which was fortunately just the right size required for the incorporation of two aromatic units stacked face-to-face. The take-home message is that it is sometimes easier to make the self-assembled structure than it is to make the molecular components ... 

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