Chemistry of anthracene-acetylene oligomers XX: synthesis, structures, and self-association of anthracene-anthraquinone cyclic compounds with ethynylene linkers.

We have synthesized anthracene-acetylene oligomers, which contained one 10-substituted anthracene unit and one anthraquinone unit, by cyclization with Sonogashira coupling. X-ray analysis revealed an almost-planar framework and significant out-of-plane deformation around the inner carbonyl moiety because of steric hindrance. These compounds underwent self-association in solution and their association constants for monomer-dimer exchange were determined by variable-concentration (1)H NMR measurements in CDCl(3): 8 mol(-1) L (10-substituent: isopropyl), <5 mol(-1) L (methoxy), and 19 mol(-1) L (octyloxy). These results were discussed on the basis of spectroscopic and molecular-orbital analysis. A linear molecular assembly of the octyloxy compound at a liquid/graphite interface was observed by STM measurements.

2D networks of rhombic-shaped fused dehydrobenzo[12]annulenes: structural variations under concentration control.

A series of alkyl- and alkoxy-substituted rhombic-shaped bisDBA derivatives 1a-d, 2a, and 2b were synthesized for the purpose of the formation of porous networks at the 1,2,4-trichlorobenzene (TCB)/graphite interface. Depending on the alkyl-chain length and the solute concentration, bisDBAs exhibit five network structures, three porous structures (porous A, B, and C), and two nonporous structures (nonporous D and E), which are attributed to their rhombic core shape and the position of the substituents. BisDBAs 1a and 1b with the shorter alkyl chains favorably form a porous structure, whereas bisDBAs 1c and 1d with the longer alkyl chains are prone to form nonporous structures. However, upon dilution, nonporous structures are typically transformed into porous ones, a trend that can be understood by the effect of surface coverage, molecular density, and intermolecular interactions on the system's enthalpy. Furthermore, porous structures are stabilized by the coadsorption of solvent molecules. The most intriguing porous structure, the Kagome pattern, was formed for all compounds at least to some extent, and the size of its triangular and hexagonal pores could be tuned by the alkyl-chain length. The present study proves that the concentration control is a powerful and general tool for the construction of porous networks at the liquid-solid interface.