Hexa self-assembly

Duati M, Grave C, Tcbeborateva N, Wu J, Mullen K, Shaporenko A, Zhamikov M, Kriebel JK, Whitesides GM, Rampi MA (2006) Electron transport across hexa-peri-hexabenzo-coronene units in a metal-self-assembled monolayer-metal junction. Adv Mater 18 329-333... 

There are two levels of self-assembly in the formation of tetra-, penta-and hexa-nuclear products from the poly-bipyridyls (L) 20 and 21 and iron(II) salts FeCl2, FeBr2 or FeS04 - the products are anion-dependent. The coordination of three bpy units, from different ligand molecules, to the Fe2+ centers produces a helical structure interaction of these helical strands with anions results in further molecular organization to form the final toroidal product. The discussion draws parallels between the helical and toroidal structures here and secondary and tertiary structure in biological systems (482). Thermodynamic and kinetic intermediates have been characterized in the self-assembly of a di-iron triple stranded helicate with bis(2,2/-bipyridyl) ligands (483). 

Fig. 9.13 a) Preparation of laterally structured SAMs by the microcontact printing (pCP) technique. A structured PDMS stamp is inked with self-assembling molecules (hexa-decanethiols HDT) and placed onto a planar substrate (gold). SAM formation occurs within seconds at the areas of contact (I). The structure can be further processed by etching (II) or deposition of a second SAM (III) onto... 

The beautiful circular tetra- 454 [24], penta- 455 [25] and hexa-nuclear 456 [24] helical structures are built of the ligands each of which coordinates with three metal ions. Interestingly, the self-assembly of trisbipyridine ligand 457 to afford the penta- or hexanuclear complex is governed by the counterion. Namely,... 

Hill, J. P., Jin, W. S., Kosaka, A., et al., Self-assembled hexa-peri-hexabenzocoronene graphitic nanotube. Science 2004, 304, 1481-1483. 

Fukushima and Aida et al. reported that an achiral amphiphilic hexa-pen-hexabenzocoronene (HBC) 3 self-assembles into a helical coil and further into nanotubes in THF containing water (20% v/v) (Fig. 2) [37]. TEM revealed... 

The formation of racemic mixtures of homochiral oligopeptides is not confined to racemates undergoing spontaneous segregation into enantiomor-phous domains it can also be extended to racemic 2-D crystallites, provided the reaction pathway takes place preferentially between homochiral molecules related by translation symmetry, as in the case of the thioethylester of N -slearoyl-lysinc (Cis-TE-Lys) [193]. It has been experimentally proven by GIXD that racemic Cis-TE-Lys self-assemble into racemic 2-D crystallites, Fig. 15. Moreover, MALDI-TOF MS analyses of oligopeptide samples obtained from the polycondensation of deuterium enantiolabeled monomers have revealed a clear trend toward enhanced formation of di- to hexa-peptides with homochiral sequences, in agreement with a reaction pathway between homochiral monomer molecules related by translation symmetry [193,195]. 

Ringsdorf showed a nice example of confinement of supramolecular polymers.192 In cyclohexane, hexa-cinnamoyl azacrown 37 self-assembles to form supramolecular columnar polymers. The periphery of photopolymerizable groups forms cross-links via photocycloaddition and allows the pre-assembled supramolecular polymer to be transferred into a rodlike covalent polymer (Figure 21). Performing the reaction on molecularly dissolved molecules gives rise to a randomly cross-linked polymer with a lower DP. 

Campbell, G. A., Mutharasan, R. Monitoring of the self-assembled monolayer of 1-hexa-decanethiol on a gold surface at nanomolar concentration using a piezo-excited millimeter-sized cantilever sensor. Langmuir 2005, 21 (25), 11568-11573... 

W. Pisula, M. Kastler, D. Wasserfallen, T. Pakula, K. Mullen, Exceptionally long-range self-assembly of hexa-peri-hexabenzocoronene with dove tailed alkyl substituents. J. Am. Chem. Soc. 126, 8074-8075 (2004)... 

Figure 2 Synthesis of tr/s-ligand 3 and hexa/c/s-ligand 7 via Suzuki coupling and subsequent, multicomponent self-assembly into a spoked wheel 8 under thermodynamic control with Cd". Adapted with permission from Ref. iiJAi1450. Copyright 2011 American Chemical Society.

PMl-substituted hexa-peri-hexabenzocoronene (HBC) 35 was designed as model compound for intermolecular energy and electron transfer studies because of its Dgh symmetry, electronic and self-assembling properties [33-35]. The multichromophore (HBC-6PM1) 35 has six PMl chromophores attached to HBC via a 3 -dodecyl-4, 5, 6 -triphenyl-1,l 2, l"-terphenyl spacer unit (Scheme 8). HBC-6PM1 35 was obtained by Diels-Alder reaction of hexa-[4-(tetradec-l-yn-l-yl)phenyl]-HBC 34 [36] and well-established building block PMI-decorated Cp 29 (as discussed above) in diphenyl ether at 250°C in 58% yield [33-35]. Indeed, electronic excitation of the HBC core of this molecule resulted in efficient energy transfer to the PMl shell [37, 38]. 

Wu J, Li J, Kolb U, Miillen K (2006) A water-soluble hexa-pcri-hexabenzocoronene synthesis, self-assembly and role as template for porous silica with aligned nanochannels. 

Ito S, Wehmeier M, Brand JD, Kiibel C, Epsch R, Rabe JP, Mullen K (2000) Synthesis and self-assembly of functionalized hexa-peri-hexabenzocoronenes. Chem Eur J 6 4327-4342... 

Dou X, Pisula W, Wu J, Bodwell GJ, Mullen K (2008) Reinforced self-assembly of hexa-peri-hexabenzocoronenes by hydrogen bonds from microscopic aggregates to macroscopic fluorescent organogels. Chem Eur J 14 240-249... 

Wu J, Watson MD, Tchebotareva N, Wang Z, Miillen K (2004) Oligomers of hexa-pcn-hexabenzocoronenes as super-oligophenylenes synthesis, electronic properties, and self-assembly. J Org Chem 69 8194-8204... 

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