Macrocycle columnar structure

The same type of columnar structure is also proposed for other polycatenar materials, such as tetrone derivatives [51], phasmidic macrocyclic liquid crystals [52], silver (I) complexes [53], or 2,2 -bipyridine derivatives [54]. 

Much attention is currently devoted to the synthesis and properties of shape-persistent macrocycles[l]. Such compounds are interesting for a variety of reasons including formation of columnar stacks potentially capable of performing as nanopores for incorporation into membranes or for the generation of nanowires[2]. Furthermore, in shape-persistent macrocycles incorporating coordination units, enc/o-cyclic metal-ion coordination may be exploited to generate nanowires[3], whereas e.ro-cyclic coordination can be used to construct large arrays of polynuclear metal complexes[4]. Shape-persistent macrocycles with reactive substituents may also be linked to other units to yield multicomponent, hierarchical structures. 

Analysis of the electron density of the dimer sheds some light about the nature of the intermolecular interactions that produce such a drastic shortening in the distances between macrocycles within a column. Thus, the arrangement of the SubPz 278 (X = F) into columnar crystalline structures implies more than a simple p-stacking along the c direction but also the presence of three beps between the fluorine atoms of one of the molecules and the fluorosubazaporphyrin that is above. In addition, three beps are found that can be associated to n-n interaction between the two molecules (Fig. 10). 

Pc macrocycle. Some of them are mesomorphic and show a Colh phase (Fig. 79 I-Gl G 115 Coin 270 I II-Gl G <-20 Colh > 320 h H-G2 G 115 Colh 250 I II-G3 94 Colh 108 I) for which the structure of the columnar mesophase is frozen at room temperature (anisotropic glasses). The functionalization of these dendrons in the 3 and 5 position of the terminal rings by oligo(ethyleneoxy) chains (0CH2CH2)30CH3, and their subsequent grafting onto the phthalocyanine of type I (Fig. 79) led to amphiphiUc materials [333]. In concentrated ethanol solutions ( 20-40% by mass), the compound with the fimctionaUzed G1 dendron behaves as a discotic amphiphUe forming a coliunnar nematic lyotropic phase. In addition, it possesses a columnar mesophase stable from room temperature up to 260 °C. Systems of type III are not mesomorphic. 

The stacking of macrocycles ureas, such as the few-urea in Figure 9(a), quickly generates tubular shaped structures with homogeneous channels. The macrocycles are relatively flat with the ureas preorganized perpendicular to the plane of the macrocycles, a conformation that aids columnar assembly (Figure 9a). The size, shape, and interior functionality of the channels are controlled by the single macrocyclic unit used in their construction. These... 

Disclike organic molecules consisting of flat-shaped aromatic macrocycles tend to form columnar stacks in the crystalline state as well as in a liquid-crystalline solution [140-148]. As such, ph-thalocyanines, which behave as molecular semiconductors in the solid state, have been investigated in considerable detail [140,141]. The basic structural unit consists of four connected pyrrole rings (see Fig. 21a), and the flat-shaped form allows a 47-electron cloud delocalized over an array of 18 carbon and nitrogen atoms. Met-allophthalocyanines can be prepared by coordinating metals, such as Fe, Ru, Co, Pd, Pt, Pb, Ni, Cu, Zn, Mn, and Cr, in the core see Figure 21b [141]. In addition, the perimeter can be substituted... 

A particular attribute of octasubstituted phthalocyanines is their liquid crystalline behavior. Phthalocyanines substituted in peripheral positions by long-chain substituents form, depending on the structure (alkyl or alkoxy), liquid discotic (from the disclike shape of the molecules) crystalline phases [68-71 ] or columnar meso-phases [72]. Liquid crystalline phases are found for side chains longer than C4 or Q (depending on the metals and substituents used) [73]. In these mesophases the phthalocyanine moieties stack in columns with arrangements of different symmetry (Fig. 15.8), depending on the nature of the side chains [71,74]. Only chains connected with a heteroatom X (X = O, S) to the aromatic macrocycle show an arrangement with the molecular planes perpendicular to the column axis. 

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