Crystal oligo

The reactions of mercury(II) salts with oligo-amines afford informative examples for the fact that counterions induce the formation of a distinct complex or select a distinct complex in an equilibrium to crystallize with. Thus, Hg11 acetate with dien under exactly the same reaction conditions, in the presence of C104- or PF6-, yields the dinuclear complex [Hg2(dien)3](C104)4 or the mononuclear species [Hg(dien)(H20)](PF6)2, respectively, both characterized by IR, H, and 13C NMR spectrometries, by fast-atom bombardment (FAB) MS, cyclovoltammetry, and X-ray structure analyses.209 In the first compound Pna2, Z = 4), one Hg adopts five-coordination with one tridentate and one bidentate dien ligand, which with the remaining N-donor binds to the... 

G. Hughes, C. Wang, A.S. Batsanov, M. Fern, S. Frank, M.R. Bryce, I.F. Perepichka, A.P. Monkman, and B.P. Lyons, New pyrimidine- and fluorine-containing oligo(arylene)s synthesis, crystal structures, optoelectronic properties and a theoretical study, Org. Biomol. Chem., 1 3069-3077, 2003. 

Belosludtsev and coworkers (2001) propose that the unmodified probes on the weakly cationic surface, although prevented from diffusing off the surface because of electrostatic interaction, nevertheless are available for hybrid nucleation. They suggest that such probe behavior could be viewed similarly to behavior observed in a liquid crystal matrix. This would be in sharp contrast to models describing the covalent attachment of short oligonucleotides as "oligo lawns" or monolayers of coiled probes (see Figure 3.6). 

The electric conductivity was also measured for complexes of taper-shaped mesogens with oligo(ethylene oxide) central groups. The DC conductivity is in a range of 10 9 to 10 6 S cm-1 and shows a step-like increase at the crystal-columnar phase transition [86]. It was also shown that taper-shaped molecules adjacent to different endo-receptors such as crown ethers or oligo(ethylene oxide) chains were miscible with a poly(methacrylate) matrix and formed isomorphic phases [87]. Applications as columnar reaction media for polymerizations were foreseen. Comprehensive summaries of Percec s taper-shaped molecules can be found in the literature [88, 89]. 

Thermochromic photoluminescent liquid crystals have been reported recently as well as the mechanochromic photoluminescent liquid crystals. Weder and coworkers reported on oligo(p-phenylene vinylene) derivative 6 showing thermochromic... 

The fact that hydrates are more common in the disaccharides provides an opportunity to study the way in which the inclusion of water molecules may influence the hydrogen-bonding patterns of oligo- and polysaccharides. The crystal structures of several compounds have been studied in both the anhydrous and hydrated forms. 

Jeffrey OA, French AD (1978) fylono-, oligo- and poly-saccharide crystal structures. Chap 8. In Sutton LE, Truter MR (eds) Molecular structure by diffraction methods, vol. 6. The Chemical Society. London, UK, pp 183-223... 

In Fig. 3 one finds a variety of functional groups that may be subdivided as follows haloalkyl groups [14-16], saturated esters (acetate [17], and benzoate [18,19]) unsaturated esters (methacrylate [19,20], acrylate [21], cinnamate [20], and others [21]) malonate and related esters [22-24] ethers and oligo(oxyethylenes) [25-28] imides [29,30] alkylsilyloxy groups [31] perfluoroalkyls [32-34] and protected carbohydrate groups [35]. Vinyl ethers with mesogenic (liquid-crystal forming) substituents will be treated separately in Section II. B.2. 

These adducts consist of cyclic dimers comprising folded M2Si2 backbones. The spectroscopic data reveal mainly ionic interactions between alkali metal cations and hypersilanide anions. Additionally, oligo-hapto coordination of the metal ions by the toluene molecules is observed. Intra- and intermolecular agostic interactions to C-H bonds finally govern the peculiarities of both, the molecular and the crystal structures of these compoimds. 

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