Further Molecular Architectures

Beside this, in the recent past some investigations on amphotropic materials of non-amphiphilic structure were made as well (see Further Molecular Architectures in this Chapter). Additionally, it is somewhat difficult to draw a sharp separation line between amphiphilic and nonamphiphilic compounds the ability to act as an amphiphile depends mainly on the size and the polarity of the hydrophilic and hydrophobic parts of a molecule. This internal equilibrium can be varied in a broad range. Thus, in this chapter, although mainly directed toward meso-gens of the amphiphilic type, some apolar mesogens will be discussed as well. 

Changes in cell-wall protein composition may regulate the molecular architecture of protein networks in a manner that allows new developmental outcomes for both fungal cell adhesion and root colonization. Further investigation of the structure and regulation of SRAP wall proteins will provide a more complete picture of their role in developing ectomycorrhizal tissues. Incompatibility between ectomycorrhizal hyphae and the host roots detected during the initial con-... 

The controlled radical polymerization techniques opened up a new era in polymer synthesis, and further growth and developments are certain. However, the control of the molecular characteristics and the variety of macro-molecular architectures reported by these methods cannot be compared with those obtained by other living polymerization techniques such as anionic polymerization. 

Further comments. The preceding discussion outlines typical syntheses for simple polyether crown rings. It needs to be noted that a considerable number of other types of crown derivatives, displaying a variety of molecular architectures, has also been synthesized. Many of these types parallel the structurally developed macrocycles (which incorporate mainly donor atom types other than ether oxygen) discussed in Chapter... 

While some new spirocyclic and bridged seven-membered heterocyclic systems were reported in 2000, the scope in these two areas is significant, particularly with respect to the design of pharmacologically active compounds with new molecular architectures. Further developments in these areas are thus expected. 

The Dess-Martin periodinane 8 is also able to oxidize aromatic compounds to the corresponding quinones. The presence of water is important and, starting from anilides 42 substituted in the 2-position, the rare class of ortho-imido-quinones 43 is accessible, Scheme 21. It has been shown that compounds of type 43 are interesting building blocks and can lead to polycyclic molecules of diverse molecular architecture [95,96]. They can undergo subsequent Diels-Alder reactions and intramolecular versions have been used for a rapid access to natural products and for synthesis of scaffolds for further manipulation.para-Quinones 45 are also easily accessible, however, only in modest yields by reacting 4-sub-stituted anilines 44 under the same reaction conditions, Scheme 21 [97]. 

One of the first alkali metal cation chemosensors was based on the molecular architecture of the anthracene derivative (Figure 16.2c) [9]. Substitution of the simple tertiary amino group with an azacrown macrocycle resulted in fluorescence of the chemosensor responding to protons and potassium cations (Figure 16.5a). Further increase in selectivity of the sensor can be achieved via reduction of Brpnsted s basicity of the macrocycle. On the other hand, this modification must retain the electron donor character of the receptor in order to preserve the PET mode of... 

The atomic and molecular architectures of each of these materials will be intimately described, to understand their respective properties. Without such an appreciation of these relationships, we will not be able to progress our civilization with new and improved materials, further improving our way of life. 

Studies of ethylene-vinyl aromatic monomer polymerizations continue to be published. Chung and Lu reported the synthesis of copolymers of ethylene and P-methylstyrene [28] and the same group extended these studies to produce and characterize elastomeric terpolymers which further include propylene and 1-octene as the additional monomers [29,30]. Returning to the subject of alternative molecular architectures for copolymers, Hou et al. [31] has reported the ability of samarium (II) complexes to copolymerize ethylene and styrene into block copolymers. 

It is noted that further reports have appeared describing other molecular shuttles exhibiting a variety of molecular architectures. ... 

In addition to practical applications, metal cluster-derived catalysts, particularly intrazeolite metal cluster compounds, may aid in the identification of catalytically important bonding and structural patterns and thereby further our molecular understanding of surface science and heterogeneous catalysis. The ship-in-bottle technique for the synthesis of bulky metal-mixed metal cluster compounds inside zeolites and/or interlayered minerals has gained growing attention for the purpose of obtaining catalytic precursors surrounded by the interior constraint, imposing molecular shape selectivity. Such approaches may pave the way to offer the molecular architecture of hybrid (multifunctional) tailored catalysts to achieve the desired selectivity and stability for industrial processes. 

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