Soluble single-substituent

The preparation of soluble, single-substituent polyphosphazenes that contained species 1-4 as side groups could not be accomplished because, as noted previously, the direct addition of the sodium salt of the chromophore to... 

In the course of developing the Polacolor and SX-70 processes many insulated dye developers were synthesized and investigated. An extensive review of this work is available (21). The insulating linkage, chromophore, and developer moiety can each be varied. Substituents on the developer modify development and solubility characteristics substituents on the chromophore modify the spectral characteristics in terms of both color and tight stability. The attachment of two dyes to a single developer by amide linkage has also been described (22). 

All of the thermotropic polyesters containing a single substituent, including 4-biphenyl, phenylalkyl, phenyl, phenoxy, tert-butyl and Br either in the TA or HQ moiety, usually are not soluble in common organic solvents. In contrast, a polyester containing a... 

In a continuous effort to circumvent the problem of poor solubility and tune the steric effects and electronic features of Pcs, several effective strategies have been developed. As a result, in recent years many neutral Pcs containing substituents at peripheral a or p positions, or in the axial direction, as well as ionic and sandwich-type Pcs have been synthesized and their single-crystal structures resolved by X-ray diffraction analysis [15-24], It therefore appears necessary to give a relatively comprehensive overview of the new progress in Pc chemistry. In this chapter, we summarize recent research results on the synthesis, crystal structures, and various physical properties of monomeric Pc compounds. 

SAR studies have shown that a weakly basic imidazole or 1,2,4-triazole rings substituted only at the N-l position are essential for activity. The substituent must be lipophilic in character and usually contains one or more five or six membered ring systems, some of which may be attached by an ether, secondary amine or thioether group to the carbon chain. The more potent compounds have two or three aromatic substituents, which are singly or multiply chlorinated or fluorinated at positions 2, 4 and 6. These nonpolar structures give the compounds a high degree of lipophilicity, and hence membrane solubility. 

This has led to the possibility that materials might be designed which have high performance and only adopt a single polymorph, making that polymorph more structurally stable than a counterpart which can adopt different crystalline phases. Designing in bulky substituents on the positions most susceptible to reaction is another approach showing some potential toward structural stability, with the added benefit that some derivatives are soluble [38]. 

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