Ditopic monomers

Figure 7.5 Water-soluble MSPs, based on a 2,6-pyridine dicarboxylate end-capped oligo(ethylene oxide) ditopic monomer (2a and 2b) and Zn ions prepared by Vermonden and coworkers (2003).

One aspect of polyelectrolytes that has received a lot of attention in recent years is their utilization in the assembly of multilayered stmctures, which are formed via alternating adsorption of oppositely charged polymers. Using a terpy-end-capped ditopic monomer with, for example, Fe salts, Schiitte et al. (1998) demonstrated that MSPs can be utilized in a layer-by-layer assembly with polyanions such as poly(styrene sulfonate). 

Figure 7.7 Schematic representation of the temperature-induced change in the MSP composed of terpy end-capped ditopic monomers and Fe dihexadecyl phosphate. The temperature-induced transition resuits in a distortion of the metal ion coordination geometry, which occurs because of the melting of the amphiphilic counterions, giving rise to a reversible transition from a diamagnetic low spin state to a paramagnetic high spin state (Bodenthin et al. 2005).

The self-assembly polymerization of ditopic monomers via metal-ligand binding is an easy route for the preparation of metallosupramolecular polymers [52]. 

Figure 9 (a) Structure of ditopic monomers UPyl-UPy6 and (b) specific viscosity versus concentration of their solutions in... 

More accurate dimerization constants, Kdetermined using a fluorescently-tagged derivative of 5 [24]. Meijer and coworkers have demonstrated that ditopic monomers containing 5 are useful for constructing hydrogen-bonded polymers with intriguing properties (vide infra). 

The same design principles used to describe hydrogen-bonded, liquid-crystalline polymers, may also be used to classify hydrogen-bonded polymers in isotropic solution. The first examples described herein are main-chain polymers constructed from ditopic monomers (Figure 7). 

C, = Total molar concentration of hydrogen-bonding groups. For example, Q of a 1 M solution of a ditopic monomer wouid be 2 M... 

Figure 17 Equations and plot relating the number-average DP to the dimerization constant for a self-complementary ditopic monomer at varying concentrations (see also Refs. 5e and 5f). Concentrations are shown at the right of the plot. Equations were derived as in Ref. 68.

Polycap formation was supported by H NMR spectroscopic analysis [73,74], Moreover, a solution of ditopic monomer in o-dichlorobenzene exhibited a concentration-dependent viscosity... 

Ring-chain equilibria are briefly introduced herein. Readers are referred to Ref. 5g fa- a more thorough discussion of this phenomenon. Ditopic monomers that are preorganized to form cyclic aggregates are described in Section IV.D of this chapter. l For a report of the foanation of a calixarene dimer through multiple hydrc en-bonding interactions as in 5 see Ref. 76. 

Figure 31 (a) A cyclic hexamer formed by the self-assembly of preorgahized dendritic monomers (54) containing complementary DDA and AAD hydrogen-bonding arrays [107,108] (b) a cyclic hexamer formed by self-assembly of a ditopic monomer (55) containing ureidopyridopyrimidine 6 [26]. 

Figure36 A schematic representation of linear coordination polymers formed from ditopic monomer units and metal ions.

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