And Selforganization In Mesophases

The stilbenoid dendrimers exhibit a high aggregation tendency in nonpolar solvents. Figure 4 shows the low-field part of the 1H NMR spectrum of 1b (R1 = R2 = OC12H25) in CDCl3 and C6D12 [19, 20]. Chloroform is a good solvent for the compound, and the spectrum in CDCl3 has a normal resolution. The measurement in C6D12, however, gives only broad, unresolved signals. The signal broadening is caused by the formation (and dissociation) of aggregates and the restricted mobility of molecules and molecule segments in aggregates. On dilution or warming to 70 °C, the spectrum in C6D12 becomes highly resolved.

Other proofs of aggregation make use of fluorescence spectra, fluorescence excitation spectra, or dynamic light scattering measurements. Compound 7a, for example, in

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