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A series of dendritic ammonium salts have been designed and synthesized. Subsequently, they were used to construct the corresponding [2]rotaxanes by a template-directed clipping approach. Unusually, two unsymmetrical dendritic [2]rotaxanes containing fluorophore (pyrene units) were also obtained; their optical properties, such as UV/vis absorption and fluorescence, were measured. The results indicate that these two rotaxanes possess stronger intermolecular interaction in the solid state than in solution. As a result, solutions of high concentration readily formed the excimer. These special rotaxanes might be applied in dynamic fluorescence-reponsive materials, and the rotaxane structure will also be used as a strategy to adjust the aggregated behaviors of fluorescent molecules. [ABSTRACT FROM AUTHOR]

A squaraine rotaxane scaffold with four alkyne groups is readily converted into a range of dendritic architectures using high-yielding copper-catalyzed alkyne azide cycloaddition (CuAAC) chemistry. A convergent synthesis approach is more efficient than a divergent pathway. Dendritic squaraine rotaxanes with peripheral amine groups can be further functionalized to produce multivalent deep-red fluorescent derivatives that exhibit high brightness and outstanding chemical stability in biological solution. The surface groups on these functionalized fluorescent dendrimers include guanidinium, mannose, and phosphatidylcholine. [ABSTRACT FROM AUTHOR]

The article discusses template-directed dynamic synthesis of mechanically interlocked dendrimers. Recently, the versatility of dynamic covalent chemistry (DCC) has been demonstrated in the multicomponent construction of complex mechanically interlocked compounds, such as molecular bundles and nanoscale Borromean rings, as well as in the highly efficient template-directed synthesis of (2) rotaxanes. It has been found that by taking advantage of dynamic covalent chemistry, dendrons from generation zero to two can be self-assembled in near quantitative yields into, first of all, kinetically labile and, then, kinetically stable mechanically interlocked dendrimers.