In spite of the regular highly branched structure that defines dendrimers, it is well documented that they can adopt a myriad of conformations with a tendency to concentrate a bigger mass density at the interior of the molecule, as a result of the pronounced back-folding of terminal segments. This general model –the so called dense core model– is not strictly followed by pi-conjugated dendrimers, which show restricted conformational freedom. As a result, they are shape-persistent and, in some particular cases, they are better described by the dense shell model.<br/>In our research group, we have used tetraphenylmethane as a building block to synthesize shape-persistent dendrimers, because of its rigidity, tetrahedral 3D geometry, 4-fold connectivity and synthetic accessibility. Computer-generated models show that at the second and third generation the dendrimers adopt a persistent globular shape having well-defined internal voids or cavities and the terminal groups located at the periphery with negligible back-folding. It must be noted that the second generation dendrimers (Fig. 1) have a high number of terminal groups and a size of a few nanometers, similar to the fourth generation in Fréchet-type dendrimers. The privileged architecture of shape-persistent porous tetraphenylmethane dendrimers, their structural versatility and fluorescent properties are interesting features for potential applications of those nanomaterials.<br/>In this communication, we will discuss the synthesis and properties of this new class of dendrimers as a function of the core, the rigid rod spacer (X) between tetraphenylmethane units and the periphery functional groups (R). In addition, we will describe our progress in the development of related hybrid lineal-dendritic copolymers.

Tetraphenylmethane shape-persistent dendritic polymers as versatile multifunctional materials

256th National Meeting (2018)

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