Amphiphilic Dendrimers Based on a Thiacalix[4]arene‐Gallic Alcohol Conjugate: Synthesis, Aggregation Behavior, and Catalytic Activity in Aqueous Media

A novel family of amphiphilic dendrimers based on a thiacalix[4]arene‐gallic alcohol conjugate was synthesized via Mitsunobu reaction followed by copper‐catalyzed azide–alkyne cycloaddition (CuAAC). Three types of polar peripheral groups—sulfonate (SO 3 Na), oligoethylene glycol (EG), and hydroxyl (OH)—were introduced to impart hydrophilic character, while the hydrophobic thiacalix[4]arene core served as the lipophilic domain. The dendrimers were employed as stabilizers for palladium nanoparticles (Pd NPs). Nanoparticle racking analysis revealed that the terminal group critically governs aggregation behavior, with SO 3 Na inducing compaction, EG promoting surface aggregation, and OH disrupting pre‐existing aggregates to generate a larger number of smaller particles. The Pd&R‐TCA composites exhibited excellent catalytic activity in the reduction of p ‐nitrophenol ( k app up to 0.9 min −1 ) and p ‐ethylnitrobenzene ( k app up to 0.6 min −1 ), significantly outperforming unsupported Pd 0 and Pd(OAc) 2 . In aqueous Suzuki–Miyaura and Heck cross‐coupling, the Pd&EG‐TCA system demonstrated the highest conversions (up to 99%) due to its superior thermal stability and substrate solubilization capacity, as confirmed by TEM and Orange OT tests. The activity order reversed compared with reduction reactions, highlighting that the optimal dendrimer stabilizer depends on both reaction type and substrate hydrophobicity.