Ad endrimeric trimer undergoes folding and unfolding in response to ac hemical stimulus. The trimer of interest contains ac entral dendrimer with ab utadiynelinked zinc porphyrin dimer ((ZnP) 2 )c ore, in addition to two terminal dendrimers with zinc porphyrin (ZnP) cores. The obtaineda bsorption spectra indicate that the unfolded form is the exclusive conformer in chloroform, while the addition of 1,4-diazabicyclo[2.2.2]octane (DABCO) in chloroform leads to transformation from the unfolded to the folded structure containing two DABCO units per trimer;t he folded structure originates from the cross-linking of (ZnP) 2 and ZnP with DABCO. Moreover,t he addition of excess DABCO promotes the generation of the unfolded structure containing four DABCO units.The folding of proteinsi sk nown to create organized three-dimensional structurest hat are essential for imparting aw ide range of biological functions. This process can also be simulated by the cross-linkage of single-chain polymers to produce discrete nanoscale macromolecules, such as organic nanoparticles (ONPs).[1] However,t he application of such methods to the construction of organized arrays of functional units is challenging due to structural diversity at the molecular level. To date, dendrimers have attracted attention as building blocks for ONPs, as the well-defineds tructures of dendrimers allow the precise arrangemento ff unctional units.[2] Indeed,w ep reviously reported au nique method for the construction of ONPs using dendrimers with rigid backbones. [3] In this method, dendrimersw ere linearly connected using alkyl chains and the self-folding of the resulting assembly produced ONPs with rigid backbones. Although such rigid backbonesa ppear to be au seful framework for the precise arrangement of functional units in ONPs,t he random aggregation of these backbones limits their utility.In contrast, folding of the dendrimer assembly through the cross-linking of rigid backbones is am ore sophisticated approach to create ONPs since the rigid cross-linkers can produce an extended backbone with ap redictable structure (Figure 1a). Thus, we herein report the preparation of at rimer of dendrimers containing ab utadiyne-linked zinc porphyrin dimer( (ZnP) 2 ) as the core of the central dendrimer,i na ddition to two terminal dendrimers containing zinc porphyrin (ZnP) cores (Figure 1b). Such porphyrins are considered particularly valuable for the formation of noncovalentc ross-linkages.[4] We expect that upon the addition of suitable bidentate ligands as crosslinkers, the trimer will undergo folding and unfolding as shown in Figure 1a.I na ddition, ZnP and (ZnP) 2 can be independently monitored by spectroscopicm easurements, thereby allowing the folding and unfolding processes to be disclosed. [5] As such, we will employ spectroscopic techniques to examine trimerf olding and unfolding in response to ac hemical stimulus.Trimer 1 andd endrimers 2 and 3 were synthesized as outlined in Scheme1.F ollowing the initial reaction of two hydroxyl groups in 2a wi...