Postassembly Modification of a Pd₆ Host and C₇₀ Encapsulation to Enhance Its ROS-Mediated Terpene Oxidation Ability...

The properties of supramolecules can be modulated by post-assembly modification (PAM) of their building blocks or via guest encapsulation. This work demonstrates a largely uncharted approach to property modulation that integrates both PAM and guest encapsulation in a single system to boost photocatalytic activity. Self-assembly of a "phenothiazine"-functionalized ligand (L) with a cis-blocked Pd(II) acceptor (A) generated an A₆L₃ trifacial tube (T). Postassembly, T could be modified via irradiation with violet light, leading to the sulfoxidation of the "phenothiazine" moieties in T and thereby generating an oxidized tube (TO). Both TO and T could stabilize a C₇₀ molecule within their cavities, forming C₇₀@TO and C₇₀@T, respectively. Although T showed relatively poor photocatalytic performance mediated by reactive oxygen species (ROS) with respect to oxidation of terpenes (S1-S4) under visible light, the modified TO was much better in that regard. Expectedly, C₇₀@T showed better photocatalytic performance than T due to the presence of photosensitizing C₇₀. While PAM or guest encapsulation alone led to reasonable improvements in photocatalytic ability, their combination within C₇₀@TO led to a significant improvement. Catalytic amounts of C₇₀@TO could instantly oxidize terpenes. Thus, we report here a new host that integrates the effects of both PAM and photosensitizer encapsulation for synergistically boosting its photocatalytic activity.