Controlled Construction of Heteroleptic [Pd₂(L^A)₂(L^B)(L^C)]⁴⁺Cages: A Facile Approach for Site‐Selective endo‐Functionalization of Supramolecular Cavities

Abstract

Construction of supramolecular structures with internal functionalities is a promising approach to build enzyme‐like cavities. The endo‐functionalized [Pd12L24] and [Pd2L4] coordination cages represent the most successful systems in this regard. However, these systems mainly contain one type of endo‐moiety. We herein provide a solution for the controlled endo‐functionalization of [Pd2L4] cages. Site‐selective introduction of the endo‐functional group was achieved through the formation of heteroleptic [Pd2(LA)2(LB)(LC)] cages. Using two orthogonal steric control elements is the key for the selective formation of the hetero‐assemblies. We demonstrated the construction of two hetero‐cages with a single internal functional group as well as a hetero‐cage with two distinct endohedral functionalities. The endo‐functionalized hetero‐cages bound sulfonate guests with fast‐exchange dynamics. This strategy provides a new solution for the controlled endo‐functionalization of supramolecular cavities.

Recent advances in aggregation‐induced emission–active type I photosensitizers with near‐infrared fluorescence: From materials design to therapeutic platform fabrication

“…PDT outcome in vivo was also evaluated, and the tumor growth could be well suppressed after white light irradiation (Figure 8f). This work developed a highly watersoluble type I PS with NIR emission, wash-free targeted bioimaging to lysosome and mitochondria, and great PDT outcome, offering great potential for clinical cancer treatment [70].…”

Heteromeric Completive Self-Sorting in Coordination Cage Systems

“…Recently, we have reported an unprecedented Pd 2 ABCD C s -symmetrical assembly 27 where four different bismonodentate ligands can fuse into a unique discrete cage under thermodynamic control, thus maximizing the structural complexity of such a 4-fold-bridged dinuclear cage. Others have recently realized dinuclear Pd(II) assemblies composed of three different ligands, either in the crystalline state 28 or in solution, 29 as well as systems assembled from four different ligands under kinetic control 30 or by taking advantage of an ancillary pairing approach. 31 While the majority of previous studies on artificial heteroleptic assembly were aimed at producing a single discrete species in solution, biological systems are composed of a multitude of coexisting complex assemblies that either act together or perform separate functions.…”

“…Recently, we have reported an unprecedented Pd 2 ABCD C s - symmetrical assembly where four different bis-monodentate ligands can fuse into a unique discrete cage under thermodynamic control, thus maximizing the structural complexity of such a 4-fold-bridged dinuclear cage. Others have recently realized dinuclear Pd­(II) assemblies composed of three different ligands, either in the crystalline state or in solution, as well as systems assembled from four different ligands under kinetic control or by taking advantage of an ancillary pairing approach …”

Assembly of Six Types of Heteroleptic Pd2L4 Cages under Kinetic Control

“…10−93 As to the Pd 2 L 4 cage assembly composed of two Pd(II) ions and four ditopic ligands (L), there are six types of heteroleptic cages (Figure 1). Type I, 94−96 II, 97−102 and III 103,104 cages composed of two types of ditopic ligands have mainly been produced under thermodynamic control so far, and very recently type IV, 105 V, 106 and VI 105 cages were achieved. Very few examples of heteroleptic Pd(II) cages composed of more than two types of ditopic ligands 107 imply the limitation of the thermodynamic approach for the creation of a variety of complicated multicomponent assemblies.…”