Palladium(II)‐Based Self‐Assembled Heteroleptic Coordination Architectures: A Growing Family

Abstract

Metal-driven self-assembly is one of the most effective approaches to lucidlydesign alarge range of discrete 2D and 3D coordinationa rchitectures/complexes. Palladium(II)-based self-assembled coordination architectures are usually preparedb yu sing suitable metal components, in either ap artially protected form (PdL')o rt ypical form (Pd; charges are not shown), and designed ligand components. The self-assembled moleculesp repared by using am etal component and only one type of bi-or polydentate ligand (L) can be classified in the homoleptic series of complexes. On the other hand, the less explored heteroleptic series of complexes are obtained by using am etal component and at least two different types of non-chelating bi-or polydentate ligands (such as L a andL b ). Methods that allow the controlled generation of single, discrete heteroleptic complexes are less understood.As urvey of palladium(II)-based self-as-sembled coordination cages that are heteroleptich as been made. This review article illustratesasystematic collection of such architectures and credible justification of their formation, along with reportedf unctional aspects of the complexes.T he collected heteroleptic assemblies are classified here into three sections:1 )[(PdL') m (L a ) x (L b ) y ]-type complexes, in which the denticity of L a and L b is equal; 2) [(PdL') m (L a ) x (L b ) y ]-type complexes, in which the denticity of L a and L b is different;a nd 3) [Pd m (L a ) x (L b ) y ]-type complexes,i n which the denticity of L a and L b is equal. Representative exampleso fs ome important homoleptic architectures are also provided, wherever possible, to set ab ackground for a better understanding of the related heteroleptic versions. The purpose of this review is to pave the way for the construction of severalu nique heteroleptic coordination assemblies that might exhibit emergents upramolecular functions.Review complexes is m + n and the total variety of components is only two. Applications of these homoleptic complexes in various fields, such as catalysis, [3] molecular recognition, [4a-c] sensing [4d] and encapsulationo fv aried guest molecules, [4c, 5] has been widely studied.Elegantarchitectures of biological multi-component systems, for example, metalloproteins and viral capsids,e xploit weak supramolecular interactions in ac ontrolled and harmonious mannerf or their construction by using relevant building blocks. [6] Occurrences of multicomponent systems in biology inspire chemistsw ho seek to advance structurala nd functional complexitieso fs upramolecular systems. Thus, in the field of metallo-supramolecular chemistry, noteworthy efforts have been directed towardt he rational design and controlled synthesis of discrete, heteroleptic structures. The methodsf or the synthesis of discrete, heteroleptic, self-assembled, coordination architectures from various metal components, such as Zn II ,F e II , Hg II ,C r III ,C o III ,R h III ,C u I ,C u II ,R u II and Pt II ,a re well explored by the groups of Lehn,F ujita, Zheng,S tang, Schm...

Self-assembled conjoined-cages

“…The cages 4a and 5a are hitherto unknown examples of heteroleptic complexes wherein ligands of different denticity are coordinated to Pd(II) 8 . Thus, the present set of cages are unique due to their structural features and associated binding properties.…”

Increasing structural and functional complexity in self-assembled coordination cages

“…As we could not cover all so far reported studies comprehensively, we apologize for what might not have found entry into this selection and refer to further reviews in this direction. 26,[39][40][41][42][43]…”

Tuning the structure and the properties of dithiafulvene metalla-assembled tweezers

“…1, 2 One reason for this success, lies on the high degree of predictability in the geometry of the resulting selfassembled structures. 3 On this basis, more and more complex systems have been produced, including chiral [4][5][6] , heteroleptic [7][8][9] and interlocked [10][11][12] ones. Those self-assembled discrete structures generally include a cavity, 13 and their host properties have been widely studied to target various applications (e.g.…”