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...

A new one-dimensional double chain photoluminescent Hg(II) coordination polymer (CP), {[Hg(L)]·(ClO)} (1), was synthesized using a benzimidazole-appended tripodal tridentate ligand, 1,3,5-tris(benzimidazolylmethyl)benzene (L). The dynamic and flexible framework of 1 allows it to be entitled as first Hg(II)-based CP belonging to the rare category of CPs that exhibit multistimuli-responsive photoluminescence sensing properties and called as "smart" material. The sensitivity of this material via luminescence quenching method showing "turn off" behavior to a range of stimuli, including anions, solvents, and nitroaromatic compounds (NACs), offers more fine-grained control over its properties. 1 can easily adjust its channel dimensions to encapsulate different guest anions forming complete/partial anion-exchanged materials 1A-1B/1C-1E using NO, BF, OTf, OTs, and PF anions, respectively. Reversible (1A and 1B) and irreversible (1C-1E) anion exchange behaviors were observed for the complete and partial anion-exchanged products, respectively. The noteworthy feature of the anion-exchanged compounds is their anion-triggered luminescent behavior depending on different properties of anions.The excellent emission in water and high hydrolytic stability of 1 allows its use for rapid and efficient fluorescence-based detections of NACs in aquatic system. The uncoordinated pendant benzimidazole moiety in 1 serves as Lewis basic recognition site for trinitrophenol (TNP) detection, and along with electron- and energy-transfer mechanisms, 1 forms a luminescent probe for detection of TNP with low detection limits (0.55 ppm), exhibiting excellent photostability and recyclability. 1 also represents the first reported Hg(II)-based sensory CP material that can discriminate nitrophenol and nitroaniline isomers through fluorescence sensing.

Coordination‐driven self‐assembly has been well recognised as an efficient strategy for the construction of a vast range of metallo‐supramolecular architectures. The combination of selected metal components with suitable bi‐ or polydentate organic ligands under suitable conditions is known to afford a variety of discrete self‐assembled coordination complexes of desired shapes/architectures. In their Review article on page 12241 ff., D. Bardhan and D. K. Chand et al. highlight recent progress in the construction of palladium(II)‐based heteroleptic complexes. These complexes are prepared by the combination of either a cis‐protected or an usual palladium(II) cation with at least two different types of ligands.