Self-assembled Coordination Architectures & Donor- Acceptor Systems: Synthesis, Characterization and Applications
Self-assembled Coordination Architectures & Donor-Acceptor Systems: Synthesis, Characterization and Applications Atul Kumar The extraordinary ability of biological systems to develop complex and functional molecular assemblies have constantly inspired chemists to design and synthesize molecular architectures that are capable to mimic biological functions. With the advent of ‘Supramolecular Chemistry’ along with the advancement of the synthetic methodologies and characterization techniques, molecular systems with brand new complexities have been synthesized. The process of molecular self-assembly is well utilized in this context to design discrete supramolecular architectures via spontaneous and reversible organization of molecular building blocks into ordered structure by non-covalent interactions which include Van der Waals forces, hydrogen bonding, 𝜋−𝜋 interactions, dynamic covalent interactions, metal-ligand coordination and solvophobic effect.1 In particular, metal-ligand coordination-driven self-assembly evolved as one of the most efficient approaches for the construction of discrete 2D and 3D supramolecular architectures with the aid of reversible bond formation.2 These self-assembled architectures found numerous applications for guest encapsulation, stabilizing reactive intermediates, catalysis, optoelectronics etc. In this context, we have designed water-soluble nanoscopic Pd6 trigonal prism (A) integrated with hydrophobic pocket. Moreover, the cage A possess large opening windows and it was explored as a molecular vessel to catalyse otherwise challenging pseudo multicomponent dehydration reaction in its confined nanospace in aqueous medium.3 In another report, we have explored flexible tri-imidazole donors to design Pd3L2 cages.4 Furthermore, formation of water-soluble hexa-nuclear interlocked cages of Pd(II)/Pt(II) was achieved by multicomponent self-assembly of a flexible tri-imidazole donor and a rigid tri-pyridyl donor based on triazine core. The formation of interlocked assemblies was also explored via self-sorting phenomena and their stability/formations were explained by DFT studies.5 In another report, we have explored self-assembly of a flexible tetra-imidazole donor with 180°/120° di-platinum(II) acceptors to design molecular cages as aggregation induced emissive (AIE) imminent supramolecular optoelectronic materials. Moreover these AIE Pt(II) metallacages were explored as artificial light-harvesting systems in aqueous medium with high energy efficiency and good antenna effect.6 Furthermore, we have explored star-shaped donor-acceptor (D-A) molecules which showed intense solvatochromism and AIE effect due to twisted intramolecular charge transfer (TICT) process. These fluorophores emit complementary colours and generate white light in solution phase when they are mixed in a requisite proportion.