Helical chirality regulation is key to biomolecules and many synthetic complexes.[1] In biological host–guest systems, enantioselective recognition plays a pivotal role because of the inherent chirality of many natural compounds. There are reports of chiral hosts based on covalent macrocyclic molecules such as crown ethers, cyclodextrins, cyclophanes, calixarenes etc.[2,3] Based on chiral backbones or the overall design, chiral metallosupramolecular self-assembled cages have been introduced recently as selective receptors and nanoreactors.[4] Upon metal coordination, racemic mixtures of ligands may undergo chiral self-sorting, leading to homochiral or heterochiral assemblies. A few quadruple stranded helicates based on Pd(II) with an symmetrical Pd2L4-type cages exhibit either left-handed (M) or right-handed (P) or racemic mixtures.[5] From literature, the use of symmetrical bidentate ligands for making Pd(II) based chiral Pd2L4, Pd3L6, Pd4L8, Pd6L12 and Pd12L24 type coordination cages are explored, while symmetrical non-chelating tri or polydentate ligands remain unexplored. Also Pd(II) based chiral coordination cages made from unsymmetrical non-chelating bi or polydentate ligands are unexplored. This inspired us to design a few unsymmetrical bidentate as well as symmetrical and unsymmetrical polydentate ligands. The complexation of Pd(II) with these ligands may result in bi-, tri-, or tetranuclear metallosupramolecular cages. These Pd(II) based chiral coordination cages are promising scaffolds for exploring chiral recognition, separation, asymmetric catalysis, polarized luminescence etc. These cages will be screened for various guest encapsulation studies.
Reference :
1. Chen, L. J.; Yang H. B.; Shionoya, M. Chem. Soc. Rev. 2017, 46, 2555–2576
2. Tsunoda, Y.; Fukuta, K.; Imamura, T.; Sekiya, R.; Furuyama, T.; Kobayashi, N.; Haino, T. Angew. Chem. Int. Ed. 2014, 53, 7243-7247
3. Weirich, L.; Tusha, G.; Engelage, E.; Schafer, L. V.; Merten, C. Phys. Chem. Chem. Phys. 2022, 24, 11721-11728
4. Wu, Z.; Hsu, J.;Hsieh C. C.; Horng. Y. C.; Chem. Commun. 2012, 48, 3436-3438
5. Paneerselvam, A. P.; Mishra, S. S.; Chand, D. K. J. Chem. Sci., 2018, 130, 96