Reversible Mechanical Interlocking of D-Shaped Molecular Karabiners bearing Coordination-Bond Loaded Gates: Route to Self-Assembled [2]Catenanes

Soumyakanta Prusty; Shobhana Krishnaswamy; Sreenivasulu Bandi; Baby Chandrika; Jingwei Luo; J Scott McIndoe; Garry S Hanan; Dillip Kumar Chand

doi:10.1002/chem.201502394

Reversible Mechanical Interlocking of D-Shaped Molecular Karabiners bearing Coordination-Bond Loaded Gates: Route to Self-Assembled [2]Catenanes

Chemistry. 2015 Oct 19;21(43):15174-87. doi: 10.1002/chem.201502394. Epub 2015 Sep 23.

Authors

Soumyakanta Prusty¹, Shobhana Krishnaswamy¹, Sreenivasulu Bandi¹, Baby Chandrika², Jingwei Luo^{3

4}, J Scott McIndoe⁴, Garry S Hanan³, Dillip Kumar Chand⁵

Affiliations

¹ Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India).
² Sophisticated Analytical Instrument Facility, Indian Institute of Technology Madras, Chennai 600036 (India).
³ Department of Chemistry, University of Montreal, Montreal (Canada).
⁴ Department of Chemistry, University of Victoria, Victoria (Canada).
⁵ Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India). dillip@iitm.ac.in.

PMID: 26394809
DOI: 10.1002/chem.201502394

Abstract

Complexation of 1,4-phenylenebis(methylene) diisonicotinate, L1, with cis-protected Pd(II) components, [Pd(L')(NO3 )2 ], in an equimolar ratio yielded binuclear complexes, 1 a-d of [Pd2 (L')2 (L1)2 ](NO3 )4 formulation where L' stands for ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2'-bipyridine (bpy), and phenanthroline (phen). The combination of 4,4'-bipyridine, L2, with the cis-protected Pd(II) units is known to yield molecular squares, 2 a-d. However, 2 b-d coexist with the corresponding molecular triangles, 3 b-d. Combination of an equivalent each of the ligands L1 and L2 with two equivalents of cis-protected Pd(II) components in DMSO resulted in the D-shaped heteroligated complexes [Pd2 (L')2 (L1)(L2)](NO3 )4 , 4 a-d. Two units of the D-shaped complexes interlock, in a concentration dependent fashion, to form the corresponding [2]catenanes [Pd2 (L')2 (L1)(L2)]2 (NO3 )8 , 5 a-d under aqueous conditions. Crystal structures of the macrocycle [Pd2 (tmeda)2 (L1)(L2)](PF6 )4 , 4 b'', and the catenane [Pd2 (bpy)2 (L1)(L2)]2 (NO3 )8 , 5 c, provide unequivocal support for the proposed molecular architectures.

Keywords: catenane; dynamic equilibrium; molecular karabiners; palladium; self-assembly.