title: Reversible Mechanical Interlocking of D-Shaped Molecular Karabiners bearing Coordination-Bond Loaded Gates: Route to Self-Assembled [2]Catenanes.
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.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India).
authors.forename: Soumyakanta
authors.initials: S
authors.lastname: Prusty
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India).
authors.forename: Shobhana
authors.initials: S
authors.lastname: Krishnaswamy
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India).
authors.forename: Sreenivasulu
authors.initials: S
authors.lastname: Bandi
authors.affiliation: Sophisticated Analytical Instrument Facility, Indian Institute of Technology Madras, Chennai 600036 (India).
authors.forename: Baby
authors.initials: B
authors.lastname: Chandrika
authors.affiliation: Department of Chemistry, University of Montreal, Montreal (Canada).|Department of Chemistry, University of Victoria, Victoria (Canada).
authors.forename: Jingwei
authors.initials: J
authors.lastname: Luo
authors.affiliation: Department of Chemistry, University of Victoria, Victoria (Canada).
authors.forename: J Scott
authors.initials: JS
authors.lastname: McIndoe
authors.affiliation: Department of Chemistry, University of Montreal, Montreal (Canada).
authors.forename: Garry S
authors.initials: GS
authors.lastname: Hanan
authors.affiliation: Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India). dillip@iitm.ac.in.
authors.forename: Dillip Kumar
authors.initials: DK
authors.lastname: Chand
keywords: catenane; dynamic equilibrium; molecular karabiners; palladium; self-assembly