Coordination-driven self-assembly of chiral palladium(ii)-based supramolecular triangle structures

Abstract

Chiral structures of palladium(ii)-based triangular supramolecular complexes, with achiral corners and edges, have been characterized in solution.

A triangular palladium(II) supramolecular coordination complex based on 1,4-bis(1H-imidazol-1-yl)benzene and (2,2′-bipyridyl)palladium(II) nitrate: synthesis and crystal structure

“…1). However, structure B, a related yet different D 3 -symmetric triangular structure, was char- Following our previous study (Gimeno et al, 2018), we herein report the synthesis of the new triangular SCC tris[bis(1H-imidazol-1-yl)benzene-2 N 3 :N 3 0 ]-triangulo-tris[(2,2 0 -bipyridyl-2 N,N 0 )palladium(II)], 2, obtained by the selfassembly of equimolar amounts of L H with [Pd(NO 3 ) 2 (bipy)] (bipy is 2,2 0 -bipyridyl) (1) (see Scheme 1). SCC 2 was characterized in the solid state by X-ray structure analysis and in solution by ( 1 H, 13 C, ROESY and DOSY) NMR spectroscopy and cold spray ionization mass spectrometry (CSI-MS).…”

“…Multiple structures with syn/anti-L H and syn/anti-[Pd] are a priori possible and expected to be in rapid equilibrium in solution (Gimeno et al, 2018). The anti-[Pd] coordination of L H was unambiguously characterized by a ROE cross peak between protons H-2 and H-4 of the imidazole rings ( Fig.…”

“…However, these experiments alone are not sufficient to assign the expected triangular geometry to 2. Under identical conditions (acetonitrile-d 3 , 15 mM, 298 K), diffusion coefficients for comparable square SCCs vary between D = 5.4 Â 10 À10 m 2 s À1 and D = 5.9 Â 10 À10 m 2 s À1 , whereas diffusion coefficients for triangular SCCs vary between D = 7.4 Â 10 À10 m 2 s À1 and D = 8.0 Â 10 À10 m 2 s À1 (Gimeno et al, 2018).…”

“…Recently, ditopic imidazole-based ligands and palladium(II) complexes have been shown to yield triangular SCCs in solution as major products at low concentration ( Fig. 1) (Gimeno et al, 2018). More specifically, the ditopic imidazole-based ligand bis(1H-imidazol-1-yl)benzene ligands (L H ) and the square-planar acceptor [Pd(NO 3 ) 2 (tmeda)] (tmeda is N,N,N 0 ,N 0 -tetramethylethylenediamine) yielded a triangular SCC whose structure was characterized in the solid state (Roy et al, 2017) and in solution (Gimeno et al, 2018).…”

“…1) (Gimeno et al, 2018). More specifically, the ditopic imidazole-based ligand bis(1H-imidazol-1-yl)benzene ligands (L H ) and the square-planar acceptor [Pd(NO 3 ) 2 (tmeda)] (tmeda is N,N,N 0 ,N 0 -tetramethylethylenediamine) yielded a triangular SCC whose structure was characterized in the solid state (Roy et al, 2017) and in solution (Gimeno et al, 2018). In the solid state, an achiral C 3 -symmetric triangular structure A was characterized by single-crystal X-ray diffraction, with L H adopting a syn conformation, i.e.…”