Crystal Engineering of 6-Carboxy-4-aryl-2,2′-bipyridine Complexes: Potent Chelators with Intrinsic Intermolecular Affinity

Abstract

Herein we report the coordination chemistry and structural properties of two multifunctional terdentate 2,2′-bipyridine derivatives 4- and 3-(4-nitrophenyl)-2,2′-bipyridine-6-carboxylate, L1/L2, respectively. We report eight new coordination complexes with CdII, CoII, and CoIII, and study their behavior in the crystalline phase with the view of establishing L1 and L2 as robust and functional chelators for use in extended metallosupramolecular systems. The divalent complexes [Cd­(L1)2]·H2O 1, [Cd­(L2)2] 2, [Co­(L1)2] 5, and [Co­(L2)2] 7 are mononuclear complexes with distorted octahedral coordination geometries dictated by the two meridionally coordinated L1/L2 ligands. Also reported are two trivalent byproducts [Co­(L1)2]­NO3 6 and [Co­(L2)2]­NO3 8 which were formed in trace quantities during the initial screening of complexes 5 and 7, respectively. The extended structures of these complexes are dominated by substantial intermolecular interactions, including anion···π hole interactions. Modification of the reaction conditions from 1 and 2 gives two closely related trinuclear cluster species [Cd3(L1)3(NO3)2­(DMF)4]­NO3 3 and [Cd3(L2)3(NO3)2­(DMF)4]­NO3·DMF 4, in which three cadmium ions, with pentagonal bipyramidal coordination geometries, form disc-shaped assemblies with L1/L2, which undergo further weak interactions between neighboring complexes in the crystalline state. With these outcomes L1 and L2 are established as exciting new building blocks for metallosupramolecular assemblies involving d-block metal ions.

Ligand isomerism fine-tunes structure and stability in zinc complexes of fused pyrazolopyridines

“…Adjacent chains associate through a dimeric π⋯π stacking interaction between parallel L3 groups at a mean interplanar distance of 3.40 Å. Similar to other systems containing angular chelating heterocycles where nitrate anions are present 26 this interaction is supported by a reciprocated pair of chelating C-H⋯O contacts, between the nitrato oxygen atom O1 and the two inward-facing pyridyl C-H groups C3 and C8. The C⋯O distances and C-H⋯O angles (3.645(2) and 3.239(2) Å, 161.6 and 138.4°for C3 and C8 respectively) are consistent with the expected values for typical C-H⋯O contacts.…”

Highly‐Luminescent DTTA‐Appended Water‐Soluble Lanthanide Complexes of 4‐(Het)aryl‐2,2′‐bipyridines: Synthesis and Photophysical Properties

“…As a first step the Knoevenagel reaction was carried out with potassium salt of pyruvic acid (Scheme ). Next, unlike in previously reported procedures where the esterification of the bipyridine carboxylic acids was suggested, we carried out the esterification of the product 2 . The thus obtained esters 3 were further involved in a next stage to form the corresponding bipyridines 4 without significant decrease of the products yields.…”

Biological evaluation of rare earth complexes bearing 1H‐imidazo[4,5‐f]‐1,10‐phenanthroline moiety as promising anticancer chemotherapeutics

“…In the research of metal‐based anticancer drugs, aside from the significance of the central metal, the choice of ligand plays an important role as well . Complexes with 1 H ‐imidazo[4,5‐f]‐1,10‐phenanthroline moieties are able to express a few meaningful properties in the medicinal area .…”