Distinct M and P Helical Complexes of H₂O and Metal Ions Ni^II, Cu^II, and Zn^II with Enantiomerically Pure Chiral Bis(pyrrol-2-ylmethyleneamine)cyclohexane Ligands:  Crystal Structures and Circular Dichroism Properties

Abstract

The enantiomerically pure bis-bidentate ligands of bis(pyrrol-2-ylmethyleneamine)cyclohexane [H2(LR,S)] are easily synthesized from condensation of the pure R,R and S,S enantiomers of the 1,2-diaminecyclohexane spacer with 2 equiv of pyrrole-2-carbaldehyde. The coordination of [H2(LR,S)] with a H2O molecule and metal ions NiII, CuII, and ZnII gives rise to distinct helical structures and crystal packing motifs: homochiral and enantiopure infinite single-helical polymeric chains of [(H2(LR,S).H2O)n] via hydrogen bonds, mononuclear single helices of [NiII(LR,S)] and [CuII(LR,S)], and a double-stranded dinuclear helicate of [ZnII2(LR,S)2], respectively. The helical structures for all metal complexes in the solid state still remain in the solution. Remarkably, chiral ligands of [H2(LR)] and [H2(LS)] predetermine the chirality of the helices and helicates, i.e., P left-handedness and M right-handedness, respectively. The structural changes of these complexes induced by different coordinators are also characterized by circular dichroism (CD) and absorption spectra in both the solid state and solution. Analysis of CD spectra, with aids of absolute determination of single-crystal X-ray diffraction structures, reveals both intraligand and interligand chromophore couplings. For the potential applications of these complexes, other experiments such as magnetism, photoluminescence, and nonlinear optical properties have also been investigated.

New Chiral and Achiral Imines and Bisimines Derived from 2‐Phenyl‐1H‐imidazole‐4‐carbaldehyde. Synthesis, Structural Studies and Complexation Stability Constants

“…Preparation of new series of bisimines derived from quinoline/pyridine‐4‐ or 2‐carbaldehyde and ethylenediamine or cyclohexane‐1,2‐diamine was performed by Patra and Amendola . Chiral bisimines are most commonly derived from ( R , R )‐ or ( S , S )‐cyclohexane‐1,2‐diamine . Many derivatives of achiral/chiral bisimines are made up by pyridine moiety .…”

Solid‐state Circular Dichroism and Hydrogen Bonding, Part 2: The Case of Hypothemycin Re‐investigated

“…[4][5][6][7][8] Special cautions must be paid in sample preparation, measurement, and data analysis because of the possible presence of spectral artifacts related to macroscopic anisotropies, instrumental defects, absorption flattening, concentration effects, and so on. First, the direct investigation of condensed states, for example, chiral solids, including metal-organic frameworks, [14][15][16][17] and other aggregation states such as gels, [18][19][20][21] thin films of polymers, [22][23][24] and fibers or fibrils. First, the direct investigation of condensed states, for example, chiral solids, including metal-organic frameworks, [14][15][16][17] and other aggregation states such as gels, [18][19][20][21] thin films of polymers, [22][23][24] and fibers or fibrils.…”

Crystal structure of [(R,R)-6,6-dimethyl-3-pyridin-2-yl-5,6,7,8- tetrahydro-5,7-methanoisoquinoline]-tris[4,4,4-trifluoro-1-(2-thienyl)- butane-1,3-dionato]dysprosium(III), Dy(C17H18N2)(C8H4O2SF3)3

“…Over the last decades, chiral complexes have been an active area of research in coordination chemistry due to their diverse application in asymmetric catalysis, enantioselective synthesis, bioinorganic and supramolecular chemistry [3][4][5][6]. An effective and facile method to prepare such kind of complexes is the generating of chiral motifs in the target molecule.…”

“…An effective and facile method to prepare such kind of complexes is the generating of chiral motifs in the target molecule. Based on this strategy, as a continuance of our research [7], we employed ac hiral ligand (R,R)-6,6-dimethyl-3-pyridin-2-yl-5,6,7,8-tetrahydro-5,7-methanoisoquinoline to react with Dy(tta) 3 · 2H2O. Subsequently, the enantiomerically pure title compound was obtained.…”