Chirality Control of Quadruple Helixes of Metal Strings by Peripheral Chiral Ligands

Abstract

Chirality control of helixes with the Δ (P) or Λ (M) form is interesting in various fields such as extended metal atom chains (EMACs), in which the metal backbones are helically wrapped by four ligands. Herein, we report two EMACs, Δ-[Ni5((-)camnpda)4] and Λ-[Ni5((+)camnpda)4], whose chiralities are controlled by chiral ligands with naphthyridine and camphorsulfonyl groups. There is a large energy difference (108 kcal mol(-1)) between the two helical structures with one chiral ligand. Furthermore, the electron communication between [Ni2](3+) units is more pronounced than in [Ni5(bna)4Cl2](2+) (bna=binaphthyridylamido). The results demonstrate control of small-scale helical structure and set the stage for future development of chiral controlled base and nanoelectronic devices.

Enantiopure Chiral Coordination Polymers Based on Polynuclear Paddlewheel Helices and Arsenyl Tartrate

“…±5000 deg·mL·g −1 ·dm −1 , comparable to those observed for some helicenes [27]. In another elegant work, Peng and coworkers were able obtain enantiopure Ni5-based paddlewheel complexes using naphthyridylpyridyldiamine ligands functionalized with bulky chiral groups [28]. Recently, an approach based on anion exchange has been employed by our group to resolve a racemic mixture of [Co3(dpa)4(MeCN)2] 2+ clusters [29].…”

From Homonuclear Metal String Complexes to Heteronuclear Metal String Complexes

“…Figure 8; the chirality of these complexes is obtained through the ligands (-)-and (+)-camnpda 2-, which contain naphthyridine and camphorsulfonyl groups. [34] The presence of the chiral camphor units at the terminal positions of the ligand backbone plays a crucial role in manipulating the helical geometry of the metal string complexes. DFT calculations indicate that the energy difference is extremely large between the Δ and Λ forms of the complexes and results in the selectivity for a specific chirality.…”

Revisit of trinickel metal string complexes [Ni3L4X2] (L = dipyridylamido, diazaphenoxazine; X = NCS, CN) for quantum transport

“…A range of coordinating groups (e.g., amido, pyridyl, naphthyridyl, anthyridinyl, and thiophenyl) are formulated as the equatorial ligands . Their electronegativity and rigidity exhibit significant effects on the oxidation number of the metal center and the metal–metal distance associated with the ligand–metal–metal–ligand torsion angle . The equatorial and axial ligands have a significant influence of metal string complexes on the spin multiplicity and magnetism .…”