Biaryl-based macrocyclic and polymeric chiral (salophen)Ni(II) complexes: synthesis and spectroscopic study.

Area of Science:

• Coordination Chemistry
• Polymer Science
• Materials Science

Background:

• Previously reported salophen)Ni(II) complexes are square planar and diamagnetic.
• Chiral biaryl-based polymers with square-planar (salophen)Ni(II) units were proposed to have helical structures.

Purpose of the Study:

• Synthesize novel polymeric/oligomeric and macrocyclic (salophen)Ni(II) complexes.
• Investigate the coordination geometry and magnetic properties of these new complexes.
• Determine if chirality is propagated in copolymers of chiral and achiral monomers.

Main Methods:

• Synthesis of polymeric/oligomeric and macrocyclic (salophen)Ni(II) complexes using achiral biphenol dialdehyde and optically active BINOL dialdehyde.
• Characterization of coordination geometry and magnetic properties.

Main Results:

• The synthesized polysalophens contain nonplanar coordination of Ni(II) units, resulting in paramagnetic complexes.
• This nonplanar coordination contrasts with the square planar, diamagnetic nature of previously reported (salophen)Ni(II) complexes.
• Copolymerization experiments showed that the chirality of the binaphthyl unit is not propagated along the biphenyl polymer chain.

Conclusions:

• The nonplanar coordination in the new polymeric Ni(II) complexes leads to distinct properties compared to planar analogues.
• The findings challenge the proposed helical structure for chiral biaryl-based polymers containing square-planar (salophen)Ni(II) units.
• Chirality transfer is not observed in the copolymerization of chiral binaphthyl and achiral biphenyl monomers.