Temperature-induced solid-to-solid transformation in helical homochiral coordination polymers.

Area of Science:

• Materials Science
• Crystallography
• Coordination Chemistry

Background:

• Homochiral coordination polymers (CPs) are valuable for chiral applications.
• Designing CPs with controllable helical structures remains a challenge.

Purpose of the Study:

• To synthesize novel homochiral coordination polymers (CPs) using (R)- and (S)-4-(1-carboxyethoxy)benzoic acid (H2CBA) and 1,3-bis(2-methyl-1H-imidazol-1-yl)benzene (1,3-BMIB).
• To investigate the structural transformation of these CPs upon thermal treatment.

Main Methods:

• Reaction of H2CBA and 1,3-BMIB ligands with zinc(II) ions.
• Single-crystal X-ray diffraction analysis.
• Thermal treatment of synthesized coordination polymers.

Main Results:

• A pair of homochiral CPs, {[Zn{(S)-CBA}(1,3-BMIB)]·H2O}n (1-L) and {[Zn{(R)-CBA}(1,3-BMIB)]·H2O}n (1-D), were successfully synthesized, each containing three types of helical chains.
• Upon heating, 1-L and 1-D transformed into {[Zn{(S)-CBA}(1,3-BMIB)]}n (2-L) and {[Zn{(R)-CBA}(1,3-BMIB)]}n (2-D), respectively.
• The transformed CPs (2-L and 2-D) exhibited a single type of helical chain, indicating a reconstruction via solid-to-solid transformation.

Conclusions:

• The study demonstrates the successful synthesis of homochiral CPs with multiple helical chain types.
• A feasible strategy for building homochiral CPs through thermally induced helical transformation was achieved.
• This work contributes to the understanding and design of CPs with tunable helical architectures.