Coordination polymers assembled from semirigid fluorene-based ligand: A couple of enantiomers

• A couple of Mg(II)-based enantiomers were obtained as the racemic conglomerate.
• The ligand is 4,4′-(9,9-dimethyl-9H-fluorene-2,7-diyl)dibenzoic acid.
• MgL features the right- or left-handed homochiral 1D Mg–O–C helical chain.
• ZnL features the 1D Zn–O–C meso-helical chain.
• Both MgL and ZnL display the intense solid-state blue emissions.

A couple of Mg(II)-based coordination polymer enantiomers [MgL(DMF)(H2O)3]n (R-MgL and S-MgL), and a Zn(II)-based coordination polymer [ZnL(DMF)]n (ZnL) have been synthesized by the solvothermal reactions between the achiral ligand 4,4′-(9,9-dimethyl-9H-fluorene-2,7-diyl)dibenzoic acid (H2L) and the corresponding metal salts. The MgL was obtained as the racemic conglomerate from the one pot reaction. The single crystal X-ray structural analyses reveal that MgL crystallize in the chiral space group P21 and possesses the right- or left-handed homochiral 1D Mg–O–C helical chain. The ZnL crystallize in the non-centrosymmetrical space group Aba2 and possesses the 2D network comprised of 1D Zn–O–C meso-helical chains and ligands. The MgL and ZnL complexes exhibit strong coordination-perturbed ligand-centered blue emissions when excited at 320 nm. Their second-order nonlinear optical effects and thermal properties have also been studied.

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