Chiralityand Polarity Modulation in SemiconductiveZinc(II) Coordination Polymers Containing Thiolate-Based Ligands

Recently, chiral semiconductors have attracted considerable attention owing to their potential applicability in optoelectronics and spintronics. In this study, homochiral and heterochiral semiconductive Zn(II) coordination polymers [Zn(tbbt)((<i>X</i>)-mba)₂]·solvent (H₂tbbt = 4,4′-thiobisbenzenethiol, mba = methylbenzylamine, <i>X</i> = <i>R</i>, <i>S</i>, <i>rac</i>) were systematically synthesized. Single-crystal X-ray diffraction analyses revealed that <b>KGF-57(</b><i><b>R</b></i><b>)</b> and <b>KGF-57(</b><i><b>S</b></i><b>)</b> (<b>KGF</b> = Kwansei Gakuin framework), of type [Zn(tbbt)((<i>X</i>)-mba)₂]·(<i>X</i>)-mba, obtained from enantiopure (<i>R</i>)-mba and (<i>S</i>)-mba isomers, exhibited chiral–nonpolar homochiral one-dimensional (1D) structures with mba lattice solvents, comprising left- and right-handed helical chains, respectively. Conversely, when using (<i>rac</i>)-mba, two heterochiral 1D architectures were obtained depending on synthetic temperature and solvent. Specifically, <b>KGF-57(</b><i><b>rac</b></i><b>)</b> of type [Zn(tbbt)((<i>rac</i>)-mba)₂]·(<i>rac</i>)-mba·<i>n</i>H₂O exhibited an achiral–nonpolar heterochiral 1D structure with (<i>rac</i>)-mba and H₂O lattice solvents, containing alternately aligned left-handed helical chains with (<i>R</i>)-mba and right-handed helical chains with (<i>S</i>)-mba. Conversely, <b>KGF-58(</b><i><b>rac</b></i><b>)</b> with the formula [Zn(tbbt)((<i>rac</i>)-mba)₂] formed an achiral–polar assembly without mba lattice solvents. This structure is composed of zigzag chains with either (<i>R</i>)-mba or (<i>S</i>)-mba in a heterochiral arrangement. Time-resolved microwave conductivity measurements and first-principles calculations revealed that a series of Zn(II) coordination polymers exhibited photoconductivity originating from the Zn-thiolate-based skeleton. Furthermore, by exchanging the mba ligands coordinated to 1D Zn-thiolate chains, a reversible structural conversion accompanied by chirality and polarity variation was achieved.