A pair of dinuclear Re(I) enantiomers: synthesis, crystal structures, chiroptical and ferroelectric properties

作者：Li Xi Li^*; Zhang Zhiqiang; Zhang Xue Li; Kang Jia Long; Wang Ai Ling; Zhou Liming; Fang Shaoming

来源：Dalton Transactions, 2015, 44(9): 4180-4185.

DOI：10.1039/c4dt03884c

The reaction of enantiomeric bis-bidentate bridging ligands (+)/(-)-2,5-bis(4,5-pinene-2-pyridyl)pyrazine (LS/LR) with [Re(CO)(5)Cl] yielded a pair of dinuclear Re(I) enantiomers formulated as [Re-2(L-S/L-R)(CO)(6)Cl-2]center dot 4CH(2)Cl(2) (R-1 and S-1, the isomers containing the respective L-R and L-S ligands). They were characterized by elemental analyses, IR spectra and X-ray crystallography. Circular dichroism spectra verified their chiroptical activities and enantiomeric nature. The measurements of second harmonic generation (SHG) and ferroelectric properties showed that R-1 displays a nonlinear optical (NLO) activity and ferroelectricity with a remnant polarization (P-r) of 1.6 mu C cm(-2) under an applied field of 7.3 kV cm(-1) at room temperature. R-1 and S-1 represent the first example of polynuclear Re(I) complexes with ferroelectric properties. Notably, the Pr value is much larger than that of the reported mononuclear chiral Re(I) analogue. In particular, unlike mononuclear Re(I) complexes of the type [Re(CO)(3)(N<^>N)(X)] (N<^>N = diimine and X = halide), which usually exhibit an intense emission in the visible range, R-1 and S-1 do not show any detectable emission at any temperature range and the reason for the nonluminescence of R-1 and S-1 was further elucidated in this work. Moreover, our research results also elucidated that Re nuclearity has a great influence on not only the emitting properties but also on ferroelectric behavior.

• 出版日期2015
• 单位郑州轻工业大学