Choi Heekyoung, Heo Sojeong, Lee Seonae, Kim Ka Young, Lim Jong Hyeon, Jung Sung Ho, Lee Shim Sung, Miyake Hiroyuki, Lee Jin Yong, Jung Jong Hwa
Department of Chemistry and Research Institute of Natural Sciences, Gyeongsang National University Jinju 660-701 Republic of Korea
Department of Chemistry, Sungkyunkwan University Suwon 16419 Republic of Korea
Chem Sci. 2019 Nov 14;11(3):721-730. doi: 10.1039/c9sc04958d.
We report kinetically controlled chiral supramolecular polymerization based on ligand-metal complex with a 3 : 2 (L : Ag) stoichiometry accompanying a helical inversion in water. A new family of bipyridine-based ligands (d-, l-, d-, and d-) possessing hydrazine and d- or l-alanine moieties at the alkyl chain groups has been designed and synthesized. Interestingly, upon addition of AgNO (0.5-1.3 equiv.) to the d- solution, it generated the aggregate I composed of the d-AgNO complex (d- : Ag = 1 : 1) as the kinetic product with a spherical structure. Then, aggregate I (nanoparticle) was transformed into the aggregate II (supramolecular polymer) based on the (d-)Ag(NO) complex as the thermodynamic product with a fiber structure, which led to the helical inversion from the left-handed (M-type) to the right-handed (P-type) helicity accompanying CD amplification. In contrast, the spherical aggregate I (nanoparticle) composed of the d-AgNO complex with the left-handed (M-type) helicity formed in the presence of 2.0 equiv. of AgNO and was not additionally changed, which indicated that it was the thermodynamic product. The chiral supramolecular polymer based on (d-)Ag(NO) was produced a nucleation-elongation mechanism with a cooperative pathway. In thermodynamic study, the standard Δ° and Δ values for the aggregates I and II were calculated using the van't Hoff plot. The enhanced Δ° value of the aggregate II compared to that of the formation of aggregate I confirms that aggregate II was thermodynamically more stable. In the kinetic study, the influence of concentration of AgNO confirmed the initial formation of the aggregate I (nanoparticle), which then evolved to the aggregate II (supramolecular polymer). Thus, the concentration of the (d-)Ag(NO) complex in the initial state plays a critical role in generating aggregate II (supramolecular polymer). In particular, NO acts as a critical linker and accelerator in the transformation from the aggregate I to the aggregate II. This is the first example of a system for a kinetically controlled chiral supramolecular polymer that is formed multiple steps with coordination structural change.
我们报道了基于配体 - 金属配合物的动力学控制手性超分子聚合，该配合物的化学计量比为3 : 2（L : Ag），在水中伴随着螺旋反转。设计并合成了一类新的基于联吡啶的配体（d -、l -、d - 和d -），其在烷基链基团处具有肼基和d - 或l - 丙氨酸部分。有趣的是，向d - 溶液中加入AgNO₃（0.5 - 1.3当量）时，会生成由d - AgNO₃配合物（d - : Ag = 1 : 1）组成的聚集体I，作为具有球形结构的动力学产物。然后，聚集体I（纳米颗粒）基于（d -）₂Ag（NO₃）₃配合物转化为聚集体II（超分子聚合物），作为具有纤维结构的热力学产物，这导致了伴随着圆二色性放大的从左旋（M型）到右旋（P型）螺旋性的螺旋反转。相比之下，在2.0当量的AgNO₃存在下形成的具有左旋（M型）螺旋性的由d - AgNO₃配合物组成的球形聚集体I（纳米颗粒）没有进一步变化，这表明它是热力学产物。基于（d -）₂Ag（NO₃）₃的手性超分子聚合物是通过具有协同途径的成核 - 伸长机制产生的。在热力学研究中，使用范特霍夫图计算了聚集体I和II的标准Δ°和Δ值。与聚集体I形成相比，聚集体II增强的Δ°值证实了聚集体II在热力学上更稳定。在动力学研究中，AgNO₃浓度的影响证实了聚集体I（纳米颗粒）的初始形成，然后它演变成聚集体II（超分子聚合物）。因此，初始状态下（d -）₂Ag（NO₃）₃配合物的浓度在生成聚集体II（超分子聚合物）中起着关键作用。特别是，NO₃⁻在从聚集体I到聚集体II的转变中充当关键的连接体和促进剂。这是一个通过多步形成且具有配位结构变化的动力学控制手性超分子聚合物体系的首个例子。
