定向攪拌能夠產生手性分子嗎？如果分子不行，能夠形成具有手性的分子自組裝形態嗎？

從打發蛋白的定向攪拌聯想到，定向攪拌的物理條件能夠催生手性分子，或者具有手性的分子自組裝形態嗎？

攪拌產生手性初看起來是非常玄學的，畢竟整個體系中只有中間一點旋度不為零，只有這一點才可能造成手性選擇。但大自然對對稱性破缺的愛好超過我們想像，這個現象其實還比較常見，在有一些體系中非常容易產生。

最早的有關手性和攪拌的文獻是1990的一篇science[1]，報道了在很粗獷的條件（文章中用了一堆「~」）下攪拌產生手性的 半面晶體，得到了很高的純度（&<99.7%）。文章很短，排版下來都不到兩頁，但還是很激動人心。我就直接引用作者的話了：

Here we report how so simple a process as constant stirring of the solution generates both autocatalysis and competition and thus can produce totally asymmetric macroscopic states of crystals that all have the same handedness.

巴斯德：mmp，老子白挑了這麼長時間

所以你從手性晶體催化一下不就出手性分子了嗎233333。但就我所知，很遺憾，還沒看到過攪拌直接出手性分子的例子。

手性超分子的產生要簡單一些。2001年一篇science[2]上報道了攪拌造成具有手性的超分子自組裝現象，來自prophyrin的組裝（就是下面這個玩意），以J-aggregation產生了螺旋的帶狀超分子。

酸性溶液中卟啉環上的氮會被質子化成正電中心，與 通過下面這個機理聚集

聚集完了這貨長這樣[3]：

同時這個機理也說明了為什麼很容易就攪出了手性超分子。相同的機理也適用於類似結構的、可以發生J聚集的分子。在這之後，出了好多篇類似的文獻。想想就有點激動，手性超分子出來了，再誘導一下，真正的手性分子也應該能攪出來了吧。

biblio:

[1]Kondepudi D. K., Kaufman R. J., Singh N. Chiral symmetry-breaking in sodium-chlorate crystallization. Science 250: 975–976 (1990)

[2]J. M. Ribo, J. Crusats, F. Sagues, J. M. Claret, R. Ruvires, Science 2001, 292, 2063.

[3]C. Escudero, J. Crusats, I. Diez-Perez, Z. El-Hachemi, J. M. Ribo, Angew. Chem. 2006, 118, 8200; Angew. Chem. Int. Ed. 2006, 45, 8032.

可以，有空回來填坑

~~~~~~~~~~~~~~~~~~~

終於回來填坑了，哎拖更拖得我自己都看不下去了。

http://onlinelibrary.wiley.com/doi/10.1002/anie.200703083/epdf

大致什麼意思呢？就是，一幫nanofiber在溶液里，假裝自己是樂高積木，拼成一個sheet。

然後在溶液里放一個攪拌子，開始攪♂基♂

攪基過程中，這個本來平整的sheet就變成螺旋狀，螺旋的手性又和攪拌方向有關，於是，就有了這個大新聞。

上圖就是，不同攪拌方向帶來的圓二色譜的變化，可見一個旋轉方向就是一種手性，不旋轉就沒有手性。

換一個棒棒來攪拌，棒棒離光路中心的距離還會影響手性。

作者還做了很多實驗來驗證這個手性產生的機理，總之很有趣，感興趣的翻到開頭點連接看原文吧~

哎終究還是懶啊

個人直覺上比較懸，你攪動的運動半徑放在微觀層面上看，還是太大了。。。

複製下另個類似題目的答案，對於大分子、超分子體系是可以觀察到手性產生的現象的。有人推測地球自轉是手性物質產生的原因，不過已經有人對簡單小分子、生物小分子進行實現，並未發現旋轉導致手性產生。

Formation of Chiral Environments by a Mechanical Induced Vortex Flow

A chiral molecule absorbs preferentially right- or left-handed circularly polarized light in a circular dichroism (CD) measurement. Usually, the chirality of individual molecules is regarded as the origin of the CD signals. However, recently, several reports have suggested that the vortex flow of a solution of an achiral molecule gives rise to a CD signal, which is dependent on the stirring direction. This article introduces types of molecular architecture and material designs that show stir-induced chirality. We also discuss the effects of the molecular structure and alignment in vortex flows on this phenomena, reviewing the related issues.

Achiral Polydialkylsilane Aggregates That Record Stirring Direction

Achiral polysilane aggregates can recognize the chirality of low-molecular-weight compounds. It was found that they can also record the stirring direction. Poly(n-decyl-2-methylpropylsilane), poly(n-nonyl-2-methylpropylsilane), poly(n-decyl-2-ethylbutylsilane), and poly(n-decyl-(S)-2-methylbutylsilane) aggregates were prepared in a mixture of tetrahydrofuran/isopropanol. Although the optical activity of the aggregates of the polysilane with chiral side chains was not tunable by changing the direction of the vortex flow, that of the aggregates of the optically inactive polysilane had a strong relationship to the direction, time, and rate of the vortex flow. The chiral stacked polysilanes were proposed to exist at the surfaces of the aggregates. The optically inactive polysilanes also exhibited optical activity under shear force with a distinct signal in the linear dichroism (LD) spectra of the achiral aggregates in vortex flows. However, the LD signals did not have a significant influence on the circular dichroism signals.

Circularly Polarized Luminescence of Rhodamine?B in a Supramolecular Chiral Medium Formed by a Vortex Flow

Sucked into the vortex: Hydrogels with embedded Rhodamine?B dye showed stir-induced circularly polarized luminescence (CPL; see picture), the sense of which can be controlled by switching the stir direction from clockwise (CW) to counterclockwise (CCW) with slow cooling from the sol to gel states. The chiral alignment of the dye was erased by heating the sample above the gel–sol transition temperature.