POSS的合成與其形成主客體複合物之自組裝行為探討

Abstract

POSS被認為是最小的氧化矽奈米粒子，其粒徑約0.5 - 0.8奈米。在POSS核心的八個頂點上修飾上不同的共軛取代基，可形成三維共軛巨分子。在先前的研究中發現，POSS核心與共軛取代基會形成一上、下具有空穴的柱狀結構 (而此空穴對角距離約為0.8 nm) ，此空間能夠使POSS在主－客體化學中，做為良好的建構單元。為了解POSS是否可做為主體，我們在POSS八個頂點修飾上多電子的(electron-rich) 的芘 (pyrene) ，並合成了缺電子的 (electron-deficient )萘二醯亞胺衍生物 (NDI; hex-NDI 及兩個NDI單元的 Di-NDI) 做為客體，將 POSS-py 與 NDI 以不同比例進行混摻，並由示差掃描量熱儀及X-ray繞射等技術確立其固態結構：POSS-py/hex-NDI以1：4的莫耳數比經由donor-acceptor charge transfer interaction形成層列型液晶相的主客體複合物；POSS-py/Di-NDI則以莫耳數比1：2形成有序結構。在小角度X光散射儀中也可得知，藉由加入NDI，可幫助POSS-py收斂共軛手臂，形成一較具特定形狀的柱形粒子。此項研究拓展分子級奈米粒子的多樣性以及提供了深具潛力的新材料。

POSS is considered to be the smallest silicon oxide nanoparticles (NPs) and the molecular shape is close to a cube (side length ~ 0.5-0.7 nm). Attaching conjugated arms to the eight vertices of a POSS core resulting in a 3D conjugated giant molecule. Our previous studies have showed that through conformational isomerization, POSS derivatives can adopt a rod-like conformation, which contain two empty cavities above and below the POSS core. The diagonal distance of the cavity is about 0.8 nm, making the conjugated POSS a suitable building-block in host-guest chemistry. We wondered whether or not conjugated POSS can properly work as a host. To look into this issue, POSS-derivative with electron-rich pyrene unit attached to the eight vertices of POSS core was synthesized to be a host. Electron-deficient naphthalene diimide derivatives such as hex-NDI and Di-NDI were synthesized to be guest. In this work, we will try to perfect the supramolecular structure of the POSS-py/hex-NDI and POSS-py/Di-NDI complex. The solid-state characterization including DSC, X-ray diffraction showed that hex-NDI molecules can be trapped within the POSS cavities at the molar ratio of POSS-py:hex-NDI = 1:4, and formed a new smectic liquid crystal phase; on the other hand, POSS/Di-NDI will form an ordered structure in molar ration of 1:2. In solution phase, the results provide that adding of hex-NDI will help to contract the arms of POSS-py, forming a more specific shape of the cylindrical particles.