Novel Chevron And Banana-Shaped Materials For Photonic And Electrical Devices

最近在克兰菲尔德的发现导致通过朗缪尔-布洛杰特（LB）技术不具有脂族尾的分子的非中心对称排列，该膜表现出高的二阶磁化率（J.Mater. Chem.2002，12，2181）和分子精馏（J. Phys. Chem. B 2002，106，12158）。这些分子与通常认为适合LB沉积的分子不同，它们具有人字形而不是线性分子结构，但是，尽管如此，正在进行的研究已经证明了75%的样品中的对齐，尽管到目前为止只有四个样品被研究。其具有与用于对准的V形相同的基本结构。尝试将作出关联的分子几何形状和香蕉形材料的组织，并利用其独特的液晶相。将合成用于LB沉积和分子自组装的类似物，后者通过分子与镀金衬底之间的硫醇连接实现。分子将在理论上建模以影响排列，从而影响非线性光学和非线性电学性质，目的是优化二次谐波强度和电流整流比。

A recent discovery at Cranfield resulted in the non-centrosymmetric alignment of molecules without aliphatic tails by the Langmuir-Blodgett (LB) technique, the films exhibiting a high second-order susceptibility (J. Mater. Chem. 2002, 12, 2181) and molecular rectification (J. Phys. Chem. B 2002, 106, 12158). The molecules differ from those normally considered suitable for LB deposition by having a chevron-shaped rather than a linear molecular structure but, nonetheless, on-going studies have demonstrated alignment in 75% of samples, albeit of only four so far investigated.This proposal concerns a development of the discovery and is driven by current research at Hull on banana-shaped liquid crystals, which have the same basic structure as the chevrons for alignment. An attempt will be made to correlate the molecular geometry and organisation of banana-shaped materials and to exploit their unique liquid crystalline phases. Analogues for both LB deposition and molecular self-assembly will be synthesised, the latter being achieved via a thiol link between the molecule and a gold-coated substrate.Molecules will be theoretically modelled to influence the alignment and consequently, the nonlinear optical and nonlinear electrical properties, with the aim of optimising the second-harmonic intensity and the current rectification ratio.