Construction of photofunctional supramolecular nanoobjects and their single molecule lithography

每个分子具有一位信息的光功能分子器件是人类终极的超高密度存储器。但当我们使用近场扫描光学显微镜（NSOM）观察单个分子的光化学反应时，探测光通常可能会引发光化学反应并破坏分子。本研究的目的是找到合适的材料系统，通过 NSOM 观察单分子或少量分子的光化学。1) 通过光照射显示出较大折射率变化的材料：聚（肉桂酸乙烯酯）的光二聚和重氮基和叠氮基的光消除在光照射后显示出非常大的折射率变化，而不降低薄膜的透明度。这些系统可以很好地用于NSOM的透射率检测。2）光致产酸剂-酸敏染料系统：制备分散有4-硝基苯甲基-9,10-二甲氧基蒽-2-磺酸盐（NAS）和尼罗蓝A基（NBAb）的聚合物薄膜，并在422 nm处进行光照射。 NAS 的光分解产生质子，质子扩散并与 NBAb 反应，产生阳离子 NAB (NBA^ )。通过选择三种不同的波长（422、488、620 nm），可以实现光化学反应和连续的 NSOM 成像。

Photofunctional molecular device having one-bit information per one molecule is an ultimate ultra-high density memory for humankind. But when we observe a photochemical reaction of a single molecule by using near-field scanning optical microscope (NSOM), the probe light usually may induce a photochemical reaction and destroy the molecule. This research was carried out in order to find appropriate materials system where we can observe photochemistry of single molecule or a small number of molecules by using NSOM.1) Materials showing large refractive index change by photoirradiation : Photodimerization of poly (vinyl cinnamate) and photoelimination of diazo-and azido-groups showed very large change in refractive index after photoirradiation without diminishing the transparency of the films. These systems can be good candidates for transmittance detection of NSOM.2) Photoacid generator-Acid-sensitive dye system : A polymer film dispersed with 4-nitrobenzyl-9,10-dimethoxyanthraccne-2-sulfonate (NAS) and Nile Blue A base(NBAb)was prepared and photo irradiated at 422 nm. Photodecomposition of NAS produced proton, which diffuses and reacts with NBAb resulting in cationic NAB (NBA^+). Photochemical reaction and successive NSOM imaging were made possible by the selection of three different wavelength (422, 488, 620 nm).