Construction of photofunctional supramolecular nanoobjects and their single molecule lithography

光功能分子器件每一个分子具有1位信息，是人类的终极超高密度存储器。但在近场扫描光学显微镜（NSOM）观察单个分子的光化学反应时，探针光通常会引起光化学反应并破坏分子。本研究的目的是寻找合适的材料体系，利用nsom1观察单分子或少量分子的光化学变化。1)光照射下折射率变化大的材料：聚苯乙烯（肉桂酸乙烯）的光二聚化和重氮基和叠氮基的光消除在不降低薄膜透明度的情况下，光照射后折射率变化非常大。2)光酸生成物-酸敏染料体系：制备了以4-硝基苄基-9,10-二甲氧基蒽-2-磺酸盐（NAS）和尼罗蓝A碱（NBAb）分散的聚合物膜，并在422 nm处进行光照射。NAS光分解产生质子，质子扩散并与NBAb反应生成阳离子NAB （NBA^+）。通过选择三种不同波长（422、488、620 nm），光化学反应和连续的NSOM成像成为可能。

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).