Furan-Containing Cyclophenes: Synthesis and Photophysics
Date Issued
2006
Date
2006
Author(s)
Lin, Hsin-Chieh
DOI
en-US
Abstract
應用官能基化的炔丙基硫縮酮進行一鍋式呋喃稠合反應，可產生相對應之寡聯芳香環化合物。後續使用McMurry偶合反應，其為一簡便的方法產生一系列聯三芳香環之環芃烯 54a-f及聯五芳香環之環芃二烯 72 化合物。此外，位置選擇的聯三芳香環之環芃二烯 67 的合成，則由縮環方法獲得。
由於存在連結兩寡聯芳香環的雙鍵，使得環芃烯及環芃二烯具有特別的光物理性質相對於飽和環芃及寡聯芳香環化合物。值得注意的是環芃二烯具有特殊的分子鏈長與放光波長的關係。由此可知，連結兩寡聯芳香環雙鍵的存在可使整個π系統可互相溝通。透過分子內分子 (Molecule-In-Molecule) 的理論方法，可以更進一步了解環芃二烯在激發態非定域化的途徑。經由分析雙鍵存在與不存在時電荷轉移激子波函數之相對比例，可以推得含呋喃之環芃二烯的激發態是透過化
學鍵而產生非定域化。
這是第一個類碳氫化合物之環芃烯分子，其具有非常大的非線性光學 μβ值。丁烷基及戊烷基連結之含呋喃寡聯芳香環之環芃烯的非線性光學 μβ 值可達到與含強推拉電子基的4-二甲基胺-4’-硝基芪 (DANS) 的 μβ 值相似。研究發現張力效應所產生的兩面角對環芃烯的 μβ 值是重要的，而相對較小張力的十二烷基環芃烯 54f 只有可忽略的非線性光學 μβ 值。密度泛涵理論 (DFT) 計算結果給出這些環芃烯具有電荷轉移性質。結合理論與實驗的結果顯示，富含電子的五元環芳香雜環以及具張力的雙鍵可分別作用為電子予體及電子受體。
Functionalized propargylic dithioacetals have been applied to one-pot furan annulation to afford the corresponding functionalized oligoaryls. Subsequently, the McMurry coupling reaction can serve as a convenient method to generate a series of teraryl cyclophenes 54a-f and pentaaryl cyclophandiene 72. Moreover, the synthesis of regio-controlled teraryl cyclophandiene 67 was carried out by ring contraction method.
The unsaturated double bond(s) in cyclophenes and cyclphandienes plays an important role in dictating the photophysical properties which is very much different from those of the saturated counterpart cyclophane and oligoaryls. It is worthy to mention that anomalous chain-length dependence of the cyclophandiene systems was observed from their emission spectra. Therefore, the presence of double bond(s) connecting the two oligoaryl groups might lead to electronic communication throughout the π-system. Furthermore, a theoretical Molecule-In-Molecule approach was used to rationalize the excited state delocalization pathway of cyclophandiene molecules. The excited state delocalization pathway of the furan-containing teraryl cyclophandienes were clearly through-bond which was deduced from the relative weights of CT-exciton wavefunctions of cyclophandienes with and without tethered double bonds.
The first example of hydrocarbon-like cyclophenes which have exceptionally high nonlinear optical (NLO) μβ values was examined. The μβ values of furan-containing teraryl [n.2]cyclophene (n=4-5) were as large as that of 4-N.N-dimethylamino-4’-nitrostilbene (DANS) which contains strong electron donor and acceptor. The importance of the dihedral angles induced by strain effect in cyclophenes was investigated and the less strained [12.2]cyclophene 54f has only negligible NLO properties. The DFT calculations suggested that charge transfer may take place in these cyclophenes. By combining theoretical and experimental results suggest that electron-rich five-membered heteroaromatic and the strained double bond may function as electron donor and acceptor, respectively.
Subjects
環芃烯
非線性光學
電荷轉移
分子內分子
cyclophene
NLO
charge-transfer
molecule-in-molecule
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-95-F90223059-1.pdf
Size
23.31 KB
Format
Adobe PDF
Checksum
(MD5):144d6a962912a1f75718794ac4a95b2a