(I)溫度和基質效應對於氮-對甲苯磺醯基取代之吡咯衍生物光解後所產生的參重態自由基對之影響 (II)芳香環駢□2-1,2,3-三唑啉衍生物之光化學反應研究及(III)含四唑基團之芳杯衍生物在金屬離子感測上的應用

Abstract

在第一部份的研究，主要是針對一系列含有氮-對甲苯磺醯基取代之吡咯衍生物光解，利用溫度與低溫介質的變換進行電子順磁共振光譜的研究，釐清sultine分子 24 與文獻報導結構極為相似的氮-對甲苯磺醯基取代偶氮 12，在相同溫度與介質光解後所產生的為自由基對或是雙自由基。控制實驗化合物氮-對甲苯磺醯基取代之吡咯 37、72-73、75 在 4 K 的 MTHF 介質下，以 230□325 nm 光解後可以得到參重態自由基對 93、94、95 與 96 的電子順磁共振光譜，其零場分裂參數 D' 值分別是 0.0239、0.0190、0.0174 與 0.0241 cm-1。若是將 37 在室溫下光解，將可以得到氮-對甲苯磺醯基斷裂後的重排產物 38 與 39 以及聚合物。而 sultine 分子 24 與其熱裂解後的環化產物 58 在 77 K 的溫度下光解所得到的自由基對 97 和 98，至少可以穩定存活十小時以上。此一系列氮-對甲苯磺醯基取代吡咯衍生物之 D' 值不僅會隨著所採用的介質而有所變動，亦會隨著量測的溫度而有所不同，證實氮-對甲苯磺醯基之鍵結會因為光解斷裂產生自由基對。除此之外，更進一步利用 X-ray 單晶繞射實驗成功的獲得自由基對 95 存在的直接證據。

第二部份則是重複文獻報導的方式，以可努夫拿哥縮合反應和 1,3-偶極環化加成反應為關鍵步驟，有效率且快速的合成一系列芳香環駢□2-1,2,3-三唑啉衍生物來進行光化學反應機制的探討。□2-1,2,3-三唑啉 186a 或 186c 在乙腈中以 254 nm 的波長光解，將以均勻性的斷裂方式脫去氮氣，產生重氮丙二酸 189 與高活性的氮丙啶中間體 188a,c 和芳香環駢吡咯B，再個別重排成 187a,c 或是聚合成高分子；當加入親二烯體進行捕捉，則可以成功捕捉這些活性中間體與親二烯體進行環化加成反應之產物。喹喔啉駢三唑啉 186c 光解後，與親二烯體進行環化所得的產物將會進行氮架橋的開環反應而得到 6% 的 192c 與 9% 的 195c；而苯駢三唑啉 186a 光解後，和反丁烯二腈進行環化的加成產物 196a 仍會保有原本反丁烯二腈的立體化學。186c 在苯中進行熱裂解後，所得的產物類型與光解的相似，推測喹喔啉駢三唑啉 186c 在熱裂解的過程中極有可能經過兩性物種的機制進行反應。

第三部份的研究，則是以上緣具有推與拉電子基團且下緣具有雙乙腈基團的偶氮芳杯 263a,b ，與疊氮三烷基矽進行 1,3-偶極環化加成反應，在偶氮芳杯中引入四唑基團，並以紫外-可見吸收光譜快速的進行 264a,b 對金屬離子之辨識能力探討。在十四種所篩檢之金屬離子中，偶氮部份含有甲氧基之四唑偶氮芳杯 264a 顯示出對 Ca2+ 的高度選擇性，而偶氮部份含有硝基之四唑偶氮芳杯 264b 則是展現出對 Ca2+、Ba2+、和 Pb2+ 的良好辨識能力；並且由 Job plot 可以得知此兩個發色基團感應器 264a,b 與金屬離子是利用 1:1 的化學計量比進行錯合。由 Benesi-Hildebrand plots 可以求得 264a•Ca2+、264b•Ca2+、264b•Ba2+ 和 264b•Pb2+ 之錯合常數分別是 9.1 □ 104、3.1 □ 105、1.1 □ 105 與 1.6 □ 105 M-1。利用氫核磁共振光譜的滴定實驗得知，264a 與 264b 分別是利用芳杯下緣的兩個部份去質子化的苯酚基團與一個四唑甲氧基基團共同協助來對 Ca2+ 進行錯合。

In part 1, the photolysis (230-325 nm) of N-tosyl pyrrole 37, 2-phenyl-N-tosyl pyrrole 72, 2,5-diphenyl-N-tosyl pyrrole 73, and N-(2-naphthyl)-sulfonyl pyrrole 75 in a 2-methyltetrahydrofuran glassy matrix at 4 K gives electron paramagnetic resonance (EPR) spectra with triplet characteristics; the zero-field-splitting (zfs) parameters D' for the corresponding radical pairs (RPs) 93, 94, 95, and 96 are 0.0239, 0.0190, 0.0174, and 0.0241 cm-1, respectively. Irradiation of 37 at RT allows the isolation of two rearranged products 38 and 39 and a polymeric material, which is consistent with cleavage of the N-S bond followed by recombination of RP 93. Triplet RPs 97, 98 obtained from the photolysis of N-tosylpyrrolosultine 24 and N-tosylpyrroloadduct 58, are stable at 77 K for at least 10 h. It is note worthy that the zfs parameters of triplet RPs 93-98 as well as their temperature and matrix dependencies are strikingly similar to those reported for triplet 3,4-dimethylene-N-tosylpyrrole biradicals 18, which possess same core structure. Furthermore, the X-ray crystallography also success proved the existence of RRs 95.

In part 2, the phenyl and quinoxaline fused □2-1,2,3-triazolines 186a and 186c were synthesized in good yields using Knoevenagel condensation and intramolecular 1,3-dipolar cycloaddition as two of the key reactions. Photolysis (254 nm light) of □2-1,2,3-triazolines 186a or 186c in acetonitrile led to the homolytic cleavage of nitrogen that generated diethyl diazomalonate 189, highly reactive intermediates aziridines 188a,c, and isoindoles B. The latter two species subsequently underwent rearrangement to give the nitrogen extrusion product 187a,c, and polymers. Furthermore, the reactive intermediates were trapped by dienophiles to give the corresponding cycloadducts. Subsequent rearrangement of the N-bridged cycloadducts gave N-substituted pyrrolo[3,4-b]quinoxaline 192c and 195c in 6% and 9% yields, respectively. Irradiation of 186a with fumaronitrile led to the isolation of cycloadduct 196a with retention of stereochemistry. Thermal reaction of 186c gave more nitrogen extruded product 187c than the photolysis did, which implied that zwitterionic intermediate might be involved in the former.

In part 3, calix[4]arenes 264a (R = OMe) and 264b (R = NO2) with 5,17-bis-p-substituted-phenylazo and 25,27-bis-oxymethyltetrazole groups were synthesized using the 1,3-dipolar cycloaddition of oxyacetonitrile azocalix[4]arenes 263a and 263b activated with trimethylsilyl azide, respectively. UV-vis screening of calix[4]arenes 264a and 264b with 14 metal ions showed that 264a (with p-methoxyphenylazo substituent) was a highly chromogenic sensor to Ca2+, while 364b (with p-nitrophenylazo substituent) showed color changes toward Ca2+, Ba2+, and Pb2+. Job plot experiments revealed a 1:1 binding stoichiometry for each of the complexes. The association constants for 264a•Ca2+, 264b•Ca2+, 264b•Ba2+, and 264b•Pb2+ were determined by Benesi-Hildebrand plots to be 9.1 □ 104, 3.1 □ 105, 1.1 □ 105, and 1.6 □ 105 M-1, respectively. Based on 1H NMR titration results, Ca2+ was bound to the two partially deprotonated hydroxyl azophenol groups and one of the two tetrazole groups of 264a and 264b.