二引哚衍生物及其金屬錯合物之光物理、光化學性質及其陰離子作用變化之研究
Abstract
我們成功的合成出以 bisquinoxaline 做為主體，其具有很好的π電子共振能力；再分別結合 phenanthrene 和 bipyridil 為發光團，indolecarbazole 及 diindole為離子辨識單元的 BN 系列的陰離子感測分子，在 DMSO的溶液中不僅對氟離子、焦磷酸根離子、磷酸根離子及氰離子以1 :1的形式錯合，同時在顏色上也可以用肉眼輕易判斷環境中所含的陰離子。在與陰離子作用後，在光譜上產生明顯的分子內電荷轉移 (ICT, intramolecular charge transfer) ，因此在吸收及放光光譜上有紅位移及新的吸收及放射峰的生成。
由於與錸（ReI ）形成錯合物，因此分子本身具有明顯的分子內電荷轉移 (ICT) 及金屬到官能基的電荷轉移 ( MLCT, metal to ligand charge transfer ）；因此當離子與我們的化合物以氫鍵作用力的方式結合後，indolecarbazole上NH的孤對電子，就更會使電荷轉移至金屬的部份，也就是電荷分離變得更明顯。
我們可以清楚的發現，化合物 BN-2 、 BN-4 上 indolecarbazole 的NH的極化程度分別是 BN-4 ＞ BN-2 ，其中化合物 BN-4 在陰離子濃度一個當量時，陰離子會用氫鍵作用力的方式與其結合，而超過一個當量時， indolecarbazole 上的 NH會被去質子化。而化合物 BN-5 在陰離子辨識上，因為 diindole 上的 NH 在空間中會翻轉一個角度，阻礙了陰離子與化合物 BN-5 以氫鍵作用力的方式結合，因此降低了對陰離子辨識的靈敏度。
We report the synthesis, characterization, and photophysical properties of a series of organic receptors and their corresponding ReI metal complexes as anion probes featuring diindole and indolecarbazole interacting sites incorporating highly chromophoric π-conjugated bisquinoxaline moieties BN-2, BN-4, and BN-5. These sensing molecules are capable of recognizing fluoride, cyanide and pyrophosphate over other anions in DMSO solution with different sensitivities. The probe-anion interactions can be easily visualized via naked-eye colorimetric or luminescent responses. By interacting with anion, the absorption and luminescence change obvious, this is causing by (ICT, intramolecular charge transfer). Coordination of probe BN-2 to a ReI center increases the intrinsic acidity of indolecarbazole N-H protons and results in an enhanced sensitivity to anions, so that nature of Lewis acidity of ReI metal exert on the indolecarbazole to enhance probe BN-4 is more sensitive than probes BN-2, and BN-5. Compared with probes BN-2 and BN-4, probe BN-2 has weaker acidic indolecarbazole N-H protons and therefore simply forms hydrogen-bonding complexes with fluoride, phosphate, cyanide and pyrophosphate. Due to the higher acidity of indolecarbazole in BN-4, at high concentration of anion, probe BN-4 forms a hydrogen-bound complex which anion followed by indolecarbazole N-H deprotonation with fluoride, pyrophosphate. The sensitivity of anion sensing of probe BN-5 is recating low, because of the non-planar conformation of diindole-based recognition motifs.
We report the synthesis, characterization, and photophysical properties of a series of organic receptors and their corresponding ReI metal complexes as anion probes featuring diindole and indolecarbazole interacting sites incorporating highly chromophoric π-conjugated bisquinoxaline moieties BN-2, BN-4, and BN-5. These sensing molecules are capable of recognizing fluoride, cyanide and pyrophosphate over other anions in DMSO solution with different sensitivities. The probe-anion interactions can be easily visualized via naked-eye colorimetric or luminescent responses. By interacting with anion, the absorption and luminescence change obvious, this is causing by (ICT, intramolecular charge transfer). Coordination of probe BN-2 to a ReI center increases the intrinsic acidity of indolecarbazole N-H protons and results in an enhanced sensitivity to anions, so that nature of Lewis acidity of ReI metal exert on the indolecarbazole to enhance probe BN-4 is more sensitive than probes BN-2, and BN-5. Compared with probes BN-2 and BN-4, probe BN-2 has weaker acidic indolecarbazole N-H protons and therefore simply forms hydrogen-bonding complexes with fluoride, phosphate, cyanide and pyrophosphate. Due to the higher acidity of indolecarbazole in BN-4, at high concentration of anion, probe BN-4 forms a hydrogen-bound complex which anion followed by indolecarbazole N-H deprotonation with fluoride, pyrophosphate. The sensitivity of anion sensing of probe BN-5 is recating low, because of the non-planar conformation of diindole-based recognition motifs.
Description
Keywords
二引哚衍生物