Department of Chemistry, Shanghai University, Shanghai 200444, China.
Inorg Chem. 2021 Apr 5;60(7):5042-5053. doi: 10.1021/acs.inorgchem.1c00083. Epub 2021 Mar 11.
A lariat anthraquinone macrocycle functionalized with catechol (HL) was synthesized via the Mannich reaction. The Mannich base HL can be partially decomposed into L1·3HO and HL1·NO·2HO in the presence of tetrabutylammonium hydroxide/Al(NO)·9HO in dimethyl sulfoxide (DMSO). Free L1·3HO is essentially coplanar, while protonated HL1·NO·2HO is highly distorted. Dark-green FeCl·HL·2HO powder and Fe(HL)Cl crystal can be isolated from ethanol (CHOH) in high/low HL concentration. Anthraquinone in HL is essentially coplanar but distorted in Fe(HL)Cl. The Fe(III) ion in Fe(HL)Cl adopts a less common five-coordination with three catecholate O and two Cl atoms in the dimer. The distortion of inbound C═O is much higher than that of outbound C═O in anthraquinone in all of these compounds. HL responds to chlorides of Li, Na, K, Cs, Mg, Ca, Sr, Ba, Fe, Cu, Zn, and Al in a DMSO solution, which can be observed by differential pulse voltammetry, UV-vis, and H NMR. All of these metal ions shift of anthraquinone to positive, especially the second reduction peak of anthraquinone. Fe, Zn, and Al change the reduction of catechol fundamentally. HL (0.50 mM) shows a chromogenic response to FeCl and Fe(NO) to form uncommon 2:1 and 3:2 (HL/Fe) complexes, both peaking at 748 nm in DMSO. In the presence of 2 equiv of sodium hydroxide (NaOH), the 748 nm absorbance shifts to 777 nm, identical with Fe(HL)Cl in DMSO. Different from the fast reaction between HL and FeCl, Fe(NO) reacts with HL rather slowly in DMSO. Catechol can coordinate to FeCl without any deprotonation in CHOH and DMSO. HL also shows a chromogenic response to fluorides and hydroxides, which peak at 670 and 684 nm, respectively, in DMSO. The binding ratio between HL and F/OH is 1:2. In a higher concentration of hydroxides, a 684 nm greenish-blue 1:2 complex forms immediately, which gradually transforms to a red complex and peaks at ∼530 nm in minutes at room temperature. No color change can be observed in an CHOH solution in the presence of OH.
通过曼尼希反应合成了一种带有邻苯二酚的轮烷蒽醌大环化合物（HL）。在四丁基氢氧化铵/Al(NO)·9HO 的存在下，Mannich 碱 HL 可以部分分解为 L1·3HO 和 HL1·NO·2HO，在二甲亚砜（DMSO）中。游离的 L1·3HO 基本上是共面的，而质子化的 HL1·NO·2HO 则高度扭曲。深绿色的 FeCl·HL·2HO 粉末和 Fe(HL)Cl 晶体可以从乙醇（CHOH）中在高/低 HL 浓度下分离出来。HL 中的蒽醌基本上是共面的，但在 Fe(HL)Cl 中是扭曲的。Fe(HL)Cl 中的 Fe(III)离子采用较少见的五配位方式，与二聚体中的三个邻苯二酚 O 和两个 Cl 原子配位。在所有这些化合物中，蒽醌中 inbound C═O 的扭曲程度远高于 outbound C═O。HL 在 DMSO 溶液中对 Li、Na、K、Cs、Mg、Ca、Sr、Ba、Fe、Cu、Zn 和 Al 的氯化物有响应，这可以通过差分脉冲伏安法、UV-vis 和 H NMR 观察到。所有这些金属离子都将蒽醌的向正移动，特别是蒽醌的第二个还原峰。Fe、Zn 和 Al 从根本上改变了邻苯二酚的还原。HL（0.50 mM）对 FeCl 和 Fe(NO)显示出显色响应，形成不常见的 2:1 和 3:2（HL/Fe）配合物，在 DMSO 中均在 748nm 处达到峰值。在 2 当量氢氧化钠（NaOH）的存在下，748nm 处的吸光度转移到 777nm，与 DMSO 中的 Fe(HL)Cl 相同。与 HL 和 FeCl 之间的快速反应不同，Fe(NO)在 DMSO 中与 HL 的反应相当缓慢。邻苯二酚在 CHOH 和 DMSO 中无需去质子化即可与 FeCl 配位。HL 对氟化物和氢氧化物也显示出显色响应，分别在 DMSO 中达到 670nm 和 684nm 处的峰值。HL 与 F/OH 的结合比为 1:2。在较高浓度的氢氧化物中，立即形成 684nm 的绿色-蓝色 1:2 配合物，几分钟后在室温下逐渐转化为红色配合物，并在 ∼530nm 处达到峰值。在存在 OH 的 CHOH 溶液中，不会观察到颜色变化。
