Fluorescence spectroscopy studies of crossed aldol reactions: a reactive Nile red dye reveals catalyst-dependent product formation
Fluorescence spectroscopy studies of crossed aldol reactions: a reactive Nile red dye reveals catalyst-dependent product formation
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DOI：
10.1039/d0cy00806k
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发表时间：
2020-08
影响因子：
5
通讯作者：
Judith Bautista-Gomez;A. Usman;Man Zhang;Ryan J. Rafferty;S. Bossmann;K. Hohn;D. Higgins
中科院分区：
文献类型：
--
作者：
Judith Bautista-Gomez;A. Usman;Man Zhang;Ryan J. Rafferty;S. Bossmann;K. Hohn;D. Higgins
报道了一种新的含有反应醛的尼罗红衍生物(NR-CHO)的合成，并将其用于交叉Aldol反应中多相催化剂活性的光谱研究。1H和13C核磁共振谱和高分辨质谱图证实得到了所需的NR-CHO。以掺镁锆铯的二氧化硅(Cs(Zr，Mg)-SiO_2)为催化剂，与市售氧化镁催化剂进行了性能比较。以气相二氧化硅为对照。羟醛与丙酮和苯乙酮在4：1(v/v)的二甲基亚砜：酮溶液中进行反应，稀释剂(1μM)和浓缩剂(1 MM)NR-CHO均存在。随着反应的进行，获得了NR-CHO荧光光谱。它的发射光谱中的位移被用来区分形成的产物和表征反应速度。染料表现出不同的行为，定义了反应是在加成(醇)产物上停止，还是同时形成加成和缩合(烯烃)产物，提供了关于催化剂活性的有价值的初始信息。加成和缩合产物的指认得到了薄层色谱、高效液相色谱和高效液相-质谱联用数据的支持。产物的形成取决于所使用的催化剂，Cs(Zr，Mg)-SiO_2同时产生加成和缩合产物，而MgO主要产生加成产物。NR-CHO在Aldol反应的光谱研究中的优势也被证明是相对于商业上可用的3-二茂碳甲醛的。本文报道的NR-CHO和所获得的结果将有助于今后对交叉Aldol反应中多相催化的广泛的系综和单分子光谱研究。
The synthesis of a new Nile red derivative incorporating a reactive aldehyde moiety (NR-CHO) is reported and its use in spectroscopic studies of heterogeneous catalyst activity in crossed aldol reactions is demonstrated. 1H and 13C NMR, and high-resolution mass spectrometry confirmed the desired NR-CHO was obtained. Mg-Zr-Cs doped silica (Cs(Zr,Mg)-SiO2) was employed as the catalyst and its performance was compared to that of commercially available MgO. Fumed silica was used as a control. Aldol reactions with acetone and acetophenone were run in 4 : 1 (v/v) DMSO : ketone solutions in the presence of both dilute (1 μM) and concentrated (1 mM) NR-CHO. NR-CHO fluorescence spectra were acquired as the reactions progressed. Shifts in its emission spectrum are used to distinguish the products formed and to characterize the reaction rate. The dye exhibits different behavior that defines whether the reaction stops at the addition (alcohol) product, or forms both addition and condensation (olefin) products, providing valuable initial information on catalyst activity. The assignment of addition and condensation products is supported by thin layer chromatography, high performance liquid chromatography (HPLC), and HPLC-mass spectrometry data. Product formation is shown to depend upon the catalyst employed, with the Cs(Zr,Mg)-SiO2 yielding both addition and condensation products, while MgO yields primarily addition products. The advantages of NR-CHO in spectroscopic studies of aldol reactions are also demonstrated relative to commercially available 3-perylenecarboxaldehyde. The NR-CHO reported here and the results obtained will facilitate a broad range of both ensemble and single molecule spectroscopic investigations of heterogeneous catalysis in crossed aldol reactions in the future.