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Guojie Li Mutasem Alshalalfeh Dr. Josef Kapitán Prof. Petr Bouř Prof. Yunjie Xu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(20):e202104302
This Concept article summarizes recent work on the development of a new form of chiral Raman spectroscopy, e CP-Raman, which combines two spectroscopies: electronic circular dichroism (ECD) and circularly polarized Raman (CP-Raman). First, some puzzling observations while carrying out Raman optical activity (ROA) measurements of several transition metal complexes under resonance are described, as well as the search for the mechanisms responsible. Then an equation for quantifying the e CP-Raman contribution is presented, followed by several examples of how e CP-Raman influences the IR−IL spectra of achiral and chiral solvent molecules and of a number of chiral solutes under resonance. The conditions to extract resonance ROA, when the e CP-Raman contribution is minimized, are also discussed. Finally, we comment on the potential applications of e CP-Raman. 相似文献
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Dr. Marcin Górecki Dr. Filippo Lipparini Dr. Gianluigi Albano Dr. Tamás Jávorfi Dr. Rohanah Hussain Dr. Giuliano Siligardi Prof. Gennaro Pescitelli Prof. Lorenzo Di Bari 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(4):e202103632
Solid-state ECD (ss-ECD) spectra of a model microcrystalline solid, finasteride, dispersed into a KCl pellet were recorded by using the synchrotron radiation source at the Diamond B23 beamline. Scanning a surface of 36 mm2 with a step of 0.5 mm, we measured a set of ECD imaging (ECDi) spectra very different from each other and from the ss-ECD recorded with a bench-top instrument (1 cm2 area). This is due to the anisotropic part of the ECD (ACD), which averages to zero in solution or on a large number of randomly oriented crystallites, but can otherwise be extremely large. Two-way singular value decomposition (SVD) analysis, through experimental and simulated TDDFT spectra, disclosed that the measured and theoretical principal components are in line with each other. This finding demonstrates that the observed isotropic ss-ECD spectrum is governed by the anisotropy of locally oriented crystals. It also introduces a new quality for ss-ECD measurements and opens a new future for probing and mapping chiral materials in the solid state such as active pharmaceutical ingredients (APIs). 相似文献
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Novel Secondary Structure of Calcitonin in Solid State as Revealed by Circular Dichroism Spectroscopy 总被引:1,自引:0,他引:1
The solid-state circular dichroic study reveals that salmon calcitonin presents a typical α-helical structure while human calcitonin appears to form a β-sheet in solid state,although both of them adopt random coil structures in aqueous solution. 相似文献
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Dr. Tao Wu Guojie Li Dr. Josef Kapitán Dr. Jiří Kessler Prof. Yunjie Xu Prof. Petr Bouř 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(49):22079-22082
Previously, we and other laboratories have reported an unusual and strong Raman optical activity (ROA) induced in solvents by chiral dyes. Various theories of the phenomenon appeared, but they were not capable of explaining fully the observed ROA band signs and intensities. In this work, an analysis based both on the light scattering theory and dedicated experiments provides a more complete understanding. For example, double-cell magnetic circular dichroism and magnetic ROA experiments with copper-porphyrin complex show that the induced chirality is observed without any contact of the solvents with the complex. The results thus indicate that a combination of electronic circular dichroism (ECD) with the polarized Raman scattering is responsible for the effect. The degree of circularity of solvent vibrational bands is a principal molecular property participating in the event. The insight and the possibility to predict the chirality transfer promise future applications in spectroscopy, chemical analysis and polarized imaging. 相似文献
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合成了2个基于手性配体L-和D-苏氨酸(L/D-thr)的Co(Ⅲ)配合物的对应异构体[Co(L-thr)3]·4.5H2O(L-1)和[Co(L-thr)3]·4.5H2O(D-1),并对2个化合物进行了单晶X射线衍射、红外、热重、紫外可见光谱以及CD谱性质研究。晶体结构分析表明,2个化合物分别结晶在四方晶系P43212和P41212手性空间群。固体CD谱测试进一步证实2个化合物具有手性。 相似文献
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合成了2个基于手性配体L-和D-苏氨酸(L/D-thr)的Co(III)配合物的对应异构体[Co(L-thr)3]·4.5H2O(L-1)和[Co(L-thr)3]·4.5H2O(D-1),并对2个化合物进行了单晶X射线衍射、红外、热重、紫外可见光谱以及CD谱性质研究。晶体结构分析表明,2个化合物分别结晶在四方晶系P43212和P41212手性空间群。固体CD谱测试进一步证实2个化合物具有手性。 相似文献
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手性锌卟啉对咪唑类客体的分子识别及圆二色光谱的研究 总被引:2,自引:0,他引:2
研究了手性α,α,α,β-四-[邻(叔丁氧羰L-酪氨酸)氨基苯基]卟啉 锌[α,α,α,β-ZnT(o-Boc)TyrTAPP](1)和手性α,α,α,β-四-[邻(叔 丁氧羰L-丙氨酸)氨基苯基]卟啉锌[α,α,α,β-ZnT(o-BocAla)TAPP](2)对 咪唑、2-甲基咪唑、N-甲基咪唑和2-乙基-4-甲基咪唑的分子识别行为,分别 求得主体(1)对咪唑类分子识别的缔合常数顺序为K(Im)>K(2-MeIm)>K(N-MeIm) >K(2-Et-4-MeIm),主体(2)对咪唑类分子识别的缔合常数顺序为K(2-MeIm)>K (Im)>K(2-Ek-4-MeIm)>K(N-MeIm),并用圆二色光谱(CD)研究了主体1和2对咪唑 在客体在CHCl3中分子识别的光谱行为,与热力学的结果做了比较。 相似文献
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Determination of the Absolute Configuration of Perylene Quinone‐Derived Mycotoxins by Measurement and Calculation of Electronic Circular Dichroism Spectra and Specific Rotations
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Prof. Dr. Joachim Podlech Dr. Stefanie C. Fleck Prof. Dr. Manfred Metzler Dr. Jochen Bürck Prof. Dr. Anne S. Ulrich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11463-11470
Altertoxins I–III, alterlosins I and II, alteichin (alterperylenol), stemphyltoxins I–IV, stemphyperylenol, stemphytriol, 7‐epi‐8‐hydroxyaltertoxin I, and 6‐epi‐stemphytriol are mycotoxins derived from perylene quinone, for which the absolute configuration was not known. Electronic circular dichroism (ECD) spectra were calculated for these compounds and compared with measured spectra of altertoxins I–III, alteichin, and stemphyltoxin III and with reported Cotton effects. Specific rotations were calculated and compared with reported specific rotations. The absolute configuration of all the toxins, except for stemphyltoxin IV, could thus be determined. The validity of the assignment was high whenever reported ECD data were available for comparison, and the validity was lower when the assignment was based only on the comparison of calculated and reported specific rotations. ECD spectra are intrinsically different for toxins with a biphenyl substructure and for toxins derived from dihydroanthracene. 相似文献
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采用含时密度泛函理论方法研究了手性钴卟啉识别手性生物小分子, 解释了分子结构与光学活性的关系. 通过基组叠加误差(BSSE)校正, Co(III)-卟啉衍生物与(S)-脯氨醇和(S)-2-丁氨之间的作用能分别为310.5和241.6 kJ/mol. 这种较强的分子识别作用起源于主体与客体之间的配位和氢键作用. 具有较大负比旋度的金属卟啉分子对具有较小的正比旋度的生物分子的分子识别作用, 极大地抵消了金属卟啉分子的负比旋度数值. 电子吸收光谱和电子圆二色谱表明, 最低能带起源于主体卟啉环-客体小分子的HOMO-LUMO电荷转移跃迁, 具有负或正的康登效应. 较高能带由配体内部的π→π*电子跃迁所致, 具有一个负的和一个正的康登效应. 最高能带由取代基到卟啉环的p→π*电子跃迁所致, 具有两个负的康登效应. 相似文献
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Zhongli Bao Ya-Chi Cheng Justin Jun Wei Mary Ziping Luo Jack Yongfeng Zhang 《Molecules (Basel, Switzerland)》2022,27(22)
Glucagon, a 29-amino acid polypeptide hormone, is an essential therapeutic agent used in the emergency treatment of hypoglycemia. However, glucagon is inherently unstable in aqueous solution. While glucagon equilibrates between unordered and the secondary α-helix state in solution, it can quickly transform into a different secondary β-sheet-rich amyloid-like fibril/oligomer structure under various conditions. Since changes in the secondary structure of glucagon can cause significant impacts, structure analysis is necessary and essential to assess the safety of the product. This study analyzed the secondary structure of glucagon products at the release and at the expiry using circular dichroism spectroscopy (CD) and 2D Nuclear Overhauser effect spectroscopy (2D NOESY). In order to also determine if structural differences exist between glucagon produced through different manufacturing processes, synthetic and recombinant glucagon products were used and compared. The CD results indicated that for all release and expired glucagon products, the structure compositions were 14 to 16% α-helix, 17 to 19% β-strand, 14 to 15% Turn, and 53 to 54% Unordered. This was consistent with the 2D NOESY analysis which showed that both products had an approximate α-helix composition of 14 to 17%. Overall, there were no significant differences in terms of the secondary structure between synthetic and recombinant glucagon products both at the release and at the expiry. 相似文献
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Multimetallic Architectures from the Self‐assembly of Amino Acids and Tris(2‐pyridylmethyl)amine Zinc(II) Complexes: Circular Dichroism Enhancement by Chromophores Organization
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Dr. Elena Badetti Dr. Klaus Wurst Prof. Giulia Licini Prof. Cristiano Zonta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(19):6515-6518
Stereodynamic optical probes are becoming very popular for their capability to act as molecular sensors for the determination of the enantiomeric excess (ee) of chiral compounds. Herein, we describe a new molecular architecture formed by the self‐assembly of three zinc metal ions, two modified tris(2‐pyridylmethyl)amine ligands, and two amino acids. This system is the structural and functional serendipitous evolution of our previous probe for the determination of amino acids ee. In the new system, one of the metals templates in close proximity two chromophores enhancing their exciton coupling. 相似文献
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A series of multidentate nitrogen donor ligands have been synthesized and characterized and their conformational distributions in solution have been investigated. Vibrational absorption (VA) and vibrational circular dichroism (VCD) spectroscopy, complemented with DFT calculations, have been used to probe the conformations of these important ligands in solution directly. These three ligands demonstrate very different conformational flexibility; the pyridine subunits and amine groups may adopt a number of different conformations. Experimental VA and VCD data measured in CDCl3 have been compared to the theoretical spectra of all possible most stable conformers. Solvent effects have been taken into account by using the implicit polarizable continuum model and explicit solvation model. The explicit hydrogen‐bonding solvation model is important for explaining the VCD sign‐reverse phenomenon in the amide I region. Good agreement has been achieved between experimental and predicted spectra for all three ligands; thus allowing detailed examination of the related conformational structures and distributions in solution. 相似文献
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Strength by Joining Methods: Combining Synthesis with NMR,IR, and Vibrational Circular Dichroism Spectroscopy for the Determination of the Relative Configuration in Hemicalide
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Ewoud De Gussem Prof. Dr. Wouter Herrebout Dr. Simon Specklin Dr. Christophe Meyer Prof. Dr. Janine Cossy Prof. Dr. Patrick Bultinck 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(52):17385-17394
The relative configuration of a key subunit of hemicalide, a recently isolated, highly bioactive marine natural product having potent antiproliferative activity against a panel of human cancer cell lines, was assigned by combining stereocontrolled synthesis of model substrates with NMR, IR, and vibrational circular dichroism (VCD) spectroscopy. The assignment of the absolute configuration of asymmetric carbon center C42 in two structurally complex epimeric substructures containing six stereocenters by VCD analysis illustrates the power and reliability of combining methods. 相似文献
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Cover Picture: Elucidating the Structure of Chiral Molecules by using Amplified Vibrational Circular Dichroism: From Theory to Experimental Realization (ChemPhysChem 16/2015)
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Dr. Sérgio R. Domingos Prof. Dr. František Hartl Prof. Dr. Wybren Jan Buma Prof. Dr. Sander Woutersen 《Chemphyschem》2015,16(16):3343-3343