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Ugras TJ, Yao Y, Robinson RD. Can we still measure circular dichroism with circular dichroism spectrometers: The dangers of anisotropic artifacts. Chirality 2023; 35:846-855. [PMID: 37331723 DOI: 10.1002/chir.23597] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/07/2023] [Accepted: 05/22/2023] [Indexed: 06/20/2023]
Abstract
Chiral materials with strong linear anisotropies are difficult to accurately characterize with circular dichroism (CD) because of artifactual contributions to their spectra from linear dichroism (LD) and birefringence (LB). Historically, researchers have used a second-order Taylor series expansion on the Mueller matrix to model the LDLB interaction effects on the spectra in conventional materials, but this approach may no longer be sufficient to account for the artifactual CD signals in emergent materials. In this work, we present an expression to model the measured CD using a third-order expansion, which introduces "pairwise interference" terms that, unlike the LDLB terms, cannot be averaged out of the signal. We find that the third-order pairwise interference terms can make noticeable contributions to the simulated CD spectra. Using numerical simulations of the measured CD across a broad range of linear and chiral anisotropy parameters, the LDLB interactions are most prominent in samples that have strong linear anisotropies (LD, LB) but negligible chiral anisotropies, where the measured CD strays from the chirality-induced CD by factors greater than 103 . Additionally, the pairwise interactions are most significant in systems with moderate-to-strong chiral and linear anisotropies, where the measured CD is inflated twofold, a figure that grows as linear anisotropies approach their maximum. In summary, media with moderate-to-strong linear anisotropy are in great danger of having their CD altered by these effects in subtle manners. This work highlights the significance of considering distortions in CD measurements through higher-order pairwise interference effects in highly anisotropic nanomaterials.
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Affiliation(s)
- Thomas J Ugras
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York, USA
| | - Yuan Yao
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York, USA
| | - Richard D Robinson
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York, USA
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York, USA
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Chen Y, Lai K, Cai J, Li Y, Wang H. Chiral Fluorescence Recognition by Anthracene Fluorescent Dyes ⊂ Water-Soluble Pillar[5] arene containing Phosphonic Acid Group (PWP[5]). J Fluoresc 2022; 32:983-992. [PMID: 35230565 DOI: 10.1007/s10895-022-02908-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/16/2022] [Indexed: 10/19/2022]
Abstract
Chirality plays a pivotal role in drugs, agrochemicals and food additives et al. The enantiomers of a chiral molecule often show huge difference in bioactivity, metabolism, and toxicity et al. thereby, the recognition of chiral molecules shows an increasingly important priority. In this paper, a novel method for chiral fluorescence recognition based on anthracene fluorescent dyes (AD) ⊂ water-soluble pillar[5] arene containing phosphonic acid group (PWP[5]) is developed. The AD as guest molecule can complex with PWP [5] to form 1:1 AD ⊂ PWP[5] assembly, and this assembly can be further used as a fluorescent probe to identify D/L-phenylalanine and D/L-phenylalaninol by fluorescent titration. The fluorescence intensity of the assembly was significantly reduced for D-phenylalanine and D-phenylalaninol, while L-phenylalanine or L-phenylalaninol was added to AD ⊂ PWP[5] assembly, the fluorescence intensity of the assembly almost unchanged. Hence, the chiral recognition based on assembly between the achiral fused ring fluorescent dye and achiral PWP[5] was developed.
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Affiliation(s)
- Yuliang Chen
- College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, 211800, Jiangsu, China
| | - Kaijie Lai
- College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, 211800, Jiangsu, China
| | - Jinmi Cai
- College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, 211800, Jiangsu, China
| | - Yicheng Li
- College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, 211800, Jiangsu, China
| | - Haibo Wang
- College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, 211800, Jiangsu, China.
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Oshina I, Spigulis J. Beer-Lambert law for optical tissue diagnostics: current state of the art and the main limitations. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-210167VRR. [PMID: 34713647 PMCID: PMC8553265 DOI: 10.1117/1.jbo.26.10.100901] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 09/28/2021] [Indexed: 05/24/2023]
Abstract
SIGNIFICANCE Beer-Lambert law (BLL) is a widely used tool for contact and remote determination of absorber concentration in various media, including living tissues. Originally proposed in the 18th century as a simple exponential expression, it has survived numerous modifications and updates. The basic assumptions of this law may not be fulfilled in real measurement conditions. This can lead to mistaken or misinterpreted results. In particular, the effects to be additionally taken into account in the tissue measurements include anisotropy, scattering, fluorescence, chemical equilibria, interference, dichroism, spectral bandwidth disagreements, stray radiation, and instrumental effects. AIM We review the current state of the art and the main limitations of remote tissue diagnostics using the BLL. Historical development of updating this law by taking into account specific additional factors such as light scattering and photon pathlengths in diffuse reflectance is described, along with highlighting the main risks to be considered by interpreting the measured data. APPROACH Literature data related to extension and modification of the BLL related to tissue assessment and concentration estimation of specific tissue molecules are collected and analyzed. The main emphasis here is put on the optical measurements of living tissue chromophore concentrations and estimation of physiological parameters, e.g., blood oxygen saturation. RESULTS Modified expressions of the BLL suitable for several specific cases of living tissue characterization are presented and discussed. CONCLUSIONS Applications of updated/modified Beer-Lambert law (MBLL) with respect to particular measurement conditions are helpful for obtaining more reliable data on the target tissue physiological state and biochemical content. MBLL accounting for the role of scattering in several ways appears to be a successful approach. Extended MBLL and BLL in the time domain form could provide more accurate results, but this requires more time resources to be spent.
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Affiliation(s)
- Ilze Oshina
- University of Latvia, Institute of Atomic Physics and Spectroscopy, Biophotonics Laboratory, Riga, Latvia
| | - Janis Spigulis
- University of Latvia, Institute of Atomic Physics and Spectroscopy, Biophotonics Laboratory, Riga, Latvia
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Cunha FC, de Holanda RC, Secchi AR, de Souza MB, Barreto AG. Simultaneous absorption of UV-vis and circular dichroism to measure enantiomeric concentrations of praziquantel under nonlinear conditions. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 241:118645. [PMID: 32652288 DOI: 10.1016/j.saa.2020.118645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 06/21/2020] [Accepted: 06/21/2020] [Indexed: 06/11/2023]
Abstract
Beer-Lambert-Bouguer law is for a limiting case and, therefore, it is not useful to describe the relationship between absorption signal and enantiomer concentration in a stream when there are nonlinear phenomena present. In this work, the Chiral Detector (CD-2095 JASCO) equipment was used to measure simultaneously the UV-Vis and circular dichroism (CD) signals of a stream with different compositions of praziquantel enantiomers. The tested models were calibrated (parameter estimation) and validated using the Leave-One-Out Cross Validation (LOOCV) method. Both UV-vis and CD signals were absorbed differently in mixtures in comparison to pure solutions, indicating a nonlinear relationship between the absorbed signal and the enantiomer concentration in a mixture stream. Empirical mathematical relationships were tested for each signal (UV-vis and CD) and the pair of equations was evaluated using the Mean Square Error (MSE) metric for each enantiomer concentration (MSEL and MSED) and the pair of equations with the smallest MSEt (=MSEL + MSED) metric was chosen. Confidence interval analysis helped to find even simpler equations in comparison to the chosen ones. Higher nonlinearity was observed for a mixture with low L-PZQ concentration. The developed methodology allowed the choice of an empiric model to give good predictions in a wide range of concentration, what is of utmost importance for monitoring and automatic control purposes, for instance.
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Affiliation(s)
- F C Cunha
- PEQ/COPPE, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, bloco G, sala 115, Cidade Universitária, Rio de Janeiro CEP 21.941-972, Brazil.
| | - R C de Holanda
- DEQ/EQ, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, bloco E, sala 209, Cidade Universitária, Rio de Janeiro CEP 21.941-972, Brazil
| | - A R Secchi
- PEQ/COPPE, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, bloco G, sala 115, Cidade Universitária, Rio de Janeiro CEP 21.941-972, Brazil; DEQ/EQ, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, bloco E, sala 209, Cidade Universitária, Rio de Janeiro CEP 21.941-972, Brazil
| | - M B de Souza
- PEQ/COPPE, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, bloco G, sala 115, Cidade Universitária, Rio de Janeiro CEP 21.941-972, Brazil; DEQ/EQ, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, bloco E, sala 209, Cidade Universitária, Rio de Janeiro CEP 21.941-972, Brazil
| | - A G Barreto
- DEQ/EQ, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, bloco E, sala 209, Cidade Universitária, Rio de Janeiro CEP 21.941-972, Brazil
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Mayerhöfer TG, Pahlow S, Popp J. The Bouguer-Beer-Lambert Law: Shining Light on the Obscure. Chemphyschem 2020; 21:2029-2046. [PMID: 32662939 PMCID: PMC7540309 DOI: 10.1002/cphc.202000464] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/10/2020] [Indexed: 01/21/2023]
Abstract
The Beer-Lambert law is unquestionably the most important law in optical spectroscopy and indispensable for the qualitative and quantitative interpretation of spectroscopic data. As such, every spectroscopist should know its limits and potential pitfalls, arising from its application, by heart. It is the goal of this work to review these limits and pitfalls, as well as to provide solutions and explanations to guide the reader. This guidance will allow a deeper understanding of spectral features, which cannot be explained by the Beer-Lambert law, because they arise from electromagnetic effects/the wave nature of light. Those features include band shifts and intensity changes based exclusively upon optical conditions, i. e. the method chosen to record the spectra, the substrate and the form of the sample. As such, the review will be an essential tool towards a full understanding of optical spectra and their quantitative interpretation based not only on oscillator positions, but also on their strengths and damping constants.
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Affiliation(s)
- Thomas G. Mayerhöfer
- Spectroscopy/ImagingLeibniz Institute of Photonic TechnologyAlbert-Einstein-Str. 907745JenaGermany
- Institute of Physical Chemistry and Abbe Center of PhotonicsFriedrich Schiller University, JenaHelmholtzweg 407743JenaGermany
| | - Susanne Pahlow
- Institute of Physical Chemistry and Abbe Center of PhotonicsFriedrich Schiller University, JenaHelmholtzweg 407743JenaGermany
| | - Jürgen Popp
- Spectroscopy/ImagingLeibniz Institute of Photonic TechnologyAlbert-Einstein-Str. 907745JenaGermany
- Institute of Physical Chemistry and Abbe Center of PhotonicsFriedrich Schiller University, JenaHelmholtzweg 407743JenaGermany
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Chen X, Hu N, Wei H, Wang H. Chiral Fluorescent Recognition by Naphthalimide. J Fluoresc 2020; 30:679-685. [PMID: 32367338 DOI: 10.1007/s10895-020-02539-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 04/13/2020] [Indexed: 11/28/2022]
Abstract
Chirality plays a very important role in medicine, biochemistry and other fields. Because the enantiomers of chiral drugs often show different pharmacology activity, metabolism, and toxicity, therefore, the recognition of chiral molecules is very important, and has become a hot spot and frontier of modern chemical research. In this paper, a new method for recognizing chiral molecular based on naphthalimide dye(NA)⊂cucurbit[5]uril(CB[7]) assembly is developed. NA as guest can be combined with the host CB[7] to form a 1:1 NA⊂CB[7] assembly. Furthermore, this assembly was used as a fluorescent probe to recognize D/L-phenylalanine and D/L-phenylalaninol by fluorescence titration. When D-phenylalanine or D-phenylalaninol was added to NA⊂CB[7] assembly, the fluorescent intensity of assembly was partially quenched, but when L-phenylalanine or L-phenylalaninol was added to NA⊂CB[7], the fluorescence intensity of the assembly almost unchanged. Herein, chiral recognition platform based on achiral NA⊂achiral CB[7] was constructed.
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Affiliation(s)
- Xuanming Chen
- College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, China
| | - Na Hu
- College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, China
| | - Huifeng Wei
- College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, China
| | - Haibo Wang
- College of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, China.
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Mayerhöfer TG, Pipa AV, Popp J. Beer's Law-Why Integrated Absorbance Depends Linearly on Concentration. Chemphyschem 2019; 20:2748-2753. [PMID: 31544999 PMCID: PMC6899465 DOI: 10.1002/cphc.201900787] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/19/2019] [Indexed: 01/31/2023]
Abstract
As derived by Max Planck in 1903 from dispersion theory, Beer's law has a fundamental limitation. The concentration dependence of absorbance can deviate from linearity, even in the absence of any interactions or instrumental nonlinearities. Integrated absorbance, not peak absorbance, depends linearly on concentration. The numerical integration of the absorbance leads to maximum deviations from linearity of less than 0.1 %. This deviation is a consequence of a sum rule that was derived from the Kramers-Kronig relations at a time when the fundamental limitation of Beer's law was no longer mentioned in the literature. This sum rule also links concentration to (classical) oscillator strengths and thereby enables the use of dispersion analysis to determine the concentration directly from transmittance and reflectance measurements. Thus, concentration analysis of complex samples, such as layered and/or anisotropic materials, in which Beer's law cannot be applied, can be achieved using dispersion analysis.
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Affiliation(s)
- Thomas G. Mayerhöfer
- Spectroscopy/ImagingLeibniz Institute of Photonic TechnologyAlbert-Einstein-Str. 9D-07745JenaGermany
- Institute of Physical Chemistry and Abbe Center of PhotonicsFriedrich Schiller UniversityHelmholtzweg 4D-07745JenaGermany
| | - Andrei V. Pipa
- PlasmadiagnosticsLeibniz Institute for Plasma Science and TechnologyFelix-Hausdorff-Str. 2D-17489GreifswaldGermany
| | - Jürgen Popp
- Spectroscopy/ImagingLeibniz Institute of Photonic TechnologyAlbert-Einstein-Str. 9D-07745JenaGermany
- Institute of Physical Chemistry and Abbe Center of PhotonicsFriedrich Schiller UniversityHelmholtzweg 4D-07745JenaGermany
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