scholarly journals Anharmonicity and Spectra–Structure Correlations in MIR and NIR Spectra of Crystalline Menadione (Vitamin K3)

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6779
Author(s):  
Krzysztof B. Beć ◽  
Justyna Grabska ◽  
Christian W. Huck ◽  
Sylwester Mazurek ◽  
Mirosław A. Czarnecki
Keyword(s):  
Single Molecule ◽  
Near Infrared ◽  
Structural Information ◽  
Molecular System ◽  
Theoretical Calculations ◽  
Vitamin K3 ◽  
Structure Correlations ◽  
Mir Spectra ◽  
Combination Bands ◽  
The Relationship

Mid-infrared (MIR) and near-infrared (NIR) spectra of crystalline menadione (vitamin K3) were measured and analyzed with aid of quantum chemical calculations. The calculations were carried out using the harmonic approach for the periodic model of crystal lattice and the anharmonic DVPT2 calculations applied for the single molecule model. The theoretical spectra accurately reconstructed the experimental ones permitting for reliable assignment of the MIR and NIR bands. For the first time, a detailed analysis of the NIR spectrum of a molecular system based on a naphthoquinone moiety was performed to elucidate the relationship between the chemical structure of menadione and the origin of the overtones and combination bands. In addition, the importance of these bands during interpretation of the MIR spectrum was demonstrated. The overtones and combination bands contribute to 46.4% of the total intensity of menadione in the range of 3600–2600 cm−1. Evidently, these bands play a key role in shaping of the C-H stretching region of MIR spectrum. We have shown also that the spectral regions without fundamentals may provide valuable structural information. For example, the theoretical calculations reliably reconstructed numerous overtones and combination bands in the 4000–3600 and 2800–1800 cm−1 ranges. These results, provide a comprehensive origin of the fundamentals, overtones and combination bands in the NIR and MIR spectra of menadione, and the relationship of these spectral features with the molecular structure.

scholarly journals Towards rational design and optimization of near-field enhancement and spectral tunability of hybrid core-shell plasmonic nanoprobes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Debadrita Paria ◽  
Chi Zhang ◽  
Ishan Barman
Keyword(s):  
Single Molecule ◽  
Rational Design ◽  
Near Infrared ◽  
Theoretical Calculations ◽  
Near Field ◽  
Field Enhancement ◽  
Infrared Region ◽  
Core Shell ◽  
Optimization Strategy ◽  
Design And Optimization

Abstract In biology, sensing is a major driver of discovery. A principal challenge is to create a palette of probes that offer near single-molecule sensitivity and simultaneously enable multiplexed sensing and imaging in the “tissue-transparent” near-infrared region. Surface-enhanced Raman scattering and metal-enhanced fluorescence have shown substantial promise in addressing this need. Here, we theorize a rational design and optimization strategy to generate nanostructured probes that combine distinct plasmonic materials sandwiching a dielectric layer in a multilayer core shell configuration. The lower energy resonance peak in this multi-resonant construct is found to be highly tunable from visible to the near-IR region. Such a configuration also allows substantially higher near-field enhancement, compared to a classical core-shell nanoparticle that possesses a single metallic shell, by exploiting the differential coupling between the two core-shell interfaces. Combining such structures in a dimer configuration, which remains largely unexplored at this time, offers significant opportunities not only for near-field enhancement but also for multiplexed sensing via the (otherwise unavailable) higher order resonance modes. Together, these theoretical calculations open the door for employing such hybrid multi-layered structures, which combine facile spectral tunability with ultrahigh sensitivity, for biomolecular sensing.

Introduction

2018 ◽  
Author(s):  
Eaton E. Lattman ◽  
Thomas D. Grant ◽  
Edward H. Snell
Keyword(s):  
Structural Biology ◽  
Single Molecule ◽  
Small Angle ◽  
Structural Information ◽  
Complementary Technique ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Future ◽  
The Relationship ◽  
Basic Level

This chapter provides an introduction to small angle solution scattering with particular reference to the complementary technique of X-ray crystallography and the relationship between the two. It describes at its most basic level the theoretical underpinnings of solution scattering starting from a single molecule and how this information is sampled in crystals versus in solution. A brief introduction is given to some of the primary types of structural information that can be obtained from experiments. The chapter concludes discussing some of the most common applications of the technique in structural biology, and where the future is likely headed.

Spectra-Structure Correlations of Some Heterocyclic Pharmaceuticals

1965 ◽  
Vol 48 (3) ◽  
pp. 596-600
Author(s):  
Alma L Hayden ◽  
Millard Maienthal
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Magnetic Resonance Data ◽  
Structure Correlations ◽  
Group Frequency ◽  
Resonance Data ◽  
The Relationship ◽  
Related Compounds

Abstract The results of a study of the relationship between spectra and structure of zoxazolamine, methimazole, and some related compounds are presented. Group frequency assignments of the infrared spectra were clarified or confirmed by comparisons with ultraviolet, near infrared, and nuclear magnetic resonance data.

scholarly journals Identification of DNA Bases and Their Cations in Astrochemical Environments: Computational Spectroscopy of Thymine as a Test Case

2021 ◽  
Vol 8 ◽  
Author(s):  
Yage Zhao ◽  
Majdi Hochlaf ◽  
Malgorzata Biczysko
Keyword(s):  
Near Infrared ◽  
Vacuum Ultraviolet ◽  
Theoretical Calculations ◽  
Photoelectron Spectra ◽  
Test Case ◽  
Molecular Systems ◽  
James Webb Space Telescope ◽  
Computational Spectroscopy ◽  
Robotic Missions ◽  
Combination Bands

Increased importance of vibrational fingerprints in the identification of molecular systems, can be highlighted by the upcoming interstellar medium (ISM) observations by the James Webb Space Telescope, or in a context of other astrochemical environments as meteorites or exoplanets, Mars robotic missions, such as instruments on board of Perseverance rover. These observations can be supported by combination of laboratory experiments and theoretical calculations, essential to verify and predict the spectral assignments. Astrochemical laboratory simulations have shown that complex organic molecules (COMs) can be formed from simple species by vacuum ultraviolet or X-ray irradiation expanding interest in searching for organic biological and prebiotic compounds. In this work an example of nucleobase, thymine, is selected as a test case for highlighting the utility of computational spectroscopic methods in astrochemical studies. We consider mid-infrared (MIR) and near-infrared (NIR) vibrational spectra of neutral (T) and cationic (T+) thymine ground states, and vibrationally-resolved photoelectron (PE) spectra in the far UV range from 8.7 to 9.4 eV. The theoretical framework is based on anharmonic calculations including overtones and combination bands. The same anharmonic wavenumbers are applied into the simulations of vibrationally-resolved photoelectron spectra based on Franck-Condon computations. The infrared and vibrationally-resolved photoelectron spectra are compared with the available experimental counterparts to verify their accuracy and provide assignment of the observed transitions. Finally, reliable predictions of spectra, going beyond currently available experimental data, either dealing with energy ranges, resolution or temperature, which can support astrochemistry studies are provided.

scholarly journals Comparison of Spectroscopic Techniques Combined with Chemometrics for Cocaine Powder Analysis

2020 ◽  
Vol 44 (8) ◽  
pp. 851-860
Author(s):  
Joy Eliaerts ◽  
Natalie Meert ◽  
Pierre Dardenne ◽  
Vincent Baeten ◽  
Juan-Antonio Fernandez Pierna ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Near Infrared ◽  
Evaluation Criteria ◽  
Classification Model ◽  
Support Vector ◽  
Spectroscopic Techniques ◽  
Data Set ◽  
Promising Tool ◽  
Powder Analysis ◽  
Mir Spectra

Abstract Spectroscopic techniques combined with chemometrics are a promising tool for analysis of seized drug powders. In this study, the performance of three spectroscopic techniques [Mid-InfraRed (MIR), Raman and Near-InfraRed (NIR)] was compared. In total, 364 seized powders were analyzed and consisted of 276 cocaine powders (with concentrations ranging from 4 to 99 w%) and 88 powders without cocaine. A classification model (using Support Vector Machines [SVM] discriminant analysis) and a quantification model (using SVM regression) were constructed with each spectral dataset in order to discriminate cocaine powders from other powders and quantify cocaine in powders classified as cocaine positive. The performances of the models were compared with gas chromatography coupled with mass spectrometry (GC–MS) and gas chromatography with flame-ionization detection (GC–FID). Different evaluation criteria were used: number of false negatives (FNs), number of false positives (FPs), accuracy, root mean square error of cross-validation (RMSECV) and determination coefficients (R2). Ten colored powders were excluded from the classification data set due to fluorescence background observed in Raman spectra. For the classification, the best accuracy (99.7%) was obtained with MIR spectra. With Raman and NIR spectra, the accuracy was 99.5% and 98.9%, respectively. For the quantification, the best results were obtained with NIR spectra. The cocaine content was determined with a RMSECV of 3.79% and a R2 of 0.97. The performance of MIR and Raman to predict cocaine concentrations was lower than NIR, with RMSECV of 6.76% and 6.79%, respectively and both with a R2 of 0.90. The three spectroscopic techniques can be applied for both classification and quantification of cocaine, but some differences in performance were detected. The best classification was obtained with MIR spectra. For quantification, however, the RMSECV of MIR and Raman was twice as high in comparison with NIR. Spectroscopic techniques combined with chemometrics can reduce the workload for confirmation analysis (e.g., chromatography based) and therefore save time and resources.

scholarly journals Solid‐State Near‐Infrared Circularly Polarized Luminescence from Chiral YbIII‐Single‐Molecule Magnet

2021 ◽  
Author(s):  
Fabrice Pointillart ◽  
Bertrand Lefeuvre ◽  
Carlo Andrea Mattei ◽  
Jessica Flores Gonzalez ◽  
Frédéric Gendron ◽  
...  
Keyword(s):  
Solid State ◽  
Single Molecule ◽  
Near Infrared ◽  
Circularly Polarized ◽  
Single Molecule Magnet ◽  
Circularly Polarized Luminescence ◽  
Polarized Luminescence

CSF chitinase 3-like 1 is associated with iron rims in patients with a first demyelinating event

2021 ◽  
pp. 135245852110100
Author(s):  
Manuel Comabella ◽  
Margareta A Clarke ◽  
Sabine Schaedelin ◽  
Mar Tintoré ◽  
Deborah Pareto ◽  
...  
Keyword(s):  
Single Molecule ◽  
Multivariable Analysis ◽  
Enzyme Linked Immunosorbent Assay ◽  
Lesion Volume ◽  
Univariable Analysis ◽  
Neurofilament Light Chain ◽  
Neurofilament Light ◽  
Multivariable Analyses ◽  
Prognostic Implications ◽  
The Relationship

Background: Chronic active lesions with iron rims have prognostic implications in patients with multiple sclerosis. Objective: To assess the relationship between iron rims and levels of chitinase 3-like 1 (CHI3L1), neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) in patients with a first demyelinating event. Methods: Iron rims were identified using 3T susceptibility-weighted imaging. Serum NfL and GFAP levels were measured by single-molecule array assays. CSF (cerebrospinal fluid) CHI3L1 levels were measured by enzyme-linked immunosorbent assay (ELISA). Results: Sixty-one patients were included in the study. The presence of iron rims was associated with higher T2 lesion volume and higher number of gadolinium-enhancing lesions. In univariable analysis, having ⩾2 iron rims (vs 0) was associated with increased CSF CHI3L1 levels (β = 1.41; 95% confidence interval (CI) = 1.10–1.79; p < 0.01) and serum NfL levels (β = 2.30; 95% CI = 1.47–3.60; p < 0.01). In multivariable analysis, however, only CSF CHI3L1 levels remained significantly associated with the presence of iron rim lesions (β = 1.45; 95% CI = 1.11–1.90; p < 0.01). The presence of ⩾2 iron rims was not associated with increased serum GFAP levels in univariable or multivariable analyses. Conclusion: These findings support an important contribution of activated microglia/macrophages to the pathophysiology of chronic active lesions with iron rims in patients with a first demyelinating event.

scholarly journals A multicolor and ratiometric fluorescent sensing platform for metal ions based on arene–metal-ion contact

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Anna Kanegae ◽  
Yusuke Takata ◽  
Ippei Takashima ◽  
Shohei Uchinomiya ◽  
Ryosuke Kawagoe ◽  
...  
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Near Infrared ◽  
Molecular Design ◽  
Theoretical Calculations ◽  
Probe Design ◽  
One Pot ◽  
Fluorescent Sensing ◽  
Sensing Platform ◽  
Ratiometric Detection

AbstractDespite continuous and active development of fluorescent metal-ion probes, their molecular design for ratiometric detection is restricted by the limited choice of available sensing mechanisms. Here we present a multicolor and ratiometric fluorescent sensing platform for metal ions based on the interaction between the metal ion and the aromatic ring of a fluorophore (arene–metal-ion, AM, coordination). Our molecular design provided the probes possessing a 1,9-bis(2′-pyridyl)-2,5,8-triazanonane as a flexible metal ion binding unit attached to a tricyclic fluorophore. This architecture allows to sense various metal ions, such as Zn(II), Cu(II), Cd(II), Ag(I), and Hg(II) with emission red-shifts. We showed that this probe design is applicable to a series of tricyclic fluorophores, which allow ratiometric detection of the metal ions from the blue to the near-infrared wavelengths. X-ray crystallography and theoretical calculations indicate that the coordinated metal ion has van der Waals contact with the fluorophore, perturbing the dye’s electronic structure and ring conformation to induce the emission red-shift. A set of the probes was useful for the differential sensing of eight metal ions in a one-pot single titration via principal component analysis. We also demonstrate that a xanthene fluorophore is applicable to the ratiometric imaging of metal ions under live-cell conditions.

Near-Infrared Combination and Overtone Bands of CH in CHX3, CHX2—CHX2, and CHX2—CX2—CHX2

2005 ◽  
Vol 59 (11) ◽  
pp. 1393-1398 ◽  
Author(s):  
Reikichi Iwamoto ◽  
Akishi Nara ◽  
Toshihiko Matsuda
Keyword(s):  
Excited State ◽  
Near Infrared ◽  
Present Report ◽  
Spectral Characteristics ◽  
The Other ◽  
Coupled Modes ◽  
Third Order ◽  
The Third ◽  
Combination Bands ◽  
Deformation Modes

In the present report we studied spectral characteristics of the near-infrared combination and overtone bands of CH vibrations of a CH sequence. The near-infrared bands of the CH in CHX3 (X, halogen), which were interpreted in terms of the CH stretching and CH deformation fundamentals without any ambiguity, typically showed how the frequency and intensity of a combination or an overtone depend on the vibrational excited state. In the CH–C–CH of CHX2CX2CHX2, the vibrations of one CH are isolated from those of the other CH, and the combination and overtone bands were similarly interpreted as those of the CH, although each of the combination bands was split into two because of non-degeneracy of the CH deformation. In the CH–CH of CHX2CHX2, the CH deformations only have coupled modes. The first combination showed four narrowly separate bands, which were reasonably interpreted on the basis of the CH stretching and the coupled CH deformation modes. We demonstrated that the first combination of coupled modes as well as the combination of up to, at least, the third order of isolated modes have the nature of the characteristic bands.

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