Further exploration of the physicochemical nature of μ-bridge-relevant deprotonations the elucidation of four kinds of alditol complexes.

Single-crystal structures of four alditol complexes are presented. In LuCl/galactitol and ScCl/-inositol complexes, μ-bridge-relevant deprotonations were observed. The polarization from two rare earth ions in the μ-bridge activates the chemically inert OH and promotes deprotonation.

Novel Developments and Progress in Two-Dimensional Correlation Spectroscopy (2D-COS).

This first of the two-part series of the comprehensive survey review on the progress of the two-dimensional correlation spectroscopy (2D-COS) field during the period 2021-2022, covers books, reviews, tutorials, novel concepts and theories, and patent applications that appeared in the last two years, as well as some inappropriate use or citations of 2D-COS. The overall trend clearly shows that 2D-COS is continually growing and evolving with notable new developments. The technique is well recognized as a powerful analytical tool that provides deep insights into systems in many science fields.

Diverse Applications of Two-Dimensional Correlation Spectroscopy (2D-COS).

This second of the two-part series of a comprehensive survey review provides the diverse applications of two-dimensional correlation spectroscopy (2D-COS) covering different probes, perturbations, and systems in the last two years. Infrared spectroscopy has maintained its top popularity in 2D-COS over the past two years. Fluorescence spectroscopy is the second most frequently used analytical method, which has been heavily applied to the analysis of heavy metal binding, environmental, and solution systems.

Dispersion Analysis of Perpendicular Modes Using a Hybrid Two-Trace Two-Dimensional (2T2D) Smart Error Sum.

Using linear dichroism theory, one would assume that a z-cut of a uniaxial crystal is equivalent to an x-cut to determine the perpendicular component of the dielectric tensor and the corresponding oscillator parameters. However, Fresnel's equations show that the effect of interfaces in the form of the continuity relations of the different components of the electric field must be considered. A consequence of the continuity relations is that perpendicular modes increase less significantly in strength with increasing angle of incidence than expected.

Patterns of Cross-Peaks in Two-Dimensional Correlation Spectra to Probe Intermolecular Interactions Described by Two Reversible Reactions.

Two-dimensional correlation spectroscopy is used to investigate the intermolecular interaction between two substances dissolved in the same solutions, where the intermolecular interaction is described by two reversible reactions producing two supramolecular aggregates. The severe overlappings expected among the characteristic peaks of the original solute and aggregates make conventional one-dimensional spectra difficult to accurately reflect the physiochemical nature of the intermolecular interaction. The double asynchronous orthogonal sample design (DAOSD) approach is utilized to analyze the simulated data for proof-of-principle demonstration.

Streamlined Multi-Attribute Assessment of an Array of Clinical-Stage Antibodies: Relationship Between Degradation and Stability.

Clinical antibodies are an important class of drugs for the treatment of both chronic and acute diseases. Their manufacturability is subject to evaluation to ensure product quality and efficacy. One critical quality attribute is deamidation, a non-enzymatic process that is observed to occur during thermal stress, at low or high pH, or a combination thereof.

Enhanced Spectral Resolution and Two-Dimensional Correlation Spectroscopy (2D-COS).

The apparent enhancement of spectral resolution is one of the attractive features of two-dimensional correlation spectroscopy (2D-COS). Highly overlapped adjacent bands often encountered in one-dimensional spectra may be effectively differentiated and identified by spreading peaks along the second dimension. This differentiating feature or selectivity is especially prominent in asynchronous spectra, where even a slight difference in the variation patterns of overlapped bands in response to a given perturbation results in the generation of cross-peaks.

Investigation of selective SERS enhancement mechanism of Au nanospheres and Au nanorods based on 2T2D-SERS correlation spectroscopy.

The selective enhancement mechanism in surface-enhanced Raman scattering (SERS) is demonstrated. Two different types of single nanoparticles (Au nanosphere and Au nanorod) were used to investigate the role of the localized surface plasmon resonance (LSPR) in SERS spectra by using the two-trace two-dimensional (2T2D) correlation spectroscopy. The SERS intensities of three probe molecules, 4-mercaptobenzoic acid (4-MBA), 4-aminothiophenol (4-ATP), and 4-bromobenzenethiol (4-BBT), respectively, were enhanced but slightly different when adsorbed on Au nanospheres and Au nanorods.

Two-Dimensional Correlation Spectroscopy (2D-COS) Analysis of Evolving Hyperspectral Images.

The evolutionary behavior is examined for heterogeneously distributed hyperspectral images of a simulated biological tissue sample comprising lipid-like and protein-like components during the aging process. Taking a simple planar average of a spectral image loses useful information about the spatially resolved nature of the data. In contrast, multivariate curve resolution (MCR) analysis of a spectral image at a given stage of aging produces a set of loadings of major component groups.

The footprint of linear dichroism in infrared 2D-Correlation spectra.

On the level of the Bouguer-Beer-Lambert approximation, the effects introduced by linear dichroism into absorbance spectra can be simulated by classic linear dichroism theory. If wave optics and dispersion theory are employed, linear dichroism can be modelled with a 4x4 matrix formalism. For linear dichroism theory, the angle between polarization direction and transition moment can be seen as a perturbation which allows to calculate corresponding infrared 2D correlation spectra.

A new approach to recognizing the correct pattern of cross-peaks from a noisy 2D asynchronous spectrum by detecting intrinsic symmetry the Kolmogorov-Smirnov test.

The characteristic cluster pattern of cross-peaks in a 2D asynchronous spectrum provides an effective way to reveal the specific physicochemical nature of subtle spectral changes caused by intermolecular interactions. However, the inevitable presence of noise in the 1D spectra used to construct a 2D asynchronous spectrum is significantly amplified, which poses a serious challenge in identifying the correct cluster pattern of the cross-peaks. While mirror symmetry occurs in some types of cross-peaks, it does not occur in other types.

A new apparatus and the relevant method to retrieve IR spectra of solutes from the corresponding aqueous solutions.

An apparatus and relevant approach to obtaining IR spectra of solutes from the corresponding aqueous solution were developed. In the experiment, aqueous solutions were converted into aerosols using an ultrasonic or a pneumatic device. Subsequently, water in the nebulized solution is completely gasified under a high-speed flow and low vacuum environment.

Robust Approach to Estimating the Stoichiometric Ratio of Supramolecular Complexes Using the Volume of Cross-Peaks in 2D Asynchronous Spectra and the Jonckheere-Terpstra Test.

Estimation of the stoichiometric ratio of a supramolecular aggregate formed by different compounds is very important in elucidating the structure and function of the aggregate. Many spectroscopic methods used to estimate the stoichiometric ratios of coordination complexes become invalid when characteristic peaks of the aggregate overlap with peaks of compounds that form the aggregate. Previously, we combined the asynchronous orthogonal sample design with Job's method to address the abovementioned problem.

Isothermal crystallization of polyhydroxyalkanoate (PHA) utilizing Raman spectroscopy to follow chain packing as well as molecular motion.

Raman spectra of bioplastic poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHx at 13.8 % Hx) were recorded between -250 cm and 3200 cm during isothermal crystallization at 25⁰C after quenching from the melt in liquid nitrogen. At room temperature the crystallization proceeds slowly, so spectra were recorded over a 14-hour period.

Continuing progress in the field of two-dimensional correlation spectroscopy (2D-COS): Part III. Versatile applications.

In this review, the comprehensive summary of two-dimensional correlation spectroscopy (2D-COS) for the last two years is covered. The remarkable applications of 2D-COS in diverse fields using many types of probes and perturbations for the last two years are highlighted. IR spectroscopy is still the most popular probe in 2D-COS during the last two years.

Retrieving Spectra of Pure Components from the DOSY-NMR Experiment via a Comprehensive Approach Involving the 2D Asynchronous Spectrum, 2D Quotient Spectrum, and Genetic Algorithm Refinement.

When diffusion coefficients of different components in a mixture are similar, NMR spectra of pure individual components are difficult to be obtained via a diffusion-ordered spectroscopy (DOSY) experiment. Two-dimensional correlation spectroscopy (2D-COS) is used to analyze the data from the DOSY experiment. Through the properties of the systematic absence of cross-peak (SACP) in the 2D asynchronous spectra, spectra of pure components can be obtained even if their diffusion coefficients are similar.

Continuing progress in the field of two-dimensional correlation spectroscopy (2D-COS), part II. Recent noteworthy developments.

This comprehensive survey review compiles noteworthy developments and new concepts of two-dimensional correlation spectroscopy (2D-COS) for the last two years. It covers review articles, books, proceedings, and numerous research papers published on 2D-COS, as well as patent and publication trends. 2D-COS continues to evolve and grow with new significant developments and versatile applications in diverse scientific fields.

Exploring the use of infrared absorption spectroscopy and two-trace two-dimensional correlation analysis for the resolution of multi-component drug mixtures.

Community drug checking provides an essential service that responds to the unpredictable and variable supply of illicit drugs. Point of care detection of trace components using portable infrared spectrometers is a harm reduction measure to prevent overdose. This study investigates the ability of weighted subtraction and two-trace two-dimensional (2T2D) correlation analysis to reveal the presence of heroin in an opioid mixture that contains heroin and fentanyl mixed with caffeine as a cutting agent.

Continuing progress in the field of two-dimensional correlation spectroscopy (2D-COS), part I. Yesterday and today.

This comprehensive survey review, as the first of three parts, compiles past developments and early concepts of two-dimensional correlation spectroscopy (2D-COS) and subsequent evolution, as well as its early applications in various fields for the last 35 years. It covers past review articles, books, proceedings, and numerous research papers published on 2D-COS. 2D-COS continues to evolve and grow with new significant developments and versatile applications in diverse scientific fields.

Two-trace two-dimensional (2T2D) correlation applied to a number of spectra beyond a simple pair.

The application of two-trace two-dimensional (2T2D) correlation analysis to a number of spectra consisting of more than a simple pair is explored, especially when such spectra are randomly collected without knowing the sampling order. Calculation and interpretation of 2T2D correlation spectra are briefly reviewed, and a systematic procedure to identify the set of characteristic bands, which are mutually asynchronous and least overlapped with each other, is described. 2T2D correlation is applied to individual spectra by selecting a representative reference spectrum, such as the average of the whole dataset.

Deprotonation from an OH on -Inositol Promoted by μ-Bridges with Possible Regioselectivity/Chiral Selectivity.

Single-crystal structures of -inositol complexes with erbium ([Er(CHO)(HO)Cl]Cl(HO), denoted ErI hereafter) and strontium (Sr(CHO)(HO)Cl, denoted SrI hereafter) are described. In ErI, deprotonation occurs on an OH of -inositol, although the complex is synthesized in an acidic solution, and the p values of all of the OHs in -inositol are larger than 12. The deprotonated OH is involved in a μ-bridge.

Estimating more than two pure component spectra from only two mixture spectra using two-dimensional correlation.

A procedure is described to estimate the pure component spectra of mixtures from only a pair of available spectra even when there are more than two component species present in the system. In contrast, traditional multivariate curve resolution (MCR) technique cannot be used for such a case. The method relies on the use of two-trace two-dimensional (2T2D) correlation spectroscopy.

Random swapping, an effective and efficient way to boost the intensities of cross peaks in a 2D asynchronous spectrum.

Analysis of mixture via chromatographic-spectroscopic and analogous experiments is a common task in analytical chemistry. A 2D/nD asynchronous spectrum is effective in retrieving spectra of pure substances even if different components cannot be separated. However, noise in the 2D/nD asynchronous spectrum becomes a bottleneck in the analysis.