Terahertz Spectral Investigation of L-Cysteine Hydrochloride and its Monohydrate

An Interview with AI About Its Potential Role in Vibrational and Atomic Spectroscopy

Spectrophotometric Determination of Thiosulfate in Desulfurization Solutions 

Visible-NIR Spectral Characteristics Analysis Using Hyperspectral Data

Advancing Wetland Classification

In an effort to combat the deceptive practice of selling aged Ningxia wolfberry as fresh produce, researchers at Hunan University in Changsha, PR China, have developed a novel method for rapidly identifying the storage year of this valuable fruit. Their study, published in 

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

, introduces the combination of front-face excitation-emission matrix (FF-EEM) fluorescence spectroscopy and interpretable deep learning as a powerful tool for this purpose (1).

Fructus lychii goji wolfberry | Image Credit: © Le Do - stock.adobe.com

 is a technique that involves illuminating a sample with various wavelengths of light and measuring the corresponding emitted fluorescence. It provides a comprehensive spectral fingerprint of the sample, capturing its unique fluorescence characteristics. By analyzing the excitation and emission spectra using deep learning, valuable chemical information about the sample can be extracted. Deep learning is a branch of machine learning that uses artificial neural networks to learn and make predictions from complex data.

Ningxia wolfberry, known for its antioxidant properties and health benefits, fetches premium prices in the market. However, unscrupulous traders may attempt to pass off old wolfberries as freshly harvested ones, leading to potential consumer deception and financial losses. The proposed method aims to address this challenge by providing a lossless, fast, and accurate means of determining the storage year of Ningxia wolfberry.

The researchers employed the alternating trilinear decomposition (ATLD) algorithm to extract chemically significant information from the three-way data array obtained from Ningxia wolfberry samples. This preprocessing step allowed for the isolation of key features related to the storage years of the fruit. Furthermore, the team introduced a convolutional neural network (CNN) model called EEMnet, specifically designed for the identification of storage years. EEMnet leverages the subtle spectral differences among wolfberry samples to achieve robust classification.

Remarkably, the EEMnet model exhibited a correct classification rate exceeding 98% for the training set, test set, and prediction set, showcasing its effectiveness in distinguishing wolfberry samples of different storage years. To enhance transparency and interpretability, the researchers conducted a series of analyses to unravel the inner workings of the deep learning model, offering insights into the decision-making process.

The results of this study demonstrate that the combined approach of FF-EEM fluorescence spectroscopy and EEMnet holds great potential for rapid and accurate identification of the storage year of Ningxia wolfberry. By providing a green and reliable solution, this method offers a valuable contribution to the identification of storage years for Chinese medicinal materials.

As the demand for high-quality agricultural products continues to rise, the development of innovative techniques like FF-EEM fluorescence spectroscopy coupled with interpretable deep learning paves the way for improved food authentication, ensuring consumer confidence and safeguarding the integrity of the market. The findings from this research could potentially be applied to other valuable food products, enabling reliable traceability and quality control across various industries.

(1) Yan, X.-Q.; Wu, H.-L.; Wang, B.; Wang, T.; Chen, Y.; Chen, A.-Q.; Huang, K.; Chang, Y.-Y.; Yang, J.; Yu, R.-Q. Front-face excitation-emission matrix fluorescence spectroscopy combined with interpretable deep learning for the rapid identification of the storage year of Ningxia wolfberry. 

Spectrochimica Acta Part A: Mol. Biomol. Spectrosc.

Articles

Researchers have developed a rapid and accurate method combining front-face excitation-emission matrix fluorescence spectroscopy and interpretable deep learning to identify the storage year of Ningxia wolfberry, offering a green solution to combat fraudulent practices in the market.

Front-face Excitation-Emission Matrix Fluorescence Spectroscopy and Interpretable Deep Learning Unveil Storage Years of Ningxia Wolfberry

Researchers from Dalian Polytechnic University in China have designed and synthesized a new fluorescent probe that can selectively detect aluminum ions (Al

). The probe, called (E)-((2,4-dihydroxybenzyl)diazenyl)(pyridin-2-yl)methanone (HL), was studied using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to understand its excited state dynamics mechanism.

Atom icon isolated on transparent background. Fusion orbit spin. Neon light atomic neutron. Atom blue color. Nuclear atom. 3d cell nucleus. Molecule fusion. Proton core symbol. Ion element. Vector | Image Credit: © Omeris - stock.adobe.com

, provides a better understanding of the excited state dynamics mechanism of HL and may lead to the development of more effective fluorescent probes for detecting metal ions (1).

DFT and TD-DFT are widely used computational tools to understand the excited state dynamics mechanisms of molecules. DFT is used to calculate the potential energy surfaces (PESs) of molecules and determine the probability of various excited state pathways. TD-DFT is used to calculate the electronic transitions and predict the spectral properties of molecules. These techniques can provide valuable insights into the electronic structure and excited state dynamics of molecules, which are crucial for designing new materials with desired optical properties. In this specific study, DFT and TD-DFT were used to explain the fluorescence quenching and enhancement behaviors of a fluorescent probe designed to detect Al

The researchers found that the excited-state intramolecular proton transfer (ESIPT) process hardly occurs because of high reaction barriers, which means that the fluorescence quenching behavior of HL is not based on ESIPT. Instead, an electron on C=N in HL can be transferred to the fluorophore during excitation, accompanied by the photo-induced electron transfer (PET) process. The excited state can then undergo a twisted intramolecular charge transfer (TICT) process, which releases non-radiative decay.

The ESIPT process is a mechanism where the excited-state proton is transferred from a donor group to an acceptor group within the same molecule. In contrast, the photo-induced electron transfer (PET) process involves the transfer of an electron from a donor to an acceptor molecule upon photoexcitation. The twisted intramolecular charge transfer (TICT) process refers to the excited-state phenomenon in which a molecule undergoes a geometrical distortion that facilitates the transfer of charge from one end to another through a twisted intramolecular pathway. In the case of HL, the PET process occurred in the absence of Al

, accompanied by an electron transfer from C=N to the fluorophore. The excited state of HL could undergo a TICT process, releasing non-radiative decay. After binding to Al

, the PET process no longer occurred, and the TICT process was eliminated, resulting in a significant fluorescence enhancement.

, the PET process no longer occurs, and the TICT process is eliminated, resulting in a significant enhancement in fluorescence. The researchers' calculation results explain the quenching and enhancement behaviors of fluorescence before and after the reaction with Al

The new probe is not only effective but also selective in detecting Al

. This is important as aluminum is widely used in industries such as construction, transportation, and packaging, and overexposure to aluminum can have negative effects on human health.

(1) Li, W.; Liu, X.; Wang, Y.; Wang, Y.; Hou, Y.; Tian, J.; Fei, X. Investigation on Non-radioactive Behavior of an Acylhydrazone-based Fluorescent Probe: Coexistence of PET and TICT Mechanisms. 

Spectrochimica Acta Part A: Mol. Biomol. Spectrosc. 

A new fluorescent probe designed and synthesized by researchers can effectively and selectively detect Al3+ ions through the coexistence of photo-induced electron transfer (PET) and twisted intramolecular charge transfer (TICT) mechanisms.

New Fluorescent Probe Developed for Detecting Aluminum (Al3+) Ions

Researchers at Universidade Federal do Maranhão in São Luís, Brazil, have conducted an 

 high-temperature Raman scattering study of monoclinic silver dimolybdate (m-Ag

) microrods. The study, published in the 

 journal, explored the temperature-dependent behavior of the m-Ag

 microrods and found an irreversible first-order structural phase transition at 698 K–723 K and a melting process at 773 K (1).

blue geometric shape abstract technology background | Image Credit: © monsitj - stock.adobe.com

 microrods by using the conventional hydrothermal method at 423 K for 24 h. Then, they conducted structural and morphological characterization of the sample using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The Raman scattering measurements were performed on m-Ag

 microrods to determine the phase transition, and doing so revealed changes in the Raman spectra, confirming the transition from the P21/c monoclinic structure to the P-1 triclinic structure.

) microrods have potential applications in various fields, such as catalysis, electrochemistry, and gas sensing. The study of their structural and morphological properties, as well as their temperature-dependent behavior, is important for understanding their potential applications and for developing new ones. The 

 high-temperature Raman scattering study of m-Ag

 microrods presented in the article provides valuable insights into their phase transition behavior and melting process, which can inform future research on this subject.

Interestingly, no morphological changes were observed during the structural phase transition of the sample at 723 K. However, time-dependent optical microscopy at 773 K showed the growth of nanowires on the Ag

 microrods in the triclinic structure. This study provides significant insights into the temperature-dependent behavior of m-Ag

 microrods and their potential use in high-temperature applications.

This paper, with lead author J.V.B. Moura, indicated that Raman spectra provide important insights into the high-temperature phase transition behavior of m-Ag

 microrods, which is essential for their practical applications in various fields. This study could lead to further research on the phase transition behavior of other materials and could potentially open up new avenues for their use in high-temperature applications.

Overall, this study highlights the importance of understanding the temperature-dependent behavior of materials and their potential for practical applications. The findings of this study could have significant implications in various fields, such as materials science, chemistry, and physics.

(1) Ferreira, A. N. C.; Ferreira, W. C.; Duarte, A. V.; Santos, C. C.; Freire, P. T. C.; Luz-Lima, C.; Moura, J. V. B. In situ high‐temperature Raman scattering study of monoclinic Ag

An in situ high-temperature Raman scattering study of monoclinic m-Ag2Mo2O7 microrods reveals an irreversible first-order structural phase transition and melting process, according to new research.

Researchers Use Raman Spectroscopy to Study Phase Transition of Monoclinic Silver Dimolybdate Microrods at High Temperatures

Scientists at Texas Christian University in Fort Worth have discovered a new form of phosphorescence in 2-aminopyridine (2APi) using direct triplet state excitation. The team was able to observe room temperature phosphorescence in 2APi embedded in poly (vinyl alcohol) (PVA) films. The findings were published in

 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Full spectrum rainbow with reflection | Image Credit: © bdavid32 - stock.adobe.com

By using UV excitation at 305 nm, they were able to detect a broad phosphorescence spectrum with a maximum of around 500 nm. Additionally, they found that the anisotropy of the phosphorescence was high and positive when using blue excitation, as opposed to the low and negative values seen with UV excitation.

The team also found that the phosphorescence emissions were strongly temperature dependent, with both UV and blue excitations exhibiting similar lifetimes at a fraction of a millisecond. The phosphorescence excitation spectrum differed from the absorption spectrum in the long-wavelength region, showing a band at about 400–450 nm. The researchers hope that this new discovery could have potential applications in materials science, such as in the development of new organic light-emitting diodes (OLEDs) and other optoelectronic devices.

The observation of room temperature phosphorescence in 2-aminopyridine (2APi) embedded in poly (vinyl alcohol) (PVA) films is important because it can help in understanding the excited state dynamics and relaxation pathways of molecules. Room temperature phosphorescence is a rare phenomenon and the ability to observe it can provide new insights into the properties of organic materials.

The use of polymeric materials such as PVA provides a convenient and cost-effective means for studying phosphorescence, with potential applications in sensors and optoelectronic devices. Additionally, the ability to control the phosphorescence emission through temperature variation can offer a means for temperature sensing in various fields. Overall, the observation of room temperature phosphorescence in 2APi-PVA films can open up new avenues for research and potential applications in various fields.

(1) Chavez, J.; Ceresa, L.; Kitchner, E.; Pham, D.; Gryczynski, Z.; Gryczynski, I. Room Temperature Phosphorescence of 2-aminopyridine with Direct Triplet State Excitation. 

A recent study has reported the observation of room temperature phosphorescence in 2-aminopyridine (2APi) embedded in poly (vinyl alcohol) (PVA) films with direct triplet state excitation, which could have implications for future technological applications.

Researchers Discover Room Temperature Phosphorescence in 2-Aminopyridine with Direct Triplet State Excitation

Scientists from Indiana University in Bloomington, Indiana, USA and University of Lucknow in Lucknow, India, investigated the structural changes of a discotic liquid crystal during its phase transitions. The study, published in 

, focuses on 4-((2, 3, 4-tris (octyloxy) phenyl) diazenyl) benzoic acid, referred to as DLC A8, which exists in a dimeric form (1).

Abstract liquid colorful textured pattern background | Image Credit: © photopsist - stock.adobe.com

The team used a combination of quantum chemical approaches and vibrational spectroscopy to analyze the structural alteration of DLC A8 during phase transition. The phase transitions of DLC A8 are Iso → Discotic nematic → Columnar → Crystalline, which were investigated using differential scanning calorimetry (DSC) accompanied by polarized optical microscopy (POM). The researchers observed a monotropic columnar mesophase during the cooling cycle while discotic nematic mesophase was observed in both the heating and cooling cycles.

DSC and POM are two techniques used for studying chemical structures. DSC measures the heat flow associated with a physical or chemical change in a material as a function of temperature or time. When used properly, this technique helps determine the phase transition temperature of a material, such as the melting point or glass transition temperature. POM is a nondestructive technique that uses polarized light to observe the optical properties of materials. It can provide information about the crystallographic orientation, birefringence, and morphology of a material, as well as the presence of defects or impurities. Together, DSC and POM can provide a comprehensive understanding of the structural changes that occur during phase transitions in materials.

Density functional theory (DFT) along with infrared (IR) and Raman spectroscopic techniques were used to study the dynamics of molecules during phase transition. To predict the most stable conformation of the molecule, one-dimensional potential energy surface scans were performed along 31 flexible bonds using the DFT/B3LYP/6-311G++(d,p) method. Vibrational normal modes were analyzed in detail, taking potential energy contribution into account. The spectral analysis of FT-IR and FT-Raman was done by deconvoluting the structural sensitive bands.

DFT is a quantum mechanical method used to study the electronic structure and energetics of materials. It can be used to predict the most stable conformation of a molecule during a phase transition. IR and Raman spectroscopic techniques are used to measure the vibrational modes of molecules. These modes are sensitive to changes in molecular structure and can provide information about the molecular dynamics during a phase transition. The spectral analysis of IR and Raman spectroscopy can be used to identify the characteristic vibrational bands associated with different functional groups in a molecule. By comparing the experimental spectra with the theoretically predicted spectra using DFT, the structural changes during phase transitions can be identified.

The study revealed that intact intermolecular hydrogen bonding of dimers exists throughout the phase transitions. The agreement between the calculated IR and Raman spectra and the observed FT-IR and Raman spectra at room temperature confirmed the team's theoretically predicted molecular model of investigated discotic liquid crystal.

According to the authors, their findings could provide important insights into the properties and potential applications of discotic liquid crystals, which have a range of technological applications, including in electronic devices and sensors (1).

This research highlights the importance of understanding the structural changes of materials during phase transitions and demonstrates the value of a multidisciplinary approach in investigating complex materials.

(1) Chaudhary, R.; Yadav, A.; Bahota, A. S.; Singh, S.; Fonseca, J. d. C.; Ayala, A. P.; Prasad, V.; Tandon, P.Monitoring Structural Fluctuations of Discotic Liquid Crystal During Phase Transitions. 

Scientists have investigated the structural changes of a discotic liquid crystal during its phase transitions using a combination of quantum chemical approaches and vibrational spectroscopy.

Study Reveals Structural Insights into Phase Transitions of Discotic Liquid Crystal

The Biomedical Raman Imaging 2023 conference (

) will be held in Atlanta, Georgia, later this year from June 25–27, 2023. The venue where this conference will take place is the Woodruff Health Sciences Administration Building (WHSCAB) at Emory University. The organizers of this conference are Marcus Cicerone of Georgia Institute of Technology, Katsumasa Fujita of Osaka University, Wei Min of Columbia University, and Duncan Graham of the University of Strathclyde.

Atlanta, Georgia, USA | Image Credit: © SeanPavonePhoto - stock.adobe.com

This three-day conference brings together scientists from all research fields with a shared interest in the biomedical space. Recently, there has been a convergence of advances when it comes to developing and implementing Raman-based technologies, as well as information processing. This conference intends to shine a light on these new technologies, focusing on how these technological advancements has expanded into the biology, medicine, and materials science fields. By bringing together scientists that are all involved in using Raman imaging and spectral analysis in their work, the hope is that the conference serves as a forum for strengthening the network among scientists who are interested in pushing the boundaries of biomedical applications of Raman microscopy.

On Sunday the 25th at 3:00 pm, there will be a round of keynote lectures that will go until 5:00 pm EST. This will be followed by a reception, exhibition, and poster session.

On Monday the 26th, three oral sessions will take place throughout the day. The first session, which will feature talks from the keynote and invited speakers, will take place from 9:30 am EST to 10:35 am EST. The second session will last from 10:55–12:15 pm EST. The third oral session will take place from 3:00–4:20 pm EST. An evening mixer will round out the day, starting at 6:00 pm EST and going until 8:00 pm EST.

On Tuesday the 27th, five oral sessions will take place throughout the day. The first session (titled Session 4 on the program) will start at 9:30 am and go to 10:35 am EST. The second session (Session 5) will take place from 10:55 am to 12:15 pm EST. The third session (Session 6) will go from 1:30 pm to 2:50 pm. The fourth session (Session 7) takes place starting at 3:10 pm and going until 4:20 pm. The final session will start at 4:45 pm and lead directly into the Closing Remarks, which will conclude the conference at 6:00 pm EST.

For more information about this conference, and to see the list of invited speakers, please click the link below: 

Biomedical Raman imaging is growing in the biomedical space, where technical advances and new information processing tools and techniques aim to propel the field into the future. An upcoming conference in Atlanta, Georgia, will explore these developments while bringing scientists in this field together.

Previewing the Biomedical Raman Imaging 2023 Conference

Researchers at the National Centre for Nuclear Research in Otwock-Swierk, Poland have published a paper in the journal 

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 

comparing two methods of Raman imaging analysis (1). The study focuses on zirconium oxide, a material used in the development of zirconium alloys for nuclear applications.

Astronomy concept backdrop | Image Credit: © Sergey Nivens - stock.adobe.com

Zirconium oxide plays a crucial role in the development of zirconium alloys for nuclear applications because of its properties such as corrosion resistance, thermal stability, and mechanical strength. Zirconium alloys are commonly used in nuclear fuel cladding and structural components of nuclear reactors due to their ability to withstand high temperatures and radiation exposure.

The paper describes how the researchers used both the built-in fitting function and K-means cluster analysis (KMC) followed by fitting in an external environment to evaluate data obtained from Raman imaging. The two methods were compared in terms of their principles, limitations, versatility, and process duration.

Built-in fitting function in Raman spectroscopy refers to the use of pre-defined mathematical models to fit Raman spectra to obtain the desired information such as peak positions, peak heights, and bandwidths. In contrast, K-means cluster analysis (KMC) is a statistical method that involves grouping Raman spectra into clusters based on their similarities without any prior assumptions. The main difference between these two approaches is that built-in fitting function relies on a priori knowledge of the system under study, whereas KMC is a data-driven approach that does not require any prior knowledge. Built-in fitting function is suitable for simple spectra where the peaks are well-defined and distinct, while KMC is more appropriate for complex spectra where the peaks overlap.

The researchers found that Raman imaging is indispensable for determining phase distribution, calculating phase content, and analyzing stress in zirconium oxide. By comparing the results obtained from the two methods, the researchers were able to identify the advantages and limitations of each. They hope that this will help researchers to select the most appropriate evaluation method for different applications.

Zirconium oxide is an important material in the development of zirconium alloys for nuclear applications. The ability to accurately analyze the phase distribution and stress in zirconium oxide is crucial for the development of these alloys. Raman imaging is a powerful tool for this type of analysis, as it allows researchers to visualize the distribution of different phases and the stresses present in the material.

The researchers used zirconium oxide formed on different zirconium alloys under various oxidation conditions as an exemplary material for their analysis. By comparing the results obtained from the two methods, they were able to demonstrate the importance of Raman imaging in this type of analysis.

The researchers believe that their work will be useful for researchers working in the field of materials science, particularly those working on the development of zirconium alloys for nuclear applications. By identifying the advantages and limitations of different evaluation methods, the researchers hope to help others select the most appropriate method for their specific needs.

(1) Suchorab, K.; Gaweda, M.; Kurpaska, L. Comparison of Raman imaging assessment methods in phase determination and stress analysis of zirconium oxide layer. 

The article discusses a comparison of Raman imaging assessment methods for phase determination and stress analysis of zirconium oxide layers and their application in the development of zirconium alloys, especially for nuclear applications.

Raman Imaging Techniques Compared for Analysis of Zirconium Oxide Layer

 has investigated the interactions between benzeneacetamide and other molecules in various organic solvents (1). The researchers used infrared (IR) spectroscopy to obtain the frequencies of the carbonyl stretching vibration (ν(C=O)) of benzeneacetamide (N-phenylacetamide, C

The study found that solvent effects on the frequencies of the C=O stretching vibrations of benzeneacetamide were evident, with self-association of alkanol leading to an enhancement of the hydrogen bond strength and a red-shift of the ν(C=O) peak. The results also revealed that the ν(C=O) of benzeneacetamide is more sensitive to the acidity of the hydrogen bond donor in the solvent.

In addition to providing insights into the molecular interactions and microstructures in liquid mixtures, the study also correlated the frequencies of carbonyl stretching vibration with empirical parameters of the solvents, such as the acceptor number (AN), the van der Waals interaction parameters (SVW), and the linear solvation energy relationships (LSER). This correlation helped to estimate the contributions of intermolecular interactions.

Acceptor number (AN), van der Waals interaction parameters (SVW), and linear solvation energy relationships (LSER) are all empirical parameters used to study the interactions of molecules in solvents. AND is a measure of a solvent's ability to accept electron pairs from a solute molecule. SVW is a parameter that describes how strongly a solvent interacts with a solute molecule through van der Waals forces. LSER is a method used to quantify the contribution of various types of interactions to the solvation energy of a solute molecule in a solvent. In this study, these parameters were used to estimate the contributions of intermolecular interactions to the frequencies of carbonyl stretching vibrations of benzeneacetamide in different solvents. The results showed that the solvent effects on the frequencies of C=O stretching vibrations of benzeneacetamide were significant.

The findings of this study have significant implications for the pharmaceutical and chemical industries, where understanding the interactions between molecules in solution is crucial for developing new drugs and optimizing chemical processes. The study provides a comprehensive understanding of how different solvents affect the vibrational frequency of the C=O groups in benzeneacetamide, which can be used to inform solvent selection and optimize molecular interactions.

Overall, this study provides important insights into the behavior of benzeneacetamide in solution and has implications for a wide range of industries. Further studies can build upon these findings to gain a more thorough understanding of the complex molecular interactions that underpin chemical processes.

(1) Xu, L.; Zhang, F. FTIR study on the C = O interactions of benzeneacetamide in solution. 

A study investigated the interactions of benzeneacetamide with other molecules in organic solvents by obtaining frequencies of C=O groups in 18 solvents using infrared spectroscopy, and correlated empirical parameters with the frequencies to estimate their contributions in intermolecular interactions, finding that solvent effects on the frequencies of C=O stretching vibrations were significant.

FT-IR Study Reveals How C=O Stretching Vibrations in Benzeneacetamide Interact With Other Molecules in Solution

A team of scientists from the Nicolaus Copernicus University in Poland and the Wroclaw University of Science and Technology in Poland have conducted a study on the potential applications of multiphoton absorbers. In their research, published in the journal 

, the team focused on the symmetry-relaxation effects in one- and two-photon absorption spectra in two bichromophore systems based on difluoroborate core linked by biphenylene or bianthracene moieties (1).

 are molecules that can absorb multiple photons of light simultaneously. They are used in various applications such as bioimaging, photodynamic therapy, and data storage. Compared to single-photon absorbers, multiphoton absorbers offer better resolution, deeper penetration, and less photodamage to biological tissues. They typically have large two-photon absorption cross sections, which means that they can be excited by two photons of lower energy instead of one photon of higher energy.

The team utilized a variety of experimental methods, including synthesis, one- and two-photon spectroscopy, and X-ray crystallography, along with computational methods to explore how symmetry relaxation, which occurs as a result of twisting building blocks, affects the one- and two-photon absorption of the two fluorescent dyes studied.

In this study, researchers examined the impact of symmetry relaxation on the absorption spectra of two fluorescent dyes, which are made up of difluoroborate core connected to biphenylene or bianthracene moieties. The study found that deviations from planarity, resulting from twisting of the building blocks, had a significant effect on the two-photon transition strengths. Specifically, the researchers discovered that the planarity of the central biphenyl moiety, as well as deviations from planarity up to 30-40 degrees, resulted in maximum values of two-photon transition strengths. On the other hand, the perpendicular arrangement of phenylene units in the biphenylene moiety resulted in a 20% reduction in the two-photon transition strengths. Overall, these findings suggest that the structure and geometry of bichromophore systems can play a crucial role in determining their optical properties.

Moreover, detailed studies of the equilibrium structures of both compounds in chloroform solution demonstrated that they have very different values of two-photon absorption cross sections at absorption band maxima. The biphenyl and bianthracene linkers exhibited two-photon absorption cross sections of 224 GM and 134 GM, respectively. The latter value was in good agreement with the experimental value obtained using the Z-scan method.

The difference in two-photon absorption cross section between both compounds can be explained based on equilibrium geometry differences, where the interplanar angle was found to be 35 deg and 91 deg in the case of the biphenylene and bianthracene moieties, respectively. The study suggests that it is not beneficial to introduce conformationally locked central linker based on bianthracene moiety.

Overall, the findings of this study shed light on the potential applications of bichromophores as multiphoton absorbers and highlight the importance of understanding the effects of symmetry relaxation on one- and two-photon absorption spectra.

(1) Petrusevich, E. F.; Glodek, M.; Antoniak, M. A.; Muziol, T.; Plazuk, D.; Siomra, A.; Nyk, M.; Osmialowski, B.; Zalesny, R.Difluoroborate-based bichromophores: Symmetry relaxation and two-photon absorption. 

The study investigated the effects of symmetry relaxation on one- and two-photon absorption spectra of two bichromophore systems based on difluoroborate core linked by biphenylene or bianthracene moieties, and found that deviations from planarity of building blocks ensure maximum values of two-photon transition strengths.

Scientists Study Bichromophores for Potential Applications in Multiphoton Absorbers

Researchers from Zhejiang University of Technology in Hangzhou have conducted a study to explore the binding characteristics of entrectinib (ENB), a tyrosine kinase inhibitor, with bovine serum albumin (BSA).

The study was conducted by multi-spectral analysis and theoretical calculations. 

 is a multi-target tyrosine kinase inhibitor that is mainly used for treating neurotrophic tyrosine receptor kinase gene fusion-positive solid tumors. The study found that ENB and BSA had moderate affinity and formed a complex with a stoichiometric ratio of 1:1 at 298 K. The binding constant was about 105/M, and Förster non-radiative energy transfer occurs. The researchers also found that hydrogen bond, van der Waals force, and hydrophobic force were the main factors affecting the stability of the ENB-BSA complex. The study was published in 

This experiment aims to study the binding mechanism of ENB and BSA through multi-spectral analysis (fluorescence, ultraviolet and circular dichroism spectroscopy), molecular docking, and molecular dynamics simulation. The goal is to understand the binding ability, quenching mechanism, conformational changes, and binding energy of the ENB-BSA complex. The results of this study could provide insight into the pharmacology and pharmacokinetics of ENB 

 and assist in developing new tyrosine kinase inhibitors. The use of multi-spectral analysis and molecular modeling techniques may lead to a better understanding of the binding mechanism of other drug-protein complexes.

Entrectinib (ENB) is a small molecule inhibitor that selectively targets the tropomyosin receptor kinases (TRK) A, B, and C, which are involved in cell growth and differentiation. ENB also targets the anaplastic lymphoma kinase (ALK), which plays a role in certain types of cancer. ENB has shown promising results in clinical trials for the treatment of a range of solid tumors, including lung, breast, and colorectal cancer.

The researchers found that ENB quenched the fluorescence of BSA through mixed quenching and was dominated by static quenching at low concentration. The study also showed that Co

 metal ions can enhance the binding effect, thus prolonging the half-life of ENB 

, which may improve the efficacy of ENB. However, Ca

 metal ions will reduce the efficacy of ENB.

Furthermore, molecular docking and site markers competition showed that ENB spontaneously bound to the Site III of BSA, causing changes in the spatial structure of BSA (α-helix decreased by 3.1%, random coil increased by 1.7%), and the microenvironment of tyrosine (Tyr) and tryptophan (Trp) residues. The study also revealed that the existence of metal ions affected the binding of ENB with BSA.

The study provides important insights into the binding characteristics of ENB with BSA, which is crucial for understanding the pharmacokinetics and pharmacodynamics of ENB. The findings of the study may help in improving the efficacy of ENB and enhancing its therapeutic potential for the treatment of neurotrophic tyrosine receptor kinase gene fusion-positive solid tumors.

(1) Jiang, S.-L.; Hu, L.; Hu, Z.-Y.; Wang, W.-J. Shi, J.-H. Exploring the binding characteristics of bovine serum albumin with tyrosine kinase inhibitor entrectinib: Multi-spectral analysis and theoretical calculation. 

A recent study explored the binding characteristics of the tyrosine kinase inhibitor entrectinib with bovine serum albumin through multi-spectral analysis and theoretical calculations, revealing the factors affecting the stability of the ENB-BSA complex and potential ways to enhance the efficacy of ENB.

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