Red-shifted Band Research Articles

Long-Term Stabilized and Highly Soluble Bezafibrate-Gliclazide Co-Amorphous Binary System.

Metabolic syndrome (MS) has a high prevalence, with an estimated one-quarter of the world population affected by this pathological condition. Among the diseases of this syndrome are dysregulation of lipids, hypertension, and insulin resistance. Unfortunately, available drugs in the market used for treating MS, as almost 75% of all drugs, are highly insoluble, presenting a significant demand for strategies to increase their solubility. Taking advantage of the fact that drugs in the amorphous state can provide a solubility enhancement, a new drug-drug co-amorphous (CoA) formulation to potentially simultaneously treat two or more MS conditions was explored, combining the co-formers Bezafibrate (BZT) a lipid-regulating drug, and Gliclazide (GZD) a hypoglycemic agent. A phase diagram was constructed to characterize the binary system's thermal properties, including glass transition temperatures of all compositions studied. The formulations were characterized by FTIR; redshifts of IR bands from 1547 to 1538cm-1 and 1717 to 1609cm-1 were observed due to the formation of intermolecular interactions, such as hydrogen bonds. The co-amorphous binary systems lead to an increase in the solubility of both BZT and GZD; specifically, for the composition xBZT = 0.5, the increase was 2.1× for BZT and 1.5 times for GZD while for xBZT = 0.7 an increase of 4× of BZT was achieved. The structural stability of the samples was verified by XRD and DSC, showing long-term stability retention of the amorphous state for more than eight years. The enhanced solubility and stability of the co-amorphous systems make them potential formulations for regulating lipids and lowering glycemia.

Understanding Anionic Hyperporphyrins: TDDFT Calculations on Peripherally Deprotonated meso-Tetrakis(4-hydroxyphenyl)porphyrin.

Presented herein is a DFT/TDDFT study of meso-tetrakis(4-hydroxyphenyl)porphyrin (H2[THPP]) and its O-deprotonated tetraanionic form; the latter was modeled as both a free tetraanion and with various counterions. Based on our calculations, the experimentally observed hyperporphyrin spectra are attributed to an admixture of phenol/phenoxide character into the a2u-type HOMO of tetraphenylporphyrin. The admixture results in an elevation of the orbital energy of the HOMO in relation to other frontier orbitals, which accounts for the observed spectral redshifts. The calculations underscore differences in the performance of different exchange-correlation functionals. Thus, while the popular hybrid functional B3LYP greatly exaggerates the redshift of the far-red hyperporphyrin band of O-deprotonated H2[THPP], the range-separated functional CAMY-B3LYP predicts a more moderate redshift. The latter, however, fails to reproduce experimentally observed absorptions in the 550-600 nm range, potentially underscoring the still imperfect modeling of anionic hyperporphyrins.

Band structure engineering, optical, transport, and photocatalytic properties of pristine and doped Nb3O7(OH): a systematic DFT study.

Nb3O2(OH) has emerged as a highly attractive photocatalyst based on its chemical stability, energetic band positions, and large active lattice sites. Compared to other various photocatalytic semiconductors, it can be synthesized easily. This study presents a systematic analysis of pristine and doped Nb3O7(OH) based on recent developments in related research. The current study summarizes the modeling approach and computationally used techniques for doped Nb3O7(OH) based photocatalysts, focusing on their structural properties, defects engineering, and band structure engineering. This study demonstrates that the Trans-Blaha modified Becke-Johnson approximation (TB-mBJ) is an effective approach for optoelectronic properties of pristine and Ta/Sb-doped Nb3O7(OH). The generalized gradient approximation is used for structure optimization of all systems studied. Spin-orbit (SO) coupling is also applied to deal with the Ta f orbital and Sb d orbital in the Ta/Sb-doped systems. Doping shifts the energetic band positions and relocates the Fermi level i.e. both the valence band maximum and the conduction band minimum are relocated, decreasing the band gap from 1.7 eV (pristine), to 1.266 eV (Ta-doped)/1.203 eV (Sb-doped). The band structures of pristine and doped systems reflect direct band behavior. Investigation of the partial density of states reveals that the O p orbital and Nb d/Ta d/Sb-d orbitals contributed to the valence and conduction bands, respectively. Optical properties like real and imaginary components of the dielectric function, reflectivity, and electron energy loss function are calculated using the OPTIC program implemented in the WIEN2k code. Moreover, doped systems shift the optical threshold to the visible region. Transport properties like effective mass and electrical conductivity are calculated, reflecting that the mobility of charge carriers increases with the doping of Ta/Sb atoms. The reduction in the band gap and red-shift in the optical properties of the Ta/Sb-doped Nb3O7(OH) to the visible region suggest their promising potential for photocatalytic activity and photoelectrochemical solar cells.

Isomer-Specific, Cryogenic Ion Vibrational Spectroscopy Investigation of D2- and N2-Tagged, Protonated Formic Acid Complexes Using Two-Color, IR-IR Photobleaching.

Here we analyze cryogenic ion vibrational spectra of tagged protonated formic acid (PFA) with electronic structure and anharmonic vibrational calculations to establish the isomers generated by electrospray ionization (ESI) followed by buffer gas cooling to ∼25 K. Two isomers are identified (the trans form (E,Z) and the cis form (E,E)) and generated in comparable abundance despite the fact that the calculated E,E structure lies 6.40 kJ mol-1 above the E,Z form. A large (∼60 kJ mol-1) barrier separates them such that the E,E form can be kinetically trapped upon cooling in the ion trap. The anticooperativity between the H-bonds of the OH groups is explored by measuring the shift in the D2-bound OH fundamental when a second D2 is attached. Both isomers are observed in the N2-tagged counterparts, displaying the expected red-shifted OH bands. These results indicate that ESI generates both isomers and both must be considered when analyzing cluster spectra based on the PFA core ion.

Temperature dependence of Ce luminescence characteristics in LaBr3: Ce crystal

Despite the large interest in the scintillation properties of LaBr3:Ce, a detailed understanding of the underlying mechanism of temperature-dependence properties of Ce luminescence remains elusive. This study introduces a self-designed spectral apparatus to explore these properties in LaBr3:5%Ce. We observed a redshift phenomenon and band changes in the emission peak bands, indicating a reduction of the bond length between Ce and the host with increasing temperature. Moreover, the probability of low-energy peak emission decreases and the probability of high-energy peak emission increases, with increasing temperature was observed, suggesting a correlation with the proximity of Ce's 4f energy level to the valence band. Utilizing intensity parameters from the spectra, we identified the impact of temperature on LaBr3:Ce's self-absorption effect, revealing a significant self-absorption effect at the high-energy peak for the first time. A simple self-absorption model indicated that, despite high quantum efficiency of Ce, the overall self-absorption is minimal, establishing a correlation between the self-absorption coefficient of the high-energy peak and overall absorption. This research offers insights for developing radiation-resistant high-temperature luminescent devices and advances the field of high-temperature luminescent materials.

Tuneable Red and Blue Emission of Bi3+-Co-Doped SrF2:Eu3+ Nanophosphors for LEDs in Agricultural Applications.

Tunable blue/red dual-emitting Eu3+-doped, Bi3+-sensitized SrF2 phosphors were synthesized utilizing a solvothermal-microwave method. All phosphors have cubic structure (Fm-3m (225) space group) and well-distinct sphere-like particles with a size of ~20 nm, as examined by X-ray diffraction and transmission electron microscopy. The diffuse reflectance spectra reveal a redshift of the absorption band in the UV region as the Bi3+ concentration in SrF2: Eu3+ phosphor increases. Under the 265 nm excitation, photoluminescence spectra show emission at around 400 nm from the host matrix and characteristic orange 5D0 → 7F1,2 and deep red 5D0 → 7F4 Eu3+ emissions. The red emission intensity increases with an increase in Bi3+ concentration up to 20 mol%, after which it decreases. The integrated intensity of Eu3+ red emission in the representative 20 mol% Bi3+ co-doped SrF2:10 mol% Eu3+ shows twice as bright emission compared to the Bi3+-free sample. To demonstrate the potential application in LEDs for artificial light-based plant factories, the powder with the highest emission intensity, SrF2: 10Eu, 20 Bi, was mixed with a ceramic binder and placed on top of a 275 nm UVC LED chip, showing pinkish violet light corresponding to blue (409 nm) and red (592, 614, and 700 nm) phosphors' emission.

Dy3+-doped niobate phosphor based on charge transfer band red-shift effect: Luminescence thermal stability and temperature sensing performance

The thermal quenching behavior seriously limits the application prospect of phosphors, so it is urgent to improve the thermal quenching behavior of phosphors. It is expected that the red-shift of charge transfer band (CTB) caused by temperature can be used to improve the luminescent stability of phosphor. Therefore, we designed a family of LuNbO4:x%Dy3 (x = 0.25, 1, 2, 5) phosphors based on the characteristic of the red-shift of CTB edge, and investigated the relationship between the red-shift of the CTB edge and the luminescence thermal stability of the phosphor, further broadening the application of this phosphor in temperature sensing. The effects of three different excitation positions, CTB (260 nm), CTB edge red-shift (288 nm) and Dy3+ 4f-4f transition (354 nm), on the luminescence thermal stability of phosphors were also investigated. It was found that only excitation in the red-shift range of CTB edge showed complete antithermal quenching behavior. The LuNbO4:2 %Dy3+ phosphor showed complete antithermal quenching under the excitation of CTB edge, and the comprehensive emission intensity at 573 K is 741 % of that at 298 K. According to the above characteristics, a dual-mode optical thermometry based on fluorescence intensity ratio (FIR) and International Commission on Illumination (CIE) chromaticity coordinates is proposed, in which the maximum relative temperature sensitivity of LuNbO4:x%Dy3+ is 5.04 % K−1 (298 K, FIR) and 3.14 % K−1 (573 K, CIE). Interestingly, when constructing CIE temperature measurement model, we found that LuNbO4:0.25 %Dy3+ phosphor at 260 nm excitation position has obvious color change at each temperature stage, showing temperature visualization characteristics. At 354 nm excitation position, it shows constant white light emission. The excellent optical temperature measurement performance and temperature visualization characteristics of the phosphor shows that it has excellent application potential in optical sensing.

Synthesis and Properties of Dibenzo-Fused Naphtho[2,3-b:6,7-b']disilole and Naphtho[2,3-b:6,7-b']diphosphole.

Silole- and phosphole-containing polycyclic aromatic compounds have attracted significant attention in the field of organic functional materials. The structure of the aromatic units has great impact on the photophysical properties of the resulting silole- and phosphole-containing polycyclic aromatic compounds. Here, dibenzo-fused naphtho[2,3-b:6,7-b']disilole (NDS) and naphtho[2,3-b:6,7-b']diphosphole (NDP), where a naphthalene unit is arranged between two silole and phosphole units, respectively, were designed and synthesized. The solid-state structures of them were confirmed by X-ray crystallographic analysis. The photophysical properties were evaluated by UV-vis absorption and photoluminescence spectroscopies and compared with those of their related compounds, such as dibenzo-fused silolo[3,2-b]silole and benzo[1,2-b:4,5-b']disilole, ever reported. The longest wavelength absorption band of a series of silole-fused compounds was found to be red-shifted in the order benzo[1,2-b:4,5-b']disilole < NDS < silolo[3,2-b]silole derivatives. For a series of phosphole-fused compounds, π-extension from phospholo[3,2-b]phosphole to NDP derivatives induces the lower absorption coefficient of the longest wavelength absorption band and the red-shift of the second longest wavelength absorption band. Both NDS and NDP exhibit much lower fluorescence quantum yields than their related compounds.

Spectral modulation of B850 bacteriochlorophyll a in light-harvesting complex 2 from purple photosynthetic bacterium Thermochromatium tepidum by detergents and calcium ions

Spectral variations of light-harvesting (LH) proteins of purple photosynthetic bacteria provide insight into the molecular mechanisms underlying spectral tuning of circular bacteriochlorophyll (BChl) arrays, which play crucial roles in photoenergy conversion in these organisms. Here we investigate spectral changes of the Qy band of B850 BChl a in LH2 protein from purple sulfur bacterium Thermochromatium tepidum (tepidum-LH2) by detergents and Ca2+. The tepidum-LH2 solubilized with lauryl dimethylamine N-oxide and n-octyl-β-D-glucoside (LH2LDAO and LH2OG, respectively) exhibited blue-shift of the B850 Qy band with hypochromism compared with the tepidum-LH2 solubilized with n-dodecyl-β-D-maltoside (LH2DDM), resulting in the LH3-like spectral features. Resonance Raman spectroscopy indicated that this blue-shift was ascribable to the loss of hydrogen-bonding between the C3-acetyl group in B850 BChl a and the LH2 polypeptides. Ca2+ produced red-shift of the B850 Qy band in LH2LDAO by forming hydrogen-bond for the C3-acetyl group in B850 BChl a, probably due to a change in the microenvironmental structure around B850. Ca2+-induced red-shift was also observed in LH2OG although the B850 acetyl group is still free from hydrogen-bonding. Therefore, the Ca2+-induced B850 red-shift in LH2OG would originate from an electrostatic effect of Ca2+. The current results suggest that the B850 Qy band in tepidum-LH2 is primarily tuned by two mechanisms, namely the hydrogen-bonding of the B850 acetyl group and the electrostatic effect.

Regulating the redshift of the charge transfer band edge and antithermal quenching by ion substitution strategy in YP1-xVxO4:Eu3+ phosphor

The redshift of the charge transfer band (CTB) edge of phosphor induced by temperature rise is pervasively accompanied by antithermal quenching. Accordingly, exploring the mechanism of the CTB redshift is thus not only propitious for optimizing the sensitivity of optical thermometry but also tenders a new idea for the design of antithermal quenching phosphors. Herein, a family of YP1-xVxO4:Eu3+ phosphors were designed via the V5+/P5+ ion substitution strategy. With the increase of the V5+ ratio, the relative integral intensity of the 5D0→7F2 transition multiplies from 1.25 to 28.67 times under CTB edge excitation. Moreover, by Gaussian fitting, the reduction degree of vanadate band gap energy 1E (1T1)→1B2 (1T2), 1A2 (1T1)→1B2 (1T2) increased from 0.122 eV and 0.065 eV to0.162 eV and 0.083 eV, respectively, in the range of 303–523 K. Both reveal an enhance in redshift of the excitation spectra. The decrease of charge transfer state (CTS) energy level and the alteration of photoelectron thermal population are two mechanisms that induce CTB redshift. Specifically, the decrease of the CTS level is dominant in the YPO4:Eu3+ sample, and the thermal population of the higher vibrational levels of the VO43−ground state is dominant in the presence of a tiny amount of V5+ doping. In addition, according to the experimental phenomenon, a dual-mode temperature sensing scheme based on excitation intensity ratio (EIR) and single band ratiometric (SBR) is proposed. Y0.9P0.1V0.9O4:0.1Eu3+ achieves a maximum sensitivity of Sr-max = 4.040 % K−1 and a minimum temperature determination uncertainty of δT = 0.124 K at 323 K, which excellent performance indicates that this is a promising non-contact optical thermometer.

Enhanced Quantum Efficiency of Near-IR Perovskite Light Emitting Diodes Via Dual Interfacial Modification

Near-infrared (NIR) light-emitting diodes play a crucial role in a wide range of applications, including sensors, night vision displays, security systems, medicine, spectroscopy, and military applications. The potential for high-performance NIR perovskite light-emitting diodes (NIR-PeLEDs) has been highlighted with the impressive advancement of fluorescent perovskite thin films. These PeLEDs exhibit promising features such as a tunable band gap, high color purity, and low non-radiative recombination rates. Despite these advantages, the current state-of-the-art NIR-PeLEDs faces challenges primarily related to poor film quality and increased defect states, leading to limitations in external quantum efficiency (EQE) and operational stability. In addressing these issues, we present a novel dual interfacial modification approach involving the incorporation of fluorinated phenethylammonium iodide (F-PEAI), a bulky organic cation, at both the bottom and top interfaces of perovskite emitting films. The modified interfaces result in perovskite films with a smoother surface morphology, complete coverage, and high crystallinity, leading to a red-shifted fluorescence band extending toward 800 nm. Furthermore, the introduction of F-PEAI facilitates the formation of compact and fine grains in perovskite films, contributing to an enhanced photoluminescence quantum yield (PLQY). Consequently, NIR-PeLEDs modified with F-PEAI demonstrate improved EQE values coupled with enhanced operational stability. The combination of electrical, optical, and physical analyses of both films and devices underscores the effectiveness of the dual interface modification in developing efficient NIR perovskite LEDs suitable for practical applications.

How Polyoxometalate Promote the Aggregation of a Cyanine Dye in the Aqueous Solution of Non-Ionic Copolymers of Varying Hydrophilic-Lipophilic Balance?

The nonradiative pathway leading to the photoisomerization of a cyanine dye is well-established information. However, the modulations induced in the photoisomerization pathway by a Keggin-type polyoxometalate in a confined media is new. Our study reveals that, in the presence of pluronic block copolymers F-108 and P-123, phosphomolybdic acid hydrate (PMA) promotes the aggregation of 3,3'-diethylthiadicarbocyanine iodide (DTDCI). The absorption spectra show a clear indication of a red-shifted trimer band in F-108 and P-123, whereas it is absent in F-127 and P-84. Fluorescence emission studies suggest that, in the presence of PMA, the rate of photoisomerization is accelerated in F-108, P-123, and P-84 micelles, whereas it is retarded in F-127 micelles. Time-resolved studies in the presence of PMA indicate the preference of F-108, P-84, and P-123 toward the trapped conformer of DTDCI, whereas F-127 favors the formation of photoisomer of DTDCI. Our findings imply the importance of the interplay between the hydrophobic and electrostatic interactions between the DTDCI cations and the PMA anions in nonionic micelles of varying hydrophilic-lipophilic balance (HLB). Dynamic light scattering (DLS) data suggest a modulation by PMA in the intermicellar electrostatic repulsions of a hydrophilic copolymer micelle, whereas its unaffected in a hydrophobic copolymeric micelle.

Exploring the structural, photophysical, and electrical properties of Dopant-Free hole transporting material based on 2, 7-carbazole from experimental to simulation

This paper presents the development of a dopant-free HTM as a thin film, utilizing carbazole (2,7) as a central building block. The deposition of homogeneous thin films of HTM2 was successfully achieved through Physical Vapor Deposition. The morphological, optical, and electrical properties of the fabricated samples were extensively studied using techniques such as Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), UV–visible spectroscopy, and Photoluminescence Technique. The AFM and SEM analyses demonstrated the uniformity and flatness of the thin film surfaces. The UV spectra results indicated that the maximum absorption spectra did not exhibit significant shifts when measured in chlorobenzene solvent, with an estimated band gap of approximately 2.96 eV. Photoluminescence spectroscopy and decay time measurements were conducted on HTM2 thin films, which revealed emission in the green-yellow region. The photoluminescence spectra of the thin films exhibited red-shifted emission bands compared to the solution, attributable to stronger π-π intermolecular interactions resulting in the closeness of the molecules in the solid state. This work finally couples the theoretical and experimental results to validate our obtained results and to get an idea about the efficiency of the cell-based HTM2. The obtained results confirmed that the investigated material can find applications in perovskite solar cells.

Antibacterial and cytotoxicity studies of pyrrolo-based organic scaffolds and their binding interaction with bovine serum albumin.

Two pyrrolo-based compounds, 1H-pyrrolo[3,2-b]pyridine-3-carboxylic acid (L1) and 1H-pyrrolo[3,2-c]pyridine-4-carboxylic acid (L2), were employed for the detection of bovine serum albumin (BSA) by UV-Vis and fluorescence spectroscopic methods in phosphate buffer solution (pH = 7). In the presence of L1 and L2, the fluorescence emission of BSA at 340 nm was quenched and concomitantly a red-shifted emission band appeared at 420 nm (L1)/450 nm (L2). The fluorescence spectral changes indicate the protein-ligand complex formation between BSA and L1/L2. An isothermal titration calorimetry (ITC) experiment was conducted to determine the binding ability between BSA and L1/L2. The binding constants are found to be 4.45 ± 0.22 × 104 M-1 for L1 and 2.29 ± 0.11 × 104 M-1 for L2, respectively. The thermodynamic parameters were calculated from ITC measurements (i.e. ∆rH = -40 ± 2 kcal/mol, ∆rG = -4.57 ± 0.22 kcal/mol and -T∆rS = 35.4 ± 1.77 kcal/mol), which indicated that the protein-ligand complex formation between L1/L2 with BSA is mainly due to the electrostatic interactions. The protein-ligand interactions were studied by performing molecular docking. Further, the antibacterial assay of L1 and L2 was conducted against gram-positive and gram-negative bacterial strains in an effort to address the difficulties caused by the co-occurrence of antimicrobial and multidrug-resistant bacteria. E. coli and S. aureus were significantly inhibited by L1 and L2. The L1 exhibits 13, 12 and 15 mm, whereas L2 exhibits a 2, 3 and 5 mm zone of inhibition against S. aureus, S. pyogenesand E. coli, respectively. In silico molecular docking of L1 and L2 was performed with bacterial DNA gyrase to establish the intermolecular interactions. Finally, the in vitro cytotoxicity activities of the ligands L1 and L2 have been carried out using drosophila.

A novel optical thermometry strategy: Based on the combined effects of red-shift charge transfer band and thermal coupling

The non-contact temperature measurement method based on the fluorescence intensity ratio of thermally coupled energy levels has emerged as a focal point of research in recent years due to its characteristics of short response time, suitability for extreme environments, and high sensitivity. The enhancement of relative sensitivity (Sr) is a key objective in refining ratio-metric optical thermometry. However, the Sr is limited by the thermometry strategies. Regarding excitation and monitoring methods, ratio-metric temperature measurement strategies typically adopt two distinct approaches: single-excitation dual-emission (S-D), and dual-excitation single-emission (D-S). In this study, we developed a dual-excitation dual-emission (D-D) thermometry strategy that theoretically and experimentally demonstrates higher Sr and reduced temperature uncertainty (δT). This advancement was achieved by analyzing thermal coupling energy levels (TCELs) and the red-shift charge transfer band (CTB) properties. YVO4:Er3+ was selected for experimental validation due to its pronounced thermal coupling and red-shift CTB effects. The experimental results show that the Sr(D-D) equal to the sum of Sr(S-D) and Sr(D-S), and 1/δT(D-D) equal to the sum of 1/δT(S-D) and 1/δT(D-S), which well verifies the theoretical expectations. Thus, the D-D strategy emerges as a novel and effective method for ratio-metric thermometry, promising enhanced precision in temperature measurements.

Structure and Chemical Reactivity of Y-Stabilized ZrO2 Surfaces: Importance for the Water-Gas Shift Reaction.

The surface structure and chemical properties of Y-stabilized zirconia (YSZ) have been subjects of intense debate over the past three decades. However, a thorough understanding of chemical processes occurring at YSZ powders faces significant challenges due to the absence of reliable reference data acquired for well-controlled model systems. Here, we present results from polarization-resolved infrared reflection absorption spectroscopy (IRRAS) obtained for differently oriented, Y-doped ZrO2 single-crystal surfaces after exposure to CO and D2O. The IRRAS data reveal that the polar YSZ(100) surface undergoes reconstruction, characterized by an unusual, red-shifted CO band at 2132 cm-1. Density functional theory calculations allowed to relate this unexpected observation to under-coordinated Zr4+ cations in the vicinity of doping-induced O vacancies. This reconstruction leads to a strongly increased chemical reactivity and water spontaneously dissociates on YSZ(100). The latter, which is an important requirement for catalysing the water-gas-shift (WGS) reaction, is absent for YSZ(111), where only associative adsorption was observed. Together with a novel analysis Scheme these reference data allowed for an operando characterisation of YSZ powders using DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy). These findings facilitate rational design and tuning of YSZ-based powder materials for catalytic applications, in particular CO oxidation and the WGS reaction.

Tunable Near-Infrared Transparent Bands Based on Cascaded Fabry–Perot Cavities Containing Phase Change Materials

In this paper, we construct a near-infrared Fabry–Perot cavity composed of two sodium (Na) layers and an antimony trisulfide (Sb2S3) layer. By cascading two Fabry–Perot cavities, the transmittance peak splits into two transmittance peaks due to the coupling between two Fabry–Perot modes. We utilize a coupled oscillator model to describe the mode coupling and obtain a Rabi splitting of 60.0 meV. By cascading four Fabry–Perot cavities, the transmittance peak splits into four transmittance peaks, leading to a near-infrared transparent band. The near-infrared transparent band can be flexibly tuned by the crystalline fraction of the Sb2S3 layers. In addition, the effects of the layer thickness and incident angle on the near-infrared transparent band and the mode coupling are investigated. As the thickness of the Na layer increases, the coupling strength between the Fabry–Perot modes becomes weaker, leading to a narrower transparent band. As the thickness of the Sb2S3 layer increases, the round-trip propagating of the Sb2S3 layer increases, leading to the redshift of the transparent band. As the incident angle increases, the round-trip propagating of the Sb2S3 layer decreases, leading to the blueshift of the transparent band. This work not only provides a viable route to achieving tunable near-infrared transparent bands, but also possesses potential applications in high-performance display, filtering, and sensing.

Light Induced Proton Coupled Charge Transfer Triggers Counterion Directional Translocation.

We demonstrate directed translocation of ClO4 - anions from cationic to neutral binding site along the synthetized BPym-OH dye molecule that exhibits coupled excited-state intramolecular proton-transfer (ESIPT) and charge-transfer (CT) reaction (PCCT). The results of steady-state and time-resolved spectroscopy together with computer simulation and modeling show that in low polar toluene the excited-state redistribution of electronic charge enhanced by ESIPT generates the driving force, which is much stronger than by CT reaction itself and provides more informative gigantic shifts of fluorescence spectra signaling on ultrafast ion motion. The associated with ion translocation red-shifted fluorescence band (at 750 nm, extending to near-IR region) appears at the time ~83 ps as a result of electrochromic modulation of PCCT reaction. It occurs at substantial delay to PCCT that displayed fluorescence band at 640 nm and risetime of <200 fs. Thus, it becomes possible to visualize the manifestations of light-triggered ion translocation and of its driving force by fluorescence techniques and to separate them in time and energy domains.

Capturing of neurotoxins causing diabetes stress and nervous breakdown in the aqueous medium by naphthazarin esters.

The fear of an increase in blood sugar can be very traumatic. Being diabetic either type I or type II leads to a disorder called diabetes distress having traits of stress, depression, and anxiety. Among risk factors of diabetes mellitus heavy and trace metal toxicity emerges as new risk factors reported in many studies. In this study we target toxic metals, viz., Ni2+, Zn2+, and Cu2+, involved in the pathogenesis of diabetes and diabetic stress with naphthazarin esters. The compounds C1-C3 isolated from the leaves and roots of Arnebia guttata were tested for their metal-binding ability in an aqueous medium in UV-Visible and nuclear magnetic resonance (NMR) studies. These probes are well-known naphthoquinones present in the Arnebia species. In the UV-Visible titrations of compounds C1-C3 with Na2+, K2+, Zn2+, Ca2+, Cu2+, Mg2+, Co2+, and Ni2+ ions, significant binding was observed with Ni2+, Cu2+, and Zn2+ ions in MeOH/H2O. There occurs a beautiful formation of red-shifted bands between the 520 to 620 nm range with a synergistic increase in absorbance. Also, the disappearance of proton peaks in the 1H NMR spectrum on addition of metal ions confirmed binding. Compounds C1-C3 isolated from A. guttata came out as potent Ni2+, Zn2+, and Cu2+ sensors that are reportedly involved in islet function and induction of diabetes.

Alcohol-Induced Denaturation of Hen Egg White Lysozyme Studied by Infrared, Circular Dichroism, and Small-Angle Neutron Scattering.

In aqueous binary solvents with fluorinated alcohols, 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), and aliphatic alcohols, ethanol (EtOH) and 2-propanol (2-PrOH), the denaturation of hen egg white lysozyme (HEWL) with increasing alcohol mole fraction xA has been investigated in a wide view from the molecular vibration to the secondary and ternary structures. Circular dichroism (CD) measurement showed that the secondary structure of α-helix content of HEWL increases on adding a small amount of the fluorinated alcohol to the aqueous solution, while the β-sheet content decreases. On the contrary, the secondary structure does not significantly change by the addition of the aliphatic alcohols. Correspondingly, the infrared (IR) spectroscopic measurements revealed that the amide I band red-shifts on the addition of the fluorinated alcohol. However, the band remains unchanged in the aliphatic alcohol systems with increasing alcohol content. To observe the ternary structure of HEWL, small-angle neutron scattering (SANS) experiments with H/D substitution technique have been applied to the HEWL solutions. The SANS experiments were successful in revealing the details of how the geometry of the HEWL changes as a function of xA. The SANS profiles indicated the spherical structure of HEWL in all of the alcohol systems in the xA range examined. The mean radius of HEWL in the two fluorinated alcohol systems increases from ∼16 to ∼18 Å during the change in the secondary structure against the increase in the fluorinated alcohol content. On contrast, the radius does not significantly change in both aliphatic alcohol systems below xA = 0.3 but expands to ∼19 Å as the alcohol content is close to the limitation of the HEWL solubility. According to the present results, together with our knowledge of the alcohol cluster formation and the interaction of the trifluoromethyl (CF3) groups with the hydrophobic moieties of biomolecules, the effects of alcohols on the denaturation of the protein have been discussed on a molecular scale.