Hypsochromic Research Articles

SOLVATOCROMISMO E AS ESCALAS EMPÍRICAS DE POLARIDADE DO SOLVENTE: UMA REVISÃO

SOLVATOCHROMISM AND THE EMPIRICAL SCALES OF SOLVENT POLARITY: A REVIEW. The term solvatochromism is used to describe the changes in the optical properties of a dye molecule by influence of the solvent characteristics. Solvatochromic shifts are governed by intermolecular interactions between solute-solvent that can be either electrostatic (non-specific interactions) or chemical (specific interactions). Due to the complexity of these interactions and absence of theoretical models that can explain the specific effects of solvent, different authors have introduced empirical parameters to building more reliable solvent polarity scales. Out of various polarity scales that have arisen from this need, those based on the effect of solvent polarity on the electronic excitation energy of indicator organic dyes are the most prevalent in literature. The use of empirical equations that correlate bathochromic (positive solvatochromism) and hypsochromic (negative solvatochromism) shifts of optical spectra of organic molecules with the polarity of solvent has become essential for understanding solute-solvent interactions. This review article presents main mathematical equations that use linear correlations between macroscopic and/or microscopic polarity functions of solvent with spectroscopic parameters of solute (dye) in construction of solvent polarity scales. In addition, main mathematical models that use solvatochromic shifts to estimate the dipole moment of ground and excited state are discussed.

Push-pull photochromic dyes for semi-transparent solar cells with light-adjustable optical properties and high color-rendering index.

We report the design, synthesis and characterization of push-pull photochromic naphthopyran dyes, incorporating different carbazole moieties as the electron-donor group for use in dye-sensitized solar cells. Compared to a reference dye incorporating a diphenylamine-type donor moiety, the introduction of functionalized carbazoles allows for a hypsochromic shift of the absorption of the coloured isomers of the dyes in the visible region and a better tuning of their spectra to the photopic response of the human eye. Under illumination, the molecules exhibit a broad absorption with a maximum comprised between 546 nm and 571 nm in solution and they reveal relatively fast discoloration kinetics. By using these dyes to fabricate photochromic solar cells whose optical and photovoltaic properties vary with the light exposure, we have achieved a PCE of up to 3% in opaque cells. Using these molecules in semi-transparent solar cells with different electrolytes, a PCE of 2.3% was achieved. We also produced a semi-transparent mini-module with an average visible transmittance varying between 66% and 50% and a colour rendering index around 95 in both the uncoloured and coloured states.

Synthesis, crystal studies, antimicrobial activity, and BSA binding studies of metal complexes derived from pyridyl-based hydrazone: Multi-spectroscopic and DFT approach

We describe herein the synthesis of a pyridyl-benzothiazole hydrazone ligand (BP) and its metal complexes (BP1–BP4) incorporating Co(II), Ni(II), Cu(II), and Zn(II) cations. The molecular structures of BP and two of its complexes, BP1 and BP3, have been determined by single-crystal X-ray diffraction analysis. Octahedral complexation of the central metal ion by the NNN donor ligand in a 1:2 stoichiometry has been confirmed by various spectroscopic techniques, that is, IR spectroscopy, NMR spectrometry, and UV/Vis spectrophotometry, and corroborated by electrospray-ionization mass spectrometry and cyclic voltammetry. Diffuse-reflectance spectra revealed the presence of d-d transitions in all of the complexes, except in the case of BP4, which has no unpaired electron. The thermal stabilities of the complexes have been assessed by thermogravimetry and differential thermogravimetry, which revealed stepwise decomposition. Significant differences in the morphologies of the complexes have been discerned by FE-SEM analysis. Hirshfeld surface analysis has revealed the establishment of N⋅⋅⋅H, H⋅⋅⋅H, and C⋅⋅⋅H noncovalent interactions. Density functional theory (DFT)-based calculations have been applied to investigate the chemical reactivities and optimized structures of BP and BP1–BP4. A 1,3-proton shift in BP was confirmed and the HOMO-LUMO energy gap was assessed through DFT-based methods. Photophysical studies have revealed a large Stokes shift for BP, which is reduced upon complexation with metal ions. In vitro anti-microbial screening of the prepared compounds has been performed against four bacterial strains (Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Xanthomonas campestris) and two fungal strains (Candida albicans and Fusarium oxysporum), which revealed most potent inhibition of bacterial and fungal growth, with minimum inhibitory concentrations of 128 and 256 μg/mL, by BP1 and BP3, respectively. BP1 exhibits broad-spectrum anti-bacterial activity exceeding that of the standard drug chloramphenicol. Spectroscopic methods have been utilized to explore the interaction between BP1 and bovine serum albumin (BSA). A hypsochromic shift in fluorescence intensity and a hyperchromic shift in the absorption band of BSA with different concentrations of BP1 have yielded significant binding information. BSA binding studies have revealed a negative value of Gibbs free energy, confirming the spontaneity of BSA–BP1 complex formation.

An easy-to-use phosphate triggered zinc-azophenine complex assisted metal extrusion assay: A diagnostic approach for chronic kidney disease and in silico docking studies

Regular monitoring of H2PO4- is inevitable owing to its physiological, chemical as well as environmental significance. Herein, a new and promising azophenine-functionalized Zn2+ complex, CN-1·Zn2+ is rationally designed for the selective and sensitive colorimetric detection (LOD = 67.9 ppb) of monophosphorylated species, H2PO4- based on H2PO4--specific metal-extrusion assay through hypsochromic shift in the UV–vis spectra. The sensing phenomenon has been authenticated via UV–vis, ESI-MS, CV, LSV, 1H NMR studies with theoretical (DFT) substantiation. CN-1·Zn2+ has been exploited towards two-input-two-output logic circuitry fabrication, advantageous for molecular-level information storage. Moreover, TLC strip-based contact mode analysis is beneficial for its on-spot applicability. Smartphone-assisted chromogenic recognition efficiency of CN-1·Zn2+via RGB analysis has been well-correlated with spectrophotometric outcomes, demonstrating reliability of the present method. Phosphate detection efficacy of CN-1·Zn2+ in serum specimens with qualified recovery (90.9–98.9 %) makes it a potential diagnostic tool for monitoring chronic kidney disease (CKD). Additionally, CN-1·Zn2+ exhibited DNA binding activity through non-intercalation mode, examined via UV–vis, fluorescence spectroscopic studies with in silico docking. This is the first Zn2+-complex in azophenine family, effectively employed for smartphone-assisted phosphate detection having promising DNA-binding activity, thereby leaving a sustainable footprint in the domain of supramolecular and bio-medical functional world of applications.

Extraction of Anthocyanins from Black Grape By-Products and Improving Their Stability Using Cobalt(II) Complexation.

This study was conducted to investigate the effect of cobalt complexation on the spectral properties of anthocyanins (AC) extracted from black grape pomace (Black Magic) and the effect of complexation on the pH stability of AC during storage. Initially, cobalt acetate tetrahydrate aqueous solution was complexed with AC crude extract and diluted separately in buffer solutions with different pH (3.5, 4.5, 5.5, and 6.5). Afterward, spectral changes were determined spectrophotometrically. pH stability was investigated using the same buffer solutions and stored for 7 days in the dark at room temperature, and the absorbance of each solution was measured daily using a spectrophotometer. Results indicated that complexation caused similar hypsochromic and hyperchromic shifts in λmax at all pH values. With regard to pH stability, the degradation of complexed AC followed first-order reaction kinetics causing half-lives to increase up to 80-fold as compared with noncomplexed AC, which was due to the sharp decrease in K (per day), indicating an improved pH stability as compared with noncomplexed AC. Therefore, Co(II) could be used in the stabilization of grape AC for the coloration of a wide range of foods and food products at near-neutral pH environments considering the health benefits of grape AC and the maximum nontoxic dose of Co(II) salt.

A Colorimetric Distinct Color Change Cu(II) 4-{[1-(2,5-dihydroxyphenyl)ethylidene]amino}-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one Chemosensor and its Application as a Paper Test Kit.

In the current research work "4-{[1-(2,5-dihydroxyphenyl)ethylidene]amino}-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one" chemosensor (C1) synthesized by condensation reaction using "4-amino-1,2-dihydro-1,5-dimethyl-2-phenylpyrazol-3-one" and "2,5-dihydroxy actophenone" was used as the effective sensor of metal ion. The C1 shows absorption peak at 326nm due to the C = C bond (π-π*transition), while the absorption peak at 364nm is caused by the C = O bond (n-π*transition). In the presence of copper, C1 only demonstrated a redshift in absorption peak from 364 to 425nm. Even in the presence of other competing metal ions, the hypsochromic shift of the absorption band and the quenching of the fluorescence emission intensity were different for detecting Cu2+, in CH3OH-H2O (v/v = 6:4). The capacity of the C1 to bind with Cu2+ was further proved using DFT simulations. The complex C1 + Cu2+ has a HOMO-LUMO energy gap of 2.8002eV, which is lesser than C1 (2.9991eV) showing improvement in the stability of the C1 + Cu2+ complex. Using the Benesi-Hildebrand and Scatchard plots, calculated Kb values were to be 47,340 and 48369M-1 respectively, showing the creation of stable complexation between Cu2+ and C1 with 1:1 stoichiometry. The limit of detection (LOD) for Cu2+ ion was 649nM. Strip sheets were also built and tested to detect varying amounts of Cu2+ in aqueous solution, and their color change suggested that they might be used for on-site Cu2+ detection in polluted water.

Effect of Hydroxyl Group on Photo-Physical Properties and Dipole Moments of Fluorescent Dyes: An Experimental and Computational Approach.

In this work, structurally similar, (E)-N'-(2-hydroxybenzylidene)-3,5-di-tert-butyl-2-hydroxybenzohydrazide (A) and (E)-N'-(2-4-dihydroxybenzylidene)-3,5-di-tert-butyl-2-hydroxybenzohydrazide (A-OH) dyes dissolved in general solvents have been studied to explore photo-physical properties, employing solvatochromic shift method, thereby determining their dipole moments in the ground (μg) and excited (μe) states. The molecule A shows a bathochromic shift of fluorescence emission maxima in aprotic solvents whereas a hypsochromic shift in protic solvents. Interestingly, A-OH follows a hypsochromic shift in both protic and aprotic solvents with increasing solvent polarity. The effect of hydroxyl substituent on UV-Visible absorption, fluorescence emission, and dipole moment of the titled organic molecules was explained. Theoretical methods such as Bilot-Kawski method for determination of μg and μe and Bakshiev, Kawski-Chamma-Viallet, Lippert-Mataga equations for μe, and Reichardt method for the difference between μg and μe were employed. It is observed that μe is higher than that of μg for both the molecules, and interestingly, upon substituting an additional hydroxyl group the value of μg has increased while μe is decreased. The DFT calculations have been performed to support experimental results by employing DFT/B3LYP/6-311G + (d) and TD-DFT/B3LYP/6-311G + (d) method using Gaussian09 software. The electrophilic and nucleophilic sites on the molecules were studied with the help of MEP. The NBO analysis results show that the interaction N24 (σ) → C22-O23 (π*) is found to be stronger in both the molecules with energy 68.90kJ/mol and the effect of hydroxyl group is also discussed on the basis of HOMO and LUMO.

Effect of meso-substituent and solvent nature on spectral properties, pH-stability and affinity to blood transport proteins of BODIPY dyes

The paper is focused on a comparative analysis of the structural and solvation factors on the spectral properties, pH-stability and lipophilicity of BODIPY biomarkers containing in meso-position methyl group, carboxylic acid residues and their esters. The affinity of meso-BODIPYs to blood transport proteins was studied. Dyes intensely absorb (ε ∼ 45000–90000) and fluoresce (to φ ∼ 100 %) in the range of 493–504 and 508–520 nm, respectively. meso-substitution causes a hypsochromic shift (by ∼4–11 nm) of the maximum of the intense absorption band and a noticeable increase of the Stokes shift (up to ∼1.7–2.6 times) of BODIPYs compared to the meso-unsubstituted analog. It has been shown that the introduction of a carboxyl group into the BODIPY meso-position significantly (by a factor of ∼2) increases the hydrophilicity of the compounds, and the presence of ester groups in the structure leads to an increase of the hydrophobicity of the luminophores by a factor of ∼1.3 compared to the meso-unsubstituted dye. It has been demonstrated that compounds are stable in a wide pH range and exhibit intense fluorescence (to φ ∼ 80 %), while carboxyl BODIPYs can be considered as pH sensors for alkaline media. Introducing carboxylic acid residues and their esters into the meso-position of BODIPY is an excellent way to increase affinity dyes to biostructures, including blood transport proteins.

UV/visible Spectroscopic Studies and Analytical Evaluation of Dicliptera verticillate Leaves Extracts as Eco-friendly Indicator for Acid-Base Titration

Synthetic indicators usually employed in acid-base titration to determine the end point is expensive and non-biodegradable. Hence there is need to develop an eco-friendly and cost effective acid-base indicator from plant origin to serve as efficient alternative for the synthetic indicators. This research work focused on the development of easily available, cost effective and eco-friendly indicator from Dicliptera verticillate leaves extracts for acid-base titration. UV/visible spectrometer was used to analyzed the ethanol extract (EE), ethanol extract in basic medium (EEB), ethanol extract in acidic medium (EEA), hot water extract (HWE), Hot water extract in basic medium (HWEB) and hot water extract in acidic medium (HWEA) to determine the wavelength of maximum absorption (λmax), and the absorbance of the extracts in different media in order to evaluate the chromophoric properties of the plant extracts phytochemicals before and after titrations. Titrimetric analysis was carried out in the reactions of strong acid/strong base (HCl/NaOH), strong acid/weak base (HCl/NH4OH), weak acid/strong base (CH3COOH /NaOH) and weak acid/weak base (CH3COOH/NH4OH). The results revealed that both extracts exhibit hypsochromic shift (shift to a shorter wavelength) with corresponding hypochromic effect (decreased in the absorption intensity) in both acidic and basic media. The titrimetric results revealed that the plant extracts give the end point comparable to that of the synthetic indicators such as methyl orange and phenolphthalein. Hence ethanol and hot water extracts of Dicliptera Verticillate can be utilized as suitable alternative indicators for acid - based titrations, since it is biodegradable and cost effective.

Multicolor emission based on a N, N'-Disubstituted dihydrodibenzo [a, c] phenazine crown ether macrocycle.

Dynamic fluorophore 9,14-diphenyl-9,14-dihydrodibenzo[a,c]phenazine (DPAC) affords a new platform to produce diverse emission outputs. In this paper, a novel DPAC-containing crown ether macrocycle D-6 is synthesized and characterized. Host-guest interactions of D-6 with different ammonium guests produced a variety of fluorescence with hypsochromic shifts up to 130nm, which are found to be affected by choice of solvent or guest and host/guest stoichiometry. Formation of supramolecular complexes were confirmed by UV-vis titration, 1H NMR and HRMS spectroscopy.

Prolonged Lifetimes of Histologic Autofluorescence in Ectopic Retinal Pigment Epithelium in Age-Related Macular Degeneration.

The purpose of this study was to investigate histologic autofluorescence lifetimes and spectra of retinal pigment epithelium (RPE) on the transition from normal aging to RPE activation and migration in age-related macular degeneration (AMD). Autofluorescence lifetimes and spectra of 9 donor eyes were analyzed in cryosections by means of 2-photon excited fluorescence at 960 nm. Spectra were detected at 483 to 665 nm. Lifetimes were measured using time-correlated single photon counting in 2 spectral channels: 500 to 550 nm (short-wavelength spectral channel [SSC]) and 550 to 700 nm (long-wavelength spectral channel [LSC]). Fluorescence decays over time were approximated by a series of three exponential functions. The amplitude-weighted mean fluorescence lifetime was determined. Markers for retinoid activity (RPE65) and immune function (CD68) were immunolocalized in selected neighboring sections. We identified 9 RPE morphology phenotypes resulting in 399 regions of interest (ROIs) for spectral and 497 ROIs for lifetime measurements. RPE dysmorphia results in a shorter wavelength peak of spectral emission: normal aging versus RPE migrated into the retina (intraELM) = 601.7 (9.5) nm versus 581.6 (7.3) nm, P < 0.001, whereas autofluorescence lifetimes increase: normal aging versus intraELM: SSC 180 (44) picosecond (ps) versus 320 (86) ps, P < 0.001; and LSC 250 (55) ps versus 441 (76) ps, P < 0.001. Ectopic RPE within the neurosensory retina is strongly CD68 positive and RPE65 negative. In the process of RPE degeneration, comprising different steps of dysmorphia and migration, lengthening of autofluorescence lifetimes and a hypsochromic shift of emission spectra can be observed. These autofluorescence changes might provide early biomarkers for AMD progression and contribute to our understanding of RPE-driven pathology.

5-Hydroxydibenzo[a,i]phenazine-8,13-dione: A selective and sensitive colorimetric and fluorescent ‘turn-off’ sensor for iodide ion

The present manuscript reports 5-hydroxydibenzo[a,i]phenazine-8,13-dione (HDP) as a novel colorimetric and fluorescent chemosensor for the selective and sensitive detection of iodide ion. The probe was synthesized by a condensation reaction of 2,3-diaminonaphthoquinone with 2-hydroxynaphthoquinone and characterized using FT-IR and NMR. The ground state geometry has been optimized using DFT based methods and utilized for the prediction of various electrostatic properties such as HOMO, LUMO, NBOs and Fukui. The vertical excitation spectra have been evaluated in different solvents and compared with experimentally determined absorption spectra. HDP exhibits solvatochromic behavior showing hypsochromic shift with change in polarity of solvent from chloroform to DMSO. The sensing application was investigated with different metal ions and anions. Addition of iodide ion to HDP solution exhibits a new absorption band at 517 nm along with disappearance of band at 405 nm. Similarly, the fluorescence intensity at 565 nm showed a reduction upon addition of I−. The developed probe exhibited high selectivity and sensitivity towards iodide ion over other tested analytes with a detection limit of 21 nM. Additionally, the probe responded within 5 sec for the sensitive detection of iodide ion. Job's plot experiment,1H NMR titration and DFT studies were performed further to evaluate the binding stoichiometry and mechanism, respectively.

Photochromism of tetrahydroindolizines. Part XXVI: Mechanochemical synthesis, tunable photophysical properties and combined experimental and theoretical studies of novel photochromic tetrahydroindolizines

Herein, eighteen novel photochromic tetrahydroindolizines (THIs) have been successfully prepared using a well-established mechanochemical synthetic approach. These products were obtained in good to excellent yields and the purification process was relatively straightforward devoid of any isolation challenges. The new THIs incorporate various substituents in region C (base part) which include both electron donating and withdrawing groups in the ortho, meta and para positions of the phenyl ring. The absorption maxima (λmax) of both closed form (THI) and the colored form (betaine, after UV-irradiation) were spectrophotometrically determined in dichloromethane solution. The colored betaines displayed two absorption maxima, one between 472 and 485 nm, and the second one appearing in the white region between 658 and 724 nm with tailing extending to the near infra-red (NIR) region. The impact of the nature and position of substituent in the 10′b-phenyl ring on the absorption of the betaines indicated that substitution in the ortho-position with absorption maxima between 658 and 690 nm leads to a hypsochromic shift largely caused by the steric effect of the substituents in the o-position of the THI molecule 10′b-phenyl ring compared to the meta- and para-substituted species with absorption maxima between 700 and 724 nm. The calculated ring closure thermodynamic activation parameters of colored betaines were found to be in good agreement with previous reported results. The 1,5-electrocyclization reaction kinetics of the investigated photochromic THIs were monitored and calculated. Intriguingly, substitution with electron donating and withdrawing groups in the o-, m-, and p-positions of the phenyl ring enabled distinctive tunability of the kinetic behavior. Furthermore, possible mechanism of the thermal 1,5-electrocyclization back reaction of betaines was explored based on density functional theory calculations (DFT), delivering more understanding into ring opening and ring closure processes in addition to the distinct THI-substituents effect (region C). The geometries and the relative energies of the THI, betaine isomers, and transition states along reaction coordinates were optimized and assessed by DFT. Based on the obtained synthetic methodology results, unprecedent tunability of the photochromic properties and the combined experimental and theoretical studies, the current work launches a new dimension and contributes further developments to the field of high-performance photochromic materials.

Спектральные характеристики комплексов Hoechst 33258 с БСА

Study on the interaction of DNA-specific compound Hoechst 33258 with bovine serum albumin (BSA) has been carried out, using the methods of absorption, differential and fluorescence spectroscopies. On the basis of the absorption and fluorescence spectra of the complexes of this ligand with BSA, in wide interval of the change of r (r=ligand/albumin), the dependence curves of the relative changes of the absorption (A/A0) and fluorescence (F/F0) maxima of the complexes H33258-BSA on the macromolecule concentration, were constructed. The dependence curve of A/A0 monotonously decreases along with protein concentration increasing due to the formation of the complexes. It was revealed that the dependence curve of F/F0 is not linear and is consisted of two regions: at low concentrations of the protein this curve decreases linearly, and passing through the minimum point, at relatively high concentrations of the protein starts linearly increasing. It was also shown that the differential spectra of the complexes H33258-BSA are characterized by hypo- and hyperchromic effects and hypsochromic shift: at low concentrations of the protein a hypochromic effect occurs, at higher concentrations of the protein (beginning from the certain ratios ligand/albumin ~1:1), the differential spectra are hypsochromically shifted with hyperchromic effect. The obtained data find out that Hoechst 33258, being DNA-specific ligand, tightly binds to albumin.

Implications of recently derived thermodynamic data and specific ionic interaction theory parameters for (Mg/Ca)nUO2(CO3)3(4-2n)- complexes on the predominance of the Mg2+–Ca2+–UO22+–OH−–CO32− systems, and application to natural and legacy-mine waters

The formation of alkaline earth(II)triscarbonatouranyl(VI) (AenUO2(CO3)3(4-2n)-) species that have been evidenced both in laboratory and in-field studies, is important from slightly acidic pH up to near degraded cementitious in carbonated waters. They are also showing distinctive luminescence properties with a hypsochromic shift relative to UO22+. The conditions of pH, activities of alkaline earth(II) free ions (mostly Mg2+ and Ca2+) and carbonate ions (HCO3−) can be predicted from the thermodynamic functions and constants. The predictive validity of the activity of major alkaline ions (mostly Na+) is determined from the models used to describe the ionic strength comportment of these species, particularly using coefficients from the specific ion interaction theory (SIT). The stability domains of these species are better defined as a function of the activity of the constituents, and applied to natural waters. In this work, using recently obtained complete thermodynamic data and SIT coefficients, we will draw the stability domains of the AenUO2(CO3)3(4-2n)- species in combinations of activities of H+, HCO3−, Mg2+, Ca2+, and Na+ for a wide selection of water compositions from the literature. Water samples were collected near a French mining legacy-site (Site du Bosc, Lodève, France). After determining the major ion compositions, we will verify that the luminescence signal of uranium is in agreement with the predicted speciation in the stability domains.

Synthesis and AIE properties of benzene fused cyclooctetrathiophenes

We have synthesized a series of benzene fused cyclooctetrathiophenes (COThs), including BCOTh, 2BCOTh, 3BCOTh, and 4BCOTh with rotor-free molecular structures, which are similar to the luminogens with the aggregation-induced emission (AIE) property based on the mechanism of restriction of intramolecular vibration (RIV). Investigation on the photophysical properties in THF-H2O mixture solvent showed that 4BCOTh exhibits the aggregation-caused quenching (ACQ) properties, while the others exhibit AIE effect. With increasing the number of the fused benzene rings, the emission behaviors of COThs showed hypsochromic shift in both rigid solution (77 K) and AIE state, which are attributed to the gradually weakened intramolecular through-space conjugation (ITSC). Theoretical calculations and crystal packing analysis indicated that the emission difference in solid between 2BCOTh and 4BCOTh is mainly affected by the factors of molecular conjugation and rigidity. In addition, the model compound COThMe, bearing two methylene groups locking the thiophene rings of COTh, was employed for the experimental investigation of RIV mechanism in the AIE case of COThs.

Preparation of carboxymethyl cellulose/polyvinyl alcohol wound dressing composite immobilized with anthocyanin extract for colorimetric monitoring of wound healing and prevention of wound infection

Novel aerogel-like wound dressing able to sense the healing progress was developed. Anthocyanins (Ac) have been reported as a significant pH-sensory extract with various biological activities. Herein, anthocyanins were extracted from red-cabbage (Brassica oleracea L. Var. capitata). The anthocyanin probe was integrated as a water-soluble direct dye at various concentrations into carboxymethyl cellulose/polyvinyl alcohol composite in the presence of potassium aluminum sulfate mordant. The generated composites were then freeze-dried to provide the corresponding aerogel-like smart wound dressing to function as an antibacterial and biochromic bulk presenting a comfort dressing biosensor to monitor the progress of a wound healing. Reducing the pH value of a wound mimicking fluid resulted in a hypsochromic shift from 592 to 446 nm. The halochromic activity of anthocyanin showed colorimetric changes from purple to pink. The colorimetric measurements of the prepared anthocyanin-containing aerogel-like diagnostic assay were explored by CIE Lab coordinates and UV–Vis absorption spectra. The effects of the anthocyanin content on the morphology, stiffness, air-permeability, and mechanical behavior of the aerogel-like wound dress were explored by various analytical methods. Both cytotoxicity and antibacterial activity of were investigated.

In Ukrainian

Curcumin, a sparingly soluble polyphenol of plant origin, has antitumor, anti-inflammatory, antithrombotic, antidiabetic and antimicrobial properties. Currently, an important task is the development of medicinal composites based on curcumin, which provide an increase in its solubility and, accordingly, bioavailability. The aim of the work is to determine the optimal conditions for the adsorption of curcumin on the surface of a silica enterosorbent as soluble supramolecular complexes with a cationic dimeric surfactant decamethoxine. The UV/Vis spectroscopy data indicate that supramolecular interactions with decamethoxine lead to changes in the spectral characteristics of curcumin in solutions and on silica surface. The bathochromic shift of the absorption spectrum of curcumin in decamethoxine solutions characterizes the polarization of its carbonyl group in supramolecular complexes. The hypsochromic shift in the absorption spectra of curcumin adsorbed from decamethoxine solutions on silica is explained by the violation of its conjugated π-bond system, resulted probably from the change in the spatial orientation of the curcumin molecule at the adsorption of its complexes on the sorbent surface. Curcumin is adsorbed on highly dispersed silica much more effectively from decamethoxine solutions than from aqueous solutions. The adsorption of curcumin is maximal (92 %) at a concentration of decamethoxine 0.002 M, and decreases sharply to 9 % in the micellar region of concentrations (≥ 0.008 M). The dependence of curcumin adsorption on decamethoxine concentration is described by a domed curve, which indicates a significant contribution of hydrophobic interactions to the formation of supramolecular complexes of curcumin with cationic surfactant and their adsorption on silica surface. The results obtained are of practical importance and can be used in the development of new, more effective medicines containing bioactive curcumin, antiseptic decamethoxine and silica enterosorbent.

A Versatile Tetraphenylethene Derivative Bearing Excitation Wavelength Dependent Emission, Multistate Mechanochromism, Reversible Photochromism, and Circularly Polarized Luminescence and Its Applications in Multimodal Anticounterfeiting

A Versatile Tetraphenylethene Derivative Bearing Excitation Wavelength Dependent Emission, Multistate Mechanochromism, Reversible Photochromism, and Circularly Polarized Luminescence and Its Applications in Multimodal Anticounterfeiting

ZnO and Ni-doped ZnO photocatalysts: Synthesis, characterization and improved visible light driven photocatalytic degradation of methylene blue

The nickel modified zinc oxide (ZnO) photocatalysts with nominal composition of Zn1-xNixO (x = 0.0–0.5) were synthesized by wet chemical approach. Optical studies were performed using Fourier transformed infrared (FTIR), electronic spectroscopy and X-ray diffraction (XRD) methods. Scanning electron microscopy (SEM) complimented with Energy Dispersive X-ray (EDX) was used to study the morphology and chemical composition of prepared photocatalysts. A significant hypsochromic shift has been observed with respect to un-doped ZnO nanocatalyst due to quantum confinement effect. Subsequently, the band gap has been tuned to the region of lower wavelength. X-ray results reveal that ZnO nanocatalyst are in hexagonal crystalline form. In addition, the effect of nickel impurity on photocatalytic activity of ZnO nanocatalysts in degradation of methylene blue (MB) was also investigated. Degradation results showed that the MB was degraded more effectively by Ni-doped ZnO photocatalysts due to large band gap under visible light irradiation.