Derivatives In Aqueous Solution Research Articles

MnO4−-triggered wavelength-changeable and rapid-response fluorescence sensor for paper-based on-site sensing of tyrosinase activity in potato

Rapid-response in situ fluorogenic reactions in aqueous solution are important for designing sensitive and stable sensing platforms. Herein, a wavelength-changeable and rapid-response (within 5 s) fluorescence sensing platform for monitoring tyrosinase (TYR) activity is constructed. The developed assay is based on TYR catalyzing the hydroxylation of mono-phenol to o-diphenol and MnO4−-triggered fluorogenic between dopamine (DA) and phenol derivatives in aqueous solution. The fluorescence wavelength can be changeable from 470 to 550 nm with strong fluorescence according to different phenol derivatives. Our proposed sensor not only exhibits a good recovery for TYR in high serum concentration (20 %), but also has been successfully applied to the screening of TYR inhibitors modeled on kojic acid. Furthermore, a paper-based wavelength-changeable fluorescence sensor was developed for on-site detection of TYR activity in potatoes with high recovery, which is consistent with our previously reported method. Consequently, the proposed sensing system has broad prospects in the practical application of TYR-associated food monitoring and clinical diagnosis.

Influence of blocking groups on photo-oxidation of tyrosine and derivatives

One-electron oxidation of tyrosine primarily results in the formation of di-tyrosine, which can induce crosslinks leading to protein damage. In this study, we investigated the 3-carboxybenzophenone-sensitized photo-oxidation of Tyr derivatives through time-resolved and steady-state photolysis under anaerobic conditions to analyze the effects of blocking groups.The mechanism for primary and secondary photoreactions in the sensitized photo-oxidation of Tyr derivatives in aqueous solution was presented based on time-resolved analysis and mass spectrometric characterization of photo-oxidation products. Identified di-Tyr products (in addition to those mentioned more often in the literature, such as 3,3′/3,O’) were in some samples presented together with Tyr-CBH adduct (resulting from radical recombination between the tyrosyl radical and CBH•). This publication discusses the possible coulombic effects of interacting ionic species (sensitizer and quencher) on quenching rate constants and the effect of amine groups and steric factors on the distribution of stable products. However, a crucial finding of this work is that the more blocked the Tyr is, the more di-Tyr isomers are formed, suggesting that Tyr residue in proteins may form several forms of di-Tyr cross-links.

Complexation of Hexavalent Neptunium(VI) with Oxydiacetic Acid and Its Amide Derivatives in Aqueous Solution: Spectrophotometry and DFT Calculations.

Unfolding the solution coordination chemistry of high-valent transuranium elements with the "CHON"-type ligands is important to understand the fundamental chemistry of actinides and to design more efficient extractants for partitioning of transuranium elements in advanced nuclear fuel cycles. Here, the complexation of a hexavalent neptunyl ion (NpO22+ or Np(VI)) with oxydiacetic acid (ODA) has been systematically investigated in comparison with its amide analogues N,N-dimethyl-3-oxa-glutaramic acid (DMOGA) and N,N,N',N'-tetramethyl-3-oxa-glutaramide (TMOGA) both experimentally and computationally. The formation of both 1:1 and 1:2 complexes between Np(VI) and the three ligands was identified by spectrophotometry, and their stability constants were obtained and compared with those of hexavalent U(VI) and Pu(VI). The corresponding bonding nature is elucidated by using energy decomposition analysis (EDA), electrostatic potential (ESP), ELF contours, and natural orbitals for chemical valence (NOCV) methods, which shows that the Np-O bonds are essentially ionic in character and the unoccupied 6d orbitals of Np play a key role in enhancing the covalent interactions between Np(VI) and the three ligands.

Construction of pyrene-based hydrogen-bonded organic frameworks as photocatalysts for photooxidation of styrene in water

Using hydrogen-bonded organic frameworks (HOFs) as photosensitizers to perform photocatalytic oxidation reactions under green and mild conditions is still a challenge for the application of HOFs materials. This study presents a novel approach that exploits HOFs to enhance the efficiency of photocatalytic oxidation for achieving visible light catalytic oxidation of styrene and its derivatives in the aqueous environment. By using 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H4TBAPy) as the monomer, a pyrene-based hydrogen-bonded organic framework (PFC-1) with a microporous structure was successfully prepared. Compared with monomer H4TBAPy, due to the exciton effect and the interlayer confinement of HOFs, the singlet oxygen (1O2) production efficiency is significantly improved, which has great potential in photocatalytic oxidation reactions. Subsequently, the practicality of PFC-1 as a photocatalyst was studied, and the photocatalytic oxidation of styrene and its derivatives in aqueous solution was achieved under visible light with high catalytic efficiency, indicating that PFC-1 has significant potential to promote photocatalytic oxidation reactions under mild conditions. The utilization of HOFs as photosensitizers in this straightforward approach enables the attainment of green photocatalytic oxidation, hence expanding the potential applications of HOFs materials within the realm of photocatalysis.

Experimental and Virtual Screening of Phenazine and Phenothiazine Derivatives in Aqueous Solution for Electrochemical Carbon Capture

Molecular redox-active compounds, including quinone and aza-aromatics, have emerged as tools for capturing carbon dioxide using renewable electricity. Given the vast and highly diverse chemical space of the candidate compounds, accessing their electrochemical properties in a rapid way is attractive for both experimental and virtual screening approaches.Here we present a study on the experimental screening of a series of commercial redox-active compounds. Phenazine and phenothiazine dyes have been experimentally tested for applications in electrochemical carbon capture, for which they are finding increasing applications as redox mediators due to their unique redox properties in aqueous solution. Nicotinamide has been used as a redox-inactive solubilizing agent to increase the solubilities of general phenazine and phenothiazine derivatives for rapid experimental screening of commercial compounds without time-consuming synthetic modifications. Cyclic voltammetry in aqueous solutions under nitrogen and carbon dioxide indicated reversible behavior in the pH swing of an aqueous solution. Bulk electrolysis experiments demonstrated the chemical stability of phenazine and phenothiazine derivatives. The redox properties and the chemical stability make phenazine and phenothiazine derivatives interesting candidates for future use as redox-active materials in electrochemical carbon capture.We also present progress towards a virtual screening for the optimization of electrochemical and physicochemical properties of redox-active compounds. Based on our experimental screening of commercial phenazine and phenothiazine compounds identifying neutral red as the lead compound, a virtual screening was performed for optimization of electrochemical and physicochemical properties using machine learning. The virtual screening development steps include (1) chemical library generation using neutral red as a lead compound, (2) molecular property prediction based on quantum chemical calculations, (3) aqueous solubility prediction using machine learning, (4) data processing and database creation, and (5) experimental validation of the optimized compounds for the use of electrochemical carbon capture. Figure 1

A unique ratiometric fluorescent probe for detection of SO2 derivatives in living cells and real food samples

Abnormal levels of SO2 in organisms can cause cardiovascular disease and respiratory allergies. In addition, the amount of SO2 derivatives used as food preservatives is strictly controlled, and excessive addition can also be harmful to health. Therefore, it is essential to develop a highly sensitive method for the detection of SO2 and its derivatives in biological systems and real food samples. In this work, a new fluorescent probe (TCMs) with high selectivity and sensitivity for the detection of SO2 derivatives was reported. The TCMs could quickly identify SO2 derivatives. It has been successfully used to detect exogenous and endogenous SO2 derivatives. Furthermore, the TCMs has high sensitivity to SO2 derivatives in food samples. Moreover, the prepared test strips could be evaluated for the content of SO2 derivatives in aqueous solutions. This work provides a potential chemical tool to detect SO2 derivatives in living cells and real food samples.

Conformational analysis of amphetamine and methamphetamine: a comprehensive approach by vibrational and chiroptical spectroscopy.

After cannabis, the most commonly used illicit substance worldwide is amphetamine and its derivatives, such as methamphetamine, with an ever-increasing number of synthetic modifications. Thus, fast and reliable methods are needed to identify them according to their spectral patterns and structures. Here, we have investigated the use of molecular spectroscopy methods to describe the 3D structures of these substances in a solution that models the physiological environment. The substances were analyzed by Raman and infrared (IR) absorption spectroscopy and by chiroptical methods, vibrational circular dichroism (VCD) and Raman optical activity (ROA). The obtained experimental data were supported by three different computational approaches based on density functional theory (DFT) and molecular dynamics (MD). Successful interpretation relies on good agreement between experimental and predicted spectra. The determination of the conformer populations of the studied molecules was based on maximizing the similarity overlap of weighted conformer spectra by a global minimization algorithm. Very good agreement was obtained between the experimental spectra and optimized-population weighted spectra from MD, providing a detailed insight into the structure of the molecules and their interaction with the solvent. The relative population of three amphetamine and six methamphetamine conformers was determined and is consistent with a previous NMR study. However, this work shows that only a few isolated conformers are not sufficient for the successful interpretation of the spectra, but the entire conformational space needs to be sampled appropriately and explicit interaction with the solvent needs to be included.

Preparation and Characterization of Highly Conductive and Biorepulsive Polypyrrole/Polyglycerol Surface Films

Highly conductive and biorepulsive polymer films can be deposited onto gold by electrochemical polymerization of a polyglycerol-modified pyrrole derivative in aqueous solution. The growth of the polymer film is linearly determined by current density and time. Thicknesses of up to 400 nm can be obtained, where the polymerization is self-terminated due to the growth mechanism. Cyclic voltammetry and electrochemical impedance measurements were employed to characterize the film formation dynamics and the conductivity of the films at different thicknesses. Furthermore, the films and their growth were characterized by reflection/absorption infrared spectroscopy, quartz crystal microbalance, atomic force microscopy, as well as contact angle measurements. The films are highly biorepulsive even at thicknesses as low as 10 nm, which could be demonstrated using protein and bacterial adhesion assays, thus opening the opportunity for their use in bioelectrical applications.

Spectroscopic and tensiometric considerations on anionic surfactants (SDS) and ascorbic acid/ascorbates interactions

The cosmetics and personal care products market is developing dynamically and the formulations of products are subject to numerous modifications due to consumer expectations and market trends. An increase in demand for products containing ascorbic acid or its more stable forms has been observed for several years. In this study, the correlation between SDS and ascorbic acid or its derivatives in aqueous solutions was assessed using spectroscopic and tensiometric methods. The influence of SDS interactions on the total antioxidant capacity of ascorbic acid/ascorbic acid derivatives was analyzed. The highest FRAP values of SDS-AA2G and SDS-EAC systems (0.17 and 2.71 mmol Fe2+/g, respectively) were at SDS concentration of 0.40 mM and were much higher than the ones of pure ascorbic acid derivatives. Based on the surface tension isotherms and Szyszkowski's equation, it was found that for the tested SDS/ascorbic acid, ascorbyl glucoside and 3-O-ethyl ascorbic acid systems, the CMC values were: 3.85, 2.54 and 3.31 mmol/dm3. There was also an influence on the values of the adsorption parameters, i.e. the surface excess at the saturated interface, the minimum molecular area in the adsorption layer at the saturated interface and the Gibbs free energy of adsorption. Moreover, in most of the analyzed cases, the tested systems had better wetting properties, which resulted in lower values of the contact angle than in the case of pure SDS solution.

Interaction between an Oxidized Fraction of Polyvinyl Alcohol and Uracil Derivatives in Aqueous Solutions

Interaction between an Oxidized Fraction of Polyvinyl Alcohol and Uracil Derivatives in Aqueous Solutions

Morphological behavior of fullerene‐steroid hybrid derivatives

Over the years, fullerene has been covalently linked to other polar structures, increasing its aqueous solubility, thereby improving its potential use for biological and biomedical applications. Here, we report on the self‐organization characteristics in water of fullerene‐steroid hybrid derivatives with broad structural features. A library of 12 hybrid derivatives was prepared and classified into three groups: (1) mono adducts with only one steroid molecule and one fullerene moiety fused; (2) hybrids bearing wings with one fullerene moiety and two steroid molecules; and (3) a structure with two fullerene moieties linked to one steroid molecule and a mixture of two different monoaducts where C60‐malonate is attached to the A or D ring of steroid moiety. Different spectroscopic techniques characterized all synthesized fullerene derivatives, such as nuclear magnetic resonance (NMR) experiments (1H and 13C), Fourier transform infrared spectroscopy (FTIR), and high‐resolution mass spectrometry (HRMS). The morphology of the derivatives in aqueous solution was determined by transmission electron microscopy (TEM). In general, all the derivatives were organized into spherical nanoscale structures, where the structural characteristics defined the particle size distribution (PSD), showing a broad range of sizes from 6 to over 50 nm, and only a low percentage of larger particles were observed. The presence of dehydroepiandrosterone moieties in fullerene derivatives bearing wings and the increase in lipophilicity conferred by two C60 in the same structure induced more homogeneous and smaller particles, ranging from 6 to 20 nm. A preliminary computational study of the wing aggregates IIb showed that theoretical curve aggregates are more stable than linear ones supporting our TEM and PDS results.

Rapid and sensitive detection of dextran sulfate sodium based on supramolecular self-assembly of a perylene diimide derivative in aqueous solution

Dextran sulfate sodium (DSS) is a heparin polysaccharide, whose overuse would cause many adverse effects, such as stiff and painful joints and loss of hair. It is crucial to search after a rapid and accurate approach for the determination of DSS in the clinical treatment and diagnosis. Regrettably, there are few literatures about analytical methods for detecting DSS at present. In this research, a sensitive and selective method for detecting DSS based on the hydrosoluble perylene diimide (PDI) derivative was established in pure aqueous solution. The sensing mechanism and performance of PDI-PdEC were systematically investigated by ultraviolet and fluorescence spectroscopy. Non-covalent interactions between DSS and PDI-PdEC, like π-π stacking, electrostatic and hydrophobic interaction, promote the aggregation of PDI-PdEC and form supramolecular aggregates, which realize the sensitive and rapid detection of DSS in aqueous system. The detection limit for DSS is as low as 5.51 ng/mL and the linear range is 20–500 ng/mL. Furthermore, this probe was triumphantly applied in the detecting of DSS in serum. To the best of our knowledge, this is the first fluorescent probe for detecting DSS in aqueous media. We consider that our study will not only broaden the range of applications of perylene diimide fluorescent sensors, but also provide valuable reference for the design of new sensors for the rapid determination method of DSS.

Molecular Dynamic Simulation Analysis on the Inclusion Complexation of Plumbagin with β-Cyclodextrin Derivatives in Aqueous Solution.

Stable encapsulation of medically active compounds can lead to longer storage life and facilitate the slow-release mechanism. In this work, the dynamic and molecular interactions between plumbagin molecule with β-cyclodextrin (BCD) and its two derivatives, which are dimethyl-β-cyclodextrin (MBCD), and 2-O-monohydroxypropyl-β-cyclodextrin (HPBCD) were investigated. Molecular dynamics simulations (MD) with GLYCAM-06 and AMBER force fields were used to simulate the inclusion complex systems under storage temperature (4 °C) in an aqueous solution. The simulation results suggested that HPBCD is the best encapsulation agent to produce stable host–guest binding with plumbagin. Moreover, the observation of the plumbagin dynamic inside the binding cavity revealed that it tends to orient the methyl group toward the wider rim of HPBCD. Therefore, HPBCD is a decent candidate for the preservation of plumbagin with a promising longer storage life and presents the opportunity to facilitate the slow-release mechanism.

The Curious Case of Aqueous Warfarin: Structural Isomers or Distinct Excited States?

Warfarin is a potent anti-coagulant drug and is on the World Health Organization's List of Essential Medicines. Additionally, it displays fluorescence enhancement upon binding to human serum albumin, making warfarin a prototype fluorescent probe in biology. Despite its biological significance, the current structural assignment of warfarin in aqueous solution is based on indirect evidence in organic solvents. Warfarin is known to exist in different isomeric forms-open-chain, hemiketal, and anionic forms-based on the solvent and pH. Moreover, warfarin displays a dual absorption feature in several solvents, which has been employed to study the ring-chain isomerism between its open-chain and hemiketal isomers. In this study, our pH-dependent experiments on warfarin and structurally constrained warfarin derivatives in aqueous solution demonstrate that the structural assignment of warfarin solely on the basis of its absorption spectrum is erroneous. Using a combination of steady-state and time-resolved spectroscopic experiments, along with quantum chemical calculations, we assign the observed dual absorption to two distinct π → π* transitions in the 4-hydroxycoumarin moiety of warfarin. Furthermore, we unambiguously identify the isomeric form of warfarin that binds to human serum albumin in aqueous buffer.

Self-Diffusion of Fullerene С60 Derivatives in Aqueous Solutions and Suspensions of Erythrocytes According to Pulsed Field Gradient NMR Data

Self-Diffusion of Fullerene С60 Derivatives in Aqueous Solutions and Suspensions of Erythrocytes According to Pulsed Field Gradient NMR Data

Understanding the electro-catalytic effect of benzene ring substitution on the electrochemical oxidation of aniline and its derivatives using BDD anode: Cyclic voltammetry, bulk electrolysis and theoretical calculations

The use of boron doped diamond (BDD) films in environmental applications has been extensively proved. This electrocatalytic material produces higher concentrations of free‑hydroxyl radicals on its surface, favoring a complete mineralization of many organic pollutants. Although efficient degradation levels are achieved using BDD films, effects such as the chemical structure of the contaminant, waste by-products, oxidants produced, weak/strong surface interactions and bulk reactions influence the electro/chemical catalytic reactions as well as on the effectiveness of the process. In this frame, this study aims to investigate the effect of benzene ring substitution on the electrochemical oxidation of aniline and its derivatives using BDD anode. To do that, the electrochemical behavior of aniline, nitro and chloro‑aniline derivatives in aqueous solution on BDD anode using cyclic voltammetry and bulk electrolysis was examined as well as their environmental elimination was explained by quantum mechanics (QM) calculations. The results clearly allowed associating the experimental measurements to theoretical estimations to comprehend the catalytic relationship between the molecular electronic properties of aniline and its derivatives and their elimination from water.

Study of Silver(I) Complex Formation with Some Thiourea Derivatives in Aqueous Solution

The equilibrium processes of the formation of mononuclear and some binuclear silver(I) complexes with thiourea, N-acetylthiourea, thiosemicarbazide, N-phenylthiourea, and N,Nʹ-diphenylthiourea at 25°C and I = 0.11 M. (0.01 M HNO3 + 0.1 M NaNO3) in aqueous solution were studied by potentiometry method with a silver electrode. The stability constants of the complexes were determined. The stability of mononuclear complexes is almost identical for all the ligands, except for complexes with acetylthiourea, for which it is lower.

One‐pot Synthesis of 2‐Amino‐4H‐chromenes Derivatives in Aqueous Solution of Choline Hydroxide

Abstract2‐Amino‐4H‐chromenes have showed broad bioactivities and attracted great attention in synthetic chemistry. Here, the aqueous solution of choline hydroxide was found to be an efficient catalytic system for the one‐pot synthesis of 2‐amino‐4H‐chromenes under room temperature. Various aldehydes, malononitrile and phenols could be converted to the corresponding 2‐amino‐4H‐chromenes smoothly with good to excellent isolated yields. This catalytic system had high chemo‐selectivity with biocompatible catalyst in green solvents, water. Its operation and work‐up procedures were very simple, and importantly, the target compounds could be obtained from simple centrifugation and washing procedures, no column purification was needed. In addition, the catalytic system involving choline hydroxide and water could be easily reused for at least five cycles with high activity. The above advantages made this catalytic system promising in the industrial production of 2‐amino‐4H‐chromenes.

On the use of the spectral luminescent method for studying acid–base equilibria of uracil derivatives in aqueous solutions

The effect of pH on fluorescence parameters (spectral composition, intensity Ifl, and quantum yield φ) of thymine (T), 5-fluorouracil (FU) and 6-aminouracil (AU) have been investigated in aqueous solutions. As found, there is the regularity of the changes in the spectral composition, intensity, and quantum yields of uracil fluorescence depending on pH. The constants of the acid–base equilibria of uracils (pKa) determined by the fluorescence titration method are: 9.9 (T), 8.0 (FU), and 9.1 (AU) at 298 K. These pKa1 values satisfactorily agree with the previous estimates obtained by independent experimental or quantum chemical methods. The possibilities of the spectral fluorescence method for the quantitative description of the acid–base equilibria of uracils depending on the fluorescent features of the pyrimidinedione and its conjugate base are discussed.

Determination of the complexation parameters of L-asparagine with some biologically active pyridine derivatives in aqueous solutions from calorimetric results

Thermodynamic functions (lgK, ΔcG, ΔcH, ΔcS) were determined by solution calorimetry for the complex formation process of L-asparagine in its zwitterionic form with pharmacologically active ligands, such as pyridoxine, nicotinic acid, isonicotinic acid and picolinic acid in aqueous solutions at 298.15 K. It was found that the complexation affinity of L-asparagine to the pyridine derivatives follows the order picolinic acid < isonicotinic acid < nicotinic acid < pyridoxine. The influence of the presence of hydrophilic substitutes and isomerism of ligands on the stability of amino acid complexes and their thermodynamic quantities was discussed.