Solutions In Organic Solvents Research Articles

Red-Light-Photosensitized NO Release and Its Monitoring in Cancer Cells with Biodegradable Polymeric Nanoparticles.

The role of nitric oxide (NO) as an "unconventional" therapeutic and the strict dependence of biological effects on its concentration require the generation of NO with precise spatiotemporal control. The development of precursors and strategies to activate NO release by excitation in the so-called "therapeutic window" with highly biocompatible and tissue-penetrating red light is desirable and challenging. Herein, we demonstrate that one-photon red-light excitation of Verteporfin, a clinically approved photosensitizer (PS) for photodynamic therapy, activates NO release, in a catalytic fashion, from an otherwise blue-light activatable NO photodonor (NOPD) with an improvement of about 300 nm toward longer and more biocompatible wavelengths. Steady-state and time-resolved spectroscopic and photochemical studies combined with theoretical calculations account for an NO photorelease photosensitized by the lowest triplet state of the PS. In view of biological applications, the water-insoluble PS and NOPD have been co-entrapped within water-dispersible, biodegradable polymeric nanoparticles (NPs) of mPEG-b-PCL (about 84 nm in diameter), where the red-light activation of NO release takes place even more effectively than in an organic solvent solution and almost independently by the presence of oxygen. Moreover, the ideal spectroscopic prerequisites and the restricted environment of the NPs permit the green-fluorescent co-product formed concomitantly to NO photorelease to communicate with the PS via Förster resonance energy transfer. This leads to an enhancement of the typical red emission of the PS offering the possibility of a double color optical reporter useful for the real-time monitoring of the NO release through fluorescence techniques. The suitability of this strategy applied to the polymeric NPs as potential nanotherapeutics was evaluated through biological tests performed by using HepG2 hepatocarcinoma and A375 melanoma cancer cell lines. Fluorescence investigation in cells and cell viability experiments demonstrates the occurrence of the NO release under one-photon red-light illumination also in the biological environment. This confirms that the adopted strategy provides a valuable tool for generating NO from an already available NOPD, otherwise activatable with the poorly biocompatible blue light, without requiring any chemical modification and the use of sophisticated irradiation sources.

Stable and low-threshold photon upconversion in nondegassed water by organic crystals.

Photon upconversion (UC) is a technology that converts lower-energy photons (longer wavelength light) into higher-energy photons (shorter wavelength light), the opposite of fluorescence. Thus, UC is expected to open a vast domain of photonic applications that are not otherwise possible. Recently, UC by triplet-triplet annihilation (TTA) between organic molecules has been studied because of its applicability to low-intensity light, although the majority of such studies have focused on liquid samples in the form of organic solvent solutions. To broaden the range of applications, solid-state UC materials have been an active area of research. We recently developed air-stable, high-performance molecular UC crystals that utilize a stable solid-solution phase of bicomponent organic crystals. This article begins with a brief overview of previous challenges in developing and improving solid-state TTA-UC materials. Then, we briefly review and explain the concept as well as advantages of our molecular solid-solution UC crystals. We applied these organic crystals for the first time to a water environment. We observed blue UC emission upon photoexcitation at 542nm (green-yellow light) and then measured the excitation intensity dependence as well as the temporal stability of the UC emission in air-saturated water. In nondegassed water, these organic crystals were stable, functioned with a low excitation threshold intensity of a few milliwatts per square centimeter, and exhibited high photo-irradiation durability at least over 40h; indicating that the developed organic crystals are also viable for aqueous conditions. Therefore, the organic crystals presented in this report are expected to extend the domain of UC-based photonic applications in practical water systems including in vivo diagnostic, clinical, and therapeutic applications.

Analysis of tetrabromobisphenol A and bisphenol A in plant sample-method optimization and identification of the derivatives.

Tetrabromobisphenol A (TBBPA) is the most abundant brominated flame retardant and bisphenol A (BPA) is often identified as the metabolic product of TBBPA. Both of them are highly bioconcentrated and show serious biological toxicity. In this study, an analytical method was optimized to simultaneously determine TBBPA and BPA in plant samples. Moreover, the uptake and metabolism of TBBPA in maize were investigated through hydroponic exposure experiment. The whole analysis procedure included ultrasonic extraction, lipid removal, purification by solid-phase extraction cartridge, derivatization, and detection by GC/MS. Optimizations were conducted for each pretreatment step above. After improvement, methyl tert-butyl ether (MTBE) was chosen as the extraction solvent; the lipid removal was conducted by repartition between organic solvent and alkaline solution. The best suitable pH condition is 2-2.5 for the inorganic solvent before used for further purification by HLB and silica column with the optimized elute solvent of acetone and mixtures of acetone and hexane (1:1), respectively. The recoveries of TBBPA and BPA spiked in maize samples were 69±4% and 66±4% with the relative standard deviation less than 5%, respectively, for the entire treatment procedure. Limits of detections were 4.10 ng/g and 0.13 ng/g for TBBPA and BPA in plant samples, respectively. In the hydroponic exposure experiment (100 μg/L, 15 d), the concentrations of TBBPA in maize cultivated in pH 5.8 and pH 7.0 Hoagland solutions were 1.45 and 0.89 μg/g in roots and 8.45 and 6.34 ng/g in stems, while they were all below the detection limit for leaves, respectively. The distribution of TBBPA in different tissues was as the following order: root>>stem>leaf, illustrating the accumulation in the root and the translocation to the stem. The uptake variations under different pH conditions were attributed to the change of TBBPA species, now that it shows greater hydrophobicity at lower pH condition as a kind of ionic organic contaminant. Monobromobisphenol A and dibromobisphenol A were identified as metabolisms products of TBBPA in maize. The efficiency and simplicity of the method that we proposed characterize its potential application as a screening tool for environmental monitoring and contribute to a comprehensive study of the environmental behavior of TBBPA.

Old Antibiotics Can Learn New Ways: A Systematic Review of Florfenicol Use in Veterinary Medicine and Future Perspectives Using Nanotechnology.

Florfenicol is a broad-spectrum bacteriostatic antibiotic used exclusively in veterinary medicine in order to treat the pathology of farm and aquatic animals. It is a synthetic fluorinated analog of thiamphenicol and chloramphenicol that functions by inhibiting ribosomal activity, which disrupts bacterial protein synthesis and has shown over time a strong activity against Gram-positive and negative bacterial groups. Florfenicol was also reported to have anti-inflammatory activity through a marked reduction in immune cell proliferation and cytokine production. The need for improvement came from (1) the inappropriate use (to an important extent) of this antimicrobial, which led to serious concerns about florfenicol-related resistance genes, and (2) the fact that this antibiotic has a low water solubility making it difficult to formulate an aqueous solution in organic solvents, and applicable for different routes of administration. This review aims to synthesize the various applications of florfenicol in veterinary medicine, explore the potential use of nanotechnology to improve its effectiveness and analyze the advantages and limitations of such approaches. The review is based on data from scientific articles and systematic reviews identified in several databases.

Synthesis and properties of water‐dispersible polyurethanes based on various diisocyanates and PEG as the hard segment

AbstractWater‐dispersible polyurethanes are a greener alternative to polyurethane solutions in organic solvents. Various polyurethane materials were prepared by a two‐step polymerization procedure of polypropylene glycol with Mn of 2000, polyethylene glycol with Mn of 1500, and diisocyanates with different chemical structures, aliphatic, cycloaliphatic and aromatic. It was investigated how the diisocyanate structure affected the molecular morphology, contact angle measurements, and physical characteristics of water‐dispersible polyurethanes. FTIR and NMR measurements showed a close relationship between the intermolecular connections and the hard segment structure, mainly of the diisocyanate used. Also, the polarized light method showed that the presence of the PEG in the hard domain improved aggregation through physical interactions due to its structural flexibility and mobility. These water‐dispersible polyurethanes can assure the use of these polyurethane materials in a broad range of applications with increased environmental protection.

Drug Release from Carrier Systems Comprising Meloxicam Crystals Formed by Impregnation-Evaporation

The impregnation of poorly water-soluble drug onto the surface of a suitable pharmaceutical excipient, used as a hydrophilic carrier, can lead to the preparation of systems with improved dissolution properties due to the separation of drug crystal particles on the carrier surface. For this purpose, a method based on impregnation of hydrophilic matrix by the hydrophobic poorly water-soluble drug Meloxicam (MX) solution in volatile organic solvent was used. After the evaporation of the solvent, the method resulted in coverage of the carrier surface by drug crystals. The influence of the amount and concentration of the impregnating solution on the formed MX crystal size and the dissolution rate was evaluated. Firstly, the impregnation forming crystals on the planar surface was studied and the MX maximum dissolution flux from that surface was determined. The optimum preparation method was further used to produce a volume of impregnated granules. The dissolution performance of the granules was evaluated, and the dissolution kinetics was described by mathematical models. The polymorphic modification of impregnated API and influence of impregnated drug amount on the hydrophilic carrier surface coverage were considered. From the results of this work, it is clear that the impregnated drug amount and the number of impregnations cycles can be optimized to achieve maximum drug release rate.

Hierarchical Aggregation in a Complex Fluid─The Role of Isomeric Interconversion.

There is an ever-increasing body of evidence that metallic complexes involving amphiliphic ligands do not form normal solutions in organic solvents. Instead, they form complex fluids with intricate structures. For example, the metallic complexes may aggregate into clusters, and these clusters themselves may aggregate into superclusters. To gain a deeper insight into the mechanisms at play, we have used an improved force field to conduct extensive molecular dynamics simulations of a system composed of zirconium nitrate, water, nitric acid, tri-n-butyl phosphate, and n-octane. The important new finding is that a dynamic equilibrium between the cis and trans isomers of the metal complex is likely to play a key role in the aggregation behavior. The isolated cis and trans isomers have similar energies, but simulation indicates that the clusters consist predominantly of cis isomers. With increasing metal concentration, we hypothesize that more clustering occurs and the chemical equilibrium shifts toward the cis isomer. It is possible that such isomeric effects play a role in the liquid-liquid extraction of other species and the inclusion of such effects in flow sheet modeling may lead to a better description of the process.

Liquid-phase microextraction of aromatic amines: hollow fiber–liquid-phase microextraction and parallel artificial liquid membrane extraction comparison

Aromatic amines (AA) are carcinogenic compounds that can enter the human body through many sources, one of the most important being tobacco smoke. They are excreted with the urine, from which they can be extracted and measured. To that end, hollow fiber-liquid-phase microextraction (HF-LPME) and parallel artificial liquid membrane extraction (PALME) were optimized for the analysis of representative aromatic amines, as alternatives to liquid–liquid extraction (LLE). Relevant extraction parameters, namely organic solvent, extraction time, agitation speed, and acceptor solution pH, were studied, and the two optimized techniques—HF-LPME: dihexyl ether, 45 min, 250 rpm, and pH 1; PALME: undecane, 20 min, 250 rpm and pH 1—were compared. Comparison of the optimized methods showed that significantly higher recoveries could be obtained with PALME than with HF-LPME. Therefore, PALME was further validated. The results were successful for nine different AA, with regression coefficients (R2) of at least 0.991, limits of detection (LOD) of 45–75 ng/L, and repeatability and peak area relative standard deviations (RSD) below 20%. Furthermore, two urine samples from smokers were measured as proof of concept, and 2-methylaniline was successfully quantified in one of them. These results show that PALME is a great green alternative to LLE. Not only does it use much smaller volumes of toxic organic solvents, and sample—enabling the study of samples with limited available volumes—but it is also less time consuming and labor intensive, and it can be automated.Graphical

How Do Liquid-Junction Potentials and Medium Polarity at Electrode Surfaces Affect Electrochemical Analyses for Charge-Transfer Systems?

The importance of electrochemical analysis for charge-transfer science cannot be overstated. Interfaces in electrochemical cells present certain challenges in the interpretation and the utility of the analysis. This publication focuses on: (1) the medium polarity that redox species experience at the electrode surfaces that is smaller than the polarity in the bulk media and (2) the liquid-junction potentials from interfacing electrolyte solutions of different organic solvents, namely, dichloromethane, benzonitrile, and acetonitrile. Electron-donor-acceptor pairs of aromatics with similar structures (i.e., 1-naphthylamine and 1-nitronaphthalene, 10-methylphenothiazine and 9-nitroanthracene, and 1-aminopyrene and 1-nitropyrene) serve as redox analytes for this study. Using the difference between the reduction potentials of the oxidized donors and the acceptors eliminates the effects of the liquid junctions on the analysis of charge-transfer thermodynamics. This analysis also offers a means for evaluating the medium polarity that the redox species experience at the surface of the working electrode and the effects of the liquid junctions on the measured reduction potentials. While the liquid-junction potentials between the dichloromethane and acetonitrile solutions amount to about 90 mV, for the benzonitrile-acetonitrile junctions, the potentials are only about 30 mV. The presented methods for analyzing the measured electrochemical characteristics of donors and acceptors illustrate a means for improved evaluation of the thermodynamics of charge-transfer systems.

Structure-emission relationship of some coumarin laser dyes and related molecules: Prediction of radiative energy dissipation and the intersystem crossing rate constants.

Dye lasers are commonly used in optical investigation because their solutions in organic solvents deliver tunable, coherent emissions. They exhibit intense fluorescence owing to some specific spectroscopic characteristics. One drawback of the laser dyes is that it shows excessive triplet-state losses (TSLs.) The lack of theoretical predictions of fluorescence rates, intersystem crossing (ISC), and phosphorescence in laser dyes prompted us to report on the predicted rates of radiative and nonradiative transitions of some laser dyes. Structural engineering by some substituents influencing the simulated rates of coumarin laser dye derivatives for an efficient operation was investigated. The NH2 functional group renders the coumarin 120 more fluorescents with reduced TLS than the other investigated materials. Tailoring new efficient laser dyes can be achieved guided by the calculated rates of emission and nonradiative processes.

High Molecular Weight AB-Polybenzimidazole and Its Solutions in a Complex Organic Solvent: Dissolution Kinetics and Rheology.

AB-polybenzimidazole (ABPBI) dissolution kinetics in an eco-friendly complex acid-free solvent based on dimethyl sulfoxide (DMSO), methanol and KOH, and the rheological behavior of their solutions are investigated. The optimal component ratio of solvent providing the complete ABPBI dissolution is determined. Methanol containing dissolved KOH contributes to the creation of a single-phase superbasic medium, which accelerates and improves the polymer solubility in a mixture with DMSO, significantly reducing the viscoelasticity of the resulting solution. The optimum methanol content is up to 60 wt.% related to DMSO. The polymer dissolution rate increases by 5 times in this composition. It found the polymer concentration of 9% is close to the dissolution limit due to the strong solution structuring, which is probably associated with an increase in the amount of water released during the KOH-methanol-DMSO interactions. As a result, the conditions for obtaining high concentrated solutions in a complex, mainly organic solvent for fiber spinning are developed. The viscoelastic properties of solutions are measured in the concentration range of 1-9% at temperatures of 20-50 °C. The flow activation energy for 7 and 9% solutions decreases by 1.5 and 2.3 times, respectively, as the content of methanol in the complex solvent increases from 10 to 60%.

DIFFERENT APPROACH TO THE MECHANISM OF ADHESION OF SURFACE TREATED WITH TRICHLOROISOCYANURIC ACID SOLUTION RUBBER AND POLYURETHANE ADHESIVE JOINTS

ABSTRACT Although the effects produced by the surface treatment of rubber with organic solvent solutions of trichloroisocyanuric acid (TCI) leading to improved adhesion to polyurethane (PU) adhesive have been established, the mechanism of adhesion involved is still unclear. In this study, the reaction of TCI species on the rubber surface with the PU adhesive leading to the formation of chemical bonds was proposed as the relevant mechanism of adhesion. As a model, TCI was added to polyurethane adhesive (PU + TCI), and a polyurethane film was immersed in TCI solution (PU − TCI), their surface, structural, and viscoelastic properties were monitored for different times. The formation of chemical bonds between the polyurethane chains and TCI species derived from the solid TCI crystals on the rubber surface during bonding formation, and the crosslinking/hardening of the PU surface were evidenced. The reaction with TCI species increased the surface energy on the PU, mainly the polar component, similar surface energies were obtained in both PU + TCI and PU − TCI after 7 days. The enhanced surface energies on the PU that reacted with TCI were ascribed to the creation of new C–Cl and C=O species, their percentages were higher on PU + TCI than on PU − TCI surface. On the other hand, new N–H stretching and carbonyl species were produced; this indicated that TCI species interacted with the hard segments. Furthermore, the crystallization peaks in PU + TCI and PU − TCI at higher temperatures and lower enthalpies than in PU indicated the disruption of the interactions between the soft segments. Therefore, the structural changes in the PU caused by reaction with TCI species affected their degree of phase separation and viscoelastic properties. The addition of solid TCI to the PU caused a noticeable degradation and hardening, the extent of degradation was more marked by increasing the time, this led to lower mechanical properties.

Preparation of Microfiltration Hollow Fiber Membranes from Cellulose Triacetate by Thermally Induced Phase Separation.

For the first time, self-standing microfiltration (MF) hollow fiber membranes were prepared from cellulose triacetate (CTA) via the thermally induced phase separation (TIPS) method. The resultant membranes were compared with counterparts prepared from cellulose diacetate (CDA) and cellulose acetate propionate (CAP). Extensive solvent screening by considering the Hansen solubility parameters of the polymer and solvent, the polymer’s solubility at high temperature, solidification of the polymer solution at low temperature, viscosity, and processability of the polymeric solution, is the most challenging issue for cellulose membrane preparation. Different phase separation mechanisms were identified for CTA, CDA, and CAP polymer solutions prepared using the screened solvents for membrane preparation. CTA solutions in binary organic solvents possessed the appropriate properties for membrane preparation via liquid–liquid phase separation, followed by a solid–liquid phase separation (polymer crystallization) mechanism. For the prepared CTA hollow fiber membranes, the maximum stress was 3–5 times higher than those of the CDA and CAP membranes. The temperature gap between the cloud point and crystallization onset in the polymer solution plays a crucial role in membrane formation. All of the CTA, CDA, and CAP membranes had a very porous bulk structure with a pore size of ∼100 nm or larger, as well as pores several hundred nanometers in size at the inner surface. Using an air gap distance of 0 mm, the appropriate organic solvents mixed in an optimized ratio, and a solvent for cellulose derivatives as the quench bath media, it was possible to obtain a CTA MF hollow fiber membrane with high pure water permeance and notably high rejection of 100 nm silica nanoparticles. It is expected that these membranes can play a great role in pharmaceutical separation.

The improvement of dispersity, thermal stability and mechanical properties of collagen fibers by silane modification: an exploration for developing new leather making technology

The effect of hydrophobic modification on the performances of collagen fibers (CFs) was investigated by using silane coupling agents with different alkyl chains as hydrophobic modifiers. It was found silane could be easily grafted onto CF surface through covalent bonds under 5% water content. This modification led to the transformation of surface wettability of CF from hydrophilic to hydrophobic. Interestingly, the change of surface wettability resulted in substantial improvement of the modified CF properties, presenting well dispersity of collagen fibers, higher thermal stability and enhanced mechanical properties in comparison with natural CF. The degree of improvement mainly depended on the length of alkyl chain in silane. Longer alkyl chain produced strong hydrophobicity and subsequently more superior performances of the modified CF. When the length of alkyl chain increased to 18 carbon atoms, the modified CF possessed durable superhydrophobicity even exposed to aqueous solutions of different pH, UV, and organic solvents, and had excellent thermal and mechanical properties like leather fibers. In general, this work clearly revealed that the properties of CF are closely and positively related to the hydrophobicity, which is suggestive in developing new leather making technology.Graphical

Wear-Resistant Hydrophobic Coatings from Low Molecular Weight Polytetrafluoroethylene Formed on a Polyester Fabric

The paper presents a comparative analysis of the surface structure and morphology of hydrophobic coatings formed on a polyester fabric from various types of low molecular weight tetrafluoroethylenes by a new method. The low molecular weight compounds used include: ultrafine polytetrafluoroethylene of the FORUM® trademark prepared through thermo-gas-dynamic decomposition of industrial polytetrafluoroethylene waste, and tetrafluoroethylene telomers, synthesized by radiation-chemical initiation from fluoromonomers in acetone, butyl chloride and trimethylchlorosilane solutions. The formation of coatings consists in deposition of low molecular weight tetrafluoroethylenes from solutions in supercritical carbon dioxide and organic solvents. The contact angle and water absorption of the polyester fabric with coatings containing the specified water-repellents are determined. The resistance of the achieved effect to various types of wear—washing, dry cleaning and abrasionis evaluated. The hydrophobic properties of the fabric are found to be affected by the coating plasticity characterized by the stiffness coefficient. The importance of this indicator to targeted changes in fabric properties is proved. All the considered types of low molecular weight polytetrafluoroethylene (PTFE) are shown to be effective water-repellents for the polyester fabric.

Evaluation of deep eutectic solvent pretreatment towards efficacy of enzymatic saccharification using multivariate analysis techniques

In this paper, deep eutectic solvent (DES) pretreatment of lignocellulosic biomass was analysed using principal component analysis (PCA) and partial least square (PLS) methods to determine correlations between the pretreatment process variables and assess their significance level. The analysis was conducted on the dataset containing 103 experimental observations and 32 variables. Both PCA and selected PLS model (M4) had substantial prediction power and prediction relevance, as exhibited by their good cumulative explained variance (R2cum, 0.787) and cumulative predicted variance (Q2cum, 0.524) for six principal components of PCA model, and explained variance of independent variable (R2Xcum, 0.781), explained variance of dependent variable (R2Ycum, 0.803) and cumulative predicted variance (Q2cum, 0.776) for the best PLS model. The results of PCA and PLS analyses revealed that the most significant variables for DES pretreatment were severity factor , temperature, type of antisolvent, particle size, agitation intensity and type of hydrogen bond donor (HBD) of the DES. The use of carboxylic acid and hydroxy acid HBD was associated with higher glucose yield and shorter duration of saccharification . The models also showed that enzymatic saccharification was more efficient when organic solvent or inorganic salt solution was used as antisolvent for lignocellulose regeneration. Usage of water as antisolvent was associated with reduced glucose yield during saccharification. Another notable outcome of this work was that intensive stirring during pretreatment had negative effect on glucose yield due to the shear thickening properties of DESs. This work provided a systematic analysis of DES pretreatment process of lignocellulosic biomass using PCA and PLS methods that allowed better understanding of the factors affecting the pretreatment process. • Multivariate analysis of PCA and PLS were used to study DES pretreatment. • The models had high predictive accuracy with good R2Xcum, R2Ycum, Q2cum values. • SF, antisolvent, particle size, agitation and HBD had great impact on pretreatment. • Long p-time, low t, AS (organic, inorganic), HBD (–COOH, –OH) favored pretreatment. • High agitation intensity and large particle size led to poor pretreatment.

The water effect on the spectral properties of porphyrin sensitizers

Porphyrin derivatives, which played a key role in photodynamic therapy (PDT), exhibit different photophysical and photochemical properties in aqueous solution of organism and organic solvents. Limited by the poor water-soluble, present studies on porphyrin derivatives covered the real performance in aqueous solution of organism. In this study, the water effect on the properties of porphyrin derivatives was investigated by the water proportion evolution spectroscopy. The variation in fluorescence intensities of hematoporphyrin monomethyl ether (HMME) in solvents with different proportions of methanol and water were analyzed. Corresponding absorption spectra were measured, and the absorption intensity at the excitation wavelength is found to be unchanged. Utilizing Perrin-Jablonski energy level structure, as well as related rate equations, the fluorescence variation is supposed to be origin from both the decreased intersystem crossing rate (kISC) and increased non-fluorescence transition rate (knF). The decrease of kISC is induced by the raise of the lowest vibrational energy level of the first singlet excited state (S1), which can be verified by the blue-shift of the absorption and fluorescence spectra. The increase of the knF was caused by the high-energy vibrations in aqueous solutions. The fluorescence lifetimes are also measured, which consist with our analysis. Our research not only uncovered the water effect on the properties of HMME, but also provided a way to insight the PDT behavior of porphyrin derivatives in the aqueous solution of organism.

Structure-performance relationships of four lysosomal markers used for the imaging of HT-29 cancer cells and a cellular model of lysosomal storage disease (Niemann-Pick C)

Four new BODIPY derivatives with a potential tendency to aggregation have been synthesized and characterized by means of NMR techniques, mass spectrometry and UV–Vis/fluorescence spectroscopies. The objective of this study is to determine which structural factors of the new molecules influence most notably the cellular uptake, intracellular location and fluorescence imaging abilities. The behaviour of the compounds in organic solvent and aqueous solution has been studied. In organic solvents (DMSO, ethanol and toluene), the photophysical properties of the new molecules are almost independent of the building blocks used to synthesize the pendant moieties (non-fluorogenic parts). In an aqueous environment (HEPES Buffer Solution, pH 7), at 10 μM, three of the compounds (1, 2 and 4) tend to form weakly emissive nanoparticles (DLS determination) whereas one of them (3) remains soluble and highly fluorescent. In the nanomolar range of concentration, all the compounds are aqueous soluble. The cellular internalisation of the compounds (10 nM) has been studied in human colon adenocarcinoma HT-29 cells by means of flow cytometry and confocal laser scanning microscopy. All the compounds were uptaken by HT-29 cells, but notably molecule 3 (made with lysine as a building block) was the one displaying a higher loading and a more clear lysosomal location (0.88 Pearson's correlation coefficient in colocalization assays using lysosomal fluorescent probe LysoTracker DND-99). Molecule 3 also performed better than the valine derivative 1 as a lysosomal marker in a cellular model (human adrenal carcinoma SW13/cl.2 cells) of lysosomal storage disease (Niemann-Pick type C).

Rational design of an AIE-active metal-organic framework for highly sensitive and portable sensing nitroaromatic explosives

Herein, we report a new metal-organic framework with an AIE ligand (H4TCPP = 2,3,5,6-tetra-(4-carboxyphenyl)pyrazine) and Mg2+ ions, that is, [Mg2(H2O)4TCPP]·DMF·5CH3CN (Mg-TCPP, TCPP = tetra-(4-carboxyphenyl)pyrazine) for detection of nitroaromatic explosives. Due to the coordination effect and restricted intramolecular rotation, Mg-TCPP exhibits bright blue light. As a fluorescent sensor, Mg-TCPP exhibits high selectivity and sensitivity for sensing 2,4,6-trinitrophenol (TNP) by quenching behaviors with the Stern-Volmer quenching constant (KSV) of 3.63×105 L/mol and achieves the low limit of detection of 25.6 ppb, which is beyond most of the previously reported fluorescent materials. Notably, the portable Mg-TCPP films are prepared and it can be used for rapid and sensitive TNP detection in a variety of environments including organic solvent and aqueous solution. Moreover, TNP vapor can be detected within 3 min by naked eye and the film could be regenerated under simple solvent cleaning.

Influence of structural and solvation factors on spectral properties and lipophilicity of iodo- and bromosubstituted zinc(II), cadmium(II) and boron(III) dipyrromethenates

The paper presents a comparative analysis of the effect of structural and solvation factors on the spectral characteristics and lipophilicity of a series of iodo- and bromosubstituted zinc(II), cadmium(II), and boron(III) dipyrromethethenes. The studied chelates [ZnL2], [CdL2], and [BF2L] fluoresce in organic solvents solutions with a quantum yield from 1% to 50%, depending on their molecular structure and the solvent nature. It was noted that the high sensitivity of [ZnL2] and [CdL2] fluorescence to the presence of electron- and proton-donor solvents are due to the additional coordination of M···Solv or acid-base interactions ≥ N⋯H–Solv. It was found that [BF2L] have up to 1.5 times higher lipophilicity compared to [ZnL2] with the same functional substitution. The hydrophobicity of 4,4′-dibromosubstituted luminophores is noticeably higher than that of 5,5′-dibromosubstituted analogs. The obtained results indicate the prospects for the development of new effective fluorescent markers and sensors of medium polarity based on halogen-substituted dipyrromethenates.