Solvents Of Different Polarity Research Articles

Photodynamics of azaindoles in polar media: the influence of the environment.

We have studied the relaxation dynamics of a family of azaindole (AI) structural isomers, 4-, 5-, 6- and 7-AI, by steady-state and time-resolved methods (fs-transient absorption and fluorescence up-conversion), in solvents of different polarity. The measurements in aprotic solvents show distinctive fluorescence yields and excited state lifetimes among the isomers, which are tuned by the polarity of the medium. Guided by simple TD-DFT calculations and based on the behavior observed in the isolated species, it has been possible to address the influence of the environment polarity on the relaxation route. According to the obtained picture, the energy of the nπ* state, which is strongly dependent on the position of the pyridinic nitrogen, controls the rate of the internal conversion channel that accounts for the distinctive photophysical behavior of the isomers. On the other hand, preliminary measurements in protic media (methanol) show a very different photodynamical behavior, in which the anomalous measured fluorescent patterns are very likely the result of reactive channels (proton transfer) triggered by the electronic excitation.

Bio-oil from coconut fibers: fractionation by preparative liquid chromatography for phenols isolation

The great potential of bio-products generated from agro-industrial residues from the biomass processing, as is the case with the green coconut fibers (Cocos nucifera L. var. dwarf), makes Brazil stand out in the field of transformation of these residues, mainly due to its high biodiversity and favorable climatic conditions. In this work, residual green coconut fibers were used in the production of bio-oil by pyrolysis. The bio-oil was fractionated using preparative liquid chromatography (PLC) in silica using solvents of different polarities: hexane, hexane/toluene, toluene/dichloromethane, dichloromethane/acetone, and methanol. Bio-oil and its fractions were analyzed by gas chromatograph /quadrupole mass spectrometer (GC/qMS). The concentration of each compound was carried out by multiplying the percentage area of the corresponding peak by the mass yield of the respective fraction. PLCof bio-oil increased the number of compounds identified by about 170% compared to the original bio-oil (non-fractionated), besides allowing the isolation of nonpolar compounds (mostly hydrocarbons) from polar compounds (mainly phenols, aldehydes, and ketones). Anotheradvantage of PLC was the increase in the number of hydrocarbons identified in the fractions, as opposed to the crude bio-oil analysis. Among the major compounds, phenols can be highlighted, besides furfural derivatives and hydrocarbons, which indicates the potential use of bio-oil mainly for industrial purposes.

Antibacterial Activity and Proposed Mode of Action of Extracts from Selected Zimbabwean Medicinal Plants against Acinetobacter baumannii.

Acinetobacter baumannii was identified by the WHO as a priority pathogen in which the research and development of new antibiotics is urgently needed. Plant phytochemicals have potential as sources of new antimicrobials. The objective of the study was to determine the antibacterial activity of extracts of selected Zimbabwean medicinal plants against A. baumannii and determine their possible mode of action. Extracts were prepared from the leaves of the eight plants including the bark of Erythrina abyssinica using solvents of different polarities. Antibacterial activity was evaluated using the microbroth dilution method coupled with the in vitro iodonitrotetrazolium colorimetric assay. The effect of the extracts on membrane integrity was determined by quantifying the amount of protein and nucleic acid leaked from the cells after exposure to the extracts. The effects of the extracts on biofilms were investigated. Toxicity studies were carried out using sheep erythrocytes and murine peritoneal cells. Seven out of eight evaluated plant extracts were found to have antibacterial activity. The Combretum apiculatum acetonie (CAA) extract showed the highest inhibitory activity against A. baumannii with a minimal inhibitory concentration of 125 µg/mL. The minimum inhibitory concentration (MIC) of the CAA extract caused a protein leakage of 32 µg/mL from A. baumannii. The Combretum apiculatum acetonie (CAA), C. apiculatum methanolic (CAM), Combretum zeyheri methanolic (CZM), and Erythrina abyssinica methanolic (EAM) extracts inhibited A. baumannii biofilm formation. The EAM extract was shown to disrupt mature biofilms. The potent extracts were nontoxic to sheep erythrocytes and mouse peritoneal cells. The activities shown by the extracts indicate that the plants have potential as sources of effective antibacterial and antibiofilm formation agents against A. baumannii.

Tenability on schiff base Hydrazone derivatives and Frontier molecular orbital

Context hydrazine compounds based on 1,3,5-triazine were synthesised and their molecular structures were characterised by elemental analysis, Electronic, IR and 1H NMR spectra. The spectral behaviour of the newly prepared compounds in organic solvents of different polarities was extensively studied and correlated to the molecular structure. In this study, 1,3,5-Triazine derivatives (L1, L6, L7, L8) have been subjected to theoretical studies using the Semi-empirical PM3 quantum chemical method. The physical-chemical properties of some Hydrazone derivatives are determined theoretically. The molecular geometry, the Highest Occupied Molecular Orbital (HOMO) - Lowest Unoccupied Molecular Orbital (LUMO) energy gap, molecular hardness (η), ionisation energy (IE), Electron affinity and total energy were analysed, and applications as biological effects were done.

Qualitative and Quantitative Study of the Bioactive Compounds in Arbutus Unedo L. from the Ait Ammart Area in Northern Morocco

The qualitative and quantitative analysis aims to identify secondary metabolites, including phenolic compounds, alkaloids, terpenes, and other substances commonly referred to as phytochemicals. Qualitative phytochemical screening relies on color and precipitation tests that indicate the presence or absence of a metabolite, while quantitative analysis accounts for the quantity or concentration of the bioactive compounds contained within the extracts. During the quantitative determination of the total content of phenolics and flavonoids present in the extracts, we used the conventional soxhlet extraction (SE) method with solvents of different polarities. The purpose of this study is to ascertain the impact of solvents with varying polarity on both the extraction yield and phytochemical composition of A. unedo leaves. The findings indicate that yield and polyphenol content vary from one extract to another. Thus, the ethanol extract (EEAU) showed the highest percentage extraction yield (15.23%) and the highest total phenolic content (TPC) with 122.82 ± 5.42 mg GAE/gext. In contrast, the dichloromethane extract (EDAU) had the lowest extraction yield (1.76%), while the methanol extract (EMAU) showed the highest total flavonoid content (TFC) with 45.8 ± 1.3 mg QE/gext. Generally, these data provide information into the phytochemical content of various extracts of the plant growing in the Ait Ammart region. These extracts contain several bioactive substances that will be useful in the formulation of pharmaceutical products for a variety of diseases and may have applications in the food industry.

Simulating the Fluorescence of the Locally Excited State of DMABN in Solvents of Different Polarities.

4-(N,N-Dimethylamino)benzonitrile (DMABN) is a luminescent probe that can be used for tracking changes in the surrounding solvent due to the large change in polarity between its ground and excited states. An important characteristic of DMABN is that it exhibits dual fluorescence with two different emission energies that can be monitored, allowing for better characterization of the surrounding system. The first excited state is called the locally excited (LE) state and is characterized by the movement of charge over the conjugated ring structure. In nonpolar solvents and in the gas phase, the fluorescence of DMABN is entirely attributed to the transition from the near-planar LE state. In more polar environments, emission occurs from both the LE and a second excited state, corresponding to a twisted intramolecular charge-transfer (ICT) structure. For the sake of simplicity, this work considers transitions between only the ground and LE state. Molecular mechanical force field models of DMABN in its ground and LE states have been developed to investigate the sensitivity of the LE state to the polarity of the solvent. Both nonpolarizable and polarizable force fields were developed to simulate the molecule in a series of 10 different solvents of different polarities. The calculated Stokes shift of DMABN increases with increasing orientation polarizability of the surrounding solvent, which is the expected trend, as seen in experimental studies.

Simulating the Fluorescence of Di-8-ANEPPS in Solvents of Different Polarity.

Voltage-sensitive fluorescent probes, such as di-8-amino-naphthyl-ethylene-pyridinium-propyl-sulfonate (di-8-ANEPPS), are extremely useful for monitoring the membrane potential in biological and biophysical studies. However, because di-8-ANEPPS is very sensitive to its environment, it can be difficult to distinguish the degree to which a given external factor affects the observed fluorescence. Molecular dynamics simulations based on detailed atomic models make it possible to examine the particular characteristics of the system and predict the effects of the surroundings. Here, the sensitivity of the spectra of di-8-ANEPPS to solvent polarity is investigated by modeling the electronic transition between the ground and excited states using classical molecular mechanical force fields. The absorption and emission of di-8-ANEPPS were simulated in 12 solvents of increasing polarity using nonpolarizable and polarizable force fields. While the computational results and experimental data do not match perfectly, classical Lippert plots of both models show the expected increase of the Stokes shift of di-8-ANEPPS with the orientation polarizability of the surrounding solvent.

Triple B←N Lewis Pair-Functionalized Triazatruxenes with Large Stokes Shifts.

A novel class of multiple B←N Lewis pair-functionalized polycyclic aromatic hydrocarbons with different BR2 groups (R = Cl or Et) directly attached at positions 1, 6, and 11 of triazatruxene was synthesized. The triazatruxene backbone of 4 displays a bowl shape, and its molecular skeleton shows a highly twisted propeller-like structure with C3 symmetry. The introduction of B←N Lewis pairs not only results in a large decrease in the HOMO-LUMO gap but also lowers the LUMO to -3.00 eV. Both compounds show excellent stability with large Stokes shifts of ≤8234 cm-1 and solvatochromic emission in solvents of different polarities.

The effect of substituent position and solvent on thermal Z‒E isomerization of dihydroquinolylazotetrazole dyes: kinetic, thermodynamic, and spectral approaches.

Kinetic and thermodynamic parameters have been investigated for the thermal Z‒E isomerization of dihydroquinolylazotetrazole dyes with alkyl substituents (Me, t-Bu, and Adm) at positions 1 (dyes 2) and 2 (dyes 3) of the tetrazole moiety in two solvents of different polarity, acetonitrile (MeCN) and toluene. The experimental results show crucial dependence of these parameters on a substituent position in the tetrazole moiety and on a solvent. For dyes 2, Eact and ΔH‡ are lower in MeCN than in toluene that results in a high increase in the lifetimes of the Z isomers: from milliseconds in MeCN to minutes in toluene. For dyes 3, the difference in Eact and ΔH‡ in the two solvents is opposite: Eact and ΔH‡ are by more than 20kJmol-1 higher in MeCN, nevertheless, the rate constants for 3 in toluene are comparable with those in MeCN at the ambient temperature and the difference in the behavior is determined by the value of negative entropy of activation. Quantum-chemical calculations of the thermal Z‒E isomerization show the possibility of the process to occur via crossing from the S0 to the thermally induced T1 state. The contribution of this path is highest for 3 in toluene. The analysis of the absorption spectra demonstrates that for the E isomers, the n‒π* and π‒π* transitions are within the long-wavelength absorption band and their positions relative each other are opposite in the solvents: the n‒π* transition is blue-shifted relative to the π‒π* transition in MeCN and is red-shifted in toluene.

Towards nanomaterials with tubular pores: synthesis and self-assembly of bis-pillar[5]arene

Recently, materials obtained using supramolecular chemistry approaches, and, in particular, spatially preorganized macrocyclic compounds, have attracted close attention of the researchers. Pillar[n]arenes are of special interest due to their tubular spatial structure and macrocyclic cavity. A similar tubular structure is retained in the supramolecular packaging of pillar[5]arene crystals, forming pores. In this study, we developed a block synthetic approach for the preparation of bis-pillar[5]arene containing amide groups. The ability of the synthesized bis-pillar[5]arene to form stable self-associates in solvents of different polarity (CHCl3 and CH3OH) was demonstrated by the DLS method. In trichloromethane at concentration of 1·10–3 M, monodisperse associates with average hydrodynamic diameter of 227 nm (PDI = 0.28) are formed; in methanol, stable associates (1·10–6 M) have an average hydrodynamic diameter of 136 nm (PDI = 0.21). The results obtained can be used to create new supramolecular systems, molecular machines, or capture and detect various organic molecules.

Litsea glaucescens Kuth possesses bactericidal activity against Listeria monocytogenes.

Litsea glaucencens Kuth is an aromatic plant used for food seasoning food and in Mexican traditional medicine. Among, L. glaucencens leaves properties, it has proven antibacterial activity which can be used against opportunistic pathogens like Listeria monocytogenes, a foodborne bacteria that is the causal agent of listeriosis, a disease that can be fatal in susceptible individuals. The aim of this work was to investigate the antibacterial activity of L. glaucescens Kuth leaf extracts against L. monocytogenes and to identify its bioactive components. L. glaucences leaves were macerated with four solvents of different polarity (n-hexane, dichloromethane, ethyl acetate, and methanol). To determine the capacity to inhibit bacterial proliferation in vitro, agar diffusion and microdilution methods were used. Next, we determined the minimal bactericidal concentration (MBC). Finally, we determined the ratio of MBC/MIC. Metabolites present in the active methanolic extract from L. glaucescens Kuth (LgMeOH) were purified by normal-phase open column chromatography. The structure of the antibacterial metabolite was determined using nuclear magnetic resonance (1H, 13C, COSY, HSQC) and by comparison with known compounds. The LgMeOH extract was used to purify the compound responsible for the observed antimicrobial activity. This compound was identified as 5,7-dihydroxyflavanone (pinocembrin) by analysis of its spectroscopic data and comparison with those described. The MIC and MBC values obtained for pinocembrin were 0.68 mg/mL, and the ratio MBC/MIC for both LgMeOH and pinocembrin was one, which indicates bactericidal activity. L. glaucences Kuth leaves and its metabolite pinocembrin can be used to treat listeriosis due the bactericidal activity against L. monocytogenes.

Fluorescent probes based on quinoline and naphthidine derivatives with NIR and AIE properties for real-time monitoring mitochondrial viscosity during mitophagy

As a special form of autophagy, mitophagy is a pivotal mechanism governing cellular metabolism and physiology. Viscosity monitoring is an important aspect for real-time visualization of the mitophagy process. Hence, the development of high-performance viscosity probes is crucial for investigating dynamic pathological processes related to mitophagy. This study presents the discovery of mitochondria near-infrared and aggregation-induced emission probes with neutral structure. Probes 1a-1b were connected quinoline/naphthidine malononitrile and coumarin units with a double bond, the absorption maxima were at 433–471 nm; emission maxima were at 605–720 nm with large Stokes shifts of 170–279 nm in solvents of different polarity. As the environmental viscosity increases from 0.89 cP to 856 cP, the fluorescence intensity of probe 1a and probe 1b is enhanced by 418-fold and 769-fold, respectively, which due to the restricted rotation and inhibited twisted intramolecular charge transfer in high viscosity systems. In addition to excellent NIR, hypotoxicity, and mitochondrial targeting capabilities, probes 1a-1b were successfully applied to detect changes in mitochondrial viscosity during starvation or rapamycin-induced mitophagy. These remarkable features make probes 1a-1b as promising candidates for investigating dynamic pathological processes related to mitophagy with significant potential for biological applications.

Identification and quantification of bioactive compounds indifferent extracts of <i>morinda lucida</i> benth (rubiaceae) root using GC–MS analysis

This study aims to analyze and describe the chemical constituents of various crude extracts derived from the root of Morinda lucida Benth (Rubiaceae), an ethnomedicinal plant commonly found in Nigeria. The root of Morinda lucida was dried at room temperature and pulverized into powder. The soxhlet extraction technique was used with solvents of different polarities, namely hexane, chloroform, and methanol, to obtain three distinct extracts. Subsequently, gas chromatography-mass spectrometry analysis was carried out on the extracts. A total of 69 compounds were identified from the different extracts of M. lucida root. The hexane extract had 3 major compounds and 8 minor ones, with diethyl phthalate being the most prominent with 87.10% peak area. The chloroform extract had 24 compounds, with phthalic acid, 2-Ethylhexyl isohexyl ester being the highest with 16.61% peak area. Six of these compounds had more than 5%, while the remaining 18 ranged from 2.50% to 1.00%. The ethanol extract contained 36 compounds, with 6 compounds being greater than 5% and the remaining 30 less than 5%. The highest percentage in the ethanol extract was 2-Pyrrolidinone, 1-methyl-, at 16.05%. In terms of the biological and pharmacology benefits, these chemicals are regarded as crucial. Also, each of the three extracts has a few similarities in their physicochemical properties that can be related to the natural substances that are abundantly found in M. lucida root. The GC-MS analysis of different extracts of M. lucida revealed the presence of several bioactive compounds that have potential therapeutic properties.

OPTIMIZATION OF AFRICAN LEAF EXTRACT CREAM FORMULA (Vernonia amygdalina Del.) AS AN ANTIBACTERIAL Staphylococcus aureus

The use of natural ingredients as active medicinal substances has been developed again, one of which is African leaf extract (Vernonia amygdalina Del.), which is used as an antimicrobial bacterium against Staphylococcus aureus, which causes skin disease. The aim of this study was to compare the antibacterial activity of African leaf extracts and fractions, as well as to optimize the cream preparation formula using a factorial design with a combination of stearic acid, triethanolamine (TEA), and Adeps lanae with the critical parameters of pH, viscosity, spreadability, Franz diffusion, and KBM value. This study used experimental methods to determine the highest antibacterial activity by disc diffusion from extracts and active fractions of African leaves using solvents of different polarities. The extract or fraction with the highest antibacterial activity was formulated using a combination cream of stearic acid, triethanolamine, and adeps lanae. After obtaining the cream formula, physical testing of the cream, penetration test, and antibacterial test using macrodilution were performed, and the most optimal formula was determined using a factorial design. The extract standardization test results met both specific and non-specific parameters. In the disc diffusion antibacterial test, the highest activity was found in the African leaf extract (13.23 ± 0.757 mm) against Staphylococcus aureus bacteria. Variations in cream composition affect pH, viscosity, spreadability, and Franz diffusion...

Qualitative Identification of Secondary Metabolites and Determination of the Toxicity of Extracts Obtained from the Flower of Kalanchoe Pinnata

Kalanchoe pinnata, also known as air leaf or life leaf, is a plant used in traditional medicine in different world regions. In Mexico, it is included in the Atlas de la Medicina Tradicional Mexicana with a wide variety of applications, such as antimicrobial, anti-inflammatory, anticancer, and antihistamine, among others. However, neither a secondary metabolite profile of the flower has been reported nor information on its possible toxicity. The latter is the purpose of this work. A phytochemical profile of extracts with solvents of different polarity (aqueous, methanol, ethanol, and ether) was carried out. In this profile, the structural compounds could be qualitatively determined by chemical reactions, and some changes in coloring or precipitation were observed. The acute toxicity test of the extracts was performed with an aquatic organism, Artemia sp, and a terrestrial organism Eisenia foetida, as well as the evaluation of the antioxidant capacity of the extracts in the organism of Eisenia foetida. The ABTS radical method and TROLOX were applied as synthetic antioxidants for the evaluation of the inhibition percentage. Most important secondary metabolites were qualitatively identified in the extracts of K. pinnata flowers. Mainly in the alcoholic extracts (methanol and ethanol) tannins, alkaloids, and flavonols were found. As mentioned above, they are reported to have toxicological effects. The toxicity and antioxidant activity tests confirm the preliminary results obtained in the identification of secondary metabolites. It is therefore concluded that the flower of Kalanchoe pinnata contains secondary metabolites that may be of great therapeutic interest.

Chemical composition, bioactive compounds, antioxidant activity, and inhibitor alpha-glucosidase enzyme of Sargassum sp.

Sargassum sp. has the potential to be a source of bioactive components. The purpose of this study was to determine the chemical composition, bioactive compounds, antioxidant activity, and α-glucosidase enzyme inhibitory activity of Sargassum sp. extract. The exploratory research method involved extracting Sargassum sp. for 72 h using solvents of different polarities. The chemical composition of Sargassum sp. was analyzed using parameter analysis as well as the identification of phytochemicals and total phenolics. Antioxidant activity was measured using the DPPH method as well as inhibition of α-glucosidase enzyme activity. The chemical composition of Sargassum sp. was found to be 15.67, 17.56, 13.46, 0.6, 57.82, and 13.62% moisture content, ash, protein, fat, carbohydrates (by difference), and total crude fiber, respectively. The bioactive compounds of Sargassum sp. include saponins and phenolic compounds that were extracted with methanol (617.778 GAE/100 g) and ethyl acetate (309.55 GAE/100 g). The antioxidant activity with IC50 value of Sargassum sp. extract successively extracted 648.33 mg/mL of methanol, 864.22 mg/mL of ethyl acetate, and 884 mg/mL of n-hexane. Sargassum sp. extract inhibited the activity of α-glucosidase enzyme methanol extract (9.44–0.35%), n-hexane extract (11.72–0.46%), and ethyl acetate did not. Except for the ethyl-acetate extract, Sargassum sp. extract has antioxidant and enzyme α-glucosidase inhibitor properties.

Influence of anion structure on volumetric properties of dilute binary systems containing carboxylate functioned trihexylammonium ionic liquids in toluene / dodecane

We are actively involved in synthesis of hydrophobic ionic liquids, their volumetric behaviour in various solvents of different polarity and their application in metal ions extraction from water. In continuation of previous work, we are presenting new protic ionic liquids (PILs) containing Trihexylammonium cation and carboxylate anions namely Trihexylammonium propionate [THA][Pro] and Trihexylammonium pentanoate [THA] [Pent]. The simultaneous measurements of densities, ρ along with speeds of sound, u for binary systems of [THA][Pro] and [THA][Pent] in toluene and in dodecane were collected. The measurements were carried out in dilute concentrations range of PILs, at 0.1 MPa and different temperatures from 293.15 K to 328.15 K. The experimental values of densities, ρ and speeds of sound, u, were utilized to obtain calculated values of apparent molar properties: Vϕ (apparent molar volume) and Ks,ϕ (apparent molar isentropic compressibility). It is observed that the apparent molar properties of investigated systems are quite sensitive to variation in temperature, solvent and anion’s structure of PILs. The values of Vϕ and Ks,ϕ increases with each increment in studied temperature and when toluene was replaced by dodecane as a solvent in the system. The each addition of –CH2 group in anion chain of PILs leading to increase Vϕ whereas decrease with concentration of PILs in the binary system. The limiting values of apparent molar volume, Vϕ∞ and apparent molar isentropic compressibility, Kϕ∞ were also reported. The strength of interactions between PIL-PIL and PIL-solvent in studied binary systems was explained by Sk and Sv parameters. The PILs + dodecane systems exhibit greater interaction between PILs and solvent than binary systems of PIL + toluene.

An unique furan/thiophene substituted β-diketonate derivatives bearing triphenylamine with dual-state emission

Traditional β-diketones are rarely used as fluorescent emitters. Here, two novel triphenylamine-modified β-diketonate derivatives containing either a furan or thiophene unit (TPA-DK-O and TPA-DK-S) have been designed, synthesized and fully characterized. Both of the emitters have D-A type configuration, and show abnormal dual-state emissive characters with high quantum efficiency both in dissolved and aggregate state owning to rational design strategy. Additionally, owing to their molecular conformational flexibility and inherent intramolecular charge transfer characteristics, TPA-DK-O and TPA-DK-S show intriguing optical features such as solvatochromism, vicosity-dependent fluorescence and temperature response characteristics. The solvatochromism is derived from the intramolecular charge transfer effect which is confirmed by density functional theory calculation and fluorescence in solvents of different polarities. These unique optical properties of TPA-DK-O and TPA-DK-S are expected to be utilized for detecting local viscosity, polarity of system and temperature sensing. Moreover, the excellent dual-state emissive characters of TPA-DK-O are utilized for chemical sensors and cell imaging. The metal ion detection experiments indicated that TPA-DK-O has a fluorescence response capability to Fe3+ and Mg2+, and has a good linear relationship in the concentration range of 48–800 μM and 0–30 μM for Fe3+ and Mg2+, respectively. The cell incubation experiments shows that TPA-DK-O has low toxicity and good biocompatibility for cells. The cell imaging experiments reveals that TPA-DK-O not only stains and images cells, but also responds to Fe3+ in living cells. Making a contrast between TPA-DK-O and TPA-DK-S, it is found that replacing furan with thiophene in the β-diketonate derivatives showed slight effects on optical properties.

Finding the right balance between tertiary amine steric effect and solvent polarity for the regioselectivity and kinetics of epichlorohydrin acetolysis

AbstractThe asymmetric oxirane ring‐opening reaction leading to the formation of regioisomeric chlorohydrin esters was studied in the reaction series “acetic acid–epichlorohydrin–tetrahydrofuran (nitrobenzene)–trialkylamine” by kinetic methods and FT‐IR spectroscopy. The effect of solvent polarity and the structure of tertiary amines on the regioselectivity and reaction rate were studied. Tertiary amines with comparable basicity but different nucleophilicity and spatial structure were chosen as catalysts. It was shown that in solvents of different polarity, the components of the initial reaction system are present both as hydrogen‐bonded complexes and as individual substances. The reaction orders with respect to acid and amine in solvents of different polarity were established. Correlations between the reaction rate and the parameters of nucleophilicity and structure of amines as well as the polarity of the solvent were established. The regioselectivity of the reaction was studied by 1H NMR spectroscopy using the ratio of regioisomeric reaction products. It was shown that the regioselectivity and rate of catalytic acetolysis of epichlorohydrin are effectively controlled by the structure of tertiary amines and the polarity of the solvent. The scheme of reaction regio‐flows was detailed.

The Surface Modification Strategy Toward Long Wavelength Emission of Carbon Dots

Carbon dots (CDs), as an important carbon-based nanomaterial, have been widely used in fluorescence (FL) detection, bioimaging, photocatalysis, light-emitting devices (LEDs) and many other fields, owing to their excellent optical properties. Regulating the fluorescent properties of carbon dots (CDs) in a controlled manner has been a fundamental research goal. Herein, solvent-dependent CDs (N-CDs) are synthesized through the solvothermal reaction of [Formula: see text]-phenylenediamine (OPD) in ethanol. When N-CDs are dispersed in solvents of different polarities, the emission wavelength only turned 39[Formula: see text]nm red-shift. While, the O-CDs are obtained by modifying the surface of N-CDs with 1,2,4-benzenetricarboxylic acid (TMA). O-CDs show four obvious FL emission peaks in the yellow, orange and red regions at 554[Formula: see text]nm, 604[Formula: see text]nm, 650[Formula: see text]nm and 712[Formula: see text]nm with a tail extending to 750[Formula: see text]nm, even entering into near-infrared-I (NIR-I) region. Thus, according to the special structure of CDs, this work provides a novel donor-[Formula: see text]-acceptor (D-[Formula: see text]-A) strategy for preparing long wavelength emissive CDs. Finally, the N-CDs and O-CDs are successfully applied to cellular imaging.