Gelation of the organic liquid electrolytes and the conductivities as gel electrolytes

The gelation of multi-component solvent mixtures with lithium salts was investigated in the presence of gelator 4, 4′bis(stearoylamino)diphenyl ether (BSDE). Ordered structures can be formed by non-covalent interactions in both miscible and non-miscible solvent mixtures. In a non-miscible solvent mixture, there was a soluble competition for BSDE, which can be explained by the different polarities of the solvents. The presence of lithium salt in the solvent mixtures seems to not affect the microscopic morphologies of the aggregates. TEM and SEM images of the gels indicated that BSDE aggregated and self-assembled into flexual, wrinkled and interconnected sheets in the solvent mixtures. These sheet-like aggregates are different from the fibril-like aggregates formed in single component solvents as reported previously. The ion conductivity of the organogels formed by these solvent mixtures confirms that the three-dimensional network does not affect the ions diffusion in the large interconnected liquid domains. The organogels of solvent mixtures containing lithium salts exhibit high conductivities which are in the range of 10⁻¹–10⁻² S cm⁻¹ at room temperature, and in the range of 10⁻³–10⁻⁴ S cm⁻¹ at −40 °C.     

Low-molecular-weight gelators based on Nα-acetyl-Nε-dodecyl-L-lysine and their amphiphilic gelation properties

A simple amphiphilic low-molecular-weight gelator based on L-lysine, N^α-acetyl-N^ε-lauroyl-L-lysine (1), its alkali metal salts [Na (2) and K (3)], and two-component gelators [1 and 2 and 1 and 3] were synthesized. Compound 1 had a good hydrogelation ability that formed a pure water gel at 2 g L^?1 (0.2 wt.%) and a saline gel at 4 g L^?1 (0.4 wt.%). Two-component compounds were able to form hydrogels in aqueous solutions containing alkali metal and alkali earth metal ions in addition to pure water and saline. Although 1 formed organogels in a few organic solvents, two-component compounds also functioned as a good organogelator. The FT-IR study indicated that the driving forces for the formation of supramolecular gels were hydrogen-bonding and hydrophobic interactions. Furthermore, the thermal properties of the hydrogels are discussed.     

Chiral separation of trans-stilbene oxide through cellulose acetate butyrate membrane

An enantioselective membrane was prepared using cellulose acetate butyrate as a membrane material. The flux and permselective properties of membrane using 50% ethanol solution of (R,S)-trans-stilbene oxide as feed solution were studied. The top surface and cross-section morphology of the resulting membrane were examined by scanning electron microscopy. The resolution of over 92% enantiomeric excess was achieved when the enantioselective membrane was prepared with 15 wt % cellulose acetate butyrate and 30 wt % N,N-dimethylformamide in the casting solution of acetone, 10 °C temperature of water bath for the gelation of the membrane, and the operating pressure and the feed concentration of the trans-stilbene oxide were 3 kgf/cm² and 5.2 mmol/L, respectively. Since the cellulose acetate butyrate contained a large amount of asymmetric carbons on the backbone structure, it was possible to form helical structure, this was considered to be the reason for the enantioselectivity of the membrane.     

Low molecular weight organogelators derived from threefold symmetric tricarbamates

A group of new low molecular weight organogelators based on threefold symmetric tricarbamate were synthesized and characterized. The tricarbamates with long alkyl chains were able to gelate a wide range of polar and nonpolar organic solvents such as acetonitrile and cyclohexane, generally at concentrations lower than 20 g/L. The best organogel formation was obtained using a threefold symmetric tricarbamate in n-dodecane, in which a sufficiently transparent gel was formed at the critical gelation concentration 1 g/L. Intermolecular hydrogen bonding by the tricarbamate in a nonpolar solvent benzene-d₆ was indicated by ¹H NMR spectra. Its maximum UV absorption was 11 nm higher in chloroform than in n-dodecane, and this red shift indicated increased conjugation between the benzene core and the carbamate substituents, which confirmed a change in its conformation from nonpolar to polar solvent. The self-assembling behavior of the tricarbamate in dilute solutions was investigated by TEM. Fiber-like networks were observed in a large range of solution concentrations.     

Novel poly (neutral red) nanowires as a sensitive electrochemical biosensing platform for hydrogen peroxide determination

Poly (neutral red) nanowires (PNRNWs) have been synthesized for the first time by the method of cyclic voltammetric electrodeposition using porous anodic aluminum oxide (AAO) template and were examined by scanning electron microscopy (SEM) and transmission electron microscope (TEM). Moreover, horseradish peroxidase (HRP) was encapsulated in situ in PNRNWs (denoted as PNRNWs–HRP) by electrochemical copolymerization for potential biosensor applications. The PNRNWs showed excellent efficiency of electron transfer between the HRP and the glassy carbon (GC) electrode for the reduction of H₂O₂ and the PNRNWs–HRP modified GC electrode showed to be excellent amperometric sensors for H₂O₂ at −0.1 V with a linear response range of 1 μM to 8 mM with a correlation coefficient of 0.996. The detection limit (S/N = 3) and the response time were determined to be 1 μM and <5 s and the high sensitivity is up to 318 μA mM⁻¹ cm⁻².     

Novel amphiphilic triblock copolymer based on PPDO,PCL, and PEG: Synthesis,characterization, and aqueous dispersion

Amphiphilic triblock copolymer, poly(p-dioxanone-co-caprolactone)-block-poly(ethylene oxide)-block-poly(p-dioxanone-co-caprolactone) (PPDO-co-PCL-b-PEO-b-PPDO-co-PCL) was synthesized by ring opening polymerization (ROP) of p-dioxanone and ɛ-caprolactone initiated through the hydroxyl end of poly(ethylene glycol) (PEG) in the presence of stannous 2-ethyl hexanoate [Sn(oct)₂] as a catalyst. Polymerization and structural features of the polymers were analyzed by different physicochemical techniques (GPC, ¹H NMR, ¹³C NMR, FT-IR, DSC and TGA). The splitting of ¹H NMR resonance at δ 2.3 and δ 4.1 ppm reveals the random copolymerization. Polymeric nanoparticles were prepared in phosphate buffer (pH 7.4) by co-solvent evaporation technique at room temperature (25 °C). Existence of hydrophobic domains as cores of the micelles were characterized by ¹H NMR spectroscopy and further confirmed with fluorescence technique using pyrene as a probe. Critical micelle concentration (CMC) of the polymer in phosphate buffer (pH. 7.4) was decreased from 2.3 × 10⁻³ to 7.6 × 10⁻⁴ g/L with the fraction of PCL. Polymeric nanoparticles observed by atomic force microscopy (AFM) were uniform and spherical, with smooth textured of around 50–30 nm diameter. Dynamic light scattering (DLS) and electrophoretic light scattering (ELS) measurements showed a monodisperse size distribution of around 113–90 nm hydrodynamic diameters and negative zeta (ζ) potential (−4 to −14 mV), respectively. The investigations for the polymeric nanoparticles in aqueous medium showed that the composition of the hydrophobic segment of amphiphilic block copolymer makes a significant influence on its physicochemical characteristics.     

Synthesis and application of some novel fluorescent heterocyclic disperse dyestuffs based on phenothiazine on polyester

A series of novel heterocyclic disperse dyestuffs derived from phenothiazine were prepared by standard reactions from phenothiazine as the starting material. Phenothiazine was nitrated and oxidized then reduced to obtain synthesized disperse dyestuffs. The reaction conditions were varied in order to obtain optimal yields for each stage of the preparation to obtain the corresponding derivative and final disperse dyestuffs. All intermediates and disperse dyestuffs were purified and characterized by DSC, FTIR, ¹H NMR, ¹³C NMR, elemental analysis and UV–Visible spectroscopic techniques. The molar extinction coefficients (ε), wavelengths of maximum absorption (λ_max) and solvatochromism effects were studied in solvents as toluene, acetone and N,N-dimethylformamide (DMF). Results represented that the dyestuffs had extinction coefficients of 2011–28189 L mol⁻¹ cm⁻¹, wavelengths of maximum absorption of 448–475 nm in acetone and positive solvatochromism by changing solvent from toluene to DMF. The disperse dyestuffs were applied to locally manufactured polyester fibers and their dyeing properties were investigated. Results showed that the buildup of dyestuffs was acceptable and dyed fibers had very good heat and wash fastness and medium light fastness on polyester fibers.     

A general method for the synthesis of enantiopure aliphatic chain alcohols with established absolute configurations. Part 1. Application of the MαNP acid method to acetylene alcohols

A method using (S)-(+)-2-methoxy-2-(1-naphthyl)propionic acid 1 (MαNP acid) has been applied to acetylene alcohols 4–14 to determine their absolute configurations by ¹H NMR anisotropy and/or X-ray crystallography. Diastereomeric MαNP esters prepared from racemic acetylene alcohols and (S)-(+)-MαNP acid 1 were easily separable by HPLC on silica gel. From the ¹H NMR anisotropy Δδ data of separated diastereomeric MαNP esters {Δδ = δ (R,X) − δ(S,X) = δ(2nd fr.) − δ(1st fr.)}, the absolute configurations of the first eluted esters were determined. This MαNP acid method has been successfully applied to various acetylene alcohols 4–12 and 14. In the case of MαNP esters 21b, 24a, and 26a, their absolute configurations were unambiguously determined by X-ray crystallography, which confirmed the absolute configuration assignments performed by ¹H NMR anisotropy. These acetylene alcohol MαNP esters can serve as key intermediates for the synthesis of enantiopure aliphatic chain alcohols with established absolute configurations as described in Part 2 of this series.     

Solid-state high-resolution NMR studies on spin fluctuation associated with valence tautomerism of metal–benzoquinone system: Cobalt complex in the stable and meta-stable phases

Equilibrium between low-spin [Co^III(SQ)(Cat)(N–N)] and high-spin [Co^II(SQ)₂(N–N)] redox isomers, where SQ is semiquinonate (charge: −1, spin: 1/2), Cat is catecholate (charge: −2, spin: 0) and N–N is chelating nitrogen donor ligand, respectively, is a representative valence tautomeric phenomenon. To elucidate independently the spin state of the cobalt ion and that of benzoquinone-derived ligands in the solid state, we measured ¹³C MAS NMR spectrum of 3,5-di-t-butyl-1,2-benzoquinone and ²H MAS NMR spectrum of deuterated 2,2′-bipyridine for [Co(3,5-di-t-butyl-1,2-benzoquinone)₂(2,2′-bipyridine)] · x(C₆H₅CH₃) and its deuterated analogue in a temperature range of 200–350 K. Irreversible change of an effective magnetic moment μ_eff of a virgin sample was observed around 370 K due to a partial loss of crystal solvent and a change of crystal structure, whereas the sample annealed at 390 K showed a crystal structure different from the reported one and a reversible change of μ_eff, which is ascribed to equilibrium between Co(III)-form (S = 1/2) and Co(II)-form (S = 3/2). Based on the shifts and the number of NMR peaks for the annealed sample, we concluded that (1) interconversion between redox isomers occurs faster than NMR time scale (>10⁴ s⁻¹) in the solid state, (2) intraconversion between SQ and Cat in Co(III)-form also occurs much faster than 5 × 10⁴ s⁻¹ even at 198 K and (3) electron spins on SQ ligands in Co(II)-form are quenched probably due to a strong antiferromagnetic coupling between the two SQ ligands. The enthalpy and the entropy of the interconversion were estimated to be 17 kJ/mol and 54 J/(K mol), respectively. For the virgin metastable phase, SQ and Cat were clearly distinguished by ¹³C MAS NMR spectrum. The solid-state high-resolution NMR spectrum is useful to detect independently the change of spin states of benzoquinone-derived radical and metal ion.     

Synthesis,characterization and electrocatalytic properties of carbon nitride nanotubes for methanol electrooxidation

In this paper, carbon nitride nanotubes (CNNTs) have been synthesized with porous anodic aluminum oxide membrane as template by the thermal polymerization of sol–gel precursors for the first time. Field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, elemental analysis and X-ray photoelectron spectroscopy were applied to characterize the morphology and composition of the as-prepared nanotubes. The electrocatalytic activity and stability of CNNTs, towards methanol electrooxidation in 0.5 mol/dm³ H₂SO₄ solutions containing 1 mol/dm³ CH₃OH are presented at room temperature.     

Thermo‐ and Acid‐Responsive Photochromic Spironaphthoxazine‐Containing Organogelators

A series of photochromic spironaphthoxazine derivatives has been designed, synthesized, and characterized by using ¹H NMR spectroscopy, FAB mass spectrometry, and elemental analysis. Their photophysical and photochromic behavior have been investigated. Two of the compounds (G¹²‐en‐SA‐SO and G¹⁶‐en‐SA‐SO) have been shown to be capable of forming stable thermoreversible organogels in organic solvents, tested by the “stable‐to‐inversion of a test tube” method. Addition of p‐toluenesulfonic acid was found to induce the formation of stable organogels at concentrations below that of the critical gelation concentration (c.g.c.), with a concomitant change in color from colorless to purple. Transmission electron microscopy and scanning electron microscopy of the xerogels showed typical fibrous structures in the micrometer scale. The activation parameters for the bleaching reaction of G⁸‐en‐SA‐SO in the solution state and G¹⁶‐en‐SA‐SO in the gel state have been determined in ethanol through kinetic studies at various temperatures. The results showed that the rate of the bleaching reaction in the gel state was much slower than that in the solution state.     

Enhancement of visible light-induced gelation of photocurable gelatin by addition of polymeric amine

We evaluated the effect of an electron donor on photogelation of photocurable gelatin, which is gelatin partially derivatized with eosin (eosin–gelatin). As an electron donor, ascorbic acid, 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA), and three kinds of radical polymerized amines such as poly(N,N-dimethylacrylamide-co-2-(N,N-dimethylamino)ethyl methacrylate) (poly(DMAAm-co-DMAEMA)), poly(N,N-dimethylacrylamide-co-3-(N,N-dimethylamino)propyl acrylamide) (poly(DMAAm-co-DMAPAAm)), and poly(3-(N,N-dimethylamino)propyl acrylamide) (polyDMAPAAm) were examined. Upon photo irradiation at the wavelength ranging from 400 to 520 nm with low illumination intensity (7.7 × 10³ lx), no gel was obtained from 20 wt.% of a viscous aqueous solution of the eosin–gelatin even by adding with ascorbic acid. Whereas in the presence of monomeric amine (DMAEMA, 3.0 wt.%), gel formation occurred by radical recombination between eosin groups incorporated into the gelatin. When the polymeric amines were added to the eosin–gelatin solution, gelation was markedly enhanced due to cross-linking of gelatins through polymeric amines in addition to direct bonding between gelatins. An increase in amine unit content in the polymeric amines resulted in increased gel yield and reduced swelling degree of water. In the presence of polyDMAPAAm, almost all gelatins were converted relatively rigid hydrogel. Application for a topical hemostatic glue was preliminary performed in rat injured model. A rat liver injured in laparotomy was coated with the aqueous eosin–gelatin solution containing polyDMAPAAm. Upon irradiation, the solution was immediately converted to a swollen gel, which was tightly adhered to the liver tissue and concomitantly hemostasis was completed with little tissue damage.     

Partial least squares modeling of combined infrared, 1H NMR and 13C NMR spectra to predict long residue properties of crude oils

Research has been carried out to determine the potential of partial least squares (PLS) modeling of mid-infrared (IR) spectra of crude oils combined with the corresponding ¹H and ¹³C nuclear magnetic resonance (NMR) data, to predict the long residue (LR) properties of these substances. The study elaborates further on a recently developed and patented method to predict this type of information from only IR spectra. In the present study, PLS modeling was carried out for 7 different LR properties, i.e., yield long-on-crude (YLC), density (D_LR), viscosity (V_LR), sulfur content (S), pour point (PP), asphaltenes (Asph) and carbon residue (CR). Research was based on the spectra of 48 crude oil samples of which 28 were used to build the PLS models and the remaining 20 for validation. For each property, PLS modeling was carried out on single type IR, ¹³C NMR and ¹H NMR spectra and on 3 sets of merged spectra, i.e., IR + ¹H NMR, IR + ¹³C NMR and IR + ¹H NMR + ¹³C NMR. The merged spectra were created by considering the NMR data as a scaled extension of the IR spectral region. In addition, PLS modeling of coupled spectra was performed after a Principal Component Analysis (PCA) of the IR, ¹³C NMR and ¹H NMR calibration sets. For these models, the 10 most relevant PCA scores of each set were concatenated and scaled prior to PLS modeling. The validation results of the individual IR models, expressed as root-mean-square-error-of-prediction (RMSEP) values, turned out to be slightly better than those obtained for the models using single input ¹³C NMR or ¹H NMR data. For the models based on IR spectra combined with NMR data, a significant improvement of the RMSEP values was not observed neither for the models based on merged spectra nor for those based on the PCA scores. It implies, that the commonly accepted complementary character of NMR and IR is, at least for the crude oil and bitumen samples under study, not reflected in the results of PLS modeling. Regarding these results, the absence of sample preparation and the straightforward way of data acquisition, IR spectroscopy is preferred over NMR for the prediction of LR properties of crude oils at site.     

Water-induced physical gelation of organic solvents by N-(n-alkylcarbamoyl)-L-alanine amphiphiles

A series of amino acid-based gelators N-(n-alkylcarbamoyl)-L-alanine were synthesized, and their gelation abilities in a series of organic solvents were tested. No gelation was observed in pure solvents employed. All the amphiphilic molecules were found to form stable organogels in the solvents in the presence of a small amount of water, methanol, or urea. The volume of solvent gelled by a given amount of the gelator was observed to depend upon the volume of added water. The gelation behavior of the amphiphiles in a given solvent containing a known volume of water was compared. The effects of chirality and substitution on the acid group on the gelation ability were examined. Although the corresponding N-(n-tetradecylcarbamoyl)-DL-alanine was found to form only weak organogel in pure solvents, the achiral amphiphilic compound N-(n-tetradecylcarbamoyl)-β-alanine, however, did not form gel in the absence of water. The methyl ester of N-(n-tetradecylcarbamoyl)-L-alanine was also observed to form gels in the same solvents, but only in the presence of water. The organogels were characterized by several techniques, including (1)H NMR, Fourier transform IR, X-ray diffraction, and field emission scanning electron microscopy. The thermal and rheological properties of the organogels were studied. The mechanical strength of the organogel formed by N-(n-tetradecylcarbamoyl)-DL-alanine was observed to increase upon the addition of water. It was concluded that water-mediated intermolecular hydrogen-bonding interaction between amphiphiles caused formation of supramolecular self-assemblies.     

Structural characterization,molecular dynamics,dielectric and spectroscopic properties of tetrakis(pyrazolium) bis(μ2-bromo-tetrabromobismuthate(III)) dihydrate, [C3N2H5]4[Bi2Br10]·2H2O

The structure of [C₃N₂H₅]₄[Bi₂Br₁₀]·2H₂O, (PBB) was determined by single crystal X-ray diffraction at 100 K. It crystallizes in the monoclinic space group C2/m, with a = 12.992(4) Å, b = 16.326(5) Å, c = 8.255(3) Å, β = 108.56°(3), V = 1659.9(9) Å³ and Z = 2. The structure consists of discrete binuclear [Bi₂Br₁₀]⁴⁻ anions, ordered pyrazolium cations and water molecules. The crystal packing is governed by strong N–H⋯O and weak O–H⋯Br hydrogen bonds. A sequence of structural phase transitions in PBB was established on the basis of differential scanning calorimetry and dilatometric studies. Two reversible first-order phase transitions were found: (I → II) at 381/371 K (on heating/cooling) and (II → III) at 348/338 K. Dielectric response near both phase transitions is characteristic of crystals with the “plastic-like” phases. Over the phase III a low frequency dielectric relaxator is disclosed. The possible molecular motions in the PBB compound are characterized by the ¹H NMR studies. The infrared spectra of polycrystalline compound in the temperature range 300–380 K are reported for the region 4000–400 cm⁻¹. The observed spectral changes through the structural phase transition III → II are attributed to an onset of motion both of the pyrazolium cations and water molecules.     

Synthesis and structure of 1-benzyl-5-amino-1H-tetrazole in the solid state and in solution: Combining X-ray diffraction, 1H NMR,FT–IR,and UV–Vis spectra and DFT calculations

Compound 1-benzyl-5-amino-1H-tetrazole (BAT) was synthesized and characterized by ¹H NMR, FT–IR, and UV–Vis spectroscopies and elemental (CHNS) analysis. The crystal structure was further elucidated by single-crystal X-ray diffraction. Density functional theory (DFT) calculations with B3LYP and PBE1PBE functionals of the BAT were performed to provide structural and spectroscopic information and guide spectral assignments. The compound crystallizes in monoclinic primitive system space group P2(1)/c with a = 14.91 Å, b = 5.12 Å, c = 11.19 Å, V = 852 Å³, Z = 4, R₁ = 0.0428 at 298 K. The structure exhibits intermolecular hydrogen bonds of the type N–H(amino)···N(tetrazole). Simultaneous hydrogen bonds between amino···tetrazole and tetrazole···amino establish a dimeric intermolecular structure, whereas another hydrogen bond between the remaining H atom of the amino group and the other N atoms of the tetrazole ring extends the structure into another dimension. The crystal structure of BAT is properly reproduced by DFT calculations only when a dimeric or tetrameric model is employed in the modeling. Comparisons between experimental and calculated spectral properties suggest that the monomeric form of BAT is dominant in aprotic, polar, hydrogen-bonding solvents, such as DMSO and DMF.     

The experimental and DFT studies of 1,3-dimethyl-2-[4-chloro-styryl]-benzimidazolium iodide

1,3-Dimethyl-2-[4-chloro-styryl]-benzimidazolium iodide (1) was synthesized and characterized by X-ray diffraction, ¹H NMR, MS, IR, UV–vis spectra and elemental analysis. The crystals are monoclinic, space group P2₁/c, with a = 12.507(3) Å, b = 7.3259(19) Å, c = 36.705(9) Å, V = 3358.9(15) Å³, and Z = 4 (at 296(2) K). Crystal stacking scheme indicates the face-to-face π?π aromatic stacking interactions. Molecular geometries, frequencies, IR, ¹H NMR and UV–vis were calculated at DFT/TD-DFT level using two hybrid exchange–correlation functionals, B3LYP and PBE1PBE. The stability of the molecule arising from hyperconjugative interaction and charge delocalization had been analyzed using natural bond orbital (NBO) analysis. These calculations on (1) provide deep insight into its electronic structure and properties.     

Highly selective solid-phase extraction of trace Pd(II) by murexide functionalized halloysite nanotubes

The originality on the high efficiency of murexide modified halloysite nanotubes as a new adsorbent of solid phase extraction has been reported to preconcentrate and separate Pd(II) in solution samples. The new adsorbent was confirmed by Fourier transformed infrared spectra, X-ray diffraction, scanning electron microscope, transmission electron microscope and N₂ adsorption–desorption isotherms. Effective preconcentration conditions of analyte were examined using column procedures prior to detection by inductively coupled plasma-optical emission spectrometry (ICP-OES). The effects of pH, the amount of adsorbent, the sample flow rate and volume, the elution condition and the interfering ions were optimized in detail. Under the optimized conditions, Pd(II) could be retained on the column at pH 1.0 and quantitatively eluted by 2.5 mL of 0.01 mol L^?1 HCl–3% thiourea solution at a flow rate of 2.0 mL min^?1. The analysis time was 5 min. An enrichment factor of 120 was accomplished. Common interfering ions did not interfere in both separation and determination. The maximum adsorption capacity of the adsorbent at optimum conditions was found to be 42.86 mg g^?1 for Pd(II).The detection limit (3σ) of the method was 0.29 ng mL^?1, and the relative standard deviation (RSD) was 3.1% (n = 11). The method was validated using certified reference material, and has been applied for the determination of trace Pd(II) in actual samples with satisfactory results.     

Synthesis and properties of 5,10,15,20-tetra(4-lauroylimidophenyl)porphyrin and its metal complexes

Transition metal complexes of 5,10,15,20-tetra(4-lauroylimidophenyl)porphyrin TLPPM [M = Mn(Cl), Fe(Cl), Co, Ni, Cu, Zn] have been synthesized and characterized by means of elemental analyses, UV–VIS spectra, infrared spectra, ¹H NMR spectra, molar conductance, differential scanning calorimetry (DSC), polarized optical microscopy (POM), cyclic voltammetry, luminescence spectra and surface photovoltage spectroscopies. The porphyrin ligand shows liquid crystalline behaviour, and it exhibits a high phase transition temperature 182 °C and a broad mesophase temperature span, 88 °C. The oxidation and reduction properties of the compounds were investigated by cyclic voltammetry. The photovoltaic properties and charge transfer process of the compounds were investigated by surface photovoltage spectroscopy (SPS) and electric field-induced surface photovoltage spectroscopic (EFISPS) techniques, which revealed that all the compounds are p-type semiconductors. Quantum yields of the S₁ → S₀ fluorescence were measured at room temperature. These studies will contribute to further choice and application of the liquid crystals.     

Anthracene-based macrocyclic fluorescent chemosensor for selective sensing of dicarboxylate

An anthracene-based macrocyclic receptor has been designed and synthesized for selective recognition of 1,4-phenylenediacetate (K_a = 3.34 × 10⁵ M^?1). The macrocycle binds 1,4-phenylenediacetate selectively at the charged sites of the receptor with a concomitant increase in fluorescence of anthracene. The interaction properties of the macrocycle were evaluated by ¹H NMR, UV–vis and fluorescence spectroscopic methods.