Compounds In Various Solvents Research Articles

Substituent Effect on the Excited-State Dynamics of Benzo[b]phospholium Salts Investigated Using Picosecond Time-Resolved Spectroscopy

Abstract Photophysical and photochemical properties of 1-methyl-1,2-diphenylbenzo[b]phospholium iodide (diPh-I) and 1-methyl-1,2,3-triphenylbenzo[b]phospholium iodide (triPh-I) were investigated by obtaining time-resolved fluorescence and the transient absorption spectra with sub-picosecond time-resolution. Unusually, fluorescence lifetimes of the triphenyl-substituted compound in various solvents were approximately 100 ps, which is several times shorter than the lifetime of diPh-I. Quantum chemical calculations suggest that the excited-state planarization of the dihedral angle between the benzo[b]phospholium backbone and the phenyl group at Cα possibly contributes to the non-radiative relaxation of triPh-I. In the case of diPh-I, the fluorescence excitation spectrum obtained in dichloromethane depended on the concentration, suggesting that diPh-I forms molecular aggregates in the ground state. The transient absorption spectra of diPh-I showed that, at various concentrations of dichloromethane, the dissociation dynamics of aggregation to produce the monomeric form in the excited state occurred over several picoseconds.

Synthesis and Properties of New 3-Heterylamino-Substituted 9-Nitrobenzanthrone Derivatives

In the present study, new fluorophores based on disubstituted benzanthrone derivatives were designed starting from 9-nitro-3-bromobenzanthrone with nucleophilic substitution of the bromine atom with some secondary cyclic amines. It has been found that this reaction is positively affected by the presence of a nitro group in comparison with 3-bromobenzanthrone. The new compounds exhibit intense absorption and pronounced luminescent properties in various organic solvents. In this regard, their photophysical properties were evaluated with an experimental study of the solvatochromic behavior of the obtained compounds in various solvents. It has recently been found that the addition of an electron-withdrawing nitro group to the benzanthrone core increases its first- and second-order hyperpolarizability. Such dyes can be used in the fabrication of optical limiter devices. Therefore, the developed fluorescent molecules have a potential prospect for extensive application in optoelectronics.

Color-tunable photoluminescent discotic liquid crystal based on perylene – Pentaalkynylbenzene triad

This article describes the design and development of a discotic triad, where perylene is sandwiched between two pentaalkynyl benzene units, linked via a flexible alkyl spacer. The thermotropic liquid crystalline properties of the compound were analyzed by differential scanning calorimetry (DSC), polarising optical microscopy (POM), and wide-angle X-ray diffraction (WXRD) techniques. The compound exhibits columnar oblique (Colob) mesophase that sustains over a significant temperature range. The corresponding electron density map was derived from the intensities observed in the diffraction pattern. The photophysical behaviour of the compound in various solvents of varying polarity has been studied. The compound shows positive solvatochromism with a significant increase in Stoke's shift of around 91 nm between toluene and ethanol. The compound shows high fluorescence quantum yield in non-polar solvents and the lowest in polar solvents. The presented luminescent material with positive solvatochromism will reveal its potential application in fluorescence imaging and the field of optoelectronic organic materials.

Synthesis and photophysical properties of novel nicotinonitrile-based chromophores of 1,4-diarylbuta-1,3-diene series

Facile approach to the synthesis of novel donor-acceptor chromophores containing a 1,4-diarylbuta-1,3-diene system was developed. Optical properties of compounds in various solvents and in solid state were studied. It was found that compounds with unsubstituted and methoxy-substituted phenyl moiety conjugated with 2-amino-6-chloropyridine-3,5-dicarbonitrile acceptor show moderate photoluminescence in powders and weak emission in solution. At the same time, the presence of dimethylamino group in the phenyl moiety led to stronger intramolecular charge transfer (ICT) emission of the chromophore in many organic solvents and amorphous solids as well as to interesting acidochromic properties.

TD-DFT calculations, dipole moments, and solvatochromic properties of 2-aminochromone-3-carboxaldehyde and its hydrazone derivatives.

2-Aminochromone-3-carboxaldehyde (ACC) and its hydrazones (ACMHCA and ACMNPHTCA) with semicarbazide hydrochloride and N-phenylthiosemicarbazide were synthesized and characterized by elemental analysis and spectral studies. The solvatochromic behavior of the title compounds in various solvents showed distinct bathochromic shifts on going from nonpolar to polar solvents, suggesting intramolecular-charge-transfer (ICT) solute-solvent interactions. The ground and excited state dipole moments of ACC, ACMHCA, and ACMNPHTCA were determined experimentally by the solvatochromic shift method using the Bilot-Kawski, Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet functions, and a microscopic Reichardt's solvent polarity parameter (ENT). All the investigated molecules showed a substantial increase in the dipole moment upon excitation to the emitting state. The experimental results were generally consistent with the values obtained by the TD-DFT, B3LYP/6-311G++(d,p) method. Molecular electrostatic potential (MEP) mapping and natural charge and natural bonding orbital (NBO) analysis were performed and the results were discussed. The 1H NMR chemical shifts of the prepared compounds were simulated by the gage independent atomic orbital (GIAO) method and compared with their experimental chemical shift values. The biological activity data were correlated with the frontier molecular orbitals. The photovoltaic behavior of the title compounds showed there was sufficient electron injection.

Novel V-shaped D-π-A-π-D two-photon absorption compounds with large Stokes shifts: Synthesis, optical properties, selective detection of cysteine, and imaging in living cells

The novel V-shaped donor-π-acceptor-π-donor compounds bearing an aldehyde group (1Pip, 2EtO, and 3TEG) were designed, synthesized, and evaluated as the two-photon excited fluorescence probes for the selective detection of cysteine (Cys). Their structures were fully characterized by 1H NMR, 13C NMR, FT-IR, and HRMS. The optical properties of the target compounds in various solvents were studied in details and the time-dependent density functional theory calculations were performed to shed light on their electronic structures. It is found that all of them exhibit large Stokes shifts (6331-10047 cm−1). 1Pip and 3TEG are capable of detecting Cys with high selectivity, good anti-interference ability, and favorable two-photon absorption performance. The limits of detection were determined to be equal to 0.15 μM for 1Pip and 0.73 μM for 3TEG. The possible recognition mechanism was also validated by 1H NMR and HRMS. One- and two-photon fluorescence imaging experiments indicate that 3TEG shows more satisfactory cellular membrane permeability than 1Pip, and it can successfully visualize the endogenous and exogenous Cys in living cells. These results imply that 3TEG has potential as a two-photon fluorescence probe for detecting Cys in biological samples.

Investigation of Thermodynamic Equilibria of Vitamin C in Various Solvents Via Experimental Determination and Model Correlation

Vitamin C plays an essential role in pharmaceutical industry. In general, the solubility of this vitamin in different environments is an important factor for drug development processes. Indeed, solid-liquid equilibrium (SLE) determination of the interested compound in various solvents needs high-precision determination which, however, frequently consumes a lot of time and labor work. In this study, we have developed a simple approach that allows detecting quickly solubility and other important thermodynamic data of dissolution processes. In fact, this approach bases on a combination of the polythermal SLE experimental-determination and the modified Apelblat model. Besides water as a single solvent, different alcohols will be used in this work. For all studied media, dissolution processes are found as endothemic with positive values of enthalpy of dissolution. Furthermore, different alkyl groups have shown influence on the solubility of this compound. Indeed, vitamin C tends to dissolve in water stronger than in ethanol and 2-propanol that relates to polarity properties and hydrogen bonding formation. The results in this contribution gain a good agreement comparing to the reported values from the literature.

Screening of Antibacterial Potential and Phytochemical Analysis of Medicinal Plant Barleria Prionitis

Medicinal and healing proper- ties of herbs are closely related to their chemical components which are classified into some major groups like alkaloids, phenols, terpenoids, steroids, saponins, tannins etc. and getting these chemicals out into the herbal remedy depends upon the solubility of these compounds in various solvents. In the present study aqueous ethanol diethyl ether acetone and methanol extracts of Barleria prionitis leaves were investigated for phyto-chemical and anti-microbial activity. The micro-organisms employed were Staphylococcus aureus Escherichia coli,and Pseudomonas, aeruginosa and Bacillus subtilis. The susceptibility of bacterial strains against the all extracts was determined using the disk diffusion method. The findings showed that potential antibacterial properties of the extracts against the organisms tested. The most susceptible microorganisms were S. aureus, while the least susceptible was E. coli. Aqueous extracts had no activity against the test bacteria the leaves of plant were found abundant with biologically active phytochemicals.

Aggregation induced emission (AIE), selective fluoride ion sensing and lysozyme interaction properties of Julolidinesulphonyl derived Schiff base

A novel colorimetric and fluorescent chemosensor Julolidinesulphonyl derivative (JSJ) based Schiff base was synthesized in a single-step and characterized by several spectral techniques including FT-IR, 1H NMR, mass spectral and UV–vis absorption, fluorescence methods and elemental analysis. The photophysical property of JSJ compound in various solvents and different pH medium was studied, which showed a remarkable change in its absorption and emission spectra. It also exhibited aggregation induced emission (AIE) behavior in THF:water medium through the formation of nanoaggregates, which have been observed from FE-SEM and AFM techniques. In addition, among all the anions such as F−, Cl−, Br−, I−, SCN−, ClO4−, NO3–, H2PO4− ions, the compound JSJ functioned a selective and sensitive colorimetric sensing ability for F− ion in THF by changing the color from yellow to orange. Based on the experimental results, the detection limit range was found to be 0.23 µM. The detection mechanism may be explained by complex formation at low [F−] via hydrogen bonding interaction while deprotonation of compound JSJ took place at high [F−]. Furthermore, the binding property of compound JSJ with various biomolecules such as Lysozyme (LYZ), L-Valine, Tyrosine and Tryptophan was analyzed through UV–vis absorption and emission spectral methods. Molecular docking study, the most commonly used computational tool for calculating binding affinities and predicting binding sites, was also employed to further characterize the binding site of JSJ toward LYZ.

Solubility of Tar Model Compounds in Various Solvents for Tar Removal in a Dual Fluidized Bed Biomass Gasification Process

Production of high quality product gas via biomass steam gasification is a promising technology. However, impurities in the product gas, namely tars, cause problems in the downstream gas processing operations and thus they need to be removed efficiently. Oil scrubbing is an effective solution for tar removal due to its non-polar characteristic which is similar to tar nature. In this research, solubility values of five simulated tar compounds were experimentally investigated for selecting the new scrubbing solvent. The simulated tar compounds investigated represent those found in the dual fluidized bed steam gasification of wood biomass, which are: naphthalene, biphenyl, anthracene, fluoranthene, and pyrene. The scrubbing solvents tested in this research are classified into biodiesels, vegetable oils, and diesel. Biodiesel used are rapeseed methyl ester (RME) and 2 different palm methyl esters (denoted as PME1 and PME2). Vegetable oils are sunflower oil, refined palm oil, Thai rice bran oil, and crude palm oil. All of the solubility tests were performed in the laboratory-scale test-rig at 30, 50, 70, and 80°C. Biodiesels are found to be the effective solvent in dissolving the tar compounds. PME1 shows the similar tar removal performance to RME but is more readily available; therefore, PME1 is chosen to be used as a scrubbing solvent at the Thailand 1 MWel prototype DFB gasifier at Nong Bua district in Nakhon Sawan province, Thailand.

A Study on the Optoelectronic Parameters of 4-Chloromethyl-7-Hydroxy Coumarin in Various Solvents and Concentrations

A coumarin derivative compound, 4-chloromethyl-7-hydroxy coumarin (CMEHC), was synthesized in order to test the concentration and solvent effect on its optical properties. The spectral characterization of this compound was accomplished by FTIR and 1H-NMR techniques. The UV absorption spectra of CMEHC compound in various solvents (THF, DMSO, DMF) were recorded with a UV–VIS spectrophotometer. The optical parameters such as maximum peak position, absorption band edge and direct allowed band gap were reported for these solvents and also various concentrations. The lowest direct allowed band gap was obtained with THF solvent. The absorbance spectra of CMEHC compound were dominant at the near ultraviolet region. The refractive index values were compared with each other using Moss, Ravindra, Herve-Vandamme, Reddy and Kumar-Singh relations.

Antioxidant, Preliminary Phytochemicals, and GC-MS Analysis Reveald Bioactive Potential of Mucuna Pruriens (L.) DC. Leaves and Seeds

The bioactive potential of Mucuna pruriens leaves and seed extracted in five different solvents was evaluated by preliminary phytochemicals, antioxidant and GCMS analysis. The maximum antioxidant activity was found to be 76.96% in seeds extracted with ethanol and 72.50% in leaves extracted with petroleum ether. The preliminary photochemical analysis revealed presence of alkaloids, flavonoids, phenols, tannins, saponins, glycosides, steroids and terpenoids in plant but this detection was solvent dependent. The GCMS profiling reported 24 and 30 bioactive compounds in various solvents leaves and seeds extracts respectively. Among these compounds 20 compounds from leaves and 16 compounds from seeds reported bioactivity. The solvent dependent variations in compounds extraction were also observed. The major relative percentage of compounds in leaves extract includes Benzamide,N-[2-[4-[5-[3,3-dimethyloxiranyl]-4-hydroxy-3-methyl-2-pentenyl]oxy] phenyl]ethyl (15.83%) in petroleum ether, 2-Pentanone,4-hydroxy-4-methyl (35.52%) in acetone, 2-2-Dimethyl butanedioic acid (35.52%) in ethanol and 2-Pentanone.4-methoxy-4-methyl (47.12%) in methanol. While in seed extract Oxalic acid cyclohexyl pentyl ester (13.37%), n-Hexadecanoic acid (11.28%), 9,12-octadecadienoic acid[zz] (39.08%) in petroleum ether, 1-octadecyne (19.08%) in chloroform and 2-Pentanone.4-methoxy-4-methyl (47.64%) in methanol. Most of the compounds has antioxidant, antifungal, hypocholesterolemic, antimicrobial, anti-malarial, anti-diabetic and anti-cancerous properties. Therefore these bioactive compounds validate the use of the plant to cure various ailments by traditional practitioners and bioactive profiling will helpful for researchers to explore its applicability.

Computationally Guided Molecular Design to Minimize the LE/CT Gap in D-π-A Fluorinated Triarylboranes for Efficient TADF via D and π-Bridge Tuning.

In this combined experimental and theoretical study, a computational protocol is reported to predict the excited states in D‐π‐A compounds containing the B(FXyl)2 (FXyl = 2,6‐bis(trifluoromethyl)phenyl) acceptor group for the design of new thermally activated delayed fluorescence (TADF) emitters. To this end, the effect of different donor and π‐bridge moieties on the energy gaps between local and charge‐transfer singlet and triplet states is examined. To prove this computationally aided design concept, the D‐π‐B(FXyl)2 compounds 1–5 were synthesized and fully characterized. The photophysical properties of these compounds in various solvents, polymeric film, and in a frozen matrix were investigated in detail and show excellent agreement with the computationally obtained data. Furthermore, a simple structure–property relationship is presented on the basis of the molecular fragment orbitals of the donor and the π‐bridge, which minimize the relevant singlet–triplet gaps to achieve efficient TADF emitters.

Photophysical and theoretical studies on the solvatochromic effects and dipole moments evaluation of substituted 1-phenyl-3-naphthyl-5- (4-ethyl benzoate)-2-pyrazoline

Abstract The solvatochromic behavior of four 1-phenyl-3-naphthyl-5-(4-ethylbenzoate)-2-pyrazoline with various electron donating and withdrawing substituents on N1-phenyl group were investigated in nonpolar, polar aprotic and protic solvents experimentally and theoretically. The photophysical behavior of pyrazoline in solvents was attributed to the intramolecular charge transfer (ICT) of the compound along with the specific and non-specific interactions with the solvent molecules. On view of the effect of different types of interactions on the optical properties, the Stokes shift of each compound in various solvents was correlated to various parameters such as orientation polarity parameter (Δƒ), microscopic solvent polarity parameter (ET 30), and linear solvation regression of the absorption and emission with specific and non-specific types of interaction. The dipole moments of these compounds in the ground and excited state were also explored and compared using different methods, and the results showed greater stabilization of the studied pyrazoline molecules in the excited state. The DFT and TDDFT calculations supported and explained the experimental data, by obtaining the absorption and emission energies, HOMO/LUMO energies and the dipole moments for each compound in various solvents. Analysis of electron-hole distribution suggests that the intense fluorescent of these molecules originates from a hybrid local excitation charge-transfer state (HLCT).

Suitability of N-propanoic acid spiropyrans and spirooxazines for use as sensitizing dyes in dye-sensitized solar cells.

This work deals with the fabrication and evaluation of color-changing dye-sensitized solar cells (DSSCs) that include N-propanoic acid-functionalized spiropyrans and spirooxazines as sensitizing dyes. We investigated the photophysical properties of these compounds in various solvents and pH conditions using UV-Vis spectroscopy, and their behavior on TiO2 photoanode surfaces using a combination of UV-Vis and FT-IR. Their performance as sensitizing dyes for DSSCs was also analyzed. This study revealed a number of unique properties for this class of compounds that affect their performance as both photochromic compounds and DSSC sensitizers, which allow for future creation of efficient photochromic DSSCs.

Комбинированный подход к исследованию УФ-Вид спектров 2-аллил и 2-этилтиохинолинов в различных растворителях

Combined approach to analysis of 2-allylthioquinoline and 2-ethylthioquinoline solutions has been performed on the basis of UV-Vis spectroscopy. Experimental and calculated electronic absorption spectra of these compounds in various solvents: acetone, benzene, carbon tetrachloride, dichloromethane, ethanol have been considered. The negative solvatochromic effect has been observed. The results of our calculations have revealed that the spectra of various conformers of 2-allylthioquinoline differ more essentially than the spectra of 2-ethylthioquinoline conformers. It has been shown that the location of λ max band doesn’t drastically depend on allyl or alkyl substitution at the sulfur atom.

Substituent effect on the photochemistry of 4,4-dialkoxylated- and 4-hydroxylated cyclohexenones

Photochemistry of the title compounds in various solvents was studied using a broad band of light centered at 350 nm. C-4 spiroketal cyclohexenone 4 (1.0 M) afforded dimers and 12b with the predominance of the former in polar solvent and the latter in nonpolar solvent. When the concentration was reduced to, 4 underwent solvent addition in nonpolar solvent and ring-contraction in polar solvents. 4,4-Dimethoxycyclohexenones 5a–d in TFE exhibited a different photochemical behavior. The 5-vinyl-substituted enone afforded the bridged-bicyclic ketone 16. Cyclohexenone 5b with methyl moieties at C-2 and C-3 underwent aromatization whereas cyclohexenones with butyl substituent at C-5 and 5d with silylated alcohol at C-2 underwent solvent exchange. In γ-hydroxylated cyclohexenones 6a–c ring-contraction and solvent exchange were observed. Photochemistry of the title compounds from the mechanistic viewpoint is also described.

Preparation and Characterization of Substituted 3‐Benzothiazol‐2‐Ylcoumarins

AbstractA series of substituted 3‐benzothiazolylcoumarins was prepared from condensation of 2‐hydroxy‐benzaldehyde and 2‐cyanomethylbenzothiazole to investigate the effect of the nature and position of substituents on their absorption and fluorescent behavior. Compounds with a substituent containing a heteroatom which attached at the C6 position showed a split broad absorption band. Solutions of these compounds in various solvents exhibited brilliant blue fluorescence. The emission intensity for compounds with an alkoxy group at the C6 or C7 position in DMF was approximately 7‐ and 15‐fold higher than for the corresponding precursor and quinine sulfate solution, respectively. These compounds also exhibit high thermal stability in solid state.

Comment on “Temperature and Solvent Effects on Radical Scavenging Ability of Phenols”

Comment on “Temperature and Solvent Effects on Radical Scavenging Ability of Phenols”

Hydrogen Bonding and Solvent Polarity Markers in the UV Resonance Raman Spectrum of Tryptophan: Application to Membrane Proteins

Ultraviolet resonance Raman (UVRR) spectra of tryptophan compounds in various solvents and a model peptide are presented and reveal systematic changes that reflect solvent polarity, hydrogen bond strength, and cation-pi interaction. The commonly utilized UVRR spectral marker for environment polarity that has been based on off-resonance Raman data, the tryptophan Fermi doublet ratio I1360/I1340, exhibits different values in on- and off-resonance Raman spectra as well as for different tryptophan derivatives. Specifically, the UVRR Fermi doublet ratio for indole ranges from 0.3 in polar solvents to 0.8 in nonpolar solvents, whereas the respective values reported here and previously for off-resonance Raman spectra are 0.5-1.3. UVRR Fermi doublet ratios for the more biologically relevant molecule, N-acetyl tryptophan ethyl ester (NATEE), are in a smaller range of 1.1 (polar solvent) to 1.7 (nonpolar solvent) and correlate to the solvent polarity/polarization parameters pi* and ETN. As has been reported previously, several UVRR modes are also sensitive to the hydrogen bond strength of the indole N-H moiety. Here, we report a new unambiguous marker for H-bonding: the ratio of the W10 (approximately 1237 cm-1) intensity to that of the W9 (approximately 1254 cm-1) mode (RW10). This ratio is 0.7 for NATEE in the absence of hydrogen bond acceptors and increases to 3.1 in the presence of strong hydrogen bond acceptors, with a value of 2.3 in water. The W8 and W17 modes shift more than +10 and approximately -5 cm-1 upon increase in hydrogen bond strength; this range for W17 is smaller than that reported previously and reflects a more realistic range for proteins and peptides in solution. Finally, our data provide evidence for change in the W18 and W16 relative intensity in the presence of cation-pi interactions. These UVRR markers are utilized to interpret spectra of model membrane-bound systems tryptophan octyl ester and the peptide toxin melittin. These spectra reveal the importance of intra- and intermolecular hydrogen bonding and cation-pi interactions that likely influence the partitioning of membrane-associated biomolecules to lipid bilayers or self-associated soluble oligomers. The UVRR analysis presented here modifies and augments prior reports and provides an unambiguous set of spectral makers that can be applied to elucidate the molecular microenvironment and structure of a wide range of complex systems, including anchoring tryptophan residues in membrane proteins and peptides.