Aqueous DMF Solution Research Articles

Stability and photophysical study of bright day light fluorescent material and its fabrication in laser patterning and LED application

Developing aggregation-induced emission (AIE) active highly visible fluorescent dyes is of great importance because of its numerous applications. We have successfully developed and synthesized two novel napthalimide based molecules PU1 and PU2, that exhibit bright greenish yellow in day light and vivid green emission when exposed to UV light. Compounds PU1 and PU2 exhibit variable emission behavior at different solvent polarities. Upon raising the solvent polarity from ether to DMF, emission maxima of PU1 and PU2 underwent a bathochromic shift. Additionally, compounds PU1 and PU2 show signs of AIE, which cause a restriction in intramolecular mobility. A distinct self-assembled structure was generated at 30 % aqueous DMF solution following aggregation, as demonstrated by experiments using dynamic light scattering and field emission scanning electron microscopy. Compounds PU1 and PU2 have been blended with poly(urethane) to develop a polymeric film. Tensile strain studies, and TGA, DSC analyses were used to examine the thermal/mechanical stability of PU films. The photostability of PU1 and PU2 in both solution and polymeric film was examined using a 5-h UV-beam irradiation. Furthermore, in the presence of trifluoroacetic acid, the blended polymeric film and 365 nm LED light coated material exhibits distinct colorimetric and fluorimetric transformations. Finally, laser-induced periodic surface structure (LIPSS) pattern processing on PU1 coated substrates can be extended for optical applications.

Slowdown of solvent structural dynamics in aqueous DMF solutions

This study presents a comprehensive investigation into the molecular dynamics of solvation environments through an integrated approach combining Fourier-transform infrared (FTIR) spectroscopy, molecular dynamics (MD) simulations, and two-dimensional infrared (2D IR) spectroscopy. We explore the solvation of an ionic solute (ammonium thiocyanate) in various solvent systems, including N,N-dimethylformamide (DMF), water, and a 0.5 mole fraction of DMF in water, aiming to unravel the intricate interplay between solute-solvent interactions and solvent dynamics across diverse solvation environments. By integrating FTIR spectral analysis with radial distribution functions and coordination numbers obtained from MD simulations, we decipher the solvent composition around the solute molecule. Analysis of 2D IR spectra and hydrogen bond, as well as dipolar autocorrelation function from MD simulations, further elucidates the nuances of solute-solvent interactions, highlighting the impact of solvent dynamics on solvation structures. Our results reveal a significant slowdown of the solvent structural dynamics in the equimolar binary solvent mixture compared to the neat solvents. This slowdown underscores the complex relationship between solute-solvent interactions and solvent dynamics. The integration of FTIR, MD simulations, and 2D IR spectroscopy provides a unified framework for obtaining a holistic understanding of solvation dynamics, offering valuable insights into the underlying molecular mechanisms governing solute-solvent interactions in complex systems. These results pave the way for future studies to delve deeper into the molecular intricacies of solvation phenomena.

Synthesis, crystal structure and properties of electro-catalysis for hydrogen production of a molecular nickel catalyst based on bis(1,2,5-thiadiazole-3,4-dithiolate) ligand

A new molecular nickel catalyst, [Bz-1-MeIm]2 [Ni(tdas)2]( [Bz = benzyl, 1-MeIm = 1-methyl-limidazolium, tdas2− = 1,2,5-thiadiazole-3,4-dithiolate) was synthesized and characterized by elemental analysis, single crystal X-ray diffraction, infrared spectrum, ultraviolet-visible spectrum and thermo-gravimetric analysis. The as-prepared nickel complex crystallizes in the triclinic system with space group P−1 in which weak interactions such as S···N, N···N, π···π, N···S, and C−H···π further induce the formation of a three-dimensional network structure. Electrochemical studies indicated that the complex can electro catalyze the hydrogen evolution of buffered aqueous solution (pH 7.0) and DMF solution. Under an overpotential (OP) of 837.6 mV, the turnover frequency (TOF) reached 772.85 mols of hydrogen per mol of catalyst per hour from the water buffers solution with the turnover numbers (TONs) of 1545.7 after 2 h of reaction.

Syntheses, spectral, thermal and pH-metric studies on bivalent metal ion complexes of N,N’-bis(3-carboxy-1-oxo-z-prop-2-elenyl)ethylenediamine

A novel carboxyamide ligand has been synthesized using maleic anhydride and ethylenediamine. Co(II), Ni(II), Cu(II) and Pd(II) complexes of the ligand, i.e., N,N’-bis(3-carboxy-1-oxo-z-prop-2-elenyl)ethylenediamine [H2L] have been prepared and characterized by elemental analyses, IR, electronic, 1H NMR, EPR spectral and thermal studies. It is revealed by IR and 1H NMR spectral studies that the ligand coordinated to the metal ions through deprotonated carboxylate oxygen and non-deprotonated amide nitrogen in all the complexes. It is suggested by electronic spectral and magnetic moment studies that N2O2 coordination is around each metal center with a strong field square planar chromophore. All the complexes have been studied by TGA and DTA studies done simultaneously. The complex formation between ligand and metal ions [Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)] has also been studied pH metrically in 75% aqueous DMF solution at 298 K in 0.1 M NaClO4. The probable structures of the complexes have also been proposed.

Multi-stimuli-responsive supramolecular hydrogel based on an oxidized glutathione derivative

In this study, we report the formation of a multi-stimuli-responsive supramolecular hydrogel through the self-assembly of an oxidized glutathione derivative. The hydrogels were obtained in aqueous DMF solutions after a heating–cooling process. These hydrogels exhibited fibrous structures, which formed via the self-assembly of the hydrogelator driven by the combination of hydrogen bonding, π–π stacking, and hydrophobic effect. Besides the thermo-sensitivity, the hydrogels showed redox- and light-responsiveness attributing to the presence of a disulfide bond and two azobenzene terminal groups, respectively, in the molecular structure of the hydrogelator. The multi-stimuli-responsiveness endows the hydrogels with the potential applications in the field of smart materials.

Contribution from non-ideality and preferential solvation to non-linear solvatochromism in binary mixtures

The knowledge of preferential solvation is of critical importance in description of the solute behavior in mixed solvents. The analysis of solvatochromic shifts as a function of solvent composition is popular in this regard, since it gives molecular information on solute-solvent interactions. However, due to the complexity of the interactions and possible non-ideality of mixed solvents, implementing an efficient approach for interpretation of solvent-solvent interactions is an opening major challenge in modeling solvatochromism to get reliable results on preferential solvation. Here, we proposed a new methodology to treat solvatochromism in solvent mixtures in order to reach a more reliable picture of the local composition around the solute. As the main idea, the effect of solvent-solvent interactions on spectral shift was considered by formulating the non-ideality of solvent in solvation shell of the solute as a function of the local composition by exploiting the results obtained from the analysis of the bulk mixture non-ideality. From that, the non-linear variation in spectral shift can be well separated into contributions from preferential solvation and the local non-ideality. To test this approach, solvatochroimsm of 2-methyl-4-nitroaniline was studied in some mono-solvents and binary mixtures. The spectral properties of 2-methyl-4-nitroaniline and its response to solvent were rationalized by quantum chemical calculation and linear solvation energy relationships analysis in mono-solvents. Then, the observed strong non-linear solvatochromism of 2-methyl-4-nitroaniline in aqueous mixtures of ethanol, DMF and DMSO was treated by the proposed model that provided both physically and statistically more reliable results on preferential solvation and molecular interactions, with respect to the other widely-used solvent exchange models. As an interesting and important result, non-ideality, but not preferential solvation, was responsible for non-linear solvatochromism in aqueous solutions of ethanol and DMF.

Theoretical computation of interaction parameters for the complexation of GSH with Pr(III) and Mg(II) in solution: Analysis of their reaction dynamics and thermodynamic characters

The current research focuses on the computation of absorption spectral parameters like energy interaction parameters viz. Slater-Condon factor (Fk), Racah (Ek), Lande spin-orbit interaction (ζ4f), nephelauxetic ratio (β), bonding parameter (b1/2), per cent covalency (δ), and the intensity parameters like oscillator strength (P) and Judd-Ofelt Tλ, (λ ​= ​2,4,6) parameters, of Pr3+ ion complexes with reduced Glutathione (GSH) in the presence and absence of Mg2+ in different aqueous solutions of CH3OH, C4H8O2, CH3CN and DMF. The variations in the values of the energy interaction and intensity parameters clearly demonstrates the relative sensitivity of the 4f-4f transitions and its correlation with ligand structure and the nature of metal-ligand interaction. Further, the reaction dynamics and thermodynamic properties for the complexation of Pr3+ with glutathione and Mg2+ ligand have been investigated using different computed parameters like rate constant (k), activation energy (Ea), A (pre-exponential factor) and thermodynamic parameters, ΔH0, ΔG0 and ΔS0.

Calculation of the Free Energy of Mixing as a Tool for Assessing and Improving Potential Models: The Case of the N,N-Dimethylformamide-Water System.

The Helmholtz free energy, energy, and entropy of mixing of N,N-dimethylformamide (DMF) and water are calculated in the entire composition range by means of Monte Carlo computer simulations and thermodynamic integration using all possible combinations of five DMF and three widely used water models. Our results reveal that the mixing of DMF and water is highly non-ideal. Thus, in their dilute solutions, both molecules induce structural ordering of the major component, as evidenced by the concomitant decrease in the entropy. Among the 15 model combinations considered, only 4 reproduce the well-known full miscibility of DMF and water, 3 of which strongly exaggerate the thermodynamic driving force of the miscibility. Thus, the combination of the CS2 model of DMF and the TIP4P/2005 water model reproduces the properties of the DMF-water mixtures far better than the other combinations tested. Our results also reveal that moving a fractional negative charge from the N atom to the O atom of the DMF molecule, leading to the increase in its dipole moment, improves the miscibility of the model with water. Starting from the CS2 model and optimizing the charge to be moved, we propose a new model of DMF that reproduces very accurately both the Helmholtz free energy of mixing of aqueous DMF solutions in the entire composition range (when used in combination with the TIP4P/2005 water model) and also the internal energy of neat DMF.

Aggregation of water soluble octaanionic phthalocyanines and their photoinactivation antimicrobial effect in vitro

Aggregation of sulfophenylsulfanyl-substituted phthalocyanine and its aluminum complex has been investigated in aqueous solutions of DMF or nonionic surfactant Tween 80 by UV-VIS spectroscopy and DLS. Aluminum complex is less aggregated and 4.5 orders of magnitude stronger bound to the micelles of Tween 80 compared to a metal-free ligand. Under irradiation the phthalocyanine derivatives reveal a pronounced antimicrobial activity towards both Gram(+) and Gram(−) archive microflora in vitro.

Switching of Fluorescent Zn/Cd Selectivity in N,N,N',N'-Tetrakis(6-methoxy-2-quinolylmethyl)-1,2-diphenylethylenediamine by One Asymmetric Carbon Atom Inversion.

A quinoline-based hexadentate ligand, (S,S)-N,N,N',N'-tetrakis(6-methoxy-2-quinolylmethyl)-1,2-diphenylethylenediamine ((S,S)-6-MeOTQPh2EN), exhibits fluorescence enhancement at 498 nm upon addition of 1 equiv of Zn2+ (IZn/I0 = 12, φZn = 0.047) in aqueous DMF solution (DMF/H2O = 2:1). Addition of 1 equiv of Cd2+ affords a much smaller fluorescence increase at the same wavelength (ICd/I0 = 2.5, ICd/IZn = 21%). The trivalent metal ions such as Al3+, Cr3+, and Fe3+ also exhibit fluorescence enhancement at 395 nm (IAl/I0 = 22, ICr/I0 = 6 and IFe3+/I0 = 13). In contrast, meso-6-MeOTQPh2EN exhibits a Cd2+-selective fluorescence increase at 405 nm in the presence of 1 equiv of metal ion (ICd/I0 = 11.5, φCd = 0.022), while Zn2+ induces a smaller fluorescent response under the same experimental conditions (IZn/I0 = 3.3, IZn/ICd = 29%). In this case, the fluorescence intensities of meso-6-MeOTQPh2EN in the presence of a large amount of Zn2+ and Cd2+ become similar. This diastereomer-dependent, fluorescent metal ion specificity is derived from the Zn2+-specific intramolecular excimer formation in (S,S)-6-MeOTQPh2EN-Zn2+ complex and higher binding affinity of meso-6-MeOTQPh2EN with Cd2+ in comparison to Zn2+. The more conformationally restricted diastereomeric pair, namely, cis- and trans-TQDACHs (cis- and trans-N,N,N',N'-tetrakis(2-quinolylmethyl)-1,2-diaminocyclohexanes), both exhibit Zn2+-specific fluorescence enhancement because of the high metal binding affinity and intramolecular excimer forming property derived from the rigid DACH backbone.

Novel palladium(II) complexes of N-(5-nitro-salicylidene)-Schiff bases: Synthesis, spectroscopic characterization and cytotoxicity investigation

A series of palladium(II) complexes (1e–3e) with the general formulae [Pd(L)(H2O)]·xH2O were newly synthesized by the interaction of palladium(II) chloride and the monosodium salts of N-(5-nitro-salicylidene)-Schiff base ligands (1a–3a) in aqueous DMF solution. The identities of all the complexes were proven by elemental analysis, FTIR, 1H, 13C NMR, LC–MS, UV–vis, XPS, powder XRD spectra, thermal analysis, conductivity and magnetic susceptibility measurements. The obtained analytical and physicochemical results exhibited a square-planar coordination of the palladium(II) ion having a double deprotonated ligand and a coordinated water molecule. In vitro cytotoxicity of these Pd(II) complexes was screened against tumor cell lines (HeLa and MCF-7), and a normal human cell line (HEK-293). The complexes 1e and 2e exhibited a moderate antitumor activity against HeLa cell lines, while 3e had better activity than standard anticancer drug, doxorubicin. All three complexes showed the best active cytotoxicity than doxorubicin against MCF-7 cancer lines. For HEK-293 lines, a decrease in concentration of the complexes significantly decreased their toxicity.

A novel colorimetric and ratiometric fluorescent probe for targeted detection of hypochlorous acid based on HClO-mediated anthracene-hydrazone to anthracene-triazole transformation

An anthracene-based fluorescence probe B-ClO that exhibited excellent selectivity and sensitivity for colorimetric and ratiometric detection of ClO− in 80% aqueous DMF solution has been designed and developed.

Inferences on hydrogen bond networks in water from isopermitive frequency investigations

Intermolecular hydrogen bonds play a crucial role in determining the unique characteristics of liquid water. We present low-frequency (1 Hz–40 MHz) dielectric spectroscopic investigations on water in the presence and absence of added solutes at different temperatures from 10 °C to 60 °C. The intersection points of temperature dependent permittivity contours at the vicinity of isopermitive frequency (IPF) in water are recorded and its properties are presumed to be related to the extent of hydrogen bond networks in water. IPF is defined as the frequency at which the relative permittivity of water is almost independent of temperature. The set of intersection points of temperature dependent permittivity contours at the vicinity of IPF are characterized by the mean and root-mean-square deviation/standard deviation associated with IPF. The tunability of MIPF by the addition of NaCl and MgCl2 salt emphasizes the strong correlation between the concentration of ions in water and the MIPF. The is surmised to be related to the orientational correlations of water dipoles as well as to the intermolecular hydrogen bond networks in water. Further, alterations in is observed with the addition of kosmotropic and chaotropic solutes into water and are thought to arise due to the restructuring of hydrogen bond networks in water in presence of added solutes. Notably, the solute induced reconfiguration of hydrogen bond networks in water or often-discussed structure making/breaking effects of the added solutes in water can be inferred, albeit qualitatively, by examining the MIPF and . Further, the Gaussian deconvoluted OH-stretching modes present in the Raman spectra of water and aqueous solutions of IPA and DMF strongly endorses the structural rearrangements occurring in water in presence of kosmotropes and chaotropes and are in line with the results derived from the root-mean-square deviation in IPF.

Methylviologen-mediated electrochemical synthesis of platinum nanoparticles in solution bulk

Platinum nanoparticles (PtNPs) are synthesized by methylviologen-mediated reduction of PtCl2 at the potentials of the MV2+/MV•+ redox couple in 40% aqueous DMF solution. In the absence of stabilizing agents and in the presence of a stabilizer in the form of spherical silica NPs or alkylamine-modified silica NPs (SiO2-NHR), a part of PtNPs (14–18%) are deposited on the electrode while the rest of particles remain in solution to form coarse aggregates which precipitate. In the latter case, PtNPs are also partly bound to form individual ultrafine NPs (3 ± 2 nm) on the SiO2-NHR surface. In the presence of polyvinylpyrrolidone (PVP), the generated PtNPs (18 ± 9 nm) neither aggregate nor deposit on the cathode but are completely stabilized in solution being encapsulated within the PVP matrix. The obtained PtNPs are characterized by the methods of dynamic light-scattering and electron microscopy.

DMF 수용액 매개체에서 PAN 필름의 히드라진 가교 반응

DMF 수용액 매개체에서 PAN 필름의 히드라진 가교 반응

A reaction based colorimetric chemosensor for the detection of cyanide ion in aqueous solution

A conjugated naphthoquinone-benzothiazole (R) system was developed and characterized and its cyanide sensing properties were monitored in 80% aqueous DMF solution. Cyanide ions react with the receptor through a nucleophilic addition reaction, resulting in immediate color change that can be viewed and monitored colorimetrically and fluorimerically. Optical properties of R were not affected by the addition of other common anions in the presence and absence of cyanide ions. A test strip based on R was fabricated and could act as a convenient test kit to detect cyanide ions. Thus, the receptor can be used as an effective probe to detect cyanide ions in aqueous solution.

Selective colorimetric and fluorescence ‘turn-on’ sensor for Ag+ and in-situ sensing of CN− (off–on-off) via displacement approach

In this contemporary work we designed and synthesized a simple tetra dentate Schiff base, which displays colorimetric and fluorescence “turn on” sensing behavior towards Ag+ in aqueous DMF (50%) solution. Benesi Hildebrand–plot reveals 1:2 binding mode between probe and Ag+ with limit of detection down to 1.12μM. Cyclic voltammograms exhibits high anodic shift with Ag+ due to the charge transfer from ligand to metal ion. The binding mode was proved by NMR titrations, FE-SEM elemental analysis & advance DFT calculation. Additionally, the subsequent Ag+-complex also shows an extremely selective response to CN− among other anions due to the displacement of Ag+ via CN−, forming [Ag(CN)x]− species into the medium. Probe was used as coated paper test strip which served as mini colorimetric device for detection of Ag+ and CN−.

Pyridyl substituted 4-(1,3-Dioxo-1H,3H-benzo[de]isoquinolin-2-ylmethyl)-benzamides with aggregation enhanced emission and multi-stimuli-responsive properties

1,8-Naphthalimide connected to benzoic acid chloride via methylene group was condensed separately with 3-amino pyridine and 4-amino pyridine and provided compounds 4-(1,3-Dioxo-2,3-dihydro-1H-phenalen-2-ylmethyl)-N-pyridin-3-yl-benzamide 1 and 4-(1,3-Dioxo-2,3-dihydro-1H-phenalen-2-ylmethyl)-N-pyridin-4-yl-benzamide 2. The compounds are characterized by spectral (IR, UV–Visible, 1H and 13C NMR) measurements and supported by their X-ray crystallography. Their photoelectron spectroscopy, SEM and TEM measurements are also made. They are found luminescent in DMF solution as well as in the solid state and form nano-aggregates with enhanced emission (AEE) in aqueous-DMF solution. Their AEE behavior depends on the polarity of the solvents. On grinding, crystalline solids 1 and 2 turn to amorphous and the process is reversible on annealing as supported by their powder X-ray diffraction (PXRD) measurements. Both compounds show mechanochromic properties and display multi-stimuli response. Density Functional Theory calculations rationalize their optical data.

Apparent Molar Heat Capacities of n-Alcohols (C2 to C4) and Symmetric Tetraalkylammonium Bromides (C2 to C5) in Water–N,N-Dimethylformamide Mixtures: Methylene Group Contribution and Hydrophobic Hydration

The apparent molar heat capacities, ϕ C p , of ethanol, n-propanol, n-butanol, and tetraethylammonium, tetra-n-propylammonium, tetra-n-butylammonium and tetra-n-pentylammonium bromides have been measured measured using a Picker flow calorimeter (Sodev, Canada, Model CP-Cpr) at 298.15 K in water–N,N-dimethylformamide (DMF) mixtures. The contribution of the CH2 moiety, ϕ C p (CH2), was estimated from these data as the change in ϕ C p per additional CH2 unit. The values of ϕ C p (CH2) in water (ca. 100 J·K−1·mol−1) are two to three times those in neat organic solvents (ca. 30–40 J·K−1·mol−1), consistent with a substantial contribution from hydrophobic solvation in water. In water-rich aqueous DMF solutions, ϕ C p (CH2) decreases monotonically with increasing DMF concentration, the decrease being more rapid for the n-alcohols. This trend differs significantly from that reported in the literature for highly aqueous mixtures of t-butanol, where ϕ C p (CH2) passes through a maximum.

Tuning of Aggregation Enhanced Emission and Solid State Emission from 1,8-Naphthalimide Derivatives: Nanoaggregates, Spectra, and DFT Calculations.

Four new 1,8-naphthalimide based compounds, 4-(1,3-dioxo-1H,3H-benzo[de]isoquinolin-2-ylmethyl)-benzoic acid (LH), 4-(1,3-dioxo-1H,3H-benzo[de]isoquinolin-2-ylmethyl)-benzoic acid methyl ester (LMe), 4-(1,3-dioxo-1H,3H-benzo[de]isoquinolin-2-ylmethyl)-benzoyl chloride (LCl), and 4-(1,3-dioxo-1H,3H-benzo[de]isoquinolin-2-ylmethyl)-benzoic acid hydrazide (LN) are synthesized and characterized using spectral data and X-ray crystallography. They form nanoaggregates in aqueous-DMF solution and exhibited aggregation enhanced emission. The nanoaggregates are characterized using their scanning electron and atomic force microscopy images. The emission intensity follows the order as LH > LMe > LCl > LN. Their photophysical properties are recorded both in solution and in the solid-state and are correlated with the nature of benzoic acid derivatives owing to the combinatorial effect of π-π stacking and intermolecular and intramolecular interactions. The density functional theory calculations empower the understanding of their molecular and cumulative electronic behaviors. Antiparallel dimeric interactions in the solid-state extend a herringbone arrangement to LH and 2D channel and stair-like arrangement for LCl and LN, respectively.