Solvatochromic Behavior Research Articles

Methoxylated bis(pentafluorophenyl)boron‐β‐diketonates: Synthesis, Optical Properties and Hydrolytic Stability

AbstractA series of methoxylated bis(pentafluorophenyl)boron‐β‐diketonates (dkB(C6F5)2) with intense emission has been synthesized and characterized by a variety of physicochemical methods. The photophysical properties of the synthesized compounds were thoroughly investigated by electronic absorption, steady‐state, and time‐resolved fluorescence spectroscopy in both solution and solid state. The studied compounds exhibit solvatochromic behavior attributed to the intramolecular charge transfer (ICT) nature of the first excited state. The formation of exciplexes between DBMB(C6F5)2 and benzene derivatives was also studied. Notably, the studied compounds display a complex luminescence profile in the solid state, featuring fluorescence, delayed fluorescence and phosphorescence emission. Furthermore, the hydrolytical stability of the complexes was assessed, demonstrating excellent resistance to hydrolysis. Estimated rate constants, determined at 60 °C, are significantly lower (90‐2000 times) than those observed for the well‐studied dibenzoylmethanatoboron difluoride (DBMBF2). The incorporation of pentafluorophenyl substituents at the boron atom enables the synthesis of highly fluorescent and hydrolytically stable boron chelate complexes, suitable for sensing and bioimaging applications in water‐containing environments.

Dual state emissive pyrene-fused benzopyrazaacenes and their solvatochromic behaviour

This study investigates how molecular orientation and microstructure influence the photophysical and electronic properties of pyrene-fused azaacenes. Four substituted pyrene-fused benzopyrazaacene compounds were synthesized via a single step cyclo condensation of K-conjugated pyrene quinone building blocks with 3,4-diaminobenzophenone. The synthesized molecules were characterized using IR, NMR spectroscopy and HRMS analysis. Photophysical and electrochemical properties were studied to explore the impact of molecular orientation and microstructure on the properties of pyrene-fused azaacenes. Substitutions at the 2, 7-positions of the pyrene core significantly affected the photophysical properties while demonstrating moderate solubility. Notably, the compounds exhibited pronounced solvatochromic effect across various solvents. Furthermore, the additional incorporation of a carbonyl moiety adjacent to the core expanded pyrene at the K-region resulted in dual state emission, influencing solid state emission accompanied by robust thermal stability. Theoretical calculations were performed to gain insights into the energy levels of the compound and its molecular orientation using time dependent density functional theory (TD-DFT).

Photophysical and antitubercular studies on newly synthesised structurally architectured sulphonamide

This study presents the synthesis and characterisation of four mono-azo sulphonamide derivatives through diazo-coupling electrophilic substitution reactions. The structural analysis of the synthesised molecules was conducted utilising FT-IR, 1H-NMR and HR-MS techniques. Absorption and fluorescence maxima of the synthesised molecules were determined across solvents of varying polarity to explore Solvatochromic behaviour. Density functional theory was employed to elucidate electronic and optical properties, including the computation of HOMO–LUMO energies using Gaussian 09W software, with comparisons to experimental data. Molecular electrostatic potential 3D plots identified electrophilic and nucleophilic sites. Solvent interactions were evaluated using Kamlet–Abboud Taft and Catalan parameters. Further, global chemical reactivity descriptors were estimated to ascertain chemical reactivity of the molecules. Additionally, the effectiveness of the colourant anti-tubercular activity was evaluated using in vitro and molecular docking techniques. The biological activity results reveal that methyl-pyridone and barbituric acid coupled with sulphamethizole (SMP and SMB) displayed excellent anti-tubercular activity compared with the standard Gentamycin.

The Influence of the Alkylamino Group on the Solvatochromic Behavior of 5-(4-substituted-arylidene)-1,3-dimethylpyrimidine-2,4,6-triones: Synthesis, Spectroscopic and Computational Studies.

Advances in electronics and medical diagnostics have made organic dyes extremely popular as key functional materials. From a practical viewpoint, it is necessary to assess the spectroscopic and physicochemical properties of newly designed dyes. In this context, the condensation of 1,3-dimethylbarbituric acid with electron-rich alkylaminobenzaldehyde derivatives has been described, resulting in a series of merocyanine-type dyes. These dyes exhibit intense blue-light absorption but weak fluorescence. An electron-donating alkylamino group at position C4 is responsible for the solvatochromic behavior of the dyes since the lone electron pair of the nitrogen atom is variably delocalized toward the barbituric ring, which exhibits electron-withdrawing properties. This was elucidated, taking into account the different geometry of the amino group. The intramolecular charge transfer in the molecules is responsible for the relatively high redshift in absorption and fluorescence spectra. Additionally, an increase in solvent polarity moves the absorption and fluorescence to lower energy regions. The observed solvatochromism is discussed in terms of the four-parameter Catalán solvent polarity scale. The differences in the behavior of the dyes were quantified with the aid of time-dependent density functional theory calculations. The obtained results made it possible to find regularities linking the basic spectroscopic properties of the compounds with their chemical structure. This is important in the targeted search for new, practically important dyes.

A Novel Fluorescent Probe containing dihydropyrimidinone Analogue for Highly Sensitive, Selective Detection of Al(III) Ions with its Molecular Docking, ADME/T and Anticancer Impact

AbstractIn this investigation, a novel and promising chemosensor incorporating a dihydropyrimidinone moiety, namely; (E)‐4‐(4‐(dimethylamino)phenyl)‐5‐(3‐(4‐(dimethylamino)phenyl)acryloyl)‐6‐methyl‐3,4 dihydropyrimidin‐2(1H)‐one (DPDAD), has been successfully synthesized and characterized. The DPDAD chemosensor‘s response was evaluated in diverse solvents with varying polarities, shedding light on its solvatochromic behavior. The assessment of colorimetric and optical sensing attributes toward a range of metal ions such as Al(III), Cr(III), Mn II), Fe(III), Co(II), Ni(II), and Cu(II) was undertaken. Notably, DPDAD displayed discernible color alterations upon interaction with all the examined metal ions, with a significant bathochromic shift observed in the absorption spectra in the presence of Al(III), distinguishing it from the other metal ions. Furthermore, through detailed absorption and emission spectral analyses, DPDAD exhibited remarkable selectivity, sensitivity, and an on‐off‐on switchable behavior specifically with Al(III) ions, over the other metal ions. The binding constant was determined as 0.39×105 M−1, accompanied by a limit of detection (LOD) of 1.03×10−5 M. Notably, the DPDAD′s potential extends beyond metal ion sensing; it was computationally assessed for its capability to inhibit the γ‐secretase enzyme. Moreover, DPDAD′s antioxidant attributes were probed, and its inhibitory effect against a range of cancer cell lines was verified in‐vitro.

Fabrication of Large-Area Multi-Stimulus Responsive Thin Films via Interfacially Confined Irreversible Katritzky Reaction.

Fabrication of large-area thin films through irreversible reactions remains a formidable task. This study reports a breakthrough strategy for in situ synthesis of large-area, free-standing, robust and multi-stimulus responsive thin films through a catalyst-free and irreversible Katritzky reaction at a liquid-liquid interface. The as resulted films are featured with adjustable thickness of 1-3 μm and an area up to 50 cm2. The thin films exhibit fast photo-mechanical motions (a response time of ca 0.1 s), vapor-mechanical motions, as well as photo-chromic and solvato-chromic behaviors. It was revealed that the reason behind the observable motions is proton transfer from the imine groups to the carbonyl structures within the film induced by photo- and/or dimethyl sulfoxide-stimulus. In addition, the films can harvest anionic radicals and the radicals as captured can be efficiently degraded under UV light illumination. This study provides a new strategy for fabricating smart thin films via interfacially confined irreversible Katritzky reaction.

Green Synthesis of Highly Fluorescent NCQDs: A Comprehensive Study on Synthesis, Characterization, Photophysical Properties, pH Sensing, Heavy Metal Detection, and Solvatochromic Behavior through Hydrothermal Method.

Solvatochromic studies in conjunction with NCQDs and analysis of material at different pH levels provide valuable insights about the process of metal ion sensing. Metal ion sensing holds significant importance in various fields like environment monitoring, biomedical diagnostics and various industrial purpose. The detection of metal ions by mixing the nitrogen-doped quantum dots (NCQDs) in the solvent at different pH levels for the analysis of the photoluminescence spectra is the unique property to achieve selective metal ion detection.In present study, the synthesis of NCQDs was performed by the use of flowers of Tecoma stans. The synthesis of NCQDs to best of our knowledge using flowers of Tecoma stans as natural carbon source via hydrothermal process has been done for the first time. The NCQDs exhibit absorption bands ranging from 190 to 450nm, with the energy band gap varying from 3.55 to 5.42eV when mixed with different solvent such as, 1-4 dioxane, acetone, acetonitrile, ethyl- acetate, ethanol, methanol and toluene. The fluorescence spectra exhibited highly intense range from approximately 390 to 680nm across various solvents. XRD analysis further confirmed the crystalline nature of the particles with an average size of 6.96nm. Different peak positions of the FTIR spectra support functional groups having C-H stretching, C = O (carbonyl) stretching, and C = C stretching vibrations.In the study a notable solvatochromic shift was observed, indicating sensitivity to change in solvent polarity. Additionally, the investigation of the ratio of ground to excited state dipole moment based on solvatochromic shift yielded a value of 3.30. This provide valuable information about optical and electronic properties of NCQDs. Overall, our study sheds light on the unique properties of NCQDs synthesized from Tecoma stans flowers and their potential applications in metal ion sensing, pH probing, and solvent polarity studies.

Solvatochromism and preferential solvation of 2,6-dichloro-4-nitroaniline in pure and binary aqueous mixtures

In this study, the solvatochromic behavior of 2,6-dichloro para-nitroaniline (DCPNA) was investigated in a wide range of pure solvents, and binary solvent mixtures of water with ethanol, dimethyl sulfoxide, and dimethyl formamide at 298.15 K. The absorption spectrum of DCPNA in the ultraviolet–visible range exhibits a characteristic peak that shifts with changes in the solvent along the absorption wavelength. The influential factors and their roles in solvatochromism were determined through KAT-LSER analysis in pure solvents. Solvatochromism in binary solvent mixtures showed a completely non-linear trend with respect to the composition of the solution. The recently introduced preferential solvation model was utilized to model the absorbed light wavenumber in aqueous solvent mixtures. This model elucidates the separate effects of preferential solvation of DCPNA and the non-ideal behavior of aqueous solvent mixtures in the non-linearity of solvatochromism.

Extended Reichardt's Dye-Synthesis and Solvatochromic Properties.

Three new pyridinium-phenolate dyes based on the benchmark solvatochromic dye Betaine 30 were synthesised. The dyes contained phenylene spacers between the donor and acceptor groups. Their UV-Vis absorption spectra were measured, with the dyes showing strong negative solvatochromic behaviour comparable to that of Betaine 30. These results stood in contrast to the behaviour of the π-extended dye Betaine 21, originally reported in 1963. This dye was synthesised and found to be significantly more solvatochromic than previously reported but prone to degrade. All π-extended dyes synthesised were found to be unstable in certain solvents. Although the increased distance between donor and acceptor did not enhance solvatochromism to the extent predicted, it was still determined that the reduced planarity caused by a phenylene spacer is not as detrimental as believed.

Dicyanovinyl-modified small-molecular monophenyl derivative for dual-channel fluorescence recognition of acid and aliphatic primary amine regulated by intramolecular charge transfer: Synthesis, stimuli-response and LED

The dicyanovinyl-modified monophenyl derivative TSH was synthesized via Vilsmeier and Knoevenagel reactions. TSH has photoluminescence in both solution and solid. It exhibits solvatochromic behavior, shifting from blue to orange due to the intramolecular charge transfer. TSH can undergo a reversible protonation/deprotonation reaction with trifluoroacetic acid/triethylamine, leading to acidochromism. Additionally, TSH reacts with aliphatic primary amines, causing fluorescence changes from yellow to blue for specific recognition of aliphatic primary amines. The fluorescence changes resulting from the recognition of acid and aliphatic primary amines are related to the change of intramolecular charge transfer. The two recognition phenomena are different, allowing for the design of various fluorescent anti-counterfeiting measures. Moreover, TSH can be utilized in fabricating yellow light-emitting diode device with high color purity (91 %).

The rapid synthesis of 1,10-phenanthroline-5,6-diimine (Phendiimine) and its fascinating photo-stimulated behavior

Here, for the first time, we report synthesis of 1,10-phenanthroline-5,6-diimine (Phendiimine) based on an acid catalysed SN2 reaction of 1,10-phenanthroline-5,6-dione and 2-picolylamine in EtOH as a solvent. The synthesized Phendiimine molecule showed excellent photo-sensitivity against visible light, together with photoluminescence in both water and ethanol and also, it showed electrochemical activity with Fe electrode in ethanol and H2SO4 solution. Tauc plot also showed Phendiimine is a direct band-gap semiconductor. The hot-point probe test also showed that it is a n-type semiconductor. The UV–vis. absorption maximum shift in two solvents (water and ethanol) demonstrates the solvatochromism behavior of the molecule. The practical significance of this work and its guiding implication for future related research can be outlined as follows. Based on the results obtained, it appears that the Phendiimine molecule could revolutionize the medical field, potentially in the design of artificial eyes, increasing the yield of photovoltaic cells through enhanced heat transfer, improving computers and industrial photo-cooling systems, serving as photo-controller in place of piezoelectric devices, functioning as electronic opt couplers, controlling remote lasers, changing convection in photothermal heaters, designing miniaturized real photo-stimulated motors, creating photo or thermal switches through spin crossover complexes, developing electronic light-dependent resistance (LDR) devices, constructing X-ray and gamma-ray detectors, designing intelligent clothing, creating photo dynamic tumour therapy (PDT) complexes, singlet fission materials in solar cells and more.

Comparing the crystal structures and spectroscopic properties of a p-hydroxy styrylquinolinium dye with those of its p-dimethylamino analogue

Two previously synthesized styrylquinolinium dyes, namely (E)-1-butyl-4-(4-(dimethylamino)styryl)quinolinium iodide (D36) and (E)-1-butyl-4-(4-hydroxystyryl)quinolinium iodide (D34), were compared in terms of their properties by single-crystal X-ray diffraction (XRD), Hirshfeld surface analysis, Fourier transform Raman (FT-Raman), Fourier transform infrared (FT-IR), fluorescence, and ultraviolet–visible (UV–Vis) spectroscopy, and 1H- and 13C-NMR methods. Both dyes D36 and D34 crystallized in the triclinic and monoclinic systems in the centrosymmetric space groups P-1 and P21/n, respectively. The unit cell of D36 contains two molecules of the dye, participating in weak intermolecular interactions, whereas that of D34 contains four formula units. The phenolic hydroxy group of D34 participates in the formation of a hydrogen bond with the iodide anion. The 4-styrylquinolinium moieties of the cationic dye molecules are nearly planar. The dihedral angle between the mean planes through the ten-membered quinolinium system and the benzene ring is 7.5° in D36 and 5.9(1)° in D34. The structural parameters planarity and bond length alternation (BLA) are discussed, which are important for the evaluation of the first hyperpolarizability β at the molecular level, even in a centrosymmetric crystal. The UV–visible spectra of the dyes in 14 solvents of different polarities were investigated. The reversible solvatochromic behavior of the dyes is demonstrated experimentally and compared with known “binuclear dyes” by evaluating the Rezende model. Dye D36 does not fluoresce, and D34 has a very low emission in the solvents tested.

Biisoindolylidene solvatochromic fluorophores: Synthesis and photophysical properties

Environment-sensitive fluorescent probes are commonly utilized in various fields, including fluorescence sensing and imaging. This paper describes the synthesis and photophysical properties of a novel class of solvatochromic fluorophores that incorporate biisoindolylidene as the core backbone. This study investigates the structure-property relationships of these newly developed fluorophores. The central biisoindolylidene acts as an efficient electron acceptor, and by modifying the aryl ring substituent at the 3,3′ position, the photophysical properties of the fluorophores can be significantly enhanced, particularly in terms of photoluminescence quantum efficiency. Furthermore, when an electron-donor group replaces the aryl ring at the 3,3′ position, intriguing solvatochromic behavior is observed. This leads to a red-shift in the maximum emission wavelength and an increase in the Stokes shift with increasing solvent polarity. In solvent dimethyl sulfoxide (DMSO), the maximum emission wavelength can reach up to 750 nm, with a Stokes shift of approximately 150 nm. Finally, the potential application of the fluorophore in the detection of volatile acids is explored in a preliminary manner.

Synthesis, Characterization of New Benzopyran Pyrimidines and Study of their Solvatochromic Behaviour

Five new benzopyran pyrimidines (5a-e) were synthesized in three steps by using silica-sulphuric acid as catalyst. All the synthesized benzopyran pyrimidines with various substituents were characterized by spectroscopic techniques such as 1H NMR, 13C NMR, IR and mass spectroscopy. The structural features of these molecules containing pyrimidine ring with π-conjugated systems and various functional groups on the aromatic rings greatly influence their photophysical properties. Thus, they behave as better candidates for developing the photoelectric materials. Thus, it is proposed to synthesize, characterize and study their solvatochromic behaviour in various polar and non-polar organic solvents viz. dichloromethane, tetrahydrofuran, ethyl acetate, acetonitile and ethanol. Interestingly, all the target molecules exhibited greater Stoke’s shift (λf-λa) in dichloromethane except for compound 5e, which exhibited greater value in tetrahydrofuran, possibly due to the moderately polar nature of the solvent. The synthesized benzopyran pyrimidines displayed solvatochromic characteristics due to the presence of multiple substituted functional groups on the rings in different organic solvents. Due to their remarkable properties, they could serve as potential candidate molecules for future investigations into photoelectric materials.

Optical Investigation of 2-amino-7-isocyanofluorene, a Novel Blue-Emitting Solvatochromic Dye

Smart solvatochromic isocyano-aminoarenes (ICAArs) have been gaining attention owing to their unique photophysical, antifungal and anticancer properties. Using a simple dehydration reaction with in situ-generated dichlorocarbene, we prepared 2-amino-7-isocyanofluorene (2,7-ICAF). We studied the effect of the longer polarization axis provided by the fluorene core on the spectral properties and we also compared it to those of the starting diamine. 2,7-ICAF shows a clear solvatochromic behavior close to the blue part (370–420 nm) of the visible spectrum. Quantum chemical calculations show internal charge transfer (ICT) between the donor amino and the electron-withdrawing isocyano groups. 2,7-ICAF has high molar absorptivity (ε = 15–18·103 M−1cm−1) and excellent quantum yield (Φf = 70–95%) in most solvents; however, its fluorescence is completely quenched in water. The high brightness (ε·Φf) and close to zero quantum yield in water may be favorable in biolabeling applications, where background fluorescence should be kept minimal. Overall, 2,7-ICAF shows enhanced photophysical properties compared to its previously investigated relative 4-amino-4′-isocyano-1,1′-biphenyl (4,4′-ICAB).

Photochemical synthesis and solvatochromic fluorescence behavior of imide-fused phenacenes

Chrysenes, picene, fulminene, modified with imide, bromo, and amino functionalities, were synthesized through Mallory photoreaction as the key step, and their electronic spectra were investigated. Fluorescence spectra of chrysene-diimide CHRDI and bromo-substituted phencanene-imides, BrCHRI, BrPICI, BrFULI were dependent on solvent polarity to display appreciable fluorescence color changes. The solvatofluorochromic behavior was analyzed by conventional relationships between Stokes shift and solvent polarity parameters, such as Lippert-Mataga and Bilot-Kawski equations. The results indicated that the solvatofluorochromism was derived from the intramolecular charge transfer (ICT) nature in the excited state. Theoretical studies using time-dependent density-functional theory revealed that the phenacene-imide molecules in the fluorescent state possessed ICT characters between the strongly electron-withdrawing imide moiety and moderately electron-donating phenacene cores. Amino-substituted chrysene-imide NH2CHRI showed fluorescence band in a red region (λFL = 618 nm) in toluene with a very large Stokes shift (Δν∼ = 7630 cm−1) suggesting that the molecule in the fluorescent state was highly polarized. The present results indicate that phenacenes would provide potential platforms for constructing future functional fluorophores through an appropriate functionalization.

A Comparative Study of New Fluorescent Anthraquinone and Benzanthrone α-Aminophosphonates: Synthesis, Spectroscopy, Toxicology, X-ray Crystallography, and Microscopy of Opisthorchis felineus.

In this research, we explore the synthesis of and characterize α-aminophosphonates derived from anthraquinone and benzanthrone, focusing on their fluorescence properties and potential applications in confocal laser scanning microscopy (CLSM). The synthesized compounds exhibit notable solvatochromic behavior, emitting fluorescence from green to red across various solvents. Spectroscopic analysis, including 1H-, 13C-, and 31P-NMR, FTIR, and mass spectrometry, confirms the chemical structures. The compounds' toxicity is evaluated using etiolated wheat sprouts, revealing varying degrees of impact on growth and oxidative damage. Furthermore, the study introduces these α-aminophosphonates for CLSM imaging of the parasitic flatworm Opisthorchis felineus, demonstrating their potential in visualizing biological specimens. Additionally, an X-ray crystallographic study of an anthraquinone α-aminophosphonate provides valuable structural insights.

Solvatochromic Behavior of Solid-State Nitrogen-Doped Carbon Nanoparticles: Initial Study

Carbon nanoparticles (CNPs) have garnered significant attention among researchers due to their cost-effectiveness and tunable properties, rendering them applicable in a wide array of fields, including biomedicine, optoelectronics, catalysis, and sensing. The solvatochromic effect denotes the phenomenon of a compound exhibiting a color change or a shift in its photoluminescence spectrum. In this study, we investigated the solvatochromic behavior of CNPs doped Nitrogen synthesized through the solid-state route using citric acid and urea, dissolved in solvents with varying polarity indices. Significant differences in emission were analyzed using a photoluminescence (PL) spectrometer. The results exhibit the emission shifting towards longer wavelengths (red region) as the solvent’s polarity index increased. This study of solvatochromic behavior in CNPs holds substantial significance for further research into their application as sensors.

Solvatochromism, optical and electronic properties of thiosemicarbazone derivatives in solution phase

The electronic structure, solvatochromic and some optoelectronic properties of five different thiosemicarbazone (TSCs) derivatives with different substituents consisted from indole ring, benzyl ring and conjugated thiosemicarbazide have been investigated in detail. UV–vis. absorption spectra of TSC compounds have been analyzed in solvent media with different polarity. The spectral changes are observed to forming of solvent effects and substituents. Spectral behaviors and electronic transitions are interpreted based on the UV-Vis. spectra. Solvatochromic behaviors were defined by linear solvation energy relationships via multiple linear regression analysis by using Kamlet-Abboud-Taft and Catalán parameters. In addition, the correlations of electronic absorption transition energy with Marcus optical dielectric parameter and Reichardt-Dimroth parameter were also determined. Some optoelectronic parameters such as forbidden band gap energy and refractive index have been determined in different solvent medium. Thiosemicarbazone derivatives have a global electronic absorption transition energy of about 3.351 eV. According to LSER calculations, polarizability-induction of electronic transitions of the investigated molecules is effective. The (E)-4-(4-nitrobenzyl)-1-(2-oxo-2H-indol-3(3aH)-ylidene)thiosemicarbazide (TSC-B) compound that does not a methoxy group and contain nitro group substituent and has the highest forbidden energy range.

Use of DFT Calculations as a Tool for Designing New Solvatochromic Probes for Biological Applications

The intramolecular charge transfer behavior of push–pull dyes is the origin of their sensitivity to environment. Such compounds are of interest as probes for bioimaging and as biosensors to monitor cellular dynamics and molecular interactions. Those that are solvatochromic are of particular interest in studies of lipid dynamics and heterogeneity. The development of new solvatochromic probes has been driven largely by the need to tune desirable properties such as solubility, emission wavelength, or the targeting of a particular cellular structure. DFT calculations are often used to characterize these dyes. However, if a correlation between computed (dipole moment) and experimentally measured solvatochromic behavior can be established, they can also be used as a design tool that is accessible to students. Here, we examine this correlation and include case studies of the effects of probe modifications and conformation on dipole moments within families of solvatochromic probes. Indeed, the ground state dipole moment, an easily computed parameter, is correlated with experimental solvatochromic behavior and can be used in the design of new environment-sensitive probes before committing resources to synthesis.