Investigation of Solvent Effects on Photophysical Properties of New Aminophthalimide Derivatives-Based on Methanesulfonate

Photophysical Properties of Sinapic Acid and Ferulic Acid and Their Binding Mechanism with Caffeine

Sinapic acid (SA) and ferulic acid (FA) are bioactive compounds used in the food, pharmaceutical, and cosmetic industries due to their antioxidant properties. In this work, we studied the photophysical properties of SA and FA in different solvents and concentrations and their interactions with caffeine (CF), using ultraviolet-visible (UV-Vis), fluorescence spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The findings show that the quantum yield, fluorescence lifetime, radiative decay rates, and non-radiative decay rates of SA and FA are influenced by the concentrations and solvent polarity. The interaction between SA and FA with CF was also studied using UV-Vis and fluorescence spectroscopy. The results indicate that the CF quenched the fluorescence intensity of SA and FA by static quenching due to the formation of a non-fluorescent complex. The van't Hoff equation suggests that the van der Waals forces and hydrogen bonds force were responsible for the interaction between SA and CF, as indicated by a negative change in enthalpy (Δ H o  < 0) and a negative change in entropy (Δ S o  < 0). On the other hand, the interaction between FA and CF was primarily controlled by electrostatic force, as indicated by a negative change in enthalpy (Δ H o < 0) and a positive change in entropy (Δ S o > 0). The negative change in Gibbs free energy (Δ G o ) indicates that both compounds underwent a spontaneous binding process.

Effect of Hydroxyl Group on Photo-Physical Properties and Dipole Moments of Fluorescent Dyes: An Experimental and Computational Approach

In this work, structurally similar, (E)-N'-(2-hydroxybenzylidene)-3,5-di-tert-butyl-2-hydroxybenzohydrazide (A) and (E)-N'-(2-4-dihydroxybenzylidene)-3,5-di-tert-butyl-2-hydroxybenzohydrazide (A-OH) dyes dissolved in general solvents have been studied to explore photo-physical properties, employing solvatochromic shift method, thereby determining their dipole moments in the ground (μ_g) and excited (μ_e) states. The molecule A shows a bathochromic shift of fluorescence emission maxima in aprotic solvents whereas a hypsochromic shift in protic solvents. Interestingly, A-OH follows a hypsochromic shift in both protic and aprotic solvents with increasing solvent polarity. The effect of hydroxyl substituent on UV-Visible absorption, fluorescence emission, and dipole moment of the titled organic molecules was explained. Theoretical methods such as Bilot-Kawski method for determination of μ_g and μ_e and Bakshiev, Kawski-Chamma-Viallet, Lippert-Mataga equations for μ_e, and Reichardt method for the difference between μ_g and μ_e were employed. It is observed that μ_e is higher than that of μ_g for both the molecules, and interestingly, upon substituting an additional hydroxyl group the value of μ_g has increased while μ_e is decreased. The DFT calculations have been performed to support experimental results by employing DFT/B3LYP/6-311G + (d) and TD-DFT/B3LYP/6-311G + (d) method using Gaussian09 software. The electrophilic and nucleophilic sites on the molecules were studied with the help of MEP. The NBO analysis results show that the interaction N24 (σ) → C22-O23 (π*) is found to be stronger in both the molecules with energy 68.90 kJ/mol and the effect of hydroxyl group is also discussed on the basis of HOMO and LUMO.

Synthesis, spectroscopic characterization of novel phthalimides derivatives bearing a 1,2,3-triazole unit and examination as potential SARS-CoV-2 inhibitors via in silico studies

In the present study, novel phthalimide derivatives 8(a-f) and 9(a-f) bearing a 1,2,3-triazole subunit were synthesized via CuAAC reactions and characterized by 1H, 13C NMR, HR-MS, and FT-IR analyses. To support the fight against SARS-CoV-2, in silico molecular docking studies were carried out to examine their interactions with the proteins of SARS-CoV-2 (Mpro and PLpro) and the protein-protein interactions (PPI) between the ACE2-spike (S1) in comparison with various inhibitors reported to be active by in vitro experiments. The ligand-protein stabilities of compounds 8a-Mpro, 8b-PLpro, and 9a-'ACE2-S1' showing the best binding energy and predicted inhibition constant values (Ki) were examined by molecular dynamics simulation studies. Finally, in silico ADMET properties of the target compounds were investigated using the Swiss ADME and ProTox-II web tools. According to in silico results, all phthalimide analogs may block the PPI between S1 and ACE2. The compounds may also inhibit the progression of the Mpro, and PLpro proteins of SARS-CoV-2. Additionally, it has been estimated that the compounds are suitable for oral administration and exhibit low levels of toxicity.

Novel hybrid isoindole-1,3(2H)-dione compounds containing a 1H-tetrazole moiety: Synthesis, biological evaluation, and molecular docking studies

In this study, novel hybrid isoindole-1,3(2H)-dione compounds (10 and 11) carrying a 1H-tetrazole moiety were synthesized, characterized and their inhibitory properties against xanthine oxidase (XO) and carbonic anhydrase isoenzymes (hCA I and hCA II) were investigated. Allopurinol for XO and acetazolamide for carbonic anhydrase isoenzymes were used as positive standards in inhibition studies. In addition, compounds 8 and 9, which were obtained in the intermediate step, were also investigated for their inhibition effects against the three enzymes. According to the enzyme inhibition results, hybrid isoindole-1,3(2H)-dione derivatives 10 and 11 showed significant inhibitory effects against all three enzymes. Surprisingly, compound 8, containing a SCN functional group, exhibited a greater inhibitory effect than the other compounds against hCA I and hCA II. The IC₅₀ values of compound 8 against hCA I and hCA II were found to be 3.698 ± 0.079 and 3.147 ± 0.083 µM, respectively. Compound 8 (IC₅₀  = 4.261 ± 0.034 μM) showed higher activity than allopurinol (IC₅₀  = 4.678 ± 0.029 μM) and the other compounds against XO, as well. These results clearly show the effect of the SCN group on the inhibition. In addition, in silico molecular docking studies were performed to understand the molecular interactions between each compound and enzymes, and the results were evaluated.

Solvatochromism and estimation of ground and excited state dipole moments of 6-aminoquinoline

The spectral behaviour of 6AQ was investigated using fluorescence spectroscopy in several polar and non-polar solvents. Both the absorption and fluorescence spectra displayed solvatochromism. The Stokes shift increased significantly with increasing solvent polarity and signifies a more polar excited state with possible change in the excited state (ES) geometry. The involvement of π→π^∗ transition was observed. The ground state (GS) and excited state (ES) dipole moments were determined by the solvatochromic shift method using Bilot-Kawaski, Lippert-Mataga, Kawski-Chamma-Viallet, and Reichardt equations. The experimental value of GS dipole moment matches closely with the theoretical value computed using DFT/B3LYP/6-311G(d,p). The ES dipole moment is higher than the GS dipole moment. Besides, the solvatochromic study reveals that the ES of 6AQ is more polarized than the GS due to intramolecular charge transfer (ICT), possibly aided by a change in the geometry of the molecule in the ES. The influence of the non-specific and specific interactions in the photophysical properties of the titled molecule was analyzed using the Catalan scale. The study shows that 6AQ has reasonable band-gap energy and good CIE chromaticity coordinate in the blue region close to the national television standard committee system (NTSC) for the ideal blue CIE coordinate. Therefore, future research into 6AQ as a source of light-emitting diodes and fluorescent sensors may have potential applications in the field of optoelectronics.

A review on recent advances in amino acid and peptide-based fluorescence and its potential applications

Fluorescence is widely used to detect functional groups and ions, and peptides are used in various fields due to their excellent biological activity.

Evaluation of isoindole derivatives: Antioxidant potential and cytotoxicity in the HT-29 colon cancer cells

Norcantharimides have an isoindole skeleton structure, and some isoindoline derivatives have positive effects on inflammatory pathologies, including cancers. The present study aims to evaluate the antioxidant and cytotoxic potential of four synthesized isoindoline derivatives (NCTD1-4). HT-29 cells exposed to 10, 50, 100, and 200 µM doses of each derivative were incubated for 24 and 48 h, respectively. The cytotoxicity of the new derivatives was analyzed using the cell growth inhibition assay and the cell membrane damage test. In vitro antioxidant activity studies showed that the derivatives have free radical-scavenging effects in a dose-dependent manner. NCTD3 and NCTD4 apparently have antioxidant effects when compared with the control group treated with dimethyl sulfoxide. Furthermore, NCTD4 inhibited the growth of the HT-29 cells due to membrane damage and exhibited a dose-dependent cytotoxic effect on colon adenocarcinoma cells. The findings suggest that NDTD4 has the highest potential for colon cancer treatment and may be interpreted as a candidate anticancer agent.

The Synthesis, Anticancer Activity, Structure-Activity Relationships and Molecular Modelling Studies of Novel Isoindole-1,3(2H)-dione Compounds Containing Different Functional Groups

Background:

Isoindole-1,3(2H)-dione derivatives are known to have cytotoxic effects on many cancer cells. The anticancer activity of these compounds varies depending on the substituents attached to them. Therefore, the effect of substituents is very important when determining the anticancer activities of molecules. We have recently reported an example of the substituent effect.

:

According to that work, the anticancer activity against HeLa, C6, and A549 cancer cell lines of isoindole- 1,3(2H)-dione compounds containing tert-butyldiphenylsilyl ether, azido, and hydroxyl groups was examined by our group. It was found that an isoindole-1,3(2H)-dione compound containing both tert-butyldiphenylsilyl ether group and azido groups showed higher anticancer activity than 5-fluorouracil and another isoindole-1,3(2H)- dione compound containing both azido and hydroxyl groups.

:

After we discovered that tert-butyldiphenylsilyl ether group in the skeletal structure of isoindole-1,3(2H)-dione exhibits anticancer activity against HeLa, C6, and A549 cancer cell lines, we wanted to examine the anticancer activities of different silyl ether groups, i.e., OTMS, -OTBDPS, and -OTBDMS groups, and also -OH and -Br groups, by comparing them with each other according to the structure–activity relationship.

Methods:

All of the synthesized compounds were characterized by 1H and 13C NMR spectra, IR spectroscopy, and mass spectra measurements. The IC50 values of these compounds were calculated for all cancer cell lines and compared with each other and cisplatin, which is a platinum-containing chemotherapeutic drug. Molecular modelling studies were carried out using the MOE software package.

Results:

It was found that compounds 13 and 16, containing both silyl ether (-OTBDMS) and -Br groups, showed higher anticancer activity than cisplatin against both Caco-2 and MCF-7 cell lines. Compounds 20 and 23 showed anticancer activity in MCF-7 cells and compounds 8, 9, 20, and 23 in Caco-2 cells. While compounds 20 and 23 have only a silyl ether (-OTMS) group, compounds 8 and 9 have only a -OH group. Molecular modelling studies indicated that compounds 8 and 13, as well as their analogs, may bind to the active site of hRS6KB1 (pdb: 4l3j), compound 11 may bind to the active site of human mTOR (pdb: 4jt5) and additionally, compounds 10-17 are expected to be both mutagenic and reactive according to the mutagenicity and reactivity calculations.

Conclusion:

According to these results, the anticancer activities of isoindole-1,3(2H)-dione compounds (8 - 23) vary depending on the groups they contain and these groups affect each other's activities. Silyl ethers (-OTBDMS and -OTMS) and -OH and -Br groups in the skeletal structure of isoindole-1,3(2H)-dione can be regarded as anticancer agents. In this sense, compounds 13 and 16, containing both silyl ether (-OTBDMS) and - Br groups, may be regarded as alternative chemotherapeutic drugs. This work may lead to the synthesis of new isoindole-1,3(2H)-dione compounds containing different silyl ether groups and studies evaluating their anticancer activities or other biological properties.

Spectroscopic Study of Solvent Polarity on the Optical and Photo-Physical Properties of Novel 9,10-bis(coumarinyl)anthracene

Novel 7,7'-((anthracene-9,10-diylbis(methylene))bis(oxy))bis(4-methyl-2H-chromen-2-one) (BisCA) was prepared as fluorescent probe. The chemical structure of the novel BisCA was confirmed by spectroscopic data as well as elemental analyses. The solvatochromic characteristics of the new proble and its precursors were investigated in different solvents including, ethanol, DMF and toluene as protic polar, aprotic polar and non-polar solvents, respectively. Photo-physical parameters of probes, such as fluorescence quantum yields, fluorescence lifetime of excited state, radiative and non-radiative decay, were assessed in different media. The intermolecular H-bond effect on absorption and excitation spectra of the novel probe was reported in different solvents. Also, Onsager cavity radius and dipole moment of ground state and excited state of the probe were calculated as described by Bakhshiev and Reichardt methods.

Reversible mechanofluorochromism of aniline-terminated phenylene ethynylenes

Seven three-ring phenylene-ethynylene (PE) structural analogs, differing only in the lengths of alkyl chains on terminal aniline substituents, show 50-62 nm bathochromic shifts in emission maxima in response to mechanical force (mechanofluorochromism, MC). These shifts are fully reversible with heat or solvent fuming. Shearing of these solids yields a transition from green-emitting crystalline phases to orange-emitting amorphous phases as established by differential scanning calorimetry and X-ray diffraction. Molecules with shorter alkyl chain lengths required higher temperatures to recover the hypsochromically shifted crystalline phases after grinding, while the recovery with chain lengths longer than butyl occurred at room temperature. In addition to this structure-dependent thermochromism, these compounds retain their MC properties in polymer hosts to various extents. The crystalline phases of these materials have PE chromophores that are twisted due to non-covalent perfluoroarene-arene (ArF-ArH) interactions involving perfluorophenyl pendants and the terminal rings of the PE chromophore, resulting in interrupted conjugation and an absence of chromophore aggregation. The MC behavior of an analog without the perfluoroarene rings is severely attenuated. This work demonstrates the general utility of twisted PEs as stimuli-responsive moieties and reveals clear structure-property relationships regarding the effects of alkyl chain length on these materials.

Gaining insight into the photophysical properties of a coumarin STP ester with potential for bioconjugation

The photophysical properties of a coumarin 392 4-sulfotetrafluorophenyl ester, C392STP (sodium (E/Z)-4-(4-(2-(6,7-dimethoxycoumarin-3-yl)vinyl)-benzoyl)-2,3,5,6-tetrafluoro-benzenesulfonate), an amine reactive coumarine with potential for bioconjungation, have been studied in different solvents.

Carbazole- and/or triphenylamine-based D–π–D multiarylamino dyes: synthesis, characterization and photophysical properties

One-photon and two-photon fluorescence quenching by benzoyl peroxide of D–π–D multiarylamino dyes was investigated.