Synthesis of new azo compounds based on N-(4-hydroxypheneyl)maleimide and N-(4-methylpheneyl)maleimide

Novel maleic anhydride derivatives: liquid crystalline materials with enhanced mesomorphic and optical characteristics

A new class of liquid crystalline materials, 4-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)phenyl 4-(alkoxy)benzoates (Mn), derived from maleic anhydride, was synthesized and studied for mesomorphic and optical properties. These materials consist of three derivatives with varying terminal flexible chain lengths (6-12 carbons) linked to the phenyl ring near the ester bond. The study employed differential scanning calorimetry and polarized optical microscopy (POM) to characterize the mesomorphic properties. Molecular structures were elucidated using elemental analysis, FT-IR, and NMR spectroscopy. The findings reveal that all the synthesized maleic anhydride derivatives exhibit enantiotropic nematic (N) mesophases. The insertion of the heterocyclic maleic anhydride moiety into the molecular structure influences the stability and range of the N phase. Additionally, entropy changes during N-isotropic transitions are of small magnitude and exhibit non-linear trends independent of the terminal alkoxy chain length (n). This suggests that the ester linkage group does not significantly promote molecular biaxiality, and the clearing temperature values are relatively high. By comparing the investigated materials with their furan derivatives found in existing literature, it was established that the substitution examined in this study induces the formation of nematic phases.

Synthesis, Ligating Properties, Thermal Behavior, Computational and Biological Studies of Some Azo-transition Metal Complexes

Synthesis of new Fe(III), Co(II), Ni(II), and Cu(II) complexes of two azo ligands; 1-(phenyldiazenyl) naphthalene-2-ol (sudan orange R, HL1), and sodium 2-hydroxy-5-[(E)-(4-nitrophenyl) diazenyl]benzoate (alizarin yellow GG, HL2) have been reported. Stoichiometries of 1:2 and 1:3 (M:L) of the synthesized complexes were approved by total-reflection X-ray fluorescence technique (TXRF) and by elemental analyses. The geometry of complexes (octahedral and square planar) was typified by various spectroscopic, thermal, and magnetic techniques. The ESR spectroscopy showed that Cu(II) complexes are of different isotropic and rhombic symmetries with the existence of Cu–Cu ions interaction. TGA, DTA, and DSC analyses supported the multi-stage thermal decomposition mechanisms, where the thermal breakdown is ended by the formation of metal oxide in most cases. Moreover, chemical reactivity modeling using the density functional theory (DFT) method with the B3LYP/6–31 basis set, showed that metal complexes are more biologically active than their precursor ligands. The calculated lipophilicity character for metal complexes is in the range of 33.8–37.5 eV. Docking results revealed high scoring energy for [Fe(HL2)3].H2O complex and moderate inhibition strength of [Cu(L1)2].H2O complex versus 1bqb, 3t88, and 4esw proteins. Ultimately, the extent of biological effectiveness was endorsed experimentally against four microbial strains. The results are guidelines for toxicological investigations.

Graphical Abstract

Dual determination of nitrite and iron by a single greener sequential injection spectrophotometric system employing a simple single aqueous extract from Areca catechu Linn. serving as a natural reagent

Dual determination of nitrite and iron was proposed by using a single greener sequential injection (SI) spectrophotometric system employing a simple single aqueous extract from Areca catechu Linn. The extract served as a natural reagent to replace N-(1-naphthyl)ethylenediamine (NED) of the Griess reagent with nitrite and 1,10-phenanthroline with iron. The color products possessed analytical wavelengths at 430 and 560 nm, respectively. Conditions for the SI procedure were optimized using a univariate experimental design. Calibration ranges were up to 5.0 mg L⁻¹ and 10.0 mg L⁻¹ with limits of detection (LODs) of 0.04 mg L⁻¹ and 0.05 mg L⁻¹ for nitrite and iron(iii), respectively, and relative standard deviations (RSDs) being less than 3%. Recoveries of spiked standard nitrite and iron(iii) at 0.3 mg L⁻¹ and 0.5 mg L⁻¹ in water samples were 88 to 104% and 84 to 109%, respectively. The developed method successfully achieved dual determination of nitrite and total iron agreeing at a 95% confidence level with the reference methods of the conventional Griess assay and flame atomic absorption spectrometry (FAAS), respectively. The proposed method utilized locally available material from plants and serves the UN-SDGs.

Dual determination of nitrite and iron was proposed by using a single greener sequential injection (SI) spectrophotometric system employing a simple single aqueous extract from Areca catechu Linn.

Synthesis, characterization and the nonlinear optical properties of newly synthesized 4-((1,3-dioxo-1-phenylbutan-2-yl)diazenyl)benzenesulfonamide

The dye of azo compound is prepared by coupling reaction of dizonium salt of sulfanilamide with benzoylacetone. The product is characterized by FTIR spectroscopy, Mass spectroscopy and ¹H NMR spectroscopy. The geometries of the synthesized dye is optimized using B3LYP method and 6-31G (d,p) basis sets. Nonlinear optical properties are investigated theoretically by calculation of some quantum chemical descriptors using the DFT/B3LYP method with a 6-31G(d,p) basis set in comparison with urea as a standard. The UV-visible spectrum of synthesized azo dye are calculated using TD-DFT with B3LYP/6-31G(d,p) level. The nonlinear refractive index of the prepared dye is calculated via the diffraction ring patterns and Z-scan techniques using 473 nm visible, continuous wave laser light. The diffraction ring patterns are numerically simulated using the Fresnel-Kirchhoff theory with reasonable agreements. The property of optical limiting of the azo dye is tested.

Poly(oligo(ethylene glycol) methyl ether methacrylate) Capped pH-Responsive Poly(2-(diethylamino)ethyl methacrylate) Brushes Grafted on Mesoporous Silica Nanoparticles as Nanocarrier

In this paper, a new pH-responsive nanosystem based on mesoporous silica nanoparticles (MSNs) was developed for cancer therapy. Poly(2-(diethylamino) ethyl methacrylate) (PDEAEMA) was grafted on their outer surface and acts as a gatekeeper, followed by subsequent modification of the polymer by cysteine (MSN-PDEAEMA-Cys) and poly(oligo(ethylene glycol) methyl ether methacrylate) (MSN-PDEAEMA-Cys-POEGMEMA). The physicochemical properties of these nanocarriers were characterized using scanning and transmission electron microscopies (SEM and TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS). The synthesized nanoparticles were well-dispersed with a diameter of ca. 200 nm. The obtained XPS results confirm the successful modification of MSN-PDEAEMA with Cys and POEGMEMA by increasing the peak intensity of C-O and C=O groups at 286.5 and 288.5 eV, respectively. An anti-cancer drug, doxorubicin (DOX), was encapsulated into the fabricated nanoplatform. The DOX release amount at physiological pH of 7.4 was limited (10%), while an accumulation drug release of ca. 35% was accomplished after 30 h in acidic media. The MTT cell line was used to assess the cytotoxicity of the unloaded and DOX-loaded fabricated nanoplatforms. Upon loading of DOX on these nanomaterials, they showed significant toxicity to human liver cancer cells. These results suggest that the prepared nano-structured materials showed good biocompatibility as well, and they can serve as nanocarriers for the delivery of anti-cancer drugs.

Synthesis, characterization and computational study on potential inhibitory action of novel azo imidazole derivatives against COVID-19 main protease (Mpro: 6LU7)

•

Six azo imidazole derivatives have been synthesized and characterized by spectroscopic and analytical tools.

•

Inhibitory potential against main protease (6LU7) have been investigated using computational techniques.

•

Binding energy of the ligands has found in the range −6.7 Kcal/mole to −8.1 Kcal/mole.

•

The order of the ligands towards the protein 6LU7 are L5> L4≈L6>L1>L2>L3.

A series of six novel imidazole anchored azo-imidazole derivatives (L1-L6) have been prepared by the simple condensation reaction of azo-coupled ortho-vaniline precursor with amino functionalised imidazole derivative and the synthesized derivatives (L1-L6) have been characterized by different analytical and spectroscopic techniques. Molecular docking studies were carried out to ascertain the inhibitory action of studied ligands (L1-L6) against the Main Protease (6LU7) of novel coronavirus (COVID-19). The result of the docking of L1-L6 showed a significant inhibitory action against the Main protease (M^pro) of SARS-CoV-2 and the binding energy (ΔG) values of the ligands (L1-L6) against the protein 6LU7 have found to be -7.7 Kcal/mole (L1), -7.4 Kcal/mole (L2), -6.7 Kcal/mole (L3), -7.9 Kcal/mole (L4), -8.1 Kcal/mole (L5) and -7.9 Kcal/mole (L6). Pharmacokinetic properties (ADME) of the ligands (L1-L6) have also been studied.

Density Functional Theory Calculation on the Structural, Electronic, and Optical Properties of Fluorene-Based Azo Compounds

In the present work, a theoretical study was carried out to study the molecular structure, harmonic vibrational frequencies, normal force field calculations, and Raman scattering activities for fluorene π-conjugation spacer containing azo-based dye named trans- and cis-bis(9H-fluoren-2-yl)diazene (AzoFL) at density functional theory using B3LYP (Becke-3-Lee-Yang-Parr) functional and 6-31+G(d,p) basis set. The theoretical calculations have also been performed with fluorene and the trans- and cis-isomers of diazene, difluorodiazene by the same method DFT-B3LYP/6-31+G(d,p) and basis set. The present DFT calculation shows that the trans-AzoFL is more stable than the cis-AzoFL by 16.33 kcal/mol. We also report the results of new assignments of vibrational frequencies obtained on the basis of the present calculations. Time-dependent DFT (TD-DFT) and ZIndo calculations have been performed to study the UV-vis absorption behavior and frontier molecular orbitals for the above-mentioned compounds. The UV-vis spectrum from TD-DFT calculation shows the π-π* transition bands at λmax 423.53 nm (εmax 6.0 × 104 M-1 cm-1) and at λmax 359.45 nm (εmax 1.7 × 104 M-1 cm-1), respectively, for trans- and cis-AzoFL. Compared to parent trans-diazene (λmax 178.97 nm), a significant variation to longer wavelength (∼245 nm) is observed due to the incorporation of the fluorene (FL) ring into the -N=N- backbone. The co-planarity of the two FL rings with the longer N=N bond length compared to the unsubstituted parent diazene indicates the effective red shift due to the extended π-conjugation in trans-AzoFL. The nonplanarity of cis-AzoFL (48.1° tilted about the C-N bond relative to the planar N=N-C bond) reflects its ∼64 nm blue shift compared to that of trans-counterpart.

In Vitro Biological Estimation of 1,2,3-Triazolo[4,5-d]pyrimidine Derivatives as Anti-breast Cancer Agent: DFT, QSAR and Docking Studies

Background & Objective:

Series of synthesized molecular compounds were considered as anti-breast cancer. The molecular descriptors which describe the microbial activities of the studied compounds were calculated using theoretical approach.

Methods:

The calculated parameters obtained EHOMO (eV), ELUMO (eV), dipole moment (Debye), log P, molecular weight (amu), HBA, HBD, Vol and Ovality were screened. The obtained calculated descriptors were used to develop QSAR model for prediction of experimental inhibition concentration (IC50) using SPSS and Gretl software packages for multiple linear regression (MLR) and MATLAB for the artificial neural network (ANN).

Results:

From this statistical analysis, MLR and ANN were observed to be predictive, however, ANNQSAR model predicted more efficiently than MLR.

Conclusion:

Furthermore, molecular docking study was executed with breast cancer cell line (PDB ID: 1hi7); it was observed that BS20 with binding energy of -7.0 kcal/mol bounded more efficiently than other compounds also, it inhibited more than the standard used (5-FU).

Comment on: Synthesis of New Azo Compounds Based on N-(4-Hydroxyphenyl)maleimide and N-(4-Methylphenyl)maleimide. Molecules 2010, 15, 7498-7508

The synthesis of (E)-phenylazo-3-N-(4-hydroxyphenyl)maleimide (1) using a procedure previously reported in Molecules is deemed to be erroneous. A detailed re-investigation of the earlier work suggests that the spectral data for key intermediates and the final product, (1), was mis-assigned. We conclude that compound (1) was not synthesized, but rather an unusual ring opening reaction of the maleimide unit of the starting material, N-(4-hydroxyphenyl)maleimide (2) leading to the generation of (Z)-4-((4-hydroxyphenyl)amino)-4-oxobut-2-enoic acid, (3) was observed instead. Examination of the original experimental data reveals systematic errors in the reporting of all of the combustion microanalytical data. Overall, the present investigation suggests that errors in the interpretation of spectral data, falsification of analytical data and selective editing of experimental results raise questions over the veracity of the work presented in the original paper.

Hypoxia-Triggered Transforming Immunomodulator for Cancer Immunotherapy via Photodynamically Enhanced Antigen Presentation of Dendritic Cell

A key factor for successful cancer immunotherapy (CIT) is the extent of antigen presentation by dendritic cells (DCs) that phagocytize tumor-associated antigens (TAA) in the tumor site and migrate to tumor draining lymph nodes (TDLN) for the activation of T cells. Although various types of adjuvant delivery have been studied to enhance the activity of the DCs, poor delivery efficiency and depleted population of tumor infiltrating DCs have limited the efficacy of CIT. Herein, we report a hypoxia-responsive mesoporous silica nanocarrier (denoted as CAGE) for an enhanced CIT assisted by photodynamic therapy (PDT). In this study, CAGE was designed as a hypoxia-responsive transforming carrier to improve the intracellular uptake of nanocarriers and the delivery of adjuvants to DCs. Furthermore, PDT was exploited for the generation of immunogenic debris and recruitment of DCs in a tumor site, followed by enhanced antigen presentation. Finally, a significant inhibition of tumor growth was observed in vivo, signifying that the PDT would be a promising solution for DC-based immunotherapy.

Synthesis and characterization of aromatic-PDMS segmented block copolymers and their shape-memory performance

Aromatic-PDMS (AB)_n multiblock copolymers: a one-component polymeric system that combines excellent mechanical properties with shape memory capability.

Azo Compounds Derived from Electrochemical Reduction of Nitro Compounds for High Performance Li-Ion Batteries

Organic compounds are desirable alternatives for sustainable lithium-ion battery electrodes. However, the electrochemical properties of state-of-the-art organic electrodes are still worse than commercial inorganic counterparts. Here, a new chemistry is reported based on the electrochemical conversion of nitro compounds to azo compounds for high performance lithium-ion batteries. 4-Nitrobenzoic acid lithium salt (NBALS) is selected as a model nitro compound to systemically investigate the structure, lithiation/delithiation mechanism, and electrochemical performance of nitro compounds. NBALS delivers an initial capacity of 153 mAh g^-1 at 0.5 C and retains a capacity of 131 mAh g^-1 after 100 cycles. Detailed characterizations demonstrate that during initial electrochemical lithiation, the nitro group in crystalline NBALS is irreversibly reduced into an amorphous azo compound. Subsequently, the azo compound is reversibly lithiated/delithiated in the following charge/discharge cycles with high electrochemical performance. The lithiation/delithiation mechanism of azo compounds is also validated by directly using azo compounds as electrode materials, which exhibit similar electrochemical performance to nitro compounds, while having a much higher initial Coulombic efficiency. Therefore, this work proves that nitro compounds can be electrochemically converted to azo compounds for high performance lithium-ion batteries.

Azo compounds as a family of organic electrode materials for alkali-ion batteries

Organic compounds are desirable for sustainable Li-ion batteries (LIBs), but the poor cycle stability and low power density limit their large-scale application. Here we report a family of organic compounds containing azo group (N=N) for reversible lithiation/delithiation. Azobenzene-4,4'-dicarboxylic acid lithium salt (ADALS) with an azo group in the center of the conjugated structure is used as a model azo compound to investigate the electrochemical behaviors and reaction mechanism of azo compounds. In LIBs, ADALS can provide a capacity of 190 mAh g^-1 at 0.5 C (corresponding to current density of 95 mA g^-1) and still retain 90%, 71%, and 56% of the capacity when the current density is increased to 2 C, 10 C, and 20 C, respectively. Moreover, ADALS retains 89% of initial capacity after 5,000 cycles at 20 C with a slow capacity decay rate of 0.0023% per cycle, representing one of the best performances in all organic compounds. Superior electrochemical behavior of ADALS is also observed in Na-ion batteries, demonstrating that azo compounds are universal electrode materials for alkali-ion batteries. The highly reversible redox chemistry of azo compounds to alkali ions was confirmed by density-functional theory (DFT) calculations. It provides opportunities for developing sustainable batteries.

Graphene-based label-free electrochemical aptasensor for rapid and sensitive detection of foodborne pathogen

Reduced graphene oxide (rGO) has emerged as a promising nanomaterial for reliable detection of pathogenic bacteria due to its exceptional properties such as ultrahigh electron transfer ability, large surface to volume ratio, biocompatibility, and its unique interactions with DNA bases of the aptamer. In this study, rGO-azophloxine (AP) nanocomposite aptasensor was developed for a sensitive, rapid, and robust detection of foodborne pathogens. Besides providing an excellent conductive and soluble rGO nanocomposite, the AP dye also acts as an electroactive indicator for redox reactions. The interaction of the label-free single-stranded deoxyribonucleic acid (ssDNA) aptamer with the test organism, Salmonella enterica serovar Typhimurium (S. Typhimurium), was monitored by differential pulse voltammetry analysis, and this aptasensor showed high sensitivity and selectivity for whole-cell bacteria detection. Under optimum conditions, this aptasensor exhibited a linear range of detection from 10⁸ to 10¹ cfu mL^-1 with good linearity (R ² = 0.98) and a detection limit of 10¹ cfu mL^-1. Furthermore, the developed aptasensor was evaluated with non-Salmonella bacteria and artificially spiked chicken food sample with S. Typhimurium. The results demonstrated that the rGO-AP aptasensor possesses high potential to be adapted for the effective and rapid detection of a specific foodborne pathogen by an electrochemical approach. Graphical abstract Fabrication of graphene-based nanocomposite aptasensor for detection of foodborne pathogen.

Multi-tasking Schiff base ligand: a new concept of AuNPs synthesis

Multi-tasking 3,4-dihydroxysalophen Schiff base tetradentate ligand (3,4-DHS) as reductant, stabilizer, and catalyst in a new concept of gold nanoparticles (AuNPs) synthesis is demonstrated. 3,4-DHS is able to reduce HAuCl4 in water, acting also as capping agent for the generation of stable colloidal suspensions of Schiff base ligand-AuNPs assemblies of controlled size by providing a robust coating to AuNPs, within a unique reaction step. Once deposited on carbon electrodes, 3,4-DHS-AuNPs assemblies show a potent electrocatalytic effect towards hydrazine oxidation and hydrogen peroxide oxidation/reduction.

The synthesis of (Z)-4-oxo-4-(arylamino)but-2-enoic acids derivatives and determination of their inhibition properties against human carbonic anhydrase I and II isoenzymes

The synthesis of (Z)-4-oxo-4-(arylamino)but-2-enoic acid (4) derivatives containing structural characteristics that can be used for the synthesis of several active molecules, is presented. Some of the butenoic acid derivatives (4a, 4c, 4e, 4i, 4j, 4k) are synthesized following literature procedures and at the end of the reaction. In addition, structures of all synthesized derivatives (4a-4m) were determined by (1)H-NMR, (13)C-NMR and IR spectroscopy. Carbonic anhydrase is a metalloenzyme involved in many crucial physiologic processes as it catalyzes a simple but fundamental reaction, the reversible hydration of carbon dioxide to bicarbonate and protons. Significant results were obtained by evaluating the enzyme inhibitory activities of these derivatives against human carbonic anhydrase hCA I and II isoenzymes (hCA I and II). Butenoic acid derivatives (4a-4m) strongly inhibited hCA I and II with Kis in the low nanomolar range of 1.85 ± 0.58 to 5.04 ± 1.46 nM against hCA I and in the range of 2.01 ± 0.52 to 2.94 ± 1.31 nM against hCA II.

Synthesis and characterization of a novel fluorinated bismaleimide via a nucleophilic addition–elimination reaction and its polymeric networks

A novel fluorinated bismaleimide, OFCP-BMI, was designed and readily synthesized via the nucleophilic addition–elimination reaction of octafluorocyclopentene with maleimide-functionalized phenol.

1-[(E)-4-(Phenyl-diazen-yl)phen-yl]-3-pyrroline-2,5-dione

The title compound, C(16)H(11)N(3)O(2), displays a trans configuration with respect to the azo group. The mol-ecule is non-planar; the maleimide ring forms a dihedral angle of 42.35 (4)° with the benzene ring bonded to its N atom and the mean plane of this benzene ring is rotated by 21.46 (8)° with respect to the azo group mean plane, which, in turn, forms a dihedral angle of 24.48 (7)° with the 'terminal' benzene ring. Mol-ecules in the crystal are π-π stacked along the [100] direction with a mean inter-planar distance of 3.857 (1) Å. In addition, C-H⋯O inter-actions link them into double layers parallel to the ac plane.