Schiff Base Research Articles

Removal of As(V) and Cr(VI) using quinoxaline chitosan schiff base: synthesis, characterization and adsorption mechanism

AbstractElevated Arsenic and Chromium levels in surface and ground waters are a significant health concern in several parts of the world. Chitosan quinoxaline Schiff base (CsQ) and cross-linked chitosan quinoxaline Schiff base (CsQG) were prepared to adsorb both Arsenate [As(V)] and Chromium [Cr(VI)] ions. The thermo-gravimetric analysis (TGA), X-ray diffraction analysis (XRD), and Fourier-transform infrared spectroscopy (FTIR) were used to investigate the prepared Schiff bases (CsQ) and (CsQG). The UV–VIS spectra showed a shift in the wavelength area of the modified polymer, indicating the reaction occurrence, besides the variation of the shape and intensity of the peaks. The XRD patterns showed the incensement of the amorphous characteristic. On the other hand, the thermal stability of the modified polymers is better according to TGA studies; also, the morphology of the modified chitosan was investigated before and after crosslinking (CsQ and CsQG) using a scanning electron microscope (SEM) where the surface was fall of wrinkles and pores, which then were decreased after cross-linking. Contact time, temperature, pH, and initial metal ion concentration were all studied as factors influencing metal ion uptake behavior. The Langmuir, Temkin, Dubinin–Radushkevich, and Freundlich isotherm models were used to describe the equilibrium data using metal concentrations of 10–1000 mg/L at pH = 7 and 1 g of adsorbent. The pseudo-first-order and pseudo-second-order kinetic parameters were evaluated. The experimental data revealed that the adsorption kinetics follow the mechanism of the pseudo-second-order equation with R2 values (0.9969, 0.9061) in case of using CsQ and R2 values (0.9989, 0.9999) in case of using CsQG, demonstrating chemical sorption is the rate-limiting step of the adsorption mechanism. Comparing the adsorption efficiency of the synthesized Schiff base and the cross-linked one, it was found that CsQ is a better adsorbent than CsQG in both cases of As(V) and Cr(VI) removal. This means that cross-linking doesn’t enhance the efficiency as expected, but on the contrary, in some cases, it decreases the removal. In addition, the newly modified chitosan polymers work better in As(V) removal than Cr(VI); the removal is 22.33% for Cr(VI) and 98.36% for As(V) using CsQ polymer, whereas using CsQG, the values are 6.20% and 91.75% respectively. On the other hand, the maximum adsorption capacity (Qm) for As(V) and Cr(VI) are 8.811 and 3.003 mg/g, respectively, using CsQ, while in the case of using CsQG, the Qm value reaches 31.95 mg/g for As(V), and 103.09 mg/g for Cr(VI).

Developing and Characterizing a Biocompatible Hydrogel Obtained by Cross-Linking Gelatin with Oxidized Sodium Alginate for Potential Biomedical Applications

The main goal of this research was to create biocompatible hydrogels using gelatin and a double cross-linking technique involving both covalent and ionic bonds to immobilize propolis. The covalent bonds were formed through Schiff base cross-links between protein-free amino groups (NH2) from the lysine residue and aldehyde groups (CHO) produced by oxidizing sodium alginate with NaIO4, while the ionic bonds were achieved using Mg2+ ions. Hydrogel films were obtained by varying the molar ratios of –CHO/–NH2 under different pH conditions (3.5 and 5.5). The presence of aldehyde groups in the oxidized sodium alginate (OSA) was confirmed using FTIR and NMR spectroscopy. The oxidation degree was monitored over 48 h, and the influence of temperature was examined. Results showed that higher –CHO/–NH2 molar ratios led to increased conversion index values of NH2 groups, and a decrease in swelling degree values was observed in mediums with pH values of 5.5 and 7.4. The encapsulation and release efficiency of propolis decreased with an increase in the hydrogel cross-linking degree. UV irradiation enhanced the antioxidant activity of both free and encapsulated propolis. These findings offer valuable insights for the biomedical and pharmaceutical fields into designing biocompatible hydrogels for propolis immobilization, with potential for controlled release.

Synthesis and characterization of oligo(phenoxy-imine)s of Schiff bases containing phenyl-1,3,5-triazine unit: limit oxygen index values of oligomers

Synthesis and characterization of oligo(phenoxy-imine)s of Schiff bases containing phenyl-1,3,5-triazine unit: limit oxygen index values of oligomers

Novel pyrrole based triazole moiety as therapeutic hybrid: synthesis, characterization and anti-Alzheimer potential with molecular mechanism of protein ligand profile

As a springboard to explore novel potent inhibitors of cholinesterase enzymes (AChE and BChE) responsible for causing Alzheimer disorder, the current study was conducted to synthesize pyrrole derived triazole based Schiff base scaffolds by facile synthetic route. These compounds were validated by 1HNMR, 13CNMR and HREI-MS. All these scaffolds (1–16) were examined for their inhibitory activity against AChE and BChE in contrast to Donepezil (10.20 ± 0.10 and 10.80 ± 0.20 µM) and Allanzanthone (12.40 ± 0.10 and 13.10 ± 0.10 µM). All pyrrole derived triazole based Schiff base scaffolds (1–16) showed varied range of inhibitory potentials against acetylcholinesterase and butyrylcholinesterase enzymes with lowest inhibition concentration values ranging from 5.10 ± 0.40–27.10 ± 0.10 µM (for AChE) and 5.60 ± 0.30–28.40 ± 0.30 µM (for BChE). SAR analysis of these derivatives revealed analog 7 as lead molecule against targeted enzyme, while analog 6 and 11 were ranked as second and third most potent scaffolds. Binding affinity and selectivity of potent molecules against targeted enzymes were examined by molecular docking and obtained results showed that potent molecule have versatile significant binding interactions with stated enzymes. Furthermore, safety profiles of potent analogues were predicted via ADMET protocols.Graphical

Synthesis, spectroscopic characterization techniques of aromatic iminoaniline derived compound, along with the evaluation of its LNO properties using quantum chemistry

In this research work, we synthesized a Schiff base derivative, N,N-dimethyl-4-{[(4-nitrophenyl)imino]-methyl}aniline, denoted as (n1). The molecule (n1) was characterized using spectroscopic analyses, including FT-IR, NMR 1H, and 13C. Our compound (n1) is an unsaturated molecule, consisting of two benzylic rings connected by a methylimine bridge. The resulting system comprises seven alternating π bonds. At both ends of (n1) and in the para position, there are the N(CH3)2 group with a strong electron-donating effect and the NO2 group with a strong electron-accepting effect. The molecular structure of our compound prompted us to evaluate and study its properties in the field of NLO. The assessment of NLO properties is conducted by determining the Egap and employing density functional theory (DFT) quantum chemistry studies. The optical gap of (n1), measured using the Tauc method, is found to be 2.7 eV, serving as a reference value for the choice of the DFT functional in theoretical calculations. Quantum chemistry studies were carried out using Gaussian09 software, and the results were visualized with GaussView05. CAM-B3lyp functional was chosen for theoretical calculations due to its close agreement with experimental values. The studies confirm that (n1) exhibits significant NLO properties. Additionally, NBO (Natural Bond Orbital) analyses provide insight into the mechanism and trajectory of intramolecular charge transfer in (n1).

Crystal structures and circular dichroism of {2,2′-[(1S,2S)-1,2-diphenylethane-1,2-diylbis(nitrilophenylmethanylylidene)]diphenolato}nickel(II) and its ethanol solvate

The title compound, [Ni(C40H30N2O2)] (1), with an optically active Schiff base ligand derived from 2-hydroxybenzophenone and (1S,2S)-1,2-diphenylethylenediamine, was crystallized as the solvent-free and ethanol solvate forms (1 and 1·2C2H5OH). In both structures, the two phenyl groups on the stereogenic centers of the O,N,N,O-tetradentate ligand are axially oriented, and the conformation of the central diamine chelate ring is λ. The circular dichroism (CD) spectra of 1 and the analogous nickel(II) complex [Ni(C30H26N2O2)] (2) in solution show partially similar patterns in the 350–450 nm range, but are mirror images in the longer wavelength region (450–650 nm). In the latter region, the sign of CD for these complexes is sensitive to the substituents on the C=N carbon atoms (phenyl for 1 and methyl for 2) rather than the diamine chelate ring conformation.

In Situ SERS Monitoring of Schiff Base Reactions Via Nanoparticles on a Mirror Platform

Schiff base reactions are widely used in pharmacy, catalysis, and volatile aldehyde detection. However, common biomarker sensing methods struggle to monitor this reaction process precisely due to their sensitivity, their time-consuming nature, and complex substrates. Here, we introduce the Nanoparticle-on-Mirror structure for in situ monitoring this reaction process through the application of a Au nanoparticle-p-Aminothiophenol-Au thin-film platform by surface-enhanced Raman scattering (SERS). Owing to the exposure of -NH2 groups and the local ultra-strong electromagnetic field in the nanocavity, the Schiff base reactions process can be rapidly monitored within two minutes. Meanwhile, the monitoring platform can detect benzaldehyde molecules as low as 10−6 M, showing excellent SERS performance. Notably, the Au-nanoparticle-p-Aminothiophenol-Au thin-film platform exhibited anti-interference and specificity, being able to identify BA in the presence of interference. The use of the Au-nanoparticle-p-Aminothiophenol-Au thin-film platform provides a sensing method for Schiff base reactions with accuracy and simplicity of operation, achieving a balanced approach for low-cost and high-performance real-time monitoring, which is expected to be applied in various catalytic reaction process monitoring and catalyst design processes.

Evaluating the antidiabetes and antioxidant activities of halogenated Schiff bases derived from 4-(diethylamino)salicylaldehyde: in vitro antidiabetes, antioxidant and computational investigation

Six Schiff bases with general name 5-(diethylamino)-2-(((halophenyl)imino)methyl)phenol (where halo = 4-fluoro (H1), 2-fluoro (H2), 2-bromo (H3), 4-bromo (H4), 4-chloro (H5) and 3-chloro-4-fluoro (H6)) were prepared by the condensation reaction between 4-(diethylamino)salicylaldehyde and suitable halogenated aromatic amines. The six halogenated Schiff bases were elucidated using different spectroscopic techniques and the structure of H3 and H6 were confirmed using single-crystal X-ray crystallography. The bond lengths of C7–N1, C7–C8 and C8–C9 obtained from structural analysis for both compounds depicted their enol-tautomeric characteristic form. The Hirshfeld analysis revealed that H‧‧‧H intermolecular contacts contributed most towards the Hirshfeld surfaces of both H3 (47.6%) and H6 (39.9%). Quantum chemical calculation studies showed that H1 and H2 have the highest and lowest energy band gap (∆E = 3.80 eV for H1 and ∆E = 3.73 eV for H2), depicting H2 and H1 as the most and least chemically reactive respectively among all the compounds. α-Amylase and α-glucosidase assay were used to evaluate the antidiabetes prowess of the synthesized compounds. All the compounds exhibited lower IC50 values than acarbose (reference drug) in α-amylase assay experiments and H5 with lowest IC50 value of 63.54 μM could be suggested to have the highest α-amylase inhibitory potential among the test samples. For α-glucosidase assay, H1–H6 displayed good antidiabetic potential. However, none of the compounds outshined acarbose with H6 having highest α-glucosidase inhibitory potential when compared to others i.e., IC50 of H6 = 60.89 μM and IC50 of acarbose = 51.42 μM. We measured the antioxidant potential of H1–H6 exploring 2,2-diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO) and ferric reducing ability power (FRAP) assays. The DPPH as well as NO radical scavenging assay showed that all the compounds exhibited excellent antioxidant results with some of the compounds surpassing catechin (reference drug). Compound H5 with IC50 values of 30.32 mM and 31.73 mM outshined catechin with IC50 values of 31.17 mM and 140.62 mM for DPPH and NO assays respectively. All the compounds fell within the threshold of Lipinski’s Ro5 projecting them as orally bioavailable and less toxic future therapeutics.

A Comprehensive Journey of a Vanillic Aldehyde-Chloroaniline Schiff Base from Solvent-Free Synthesis to Electronic Structure, In Silico and In Vitro Biological Analysis

Schiff bases possess a range of unique physical, chemical and medicinal properties, which contribute to their potency as biological agents. A Schiff base was synthesized, which consisted of 4-chloro aniline and vanillin. The successful formation of the compound was confirmed by their comparable FTIR, UV–Vis, 1HNMR and [Formula: see text]CNMR spectra. The compound was analyzed using X-ray crystallography, which revealed that it crystallizes in the monoclinic system with the space group P21/c. The Hirshfeld surface analysis revealed valuable information about the intermolecular interactions present in the crystal lattice. The most common contacts observed were between hydrogen and hydrogen, as well as carbon and hydrogen. The obtained fluorescence values of 375 nm and 412 nm at excitation wavelength 322 nm strongly indicated the luminescent nature of the compound. The thermal stability of the compound was assessed through thermogravimetric analysis (TGA). DFT was used to optimize the geometry using the B3LYP/cc-pVDZ basis set. The compound exhibited an energy gap of 2.35 electron volts (eV). According to the analysis of molecular electrostatic potential, C and O atoms were found to be electrophilic. According to Mulliken charge analysis, C atoms possess both positive and negative charges, hydrogen atoms exclusively carry positive charges, and Cl, O and N atoms exclusively carry negative charges. Upon analysis of the molecule, the electron localization function discovered that the atoms of carbon, nitrogen and chlorine exhibited delocalized electron density. Also, the localized orbital locator identified the localized orbital positions in the hydrogen atoms. The reduced density gradient (RDG) maps exhibit a wide range of noncovalent interactions. In comparison to the standard amoxicillin, the synthesized compound demonstrated moderate antimicrobial efficacy against the gram-positive bacteria Klebsiella pneumoniae and the fungi Candida albicans. The compound’s concentration-dependent antioxidant and anti-inflammatory properties were demonstrated through in vitro biological evaluation using 2,2-diphenyl-1-picrylhydrazyl and human red blood cell (HRBC) methods. The compound was docked using the proteins 7BYE and 4LEB were chosen from both organisms. The lowest binding attractions obtained were -3.40 kcal/mol for 7BYE and -4.51 kcal/mol for 4LEB. To investigate the stability of the protein–ligand complex, molecular dynamic simulation was employed. The ligands in silico toxicity potentialities were analyzed using seven toxicity models and the results indicated that the ligand is biocompatible.

Novel Schiff bases of quinolin-4(1h)-one: Synthesis, antiproliferative evaluation, apoptosis, cell cycle, autophagy and molecular docking studies in human colon cancer cells

A green and efficient ultrasound-mediated protocol was developed for the synthesis of a series of novel Schiff bases derived from quinoline-4-one. The synthetic strategy involved the condensation of 4-oxo-1,4-dihydro-quinoline-3-carboxaldehyde with diverse anilines and heteroaryl amines. The synthesized compounds were characterized using spectroscopic techniques. A comprehensive in vitro cytotoxicity evaluation against HCT116 and HT-29 human colon cancer cell lines revealed that several compounds exhibited potent anticancer activity. Notably, compounds 3c and 3e demonstrated superior cytotoxicity compared to the clinical standard doxorubicin. Mechanistic studies indicated that these lead compounds induced apoptosis, necrosis, and cell cycle arrest at G1 and G2 phases. Furthermore, autophagy induction was observed. In silico ADMET predictions support the potential of compounds 3c and 3e as promising anticancer drug candidates. The molecular docking studies revealed that the Schiff bases 3c and 3e displayed good interaction with VEGFR-2 receptor. These findings underscore the quinoline-4-one scaffold as a valuable template for the development of novel antitumor agents.

Structures and NMR Solution Dynamics of Diorganotin Complexes with Bulky Quadridentate Salen‐ and Salphen‐Type Schiff Bases (N2O2) Incorporating Diazenylpyridyl Side Arms

AbstractA series of six complexes [n‐Bu2Sn(L1)]⋅S (S=Benzene/toluene, mixed/partial) (1), [Ph2Sn(L1)]n⋅S (S=Benzene) (2), [Bz2Sn(L1)] (3), [n‐Bu2Sn(L2)]n (4), [Ph2Sn(L2)] (5) and [Bz2Sn(L2)] (6) were synthesized using diorganotin(IV) oxide precursors and two new bis‐Schiff bases containing N2O2 donor atoms. The Schiff bases, H2L1 and H2L2, were prepared by reacting ethane‐1,2‐diamine or benzene‐1,2‐diamine with 2‐hydroxy‐5‐(pyridin‐3‐yldiazenyl)benzaldehyde in absolute ethanol. Compounds 1–6 were characterized by IR and NMR spectroscopies, as well as by solid‐state single‐crystal X‐ray diffraction (except for 3 and 6). In all the complexes the bis‐Schiff bases occupy the equatorial positions and the R groups are in axial sites. However, while 1 and 5 are discrete molecules where the tin atoms adopt distorted octahedral geometries, 2 and 4 are monoperiodic polymers with the metal cations in pentagonal bipyramidal environments. Although solid state crystallographic results revealed asymmetrical molecular configurations, solution NMR studies proved symmetric arrangements for all the compounds. Tin NMR spectroscopy confirmed that all complexes are six‐coordinate in solution, despite variations in solid‐state coordination. Further analysis using Hirshfeld surface and fingerprint plots provided insights into intermolecular interactions in compounds 1, 2, 4, and 5. This comprehensive study underscores the structural diversity and solution‐state dynamics of organotin(IV) complexes synthesized using novel Schiff bases.

Synthesis, Spectroscopy and Biological Studies of Copper and Silver Complexes Derived from 2-Substituted Amino Propanoic Acid

Synthesis of copper and silver complexes were prepared from novel Schiff base ligand. These synthesized ligand and their metal complexes were characterized by elemental analysis, FT-IR, 1H NMR, UV-Vis and Mass spectrometry. The coordination of amino nitrogen, phenolic oxygen, and carboxylato oxygen atoms is shown by the infrared spectra.The Schiff bases and its complexes were screened for their in vitro antibacterial and antifungal studies against the bacteria Pseudomonas Aeruginosa (PA, Gram -ve), Bacillus Cirroflagellosus (BC, Gram +ve), Penicillium Notatium (PN) and Aspergillus Niger (AN) strains. The results of the antibacterial investigation show that the copper and silver complexes possess more potent bactericide and fungicide properties than the ligand.

Crystal Structures and Biological Profiles of Novel Tridentate Schiff Bases Nickel (II) Complexes

ABSTRACTNovel bioactive ternary nickel (II) complexes, [Ni(5BrSal‐Phe)(phen)] (1) and [Ni(5BrSal‐Tyr)(phen)] (2) (5BrSal‐Tyr: Schiff base derived from 5‐bromosalicylaldehyde and L‐tyrosine, 5BrSal‐Phe: Schiff base derived from 5‐bromosalicylaldehyde and L‐phenylalanine, phen: 1,10‐phenanthroline), have been synthesized and characterized by electronic absorption spectroscopy, CHN, FTIR, ESI‐MS and X‐ray crystallography techniques. Interaction of the complexes with biomolecules (calf thymus DNA (CT‐DNA) and bovine serum albumin (BSA)) has been investigated by electronic absorption and fluorescence spectroscopy. The results show that the complexes can bind to CT‐DNA via a minor groove binding mode. Moreover, the fluorescence quenching mechanism between the complexes and BSA is a static quenching process. The antiproliferative activities of the complexes against breast cancer cells (MCF‐7 and MDA‐MB‐231) and healthy breast epithelial cells (MCF‐10A) were investigated. The complex 2 was found to have promising antiproliferative activity in selected cell line, with lower IC50 values than cisplatin. Molecular docking studies suggest that the complexes may serve as potential chemotherapeutic agents. These complexes have been observed to interact with various targets within cells, including the epidermal growth factor receptor (EGFR), bovine serum albumin (BSA), and B‐DNA. Analyses indicate that these interactions are supported not only by conventional hydrogen bonds but also van der Waals forces and π‐π interactions. Additionally, determining binding constants and regions enhances our understanding of how the complexes interact with target molecules. The results emphasize the importance of the complexes in cancer therapy by highlighting the necessity of understanding their molecular‐level interactions with targets.

Self-Healing Hyaluronic Acid-based Hydrogel with miRNA140-5p Loaded MON-PEI Nanoparticles for Chondrocyte Regeneration: Schiff Base Self-Assembly Approach.

Articular cartilage defects present a significant therapeutic challenge due to the inherent avascular and aneural characteristics of cartilage tissue. Gene therapy has emerged as a promising strategy for cartilage regeneration, particularly through the use of functional RNA and biomaterial-assisted frameworks. In this study, an innovative gene-activated self-healing hydrogel is developed and fabricated for the controlled release of miR140-5p, a key regulator of cartilage regeneration. The hydrogel, crosslinked via UV radiation, is composed of aminated hyaluronic acid and a modified photosensitizer (NB). To enhance the scaffold's structural integrity and gene delivery efficiency, mineralized silk fibroin and miR140-5p-loaded MON-PEI nanoparticles are incorporated. These findings demonstrate that this novel hydrogel (miR140-5p-CaP@mSF-HA-NB) effectively encapsulates and releases miR140-5p, exhibits excellent biocompatibility, and promotes enhanced cartilage regeneration in both in vitro and in vivo models. Therefore, this gene-activated hydrogel holds significant potential for clinical applications in the treatment of articular cartilage defects.

Redevelopment of natural eugenol as potential pesticidal resource: New insights into synthesis and antifungal evaluation of eugenol-derived Schiff bases with reactive oxygen species behavior

Natural products have ancient history as fascinating sources of pharmaceuticals, agrochemicals as well as NPs-derived drug/pesticide innovation. Its diversiform biological performance and skeleton diversity enable to fill the drug/pesticide discovery pipeline in response to the growing innovation demand. Eugenol, a naturally occurring phenolic compound from plant Eugenia caryophyllata, have been attracting attention in agricultural application. To further extend its value-added utilizations in agricultural application and elucidate the underlying molecule mechanism, the 35 of novel eugenol-derived Schiff bases were herein skillfully prepared by means of natural-products modification strategy. Interestingly, the antifungal activity results indicated that the optimal antifungal molecule was A10, affording an EC50 of 0.850 μg/mL toward Botryosphaeria dothidea (B. d.), which was superior to those of parent eugenol (EC50 > 100 μg/mL) and ferimzone (EC50 > 100 μg/mL). It was illustrated that introduction of Schiff base scaffold into natural eugenol contributed to enhance the antifungal performance. Furthermore, a series of bioassays showed the antifungal behavior of compound A10, which had a powerful disruptive effect on the membrane by triggering reactive oxygen species production in the mycelium. Taken together, this study redeveloped natural eugenol as potential antifungal candidates to control fungal infections by triggering reactive oxygen species production.

Innovative Thiophene Schiff Bases: Synthesis and Evaluation as Antitubercular Agents

Innovative Thiophene Schiff Bases: Synthesis and Evaluation as Antitubercular Agents

Exploring the potent corrosion inhibition properties of phenolic Schiff bases on mild steel in acidic environments, part A: coupling experimental and theoretical investigations.

In this study, we conduct a comparative investigation into the corrosion inhibition properties of two Schiff base compounds, namely 4,4'-((1E,1'E)-(ethane-1,2 diylbis(azaneylylidene))bis(methaneylylidene))diphenol (PSB5) and (1E,1'E)-N,N'-(ethane-1,2 diyl)bis(1-(4-nitrophenyl)methanimine) (PSB6), on mild steel in an acidic environment. The inhibitory efficiency and adsorption behavior of the inhibitors were assessed through electrochemical and gravimetric analyses. The inhibitors' deposition was further verified by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The findings of electrochemical tests demonstrate that these chemical compounds are potent inhibitors, with 96.5% inhibition provided by PSB5 at 10-3M. Therefore, PSB5 and PSB6 inhibitors are likely of mixed-form, as evidenced by changes in their Ecorr values of 59.8 mV and 33.0 mV, respectively when compared to the blank solution. Furthermore, the adsorption of these inhibitors onto the MS surface, as determined by the Langmuir adsorption isotherm, yielded free energy values of - 38.40 kJ mol-1 for PSB5 and - 35.20 kJ mol-1 for PSB6. These findings highlight a robust and spontaneous adsorption process for both inhibitors. Surface analysis using SEM-EDS revealed the preservation of the mild steel surface morphology and the adsorption of inhibitors. Theoretical investigations utilizing density functional theory (DFT) and molecular dynamics (MD) simulations supported and complemented the experimental findings. This research enhances the understanding of the corrosion protection potential of Schiff base compounds and their potential applications in various industries.

Optical and surface properties of Schiff base ligands and Cu(II) and Co(II) complexes

Objectives. To study the transition of electrons in 1,2-phenyl(4’-carboxy)benzylidene Schiff base ligand and transition metal ions, optical properties, as well as the surface chemistry of supported transition metals using diffuse reflectance spectroscopy (DRS); to study the roughness and morphology of the Schiff base ligand and its complexes using atomic force microscopy (AFM).Methods. DRS, AFM, and Fourier-transform infrared spectroscopy instruments were used to identify electron transitions, optical properties, and surface morphology in Schiff base ligands and their complexes.Results. The DRS revealed the d–d transitions and charge transfer shifts of all compounds, and helped identify the structure of the ligand. One of the optical properties studied was the energy gap calculation of the ligand and its complexes. The copper complex exhibited more semiconducting behavior with surface morphology properties such as surface roughness parameters lower than those of the ligand and the cobalt complex. This can be attributed to the smaller size of the copper atom, as well as lower electron transitions compared to the cobalt complex and the square planar bonding shape.Conclusions. In Schiff base ligands, the reflectance spectrum bands reveal three electron transitions: n→π*, π→π*, and σ→σ* transitions. In cobalt complexes, four transitions are indicated: 4A2(F)→4T1(F), 4A2(F)→4T1(P), charge transfer bands, and tetrahedral geometry. Copper complexes exhibit three transitions: 2B1g→2A1g, 2B1g→2Eg, and charge transfer bands, with a square planar geometry for their structure. The energy gap calculations were 2.42, 2.29, and 2.30 eV, respectively. In the case of the SH ligands, copper complexes, and cobalt complexes, all compounds exhibited semiconductor properties. However, the complexes displayed increased conductivity due to the influence of the metal and coordination structure.

Cornu-Spiral-Like Organic Crystal Waveguide Providing Discriminatory Optical Pathway for Smart Organic Photonic Circuit.

In the era of artificial intelligence, developing advanced and intelligent photonic circuits has become essential. In this work, the fabrication of a smart organic photonic circuit (OPC), is illustrated which utilizes a Cornu-spiral-like waveguide (CSW) to produce discriminating optical pathways in the circuit. The mechanical flexibility of Schiff base, (E)-1-(((5-iodopyridin-2-yl)imino)methyl)naphthalen-2-ol (IPyIN) facilitates the fabrication of a first-of-its-kind, two-ring-based CSW via the atomic force microscopy cantilever tip-assisted mechanophotonics approach. The photonic studies suggest that the CSW structure routes optical signals in discriminating trajectories. To capitalize on the discriminatory properties of the CSW, two linear waveguides onto both rings of the CSW are integrated to create a smart OPC. This smart OPC can selectively route optical signals either partially or fully in the circuit, depending on the pathways determined by the CSW, thus enabling the circuit to switch ON or OFF. Such intelligent photonic circuits are essential for advancing smart technologies.

Synthesis, crystal structures and antiproliferative activities of a new indole-containing dipyridylmethanone hydrazone Schiff base and its cadmium(II) complex.

In this study, we introduce a novel indole-containing pyridine-based Schiff base, (E)-2-({[bis(pyridin-2-yl)methylidene]hydrazin-1-ylidene}methyl)-1H-indole, C20H15N5 (2-DPHI), and its cadmium(II) complex poly[[2-({[bis(pyridin-2-yl)methylidene]hydrazin-1-ylidene}methyl)-1H-indole]di-μ-chlorido-cadmium(II)], [CdCl2(C20H15N5)]n (pCd2), as potential anticancer agents. The Schiff base was synthesized by reacting dipyridylmethanone hydrazone with indole-2-formaldehyde, while the cadmium complex was prepared by combining CdCl2 and 2-DPHI in methanol at room temperature. Both compounds were evaluated for their cytotoxicity against three human cancer cell lines (A375, A549 and HeLa) and a normal cell line (HFF-1). The ligand 2-DPHI exhibited notable antitumour activity, with an IC50 value of 12.22 µM against A375 and 15.17 µM against A549 after 48 h, while the pCd2 complex showed an even stronger inhibition of A375 cells, with an IC50 value of 4.88 µM, outperforming both 2-DPHI and CdCl2. Both compounds demonstrated lower toxicity towards normal cells compared to cancer cells. The structures of 2-DPHI and pCd2 were fully characterized using single-crystal X-ray diffraction, elemental analysis, high-resolution mass spectrometry and FT-IR, 1H NMR, 13C NMR and UV-Vis spectroscopy.