High Binding Constants Research Articles

Deciphering Binding Potential of Naphthalimide-Coumarin Conjugate with c-MYC G-Quadruplex for Developing Anticancer Agents: A Spectroscopic and Molecular Modeling Approach.

It has been well accumulated that G-quadruplex (G4-DNA) has great anticancer relevance, and various heterocyclic moieties have been synthesized and examined as potent G4-DNA binders with promising anticancer activity. Here, we have synthesized a series of naphthalimide-triazole-coumarin conjugates by substituting various amines and further examine their anticancer activity against 60 human cancer cell lines at 10 μM. One and five dose concentration results reveal low values of MG-MID GI50 for compounds including 8a (3.18 μM), 8b (13.11 μM), 8e (7.68 μM) and 8f (1.75 μM). Further cell apoptosis manifests that all compounds can induce cell apoptosis in cancer cells by stabilizing the c-MYC promoter G-quadruplex. Therefore, the G-quadruplex-mediated pathway may be responsible for the apoptosis that these naphthalimide-coumarin compounds caused in cancer cells. Therefore, multispectroscopic techniques are employed to evaluate the binding of molecules with c-MYC G4-DNA where all four molecules readily bind to G4-DNA and stabilize it with a high binding constant, leading to inhibition of cancer cells and apoptosis of cancer cells. Binding studies toward ct-DNA disclose that these compounds do not interact with ds-DNA and thus selectively target G4-DNA to exert their anticancer activity. All the active compounds have greater affinity toward Human Serum Albumin (HSA) and can readily bind with HSA with a binding constant of 12 × 104 M-1 (8a), 13.0 × 104 M-1 (8b), 14.2 × 104 M-1 (8e), 16.3 × 104 M-1 (8f). Thus, the results disclose that inhibition and killing of cancer cells by these derivatives feasibly occur due to their ability to interact with c-MYC G-quadruplex forming promoters and their high affinity toward HSA unfold potent anticancer agents and can be taken further for clinical trials.

B,N‐Embedded Helical Nanographenes Showing an Ion‐Triggered Chiroptical Switching Function

AbstractIntramolecular oxidative aromatic coupling of 3,6‐bis(m‐terphenyl‐2’‐yl)carbazole provided a bis(m‐terphenyl)‐fused carbazole, while that of 3,6‐bis(m‐terphenyl‐2’‐yl)‐1,8‐diphenylcarbazole afforded a bis(quaterphenyl)‐fused carbazole. Borylation of the latter furnished a B,N‐embedded helical nanographene binding a fluoride anion via a structural change from the three‐coordinate boron to the four‐coordinate boron. The anionic charge derived from the fluoride anion is stabilized over the expanded π‐framework, which leads to the high binding constant (Ka) of 1×105 M−1. The four‐coordinate boron species was converted back to the parent three‐coordinate boron species with Ag+, and the chiroptical switch between the three‐coordinate boron and four‐coordinate boron species has been achieved via the ion recognition with the change in the color and glum values.

B,N-Embedded Helical Nanographenes Showing an Ion-Triggered Chiroptical Switching Function.

Intramolecular aromaticoxidative coupling of3,6-bis(m-terphenyl-2'-yl)carbazole providedabis(m-terphenyl)-fused carbazole, while that of3,6-bis(m-terphenyl-2'-yl)-1,8-diphenylcarbazoleafforded abis(quaterphenyl)-fused carbazole. Borylation of the latter furnished a B,N-embedded helical nanographene binding a fluoride anion via a structural change from thethree-coordinate boron to the four-coordinate boron. The anionic charge derived from the fluoride anion is stabilized over the expandedp-framework, which leads to the high binding constant (Ka) of 1×105M-1. The four-coordinate boron species was converted back to the parent three-coordinate boron species with Ag+, and the chiroptical switch between the three-coordinate boron and four-coordinate boron species has been achieved via the ion recognition with the change in the color andglumvalues.

Unlocking the Antibacterial Potential of Naphthalimide-Coumarins to Overcome Drug Resistance with Antibiofilm and Membrane Disruption Ability against Escherichia coli.

Resistance by bacteria to available antibiotics is a threat to human health, which demands the development of new antibacterial agents. Considering the prevailing conditions, we have developed a library of new naphthalimide-coumarin moieties as broad-spectrum antibacterial agents to fight against awful drug resistance. Preliminary studies indicate that compounds 8e and 8h display excellent antibacterial activity against Escherichia coli, exceeding the performance of marketed drug amoxicillin. These drug candidates effectively inhibit biofilm formation and disrupt the biofilm virulence factor, which is accountable for the formation of strong biofilm. In addition to this, both compounds exhibit fast bactericidal properties, thus shortening the time of treatment and resisting the emergence of drug resistance for up to 20 passages. Further, biofunctional evaluation reveals that both compounds effectively disrupt the membrane, causing the leakage of cytoplasmic contents and loss in metabolic activity. Both compounds 8e and 8h efficiently induce the ROS, leading to the oxidation of GSH to GSSG, decreasing the GSH activity of the cell, and causing oxidative damage to the cells. Additionally, both compounds effectively bind with DNA to block DNA replication and form supramolecular complexes, thus exhibiting antibacterial activity. Moreover, these compounds readily bind human serum albumin with high binding constants and can be transported to the target site easily. These findings reveal that newly synthesized naphthalimide-coumarin conjugates have the potential to build as potent antibacterial agents and can be used further for clinical trials.

The necessity of enhancing the human health risk assessment of 1,3,6,8-tetrabromocarbazole: Based on in vitro experiments, theoretical calculations, and model predictions

Industrial emissions have been identified as significant contributors to polyhalogenated carbazoles (PHCZs), a novel pollutant in the environment. Enhancing the health risk assessment of PHCZs is imperative, particularly for 1,3,6,8-tetrabromocarbazole (1368BCZ), the most commonly detected PHCZs in the environment. This study revealed that 1368BCZ could bind to the important transporters, human serum albumin (HSA), with high binding constant (KA: 1.02 × 105 L/mol). 1368BCZ primary bound to the HSA binding site 2, and the impact of 1368BCZ on HSA structure was minimal, indicating 1368BCZ may has strong accumulation in human. Theoretical analysis indicated that the uniformly distributed molecular surface electrostatic potential of the 1368BCZ molecule was crucial for its strong binding affinity to HSA. van der Waals forces serve as the primary interaction force stabilizing this binding. Further model predictions results showed that 1368BCZ may cause various toxic effects including hepatotoxicity, neurotoxicology, mutagenicity, etc. In summary, this study revealed the potential human health risks associated with 1368BCZ, providing an important basis for the formulation of relevant environmental control standards.

Continuous Monitoring of Therapeutic Monoclonal Antibody Using Regenerable Aptamer Based Electrochemical Sensor

Therapeutic humanized monoclonal antibodies (mAbs) are focused on as effective medicine owing to their high specificity and efficacy compared with conventional small-molecule pharmaceuticals. To avoid side effects and improve the treatment efficacy, controlling the dose of therapeutic mAbs for the patient is the most crucial. However, the monitoring of their concentrations demands highly specific discrimination from human immunoglobulin G (IgG), since most therapeutic mAbs are designed based on IgG, which is naturally present in large quantities in human blood and differs only in residues at the complementarity determining region (CDR).Previously, we developed the therapeutic mAbs aptamer sensor utilizing an anti-idiotype aptamer, that recognizes the complementarity determining region, CDR, of a target therapeutic antibody, Bevacizumab [1,2]. This sensor can distinguish the target antibody and other human natural antibodies and succeed in detecting the bevacizumab from artificial serum that contains a high concentration of human natural IgG. Since this sensor does not require a chemical reaction nor a free redox probe in the solution, they are very suitable for in vivo continuous monitoring. However, due to the high binding constant (~nM-pM) of aptamer, binding site regeneration is only possible by denaturing both the target protein and aptamer structures with guanidine hydrochloride. Currently, the most challenging task for future therapeutic mAb sensors employing aptamers with a high binding constant to realize in vivo continuous monitoring is the development of versatile methods and technologies suitable for the in situ regeneration of aptamer binding sites.To tackle this challenging task, we have been engaged in the designing of engineered aptamers which can be modulated in their binding constant by external signals. Azobenzene is an ideal photoresponsive molecule, which reversibly changes its cis/trans forms, by UV or visible light irradiation and this structure change drives aptamer structure change and releases the target [3,4]. In this study, we designed an azobenzene-inserted anti-idiotype bevacizumab aptamer and developed an electrochemical sensor that can regenerate its binding site by light irradiation.To design the photo-regenerated anti-idiotype bevacizumab aptamer, we investigated the appropriate position to insert azobenzene without affecting the binding ability. After the confirmation of binding ability, we applied these aptamers to electrochemical measurement. Azobenzene-inserted anti-bevacizumab idiotype aptamers were immobilized on the planar electrode. Electrochemical measurements were carried out using a constructed aptamer electrode as a working electrode. After the confirmation of target binding on the electrode, we tried to regenerate the aptamer-immobilized electrode by UV light irradiation. The release of the target antibody was confirmed electrochemically.We will present the characterization of the photo-regenerated anti-idiotype aptamer, focusing on the change in binding toward the target therapeutic mAb, bevacizumab in UV and visible light irradiated conditions. Finally, we will show repeated detection of bevacizumab using this novel-engineered aptamer combined with electrochemical detection such as an extended gate FET-based sensor toward the continuous monitoring of a therapeutic mAb, bevacizumab.[1] Saito et al., Biosensors and Bioelectronics, 2022,203,114027[2] Nagata et al., Int. J. Mol. Sci., 2023, 24(6) 5277[3] Liang et al., JACS, 2003, 125, 16408[4] Liang et al., Small, 2009, 5(5) 1761]

Investigation of the anticancer potential of newly synthesized N4-substituted thiosemicarbazones: In silico and in vitro biological approaches

Four thiosemicarbazones by using tolualdehyde and cuminaldehyde having the formula, R2−(S)C−HN−N=HC−R2 [R1 = CH3 & R2 = C4H9N (TAP), R2 = C4H9NO & R1 = CH3 & (TAM), R2 = C4H9N & R1 = (CH3)2CH (CMP), R2 = C4H9NO & R1 = (CH3)2CH (CMM)] have been synthesized. The compound interactions were assessed using their UV−visible, infrared, NMR, and HRMS spectra. Single−crystal X−ray diffraction was employed to know the molecular structure of CMP and TAP. The compounds were assessed for their interactions with Calf−Thymus (CT)−DNA using spectroscopic titrations using both emission and absorption spectra. As per the research findings on DNA binding, the compounds interactively interacted with DNA, as indicated by the hypochromic and slight red shift. TAP exhibited a high binding constant (5.16 × 105), suggesting a stronger binding to CT−DNA compared to other compounds. The fluorescence titration spectra of BSA binding experiments exhibited a noteworthy hypochromic shift and red shift, displaying a strong interaction of chemicals with BSA. EGFR protein docking examination demonstrated the potential of compounds to treat the targets. TAP displayed the highest binding score (–6.4230 Kcal/mol) to EGFR with the four compounds. To compute density functional theory (DFT), B3LYP/6−311 G (d, p) level theories have been implemented. Generated compounds' computational analyses reveal the structural stability of compound TAP than the rest synthesized ligands. SwissADME investigations indicate that the LogP values for each compound are less than five indicating that they have the right lipophilicity characteristics. All newly synthesized compounds follow Lipinski's rule of drug lines. A good result for this characteristic is indicated by the low degree of synthetic accessibility, which falls between two and three. Each of the compounds (TAP−CMM) can develop into a viable oral medicine. Each compound (TAP−CMM) was tested for its anticancer potential using MCF−7, MCF−10A, A549, and human HepG−2 liver. TAP demonstrated favorable efficacy in HepG−2 liver cancer cells, exhibiting IC50 values of 23.1 μM.

In Vitro Cytotoxicity and Mechanistic Investigation of Quinazolin-4(1H)-One Linked Coumarin as a Potent Anticancer Agent.

Quinazolinone-coumarin conjugates synthesized through Late-Stage Functionalization approach are evaluated for their invitro biological activity for 60 human cancer cell lines representing nine different cancer types. Among the synthesized compounds, eight displayed significant growth inhibitory activity across a spectrum of cancer types, with compound 23 demonstrating particularly notable cytotoxicity. Further investigation involved a five-dose assay of compound 23 against NCI-60 cancer cell lines, revealing its efficacy at different concentrations. Additionally, binding studies elucidated its interaction with Human Serum Albumin (HSA) and DNA. The results indicated a strong binding affinity of 23 with HSA, evidenced by a high binding constant (2.26 × 105 M-1). Moreover, its interaction with DNA occurred via intercalation, specifically between the base pairs of DNA strands, with a binding constant of 5.51 × 104 M-1. This suggests that compound 23 has the ability to bind to both DNA and transport proteins, making it a promising pharmacophore with potential therapeutic applications.

Selective Chromogenic Chemosensors for Arsenite Anion: A Facile Approach to Analyzing Arsenite in Honey, Milk, and Water Samples.

In this study, two chemosensors, N5R1 and N5R2, based on 5-(4-nitrophenyl)-2-furaldehyde, with varying electron-withdrawing groups, were synthesized and effectively employed for the colorimetric selective detection of arsenite anions in a DMSO/H2O solvent mixture (8 : 2, v/v). Chemosensors N5R1 and N5R2 exhibited a distinct color change upon binding with arsenite, accompanied by a spectral shift toward the near-infrared region (Δλmax exceeding 200 nm). These chemosensors established stability between a pH range 6-12. Among them, N5R2 displayed the lowest detection limit of 17.63 ppb with a high binding constant of 2.6163×105 M-1 for arsenite. The binding mechanism involved initial hydrogen bonding between the NH binding site and the arsenite anion, followed by deprotonation and an intramolecular charge transfer (ICT) mechanism. The mechanism was confirmed through UV and 1H NMR titrations, cyclic voltammetric studies, and theoretical calculations. The interactions between the sensor and arsenite anions were further analyzed using global reactivity parameters (GRPs). Practical applications were demonstrated through the utilization of test strips and molecular logic gates. Real water samples, honey, and milk samples were successfully analyzed by both chemosensors for the sensing of arsenite.

Enhancing recovery of gold(III) from hydrochloric acid solutions using gemini surfactant microemulsions: The effect of spacer group

The recovery of precious metals from waste has garnered significant attention owing to their non-renewable nature and essential role in the burgeoning information industry. However, enhancing the extraction efficiency of microemulsions remains a significant challenge. In this study, three water-in-oil microemulsions were formulated using gemini surfactants with different spacers (14-OH-14, 14-SO4-14, and 14-3-14) as emulsifiers, supplemented with n-butanol as a cosurfactant, n-heptane as the oil phase, and NaCl aqueous solution as the internal aqueous phase. These microemulsions were employed for the extraction of gold(III) from hydrochloric acid solutions. The results illustrate that all three microemulsions effectively extracted gold(III) through a spontaneous, exothermic, enthalpy-driven anion-exchange mechanism, achieving notable extraction efficiency. In contrast to 14-3-14, incorporating –OH into the spacer significantly augments the positive electrostatic potential through the cationization of –OH in an HCl solution, resulting in a higher binding constant (2.43) and thereby improving the extraction efficiency. However, the presence of −SO4 diminishes the positive electrostatic potential through partial neutralization, resulting in a lower binding constant (1.17), which is detrimental to the extraction process. Response surface optimization revealed that concentrations of C(14-OH-14) and V(1-butanol) significantly influence extraction efficiency and exhibit pronounced interaction. At optimal conditions (C(14-OH-14) = 0.09 mol·L−1, V(1-butanol) = 47.41 %, R=20, and C(NaCl) = 1.57 mol·L−1), over 95.54 % of gold(III) can be extracted from actual e-waste solutions. This study offers an alternative approach for designing or selecting surfactants in microemulsion-based extraction of gold(III) from e-waste.

Colorimetric sensors for discriminatory detection of arsenite ions: Application in milk, honey and water samples and molecular logic gates

Millions of people are exposed to dangerous arsenic levels in drinking water, highlighting the urgent need for affordable, continuous on-site arsenic monitoring methods. It is crucial to specifically detect arsenite among inorganic arsenic anions because it is more poisonous than arsenate. Addressing these concerns, the present study developed 5-(4-nitrophenyl)-2-furaldehyde based two colorimetric chemosensors, N5R3 and N5R4, with different signaling groups for the selective detection of arsenite anions over arsenate in DMSO/H2O (6:4, v/v). The red-shift in the UV–Vis absorption spectra supported the distinct color changes of sensors N5R3 and N5R4 displayed upon binding with arsenite. Sensors demonstrated stability over a pH range of 6 to 12 and exhibited stability over a considerable time period. Among the chemosensors, N5R3 exhibited the lowest detection limit of 7.41 ppb with a high binding constant of 2.9976 × 106 M−1 for arsenite. The 1:1 binding interactions between the chemosensors and arsenite were confirmed using B-H plot and Job’s plot analysis. The intramolecular charge transfer (ICT) mechanism for detecting arsenite was proposed through UV and 1H NMR titrations, electrochemical studies, mass spectral analysis and DFT calculations. The interactions between the sensor and arsenite anions were further analyzed using global reactivity parameters (GRPs). Practical applications were demonstrated through the utilization of test strips and molecular logic gates. Both chemosensors efficiently recognized arsenite in real water, honey, and milk samples.

Supercritical CO2 Fluid Extraction and Microencapsulation of Oil from Anchovy (Engraulis mordax) By-Products.

Fish by-products are discarded as waste, which has a significant impact on the environment. They have no economic value, but there are many opportunities to turn them into high value products. Due to significant quantities generated internationally and the continuous expansion of the market for ω-3 and ω-6 fatty acids as nutraceuticals, innovative technological approaches are needed to transform this waste into marketable products with added value, while limiting the risk of environmental pollution. In this study, two temperatures (40 and 60 °C) at a constant pressure during the extraction of anchovy by-products with supercritical CO2 fluid were used to determine extraction yield, fatty acid, tocopherol and phytosterol composition, followed by microencapsulation with two matrices based on the transglutaminase-mediated crosslinking reaction between whey protein isolates and casein. Before microencapsulation, the binding parameters were estimated using quenching studies. The results showed a higher content of total fatty acids when extracted at 40 °C, resulting in two fractions on a dry mass basis of (712±12) mg/g in the fraction obtained in the separator with code S40 and (732±10) mg/g in the fraction obtained in the separator with code S45, respectively. The monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs) accounted for 40-44 %. The extracts showed a higher mass fraction of eicosapentaenoic acid ((28.7±1.0) mg/g) in fraction S45 when extracted at 60 °C. A minimum inhibitory and bactericidal concentration of 0.66 μg/mL against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 was found for all fractions. Higher binding constants were found for palmitoleic and oleic acids than for palmitic acid. The control variant, without crosslinking, enabled the microencapsulation of a higher amount of fatty acids, while in both powders the sum of MUFAs and PUFAs was 40 %. The approaches used in our study open up new opportunities for adding value to the fish by-products through extraction and microencapsulation, extending their potential use to food, cosmetics and nutraceuticals.

New Cu (II) and Zn (II) metal chelates derived from azo‐Schiff bases: Synthesis, DNA/BSA binding, anticancer activity and molecular docking studies

In this study, new Cu (II) and Zn (II) chelates (3–6) of 3‐/or 4‐ethyl and azo chromophore groups (NN) containing Schiff base ligands (2‐{(E)‐[(4‐ethylphenyl)imino]methyl}‐4‐[(E)‐phenyldiazenyl]phenol, HL1 (1) and 2‐{(E)‐[(3‐ethylphenyl)imino]methyl}‐4‐[(E)‐phenyldiazenyl]phenol, HL2 (2) were prepared and characterized by the analytical and spectroscopic methods. Crystal structures of chelates 3, 4 and 6 were determined by single‐crystal X‐ray diffraction studies. The ligands behaved as bidentates, coordinating through the nitrogen atom of the azomethine group (CHN) and the oxygen atom of the α‐hydroxyl group (OH). The metal:ligand ratio in the prepared copper (II) and zinc (II) chelates was found to be 1:2 by analytical and spectral analysis. The bands in the infrared spectra of the metal chelates in the region of 522–504 cm−1 and 467–455 cm−1 are attributed to ν(MO) and ν(MN) vibrations, respectively. When the DNA binding activities of the compounds were examined, it was determined that compound 4 had the highest binding constant. Fluorescence and viscosity data showed that the compounds interact with DNA through minor grove binding mode. Furthermore, anticancer properties of the compounds were investigated. Ligand 2 was found to be highly effective against the HepG2 cell with an IC50 of 0.31 μM. In addition, structural analysis, frontier molecular orbitals, molecular electrostatic potential maps, Hirshfeld surface analysis of the synthesized compounds using computational chemistry methods and anticancer activity studies were carried out by molecular docking.

A General Strategy for Enhanced Photodynamic Antimicrobial Therapy with Perylenequinonoid Photosensitizers Using a Macrocyclic Supramolecular Carrier.

Perylenequinonoid natural products are a class of photosensitizers (PSs) that exhibit high reactive oxygen species (ROS) generation and excellent activity for Type I/Type II dual photodynamic therapy. However, their limited activity against gram-negative bacteria and poor water solubility significantly restrict their potential in broad-spectrum photodynamic antimicrobial therapy (PDAT). Herein, a general approach to overcome the limitations of perylenequinonoid photosensitizers (PQPSs) in PDAT by utilizing a macrocyclic supramolecular carrier is presented. Specifically, AnBox·4Cl, a water-soluble cationic cyclophane, is identified as a universal macrocyclic host for PQPSs such as elsinochrome C, hypocrellin A, hypocrellin B, and hypericin, forming 1:1 host-guest complexes with high binding constants (≈107 m -1) in aqueous solutions. Each AnBox·4Cl molecule carries four positive charges that promote strong binding with the membrane of gram-negative bacteria. As a result, the AnBox·4Cl-PQPS complexes can effectively anchor on the surfaces of gram-negative bacteria, while the PQPSs alone cannot. In vitro and in vivo experiments demonstrate that these supramolecular PSs have excellent water solubility and high ROS generation, with broad-spectrum PDAT effect against both gram-negative and gram-positive bacteria. This work paves a new path to enhance PDAT by showcasing an efficient approach to improve PQPSs' water solubility and killing efficacy for gram-negative bacteria.

Eco-friendly Fluorescent Sensor for Sensitive and Selective Detection of Zn2+ and Fe3+ Ions: Applications in Human Hair Samples.

A new eco-friendly sensor, 3-((6-((4-chlorobenzylidene)amino)pyridin-2-yl)imino)indolin-2-one (CBAPI) was synthesized and well characterized. The CBAPI sensor was employed for detecting Zn2+ and Fe3+ ions. It exhibited a low limit of detection at pH 6.0, with values of 2.90, for Zn2+ and 3.59nmol L-1 for Fe3+ ions. The sensor demonstrated high selectivity over other interfering cations. Additionally, the high binding constants reflect the great affinity of sensor towards Zn2+ and Fe3+ ions. To further validate its quantification ability for Zn2+ ions, the synthesized CBAPI sensor was used to determine Zn levels in human hair samples, and the results were confirmed using atomic absorption spectroscopy (AAS). The AGREE metric tool was used to assess the method's environmental impact and practical applicability. These positive outcomes indicated that the new method for detecting Zn2+ and Fe3+ ions is environmentally friendly and safe for humans. The developed CBAPI sensor represents a potential development in metal ion detection, combining sensitivity, selectivity, and rapidity.

Design, synthesis, molecular docking and anti-proliferative activity of novel phenothiazine containing imidazo[1,2-a]pyridine derivatives against MARK4 protein.

A series of novel phenothiazine-containing imidazo[1,2-a]pyridine derivatives were designed and synthesized under metal-free conditions in excellent yield. These derivatives were effectively transformed further into N-alkyl, sulfoxide, and sulfone derivatives. Derivatives were deployed against human microtubule affinity regulating kinase (MARK4), some molecules play crucial roles in cell-cycle progression such as G1/S transition and regulator of microtubule dynamics. Hence, molecules have shown excellent MARK4 inhibitory potential. Molecules with excellent IC50 values were selected for further studies such as ligand interactions using fluorescence quenching experiments for the binding constant. The highest binding constant was calculated as K = 0.79 × 105 and K = 0.1 × 107 for compounds 6a and 6h, respectively. Molecular docking, cell cytotoxicity, mitochondrial reactive oxygen species measurement and oxidative DNA damage were also studied to understand the mechanism of action of the molecules on cancer cells. It was found that the designed and synthesized compounds played anti-cancer roles by binding and inhibiting MARK4 protein.

Anion Binding Interaction Enhances the Robustness of Iodide for High-Performance Perovskite Solar Cells.

Owing to the ionic bond nature of the Pb-I bond, the iodide at the interface of perovskite polycrystalline films was easily lost during the preparation process, resulting in the formation of a large number of iodine vacancy defects. The presence of iodine vacancy defects can cause nonradiative recombination, provide a pathway for iodide migration, and be harmful to the power conversion efficiency (PCE) and stability of organic-inorganic hybrid perovskite solar cells (HPSCs). Here, in order to increase the robustness of iodides at the interface, a strategy to introduce anion binding effects was developed to stabilize the perovskite films. It was demonstrated that the N,N'-diphenylurea (DPU), characterized by high anionic binding constants and a Y-shaped structure, provides a relatively strong hydrogen bond donor site to effectively reduce the iodine loss during film preparation and inhibits iodide migration in the device working condition. As expected, the reduced iodine loss considerably improves the quality of the perovskite films and suppresses nonradiative recombination. The performance of the device after DPU modification was significantly increased, with the PCE rising from 23.65 to 25.01% with huge stability enhancement as well.

Design and synthesis of simple quinoline-based organic molecules as dual/multifunctional chemosensors for the detection of Cu2+/Fe3+ ions

The current research deals with the sensitivity of a turn-on-off fluorescence chemosensor using the probe, namely (E)-2-(((2‑hydroxy-5-methylphenyl) imino)methyl) quinolin-8-ol (HQ-AMP) as a selective detection of Cu2+/Fe3+ ions in DMSO: H2O (1:1, v/v). The probe HQ-AMP was synthesized using a simple acid catalyst, Schiff base condensation, which involves the reaction between aldehyde and amine. This probe shows a significant fluorescence response towards Cu2+ and Fe3+ ions among the other alkaline earth metal ions. The HQ-AMP forms a 1:1 stoichiometry complex with a high binding constant for Cu2+ and Fe3+ ions with a low detection limit of 34 nM and 47 nM, respectively. Due to their strong intermolecular charge transfer properties, the probe HQ-AMP shows intense fluorescence at 488 nm upon excitation at 350 nm. The selective fluorescence quenching of probe HQ-AMP with Cu2+/Fe3+ ions shows static/dynamic quenching and their quenching constant of 1.93 × 10−8 and 2.06 × 10−8, respectively. Also, the probe shows the highest selectivity towards Cu2+/Fe3+ ions over the other tested metal ions.

Ciprofloxacin Metal Complexes–Silica Nanoparticles: Characterization, Spectroscopic Study, DNA Interaction and Biological Activity

Ciprofloxacin (CIPH) was classified as one of the most effective quinolone antibiotics, which is commonly used to cure a wide range of infections resulting from Gram-negative and Gram-positive microorganisms. The complexes which formed due to the interaction of Ni(II), Zn(II), Cu(II), Gd(III) and Sm(III) with ciprofloxacin were characterized by CHN% analysis, conductivity, FTIR, electronic spectra, fluorescence measurements, and magnetic susceptibility, besides studying the complex–DNA interaction. Meanwhile, the molar conductance values (0.001 mol·L−1 in DMSO) revealed the electrolytic behavior of the complexes and could be designated with the A−B+ formula. In addition, the geometry of the compounds was confirmed from the electronic transitions as well as the μeff values as octahedral for all complexes. The postulated formula could be generally assigned as [M(CIP)a(CIPH)b(H2O)c](NO3)(H2O)n(C2H5OH)m. Moreover, the interaction between metal complexes and DNA revealed that the Cu complex had the highest binding constant. Nanotechnology was applied to synthesized compounds using silica nanoparticles (SiNPs), which were prepared using a sol–gel process. The silica nanoparticles were chemically functionalized for binding the ligand and its metal complexes; this enables the as-prepared compounds to enhance their features as a drug delivery platform. Meanwhile, the antimicrobial activity was tested for the free complexes and SiNPs composites. Collectively, Sm complex gave the largest zone of inhibition, while the Cu(II)–SiNPs composite showed the strongest potential to reduce the bacterial activity. Furthermore, the fluorescence data of CIPH, ligand–metal mixture and the effect of silica nanoparticles on them were studied.

Mixed N‐heterocyclic carbene and benzyl‐, phenethyl‐, and biphenylamine coordinated Pd complexes: Anticancer activities and stereo‐electronic effects

A series of mixed N‐heterocylic carbene (NHC) palladium complexes bearing C^N bidentate ligands derived from benzylamine, phenethylamine, and biphenylamine were prepared and fully characterized by NMR spectroscopy, ESI‐MS spectrometry, and X‐ray diffraction analyses. The complexes were potent in inhibiting proliferation of HepG2 and Caco2 cancer cells, and a SAR (structure–activity relationship) study revealed C^N ligands with stronger electron donation and moderate steric hindrance are more cytotoxic. DNA binding study through UV–vis absorption titration indicated that such complexes bound stronger to CT‐DNA molecules with higher binding constants. Additional molecular docking of the best performer suggested a groove binding mode through hydrogen bonding and π‐π stacking interactions. The apoptosis induced by the two best performers of α,α‐dimethylbenzylamine and S‐α‐methylbenzylamine ligated complexes was further analyzed by morphology change, cell cycle distribution, ROS production, and mitochondrial membrane potential studies.