Photoreforming of Waste Polymers for Sustainable Hydrogen Fuel and Chemicals Feedstock: Waste to Energy.

Energy from renewable resources is central to environmental sustainability. Among the renewables, sunlight-driven fuel synthesis is a sustainable and economical approach to produce vectors such as hydrogen through water splitting. The photocatalytic water splitting is limited by the water oxidation half-reaction, which is kinetically and energetically demanding and entails designer photocatalysts. Such challenges can be addressed by employing alternative oxidation half-reactions. Photoreforming can drive the breakdown of waste plastics and biomass into valuable organic products for the production of H2. We provide an overview of photoreforming and its underlying mechanisms that convert waste polymers into H2 fuels and fine chemicals. This is of paramount importance from two complementary perspectives: (i) green energy harvesting and (ii) environmental sustainability by decomposing waste polymers into valuables. Competitive results for the generation of H2 fuel without environmental hazards through photoreforming are being generated. The photoreforming process, mechanisms, and critical assessment of the field are scarce. We address such points by focusing on (i) the concept of photoreforming and up-to-date knowledge with key milestones achieved, (ii) uncovering the concepts and challenges in photoreforming, and (iii) the design of photocatalysts with underlying mechanisms and pathways through the use of different polymer wastes as substrates.

Development of Membranes and Separators to Inhibit Cross-Shuttling of Sulfur in Polysulfide-Based Redox Flow Batteries: A Review.

The global rapid transition from fossil fuels to renewable energy resources necessitates the implementation of long-duration energy storage technologies owing to the intermittent nature of renewable energy sources. Therefore, the deployment of grid-scale energy storage systems is inevitable. Sulfur-based batteries can be exploited as excellent energy storage devices owing to their intrinsic safety, low cost of raw materials, low risk of environmental hazards, and highest theoretical capacities (gravimetric: 2600 Wh/kg and volumetric: 2800 Wh/L). However, sulfur-based batteries exhibit certain scientific limitations, such as polysulfide crossover, which causes rapid capacity decay and low Coulombic efficiency, thereby hindering their implementation at a commercial scale. In this review article, we focus on the latest research developments between 2012-2023 to improve the separators/membranes and overcome the shuttle effect associated with them. Various categories of ion exchange membranes (IEMs) used in redox batteries, particularly polysulfide redox flow batteries and lithium-sulfur batteries, are discussed in detail. Furthermore, advances in IEM constituents are summarized to gain insights into different fundamental strategies for attaining targeted characteristics, and a critical analysis is proposed to highlight their efficiency in mitigating sulfur cross-shuttling issues. Finally, future prospects and recommendations are suggested for future research toward the fabrication of more effective membranes with desired properties.

Preliminary anticancer evaluation of new Pd(II) complexes bearing NNO donor ligands.

In this study we presented a novel series of NNO tridentate ligands generating imino, amido and oxo donor pocket for Pd(II) coordination. All the compounds were meticulously characterized by elemental analysis and advanced spectroscopic techniques, including FTIR, proton and carbon NMR. The synthesized compounds underwent rigorous evaluation for their potential as anti-cancer agents, utilizing the aggressive breast cancer cell lines MDA-MB (ATCC) and MCF-7 as a crucial model for assessing growth inhibition in cancer cells. Remarkably, the MTT assay unveiled the robust anti-cancer activity for all palladium complexes against MDA-MB-231 and MCF-7 cells. Particularly, complex [Pd(L1)(CH3CN)] exhibited exceptional potency with an IC50 value of 25.50 ± 0.30 µM (MDA-MB-231) and 20.76 ± 0.30 µM (MCF-7), compared to respective 27.00 ± 0.80 µM and 24.10 ± 0.80 µM for cisplatin, underscoring its promising therapeutic potential. Furthermore, to elucidate the mechanistic basis for the anti-cancer effects, molecular docking studies on tyrosine kinases, an integral target in cancer research, were carried out. The outcome of these investigations further substantiated the remarkable anticancer properties inherent to these innovative compounds. This research offers a compelling perspective on the development of potent anti-cancer agents rooted in the synergy between ligands and Pd(II) complexes and presenting a promising avenue for future cancer therapy endeavors.

Evaluation of Antimicrobial, Anticholinesterase Potential of Indole Derivatives and Unexpectedly Synthesized Novel Benzodiazine: Characterization, DFT and Hirshfeld Charge Analysis.

The pharmacological effectiveness of indoles, benzoxazepines and benzodiazepines initiated our synthesis of indole fused benoxazepine/benzodiazepine heterocycles, along with enhanced biological usefulness of the fused rings. Activated indoles 5, 6 and 7 were synthesized using modified Bischler indole synthesis rearrangement. Indole 5 was substituted with the trichloroacetyl group at the C7 position, yielding 8, exclusively due to the increased nucleophilic character of C7. When trichloroacylated indole 8 was treated with basified ethanol or excess amminia, indole acid 9 and amide 10 were yielded, respectively. Indole amide 10 was expected to give indole fused benoxazepine/benzodiazepine 11a/11b on treatment with alpha halo ester followed by a coupling agent, but when the reaction was tried, an unexpectedly rearranged novel product, 1,3-bezodiazine 12, was obtained. The synthetic compounds were screened for anticholinesterase and antibacterial potential; results showed all products to be very important candidates for both activities, and their potential can be explored further. In addition, 1,3-bezodiazine 12 was explored by DFT studies, Hirshfeld surface charge analysis and structural insight to obrain a good picture of the structure and reactivity of the products for the design of derivatised drugs from the novel compound.

Efficient Synthesis of Imine-Carboxylic Acid Functionalized Compounds: Single Crystal, Hirshfeld Surface and Quantum Chemical Exploration.

Two aminobenzoic acid based crystalline imines (HMBA and DHBA) were synthesized through a condensation reaction of 4-aminobenzoic acid and substituted benzaldehydes. Single-crystal X-ray diffraction was employed for the determination of structures of prepared Schiff bases. The stability of super molecular structures of both molecules was achieved by intramolecular H-bonding accompanied by strong, as well as comparatively weak, intermolecular attractive forces. The comparative analysis of the non-covalent forces in HMBA and DHBA was performed by Hirshfeld surface analysis and an interaction energy study between the molecular pairs. Along with the synthesis, quantum chemical calculations were also accomplished at M06/6-311G (d, p) functional of density functional theory (DFT). The frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP), natural bond orbitals (NBOs), global reactivity parameters (GRPs) and natural population (NPA) analyses were also carried out. The findings of FMOs found that Egap for HMBA was examined to be smaller (3.477 eV) than that of DHBA (3.7933 eV), which indicated a greater charge transference rate in HMBA. Further, the NBO analysis showed the efficient intramolecular charge transfer (ICT), as studied by Hirshfeld surface analysis.

Synthesis, Crystal Structure, DFT Calculations, Hirshfeld Surface Analysis and In Silico Drug-Target Profiling of (R)-2-(2-(1,3-Dioxoisoindolin-2-yl)propanamido)benzoic Acid Methyl Ester.

The work here reflects synthesis, DFT studies, Hirshfeld charge analysis and crystal data exploration of pharmacologically important (R)-2-(2-(1,3-dioxoisoindolin-2-yl)propanamido)benzoic acid methyl ester (5) to understand its properties for further chemical transformations. The methyl anthranilate (2) was produced by the esterification of anthranilic acid in an acidic medium. The phthaloyl-protected alanine (4) was rendered by the fusion of alanine with phthalic anhydride at 150 °C, followed by coupling with (2) furnished isoindole (5). The characterization of products was performed using IR, UV-Vis, NMR and MS. Single-crystal XRD also verified the structure of (5) in which N-H⋯O bonding stabilizes the molecular configuration of (5), resulting in the formation of S(6) hydrogen-bonded loop. The molecules of isoindole (5) are connected in the form of dimers, and the π⋯π stacking interaction between aromatic rings further stabilizes the crystal packing. DFT studies suggest that HOMO is over the substituted aromatic ring, the LUMO is present mainly over the indole side, and nucleophilic and electrophilic corners point out the reactivity of the product (5). In vitro and in silico analysis of (5) shows its potential as an antibacterial agent targeting DNA gyrase and Dihydroorotase from E. coli and tyrosyl-tRNA synthetase and DNA gyrase from Staphylococcus aureus.

Structural characterization and antileishmanial activity of newly synthesized organo-bismuth(V) carboxylates: experimental and molecular docking studies.

In a quest to discover new formulations for the treatment of various parasitic diseases, a series of heteroleptic triorganobismuth(V) biscarboxylates of type [BiR3(O2CR')2], where R=C6H5 for 1-4 and p-CH3C6H4 for 5-8, were synthesized, characterized and evaluated for their biological potential against L. tropica. All the synthesized complexes were fully characterized by elemental analysis, FT-IR, multinuclear (1H and 13C) NMR spectroscopy and X-ray crystallography. The crystal structures for [BiPh3(O2CC6H4(o-Br))2] (1), [BiPh3(O2CC2H2C6H4)2] (2), [BiPh3(O2CC6H4(m-NO2))2] (3) and [BiPh3(O2CC6H4(2-OH,3-CH3))2] (4) were determined and found to have a distorted pentagonal bipyramidal molecular geometry with seven coordinated bismuth center for 1-3 and for 4 distorted octahedral geometry, respectively. All the synthesized complexes demonstrated a moderate to significant activity against leishmania parasites. A broad analytical approach was followed to testify the stability for (1-8) in solid state as well as in solution and in leishmanial culture M199, ensuring them to be stable enough to exert a significant antileishmanial effect with promising results. Cytotoxicity profile suggests that tris(tolyl) derivatives show lower toxicity against isolated lymphocytes with higher antileishmanial potential. Molecular docking studies were carried out to reveal the binding modes for (1-8) targeting the active site of trypanothione reductase (TR) (PDB ID: 4APN) and Trypanothione Synthetase-Amidase structure (PDB ID 2vob).

Advances in Graphene/Inorganic Nanoparticle Composites for Catalytic Applications.

Graphene-based nanocomposites with inorganic (metal and metal oxide) nanoparticles leads to materials with high catalytic activity for a variety of chemical transformations. Graphene and its derivatives such as graphene oxide, highly reduced graphene oxide, or nitrogen-doped graphene are excellent support materials due to their high surface area, their extended π-system, and variable functionalities for effective chemical interactions to fabricate nanocomposites. The ability to fine-tune the surface composition for desired functionalities enhances the versatility of graphene-based nanocomposites in catalysis. This review summarizes the preparation of graphene/inorganic NPs based nanocomposites and their use in catalytic applications. We discuss the large-scale synthesis of graphene-based nanomaterials. We have also highlighted the interfacial electronic communication between graphene/inorganic nanoparticles and other factors resulting in increased catalytic efficiencies.

A High-Performance Asymmetric Supercapacitor Based on Tungsten Oxide Nanoplates and Highly Reduced Graphene Oxide Electrodes.

Tungsten oxide/graphene hybrid materials are attractive semiconductors for energy-related applications. Herein, we report an asymmetric supercapacitor (ASC, HRG//m-WO3 ASC), fabricated from monoclinic tungsten oxide (m-WO3 ) nanoplates as a negative electrode and highly reduced graphene oxide (HRG) as a positive electrode material. The supercapacitor performance of the prepared electrodes was evaluated in an aqueous electrolyte (1 m H2 SO4 ) using three- and two-electrode systems. The HRG//m-WO3 ASC exhibits a maximum specific capacitance of 389 F g-1 at a current density of 0.5 A g-1 , with an associated high energy density of 93 Wh kg-1 at a power density of 500 W kg-1 in a wide 1.6 V operating potential window. In addition, the HRG//m-WO3 ASC displays long-term cycling stability, maintaining 92 % of the original specific capacitance after 5000 galvanostatic charge-discharge cycles. The m-WO3 nanoplates were prepared hydrothermally while HRG was synthesized by a modified Hummers method.

Isatin-hydrazide conjugates as potent α-amylase and α-glucosidase inhibitors: Synthesis, structure and invitro evaluations.

Managing diabetes that is a global life-threatening problem, remains a challenge for the scientific community. The inhibition of α-amylase and α-glucosidase enzymes which are responsible for the digestion of dietary carbohydrates is an effective strategy to control postprandial hyperglycemia. Herein, we report the novel and highly potent inhibitors of α-amylase and α-glucosidase, namely isatin-hydrazide conjugates 1a - 1j that are easily accessed in two steps from simple and inexpensive commercially available isatin. The in vitro bio-evaluations of these compounds revealed that conjugates 1a, 1h and 1f are highly potent inhibitors of α-amylase with IC50 values of 19.6, 12.1 and 18.3 µg/ml, respectively as compared to the standard, acarbose (IC50 = 36.2 µg/ml). Similarly, the conjugates 1a, 1b, 1d, 1f and 1i showed significant activity against α-glucosidase with IC50 values of 14.8, 25.6, 13.2, 14.5 and 16.5 µg/ml, respectively as compared to the acarbose (IC50 = 34.5 µg/ml). Notably, the compounds 1a and 1f were found to be highly potent against both α-amylase and α-glucosidase enzymes, demonstrating about two-fold better inhibitory activity than the reference inhibitor. Molecular docking studies were performed to recognize the possible binding modes of the compounds with the active pocket of the enzymes. The results of this study divulge the potential of these compounds as powerful and inexpensive lead molecules for future investigations.

Thiourea Derivatives, Simple in Structure but Efficient Enzyme Inhibitors and Mercury Sensors.

In this study six unsymmetrical thiourea derivatives, 1-isobutyl-3-cyclohexylthiourea (1), 1-tert-butyl-3-cyclohexylthiourea (2), 1-(3-chlorophenyl)-3-cyclohexylthiourea (3), 1-(1,1-dibutyl)-3-phenylthiourea (4), 1-(2-chlorophenyl)-3-phenylthiourea (5) and 1-(4-chlorophenyl)-3-phenylthiourea (6) were obtained in the laboratory under aerobic conditions. Compounds 3 and 4 are crystalline and their structure was determined for their single crystal. Compounds 3 is monoclinic system with space group P21/n while compound 4 is trigonal, space group R3:H. Compounds (1-6) were tested for their anti-cholinesterase activity against acetylcholinesterase and butyrylcholinesterase (hereafter abbreviated as, AChE and BChE, respectively). Potentials (all compounds) as sensing probes for determination of deadly toxic metal (mercury) using spectrofluorimetric technique were also investigated. Compound 3 exhibited better enzyme inhibition IC50 values of 50, and 60 µg/mL against AChE and BChE with docking score of -10.01, and -8.04 kJ/mol, respectively. The compound also showed moderate sensitivity during fluorescence studies.

Hematite and Magnetite Nanostructures for Green and Sustainable Energy Harnessing and Environmental Pollution Control: A Review.

The optoelectrical and magnetic characteristics of naturally existing iron-based nanostructures, especially hematite and magnetite nanoparticles (H-NPs and M-NPs), gained significant research interest in various applications, recently. The main purpose of this Review is to provide an overview of the utilization of H-NPs and M-NPs in various environmental remediation. Iron-based NPs are extensively explored to generate green energy from environmental friendly processes such as water splitting and CO2 conversion to hydrogen and low molecular weight hydrocarbons, respectively. The latter part of the Review provided a critical overview to use H-NPs and M-NPs for the detection and decontamination of inorganic and organic contaminants to counter the environmental pollution and toxicity challenge, which could ensure environmental sustainability and hygiene. Some of the future perspectives are comprehensively presented in the final portion of the script, optimiztically, and it is supported by some relevant literature surveys to predict the possible routes of H-NPs and M-NPs modifications that could enable researchers to use these NPs in more advanced environmental applications. The literature collection and discussion on the critical assessment of reserving the environmental sustainability challenges provided in this Review will be useful not only for experienced researchers but also for novices in the field.

Hydroxypropylcellulose-flurbiprofen conjugates: design, characterization, anti-inflammatory activity and enhanced bioavailability.

Herein, we report novel macromolecular prodrugs (MPDs) of flurbiprofen (FLB) onto a cellulose ether, hydroxypropylcellulose (HPC). The FLB was activated with a powerful acylation reagent carbonyldiimadazole (CDI) in N,N' dimethylacetamide (DMAc) solvent at room temperature. Imidazolide of FLB generated in situ reacts at 80 °C for 24 h with pre-dissolved HPC to prepare HPC-FLB conjugates. The resultant MPDs of FLB showed moderate to high degree of substitution (DS: 0.35-1.3) with good yield (70-82%). Structures were thoroughly characterized using FTIR, UV and NMR spectroscopic analyses. The pharmacokinetic studies showed that the t1/2 and tmax values of FLB from HPC-FLB conjugate were increased substantially as compare to standard FLB indicates enhanced bioavailability of drug after conjugate formation. Remarked anti-inflammatory activity of the HPC-FLB conjugate was also observed.

Synthesis, crystal studies and biological evaluation of flavone derivatives.

Three substituted flavone derivatives have been synthesized from substituted O-hydroxy acetophenones and 4-trifluoromethyl benzaldehyde in good yield. These compounds were characterized by NMR spectroscopy and single crystal X-ray Diffraction. Compound F1 and F3 were re-crystallized from their concentrated solutions in chloroform ethyl acetate mixture while F2 was re-crystallized in ethyl acetate n-hexane mixture. Compound F1 and F3 are monoclinic (space group P21/c) with lattice parameters: [a, b, c (A) / ß (°)] = 13.332 (2), 15.616 (2) / 6.2898 (8) and 13.9716 (15), 7.1868 (7), 13.6912 (14) / 91.113(6) respectively. Compound F2 is Triclinic (space group P-1) and has lattice parameters: [a, b, c (Å) / α, ß, γ (°)] = 6.5002 (6), 8.3801 (9), 13.5989 (14) / 89.348(5), 85.141(4), 84.521(5). Antioxidant, antibacterial and cytotoxic profile was investigated. The compounds showed moderate to less activity on 1,1-diphenyl-2-picryl-hydrazyl (DPPH), Hydrogen peroxide (H/2/O/2) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) models of radical scavenging activity while promising antibacterial potentials were recorded. Furthermore, these molecules can also be used as potential candidates for new antitumor agents.

Xanthenone-based hydrazones as potent α-glucosidase inhibitors: Synthesis, solid state self-assembly and in silico studies.

Xanthenone based hydrazone derivatives (5a-n) have been synthesized as potential α-glucosidase inhibitors. All synthesized compounds (5a-n) are characterized by their FTIR, 1H NMR, 13C NMR and HRMS, and in case of 5g also by X-ray crystallographic technique. The compounds unveiled a varying degree of α-glucosidase inhibitory activity when compared with standard acarbose (IC50 = 375.38 ±â€¯0.12 µM). Amongst the series, compound 5l (IC50 = 62.25 ±â€¯0.11 µM) bearing a trifluoromethyl phenyl group is found to be the most active compound. Molecular modelling is performed to establish the binding pattern of the more active compound 5l, which revealed the significance of substitution pattern. The pharmacological properties of molecules are also calculated by MedChem Designer which determines the ADME (absorption, distribution, metabolism, excretion) properties of molecules. The solid state self-assembly of compound 5g is discussed to show the conformation and role of iminoamide moiety in the molecular packing.

Discovery of Michael acceptor containing 1,4-dihydropyridines as first covalent inhibitors of L-/T-type calcium channels.

1,4-Dihydropyridines (DHPs) are an important class of blockers targeting different calcium channel subtypes and have great therapeutic value against cardiovascular and neurophysiologic conditions. Here, we present the design of DHP-based hexahydroquinoline derivatives as either selective or covalent inhibitors of calcium channels. These compounds were synthesized via a modified Hantzsch reaction under microwave irradiation and characterized by IR, 1H NMR, 13C NMR and mass spectra. Additionally, the proposed structure of HM12 was resolved by single crystal X-ray analysis. The abilities of the target compounds to block both L- and T-type calcium channels were evaluated by utilizing the whole-cell patch clamp technique. Our results identified covalent inhibitors of calcium channels for the first time, which could be achieved by introducing a Michael acceptor group into the ester side chain of the compounds. The proposed covalent binding between the compounds and the cysteine amino acid (Cys1492) within the DHP binding pocket of L-type calcium channel was supported by docking and pharmacophore analysis as well as a glutathione reactivity assay.

Correction to: An efficient protocol for the synthesis of highly sensitive indole imines utilizing green chemistry: optimization of reaction conditions.

In the original publication, one of the co-authors name Sana Jamshaid was missed out. The correct authors' group is updated in this correction.

Metal-Based Scaffolds of Schiff Bases Derived from Naproxen: Synthesis, Antibacterial Activities, and Molecular Docking Studies.

We report here the synthesis, characterization, and antibacterial evaluation of transition metal complexes of Ni, Cu, Co, Mn, Zn, and Cd (6a⁻f), using a Schiff base ligand (5) derived from naproxen (an anti-inflammatory drug) and 5-bromosalicylaldehyde by a series of reactions. The ligand and the synthesized complexes were characterized by elemental analysis, UV-Visible, FTIR, and XRD techniques. The ligand 5 behaves as a bidentate donor and coordinates with metals in square planar or tetrahedral fashion. In order to evaluate its bioactivity profile, we screened the Schiff base ligand and its metal complexes (6a⁻f) against different species of bacteria and the complexes were found to exhibit significant antibacterial activity. The complexes showed more potency against Bacillus subtilis as compared to the other species. Moreover, we modeled these complexes' binding affinity against COX1 protein using computational docking.

A possible mechanistic approach of synthetic flavonoids in the management of pain.

Flavonoids are phenolic compounds that have always attracted pharmaceutical researchers and food manufacturers. Nature has indirectly provided us flavones in our daily diet i.e. tea, fruits, juices and vegetables. Flavones have got special position in research field of natural and synthetic organic chemistry due to their biological capabilities. Three substituted flavone derivatives have been synthesized from substituted O-hydroxy acetophenones and 4-trifluoromethyl benzaldehyde in good yield. The structures have been established by different spectroscopic techniques like 1HNMR 13CNMR, IR spectroscopy. The compounds were then screened for their enzyme inhibition potential and antinociceptive response in mice models with writhings induced by acetic acid, tail immersion and formalin-induced nociception assay procedures and structure activity relationship was established. The effects following pretreatment with naloxone were also studied to reveal the involvement of opioid receptors in the antinociceptive action. The flavone derivatives showed moderate to weak inhibition against LOX. Moreover, significant to moderate decrease in the number of abdominal constrictions, increase in paw-licking response time in both phases and a significant raise in latency time in nociception models. Moreover, the antinociceptive response was significantly attenuated by pretreatment with opioid receptor antagonist suggesting the involvement of opioidergic system in the analgesic action. The flavone derivatives showed analgesic response in all models of nociception suggesting the possible involvement of opioidergic system in the antinociceptive action.

A Step into the Future: Applications of Nanoparticle Enzyme Mimics.

We describe elementary concepts, up-to-date developments, and perspectives of the emerging field of nanoparticle enzyme mimics (so-called "nanozymes") at the interface of chemistry, biology, materials, and nanotechnology. The design and synthesis of functional enzyme mimics is a long-standing goal of biomimetic chemistry. Metal complexes, polymers and engineered biomolecules capturing the structure of natural enzymes or their active centers have been made to achieve high rates and enhanced selectivities. Still, the design of new "artificial enzymes" that are not related to proteins but with capacity of production and stability at industrial level, remains a goal. Inorganic nanoparticles bear this potential. Although it seems counterintuitive to compare nanoparticles and natural enzymes because they appear very different they share many common features: nano-size, irregular shape, and rich surface chemistry. These features enable nanomaterials to mimic reactions of natural enzymes. Representative examples with biomedical and environmental applications are given.