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Among various clear energy generation processes, electrocatalytic water splitting or hydrogen evolution reaction (HER) has been considered as an efficient method for the sustainable production of hydrogen (H2) fuel. But, significant efforts are still required to develop cheap, effective and stable electrocatalysts for water splitting to achieve the economical production of H2. In the quest of finding cheap electrocatalysts, herein, we demonstrate the preparation of palladium (Pd) nanoparticles decorated nitrogen (N) doped highly reduced graphene oxide (NDG-Pd) based electrocatalysts. The nitrogen (N) doped highly reduced graphene oxide (NDG) was produced by using graphene oxide as precursor, which was reduced and doped with nitrogen, simultaneously in one-step hydrothermal method. Subsequently, Pd nanoparticles were decorated on the surface of NDG using a facile ultrasonic method to produce NDG-Pd. In order to restrict the amount of precious metal to reduce the cost of catalysts, very small percentage of Pd, such as, 1 and 3 % was utilized during the preparation of electrocatalysts. The as-prepared electrocatalysts were successfully characterized by using different methods such as, XRD, XPS, EDX, BET, SEM and TEM. Results confirmed the formation of slightly agglomerated, smaller size of Pd NPs on the surface of NDG with an average particle size of ∼ 6 nm. The as prepared nanocomposites NDG, NDG-Pd1% and NDG-Pd3% were used to prepare electrodes and their electrocatalytic activity was evaluated towards the production of H2 through water splitting. The results of electrochemical performance of as-prepared electrodes within the voltage range have revealed that among different samples prepared, the NDG did not show any current, whereas NDG-Pd3% showed a good potential for HER with current density ≈24 mA/cm2 at very low potential i.e. −0.2 V vs RHE.

Owing to the broad applications of quaternary ammonium salts (QAS), we present the synthesis of benzimidazolium-based analogues with variation in the alkyl and alkoxy group at N-1 and N-3 positions. All the compounds were characterized by spectroscopic techniques and found stable to air and moisture both in the solid and solution state. Moreover, molecular structures were established through single-crystal X-ray diffraction studies. The crystal packing of the compounds was stabilized by numerous intermolecular interactions explored by Hirshfeld surface analysis. The enrichment ratio was calculated for the pairs of chemical species to acquire the highest propensity to form contacts. Void analysis was carried out to check the mechanical response of the compounds. Furthermore, theoretical investigations were also performed to explore the optoelectronic properties of compounds. Natural population analysis (NPA) has been conducted to evaluate the distribution of charges on the synthesized compounds, whereas high band gaps of the synthesized compounds by frontier molecular orbital (FMO) analysis indicated their stability. Nonlinear optical (NLO) analysis revealed that the synthesized QAS demonstrates significantly improved NLO behaviour than the standard urea.

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.

The asymmetric unit of the title compound, [Tm2(C7H6NO2)6(H2O)4]·2H2O, contains three 4-aminobenzoate (4ABA) ligands, two coordinated water molecules, a thulium metal ion, and a water molecule of crystallization. The overall structure of the complex (4ABA-Tm) is in the form of a dimer. In the dinuclear thulium complex, symmetry-relevant TmO8 coordination polyhedra are formed by the O atoms of two chelating 4-aminobenzoate ligands, the O atoms of two non-chelating 4-aminobenzoate ligands, and two water molecules. The Tm—O bond lengths range from 2.216 (3) to 2.471 (3) Å with the Tm...Tm separation in the dinuclear complex being 4.7863 (5) Å. The crystal structure features O—H...N, N—H...O, and O—H...O hydrogen-bonding interactions. Further stabilization of the crystal packing is due to C—H...π and off-set π–π stacking interactions. Hirshfeld surface analysis indicates that H...H contacts are the most significant contributors to the crystal packing (45.9%). In addition, a void analysis was performed to check the strength of the crystal packing.

Abstract Preventing bacteria from adhering to material surfaces is an important technical problem and a major cause of infection. One of nature’s defense strategies against bacterial colonization is based on the biohalogenation of signal substances that interfere with bacterial communication. Biohalogenation is catalyzed by haloperoxidases, a class of metal-dependent enzymes whose activity can be mimicked by ceria nanoparticles. Transparent CeO2/polycarbonate surfaces that prevent adhesion, proliferation, and spread of Pseudomonas aeruginosa PA14 were manufactured. Large amounts of monodisperse CeO2 nanoparticles were synthesized in segmented flow using a high-throughput microfluidic benchtop system using water/benzyl alcohol mixtures and oleylamine as capping agent. This reduced the reaction time for nanoceria by more than one order of magnitude compared to conventional batch methods. Ceria nanoparticles prepared by segmented flow showed high catalytic activity in halogenation reactions, which makes them highly efficient functional mimics of haloperoxidase enzymes. Haloperoxidases are used in nature by macroalgae to prevent formation of biofilms via halogenation of signaling compounds that interfere with bacterial cell–cell communication (“quorum sensing”). CeO2/polycarbonate nanocomposites were prepared by dip-coating plasma-treated polycarbonate panels in CeO2 dispersions. These showed a reduction in bacterial biofilm formation of up to 85% using P. aeruginosa PA14 as model organism. Besides biofilm formation, also the production of the virulence factor pyocyanin in is under control of the entire quorum sensing systems P. aeruginosa. CeO2/PC showed a decrease of up to 55% in pyocyanin production, whereas no effect on bacterial growth in liquid culture was observed. This indicates that CeO2 nanoparticles affect quorum sensing and inhibit biofilm formation in a non-biocidal manner.

Abstract The ethyl 2-[2-(2-nitrobenzylidene)hydrazinyl]thiazole-4-carboxylate (1), a thiazole ester, was synthesized by refluxing 1-(2-nitrobenzylidene)thiosemicarbazide and ethyl bromopyruvate. The compound is characterized by spectrometric, spectroscopic and single crystal (SC-XRD) techniques. Non-covalent interactions that are responsible for crystal packing are explored by Hirshfeld surface analysis. All theoretical calculations were performed by DFT quantum chemical methods using 6-311G(d,p) and cc-pVTZ basis sets and compared. Theoretical harmonic frequencies of ethyl 2-[2-(2-nitrobenzylidene)hydrazinyl]thiazole-4-carboxylate (1) were optimized. Confirmation of hydrogen bonding sites was analyzed by molecular electrostatic potential (MEP) and Mulliken population analysis. The vibrational frequencies of characteristic functional groups and chemical shifts were found in good agreement with experimental assignments. Frontier molecular orbital (FMO) revealed relatively small HOMO–LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) gape, which speaks off the nearly planar geometry and extended conjugation, as compared to the substituents with no conjugation possible. It has also been observed that –NO2 substituent plays a vital role for this relatively small HOMO–LUMO gape and overall electronic properties when compared with similar thiazole carboxylates (2–6, Table 6). Ethyl 2-[2-(2-nitrobenzylidene)hydrazinyl]thiazole-4-carboxylate (1) was also evaluated for its anti-oxidant and anti-microbial activities. Graphical Abstract

Current energy crisis and environmental issues, including depletion of fossil fuels, rapid industrialization, and undesired CO2 emission resulting in global warming has created havoc for the global population and significantly affected the quality of life. In this scenario the environmental problems in the forefront of research priorities. Development of renewable energy resources particularly the efficient conversion of solar light to sustainable energy is crucial in addressing environmental problems. In this regard, the synthesis of semiconductors-based photocatalysts has emerged as an effective tool for different photocatalytic applications and environmental remediation. Among different photocatalyst options available, graphene and graphene derivatives such as, graphene oxide (GO), highly reduced graphene oxide (HRG), and doped graphene (N, S, P, B-HRG) have become rising stars on the horizon of semiconductors-based photocatalytic applications. Graphene is a single layer of graphite consisting of a unique planar structure, high conductivity, greater electron mobility, and significantly very high specific surface area. Besides, the recent advancements in synthetic approaches have led to the cost-effective production of graphene-based materials on a large-scale. Therefore, graphene-based materials have gained considerable recognition for the production of semiconducting photocatalysts involving other semiconducting materials. The graphene-based semiconductors photocatalysts surpasses electron-holes pairs recombination rate and lowers the energy band gap by tailoring the valence band (VB) and conduction band (CB) leading to the enhanced photocatalytic performance of hybrid photocatalysts. Herein, we have summarized the latest developments in designing and fabrication of graphene-based semiconducting photocatalysts using a variety of commonly applied methods such as, post-deposition methods, in-situ binding methods, hydrothermal and/or solvothermal approaches. In addition, we will discuss the photocatalytic properties of the resulting graphene-based hybrid materials for various environmental remediation processes such as; (i) clean H2 fuel production, photocatalytic (ii) pollutants degradation, (iii) photo-redox organic transformation and (iv) photo-induced CO2 reduction. On the whole, by the inclusion of more than 300 references, this review possibly covered in detail the aspects of graphene-based semiconductor photocatalysts for environmental remediation processes. Finally, the review will conclude a short summary and discussion about future perspectives, challenges and new directions in these emerging areas of research.

Synthetic supramolecular structures constructed through the cooperative action of numerous non-covalent forces are highly desirable as models to unravel and understand the complexity of systems created in nature via self-assembly. Taking advantage of the low cost of 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride) and the sequential nucleophilic substitution reactions with almost all types of nucleophiles, a series of six structurally related novel s-triazine derivatives 1–6 were synthesized and structurally characterized based on their physical, spectral and crystallographic data. The solid-state structures of all the six compounds showed intriguing and unique molecular duplexes featuring NH···N, CH···O and CH···π interactions. Careful analysis of different geometric parameters of the involved H-bonds indicates that they are linear, significant and are therefore responsible for guiding the three-dimensional structure of these compounds in the solid state. The prevalence of sextuple hydrogen bond array-driven molecular duplexes and the possibility of structural modifications on the s-triazine ring render these novel triazine derivatives 1–6 attractive as a platform to create heteroduplex constructs and their subsequent utility in the field of supramolecular chemistry and crystal engineering.

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.

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.

Coordination complexes (1–4) of 2-amino-4-methylbenzothiazole and 2-amino-3-methylpyridine with Cu(CH3COO)2 and AgNO3 were prepared and characterized by UV/Vis and FT-IR spectroscopy. The molecular structure for single crystals of silver complexes (2 and 4) were determined by X-ray diffraction. The coordination complex (2) is monoclinic with space group P21/c, wherein two ligands are coordinated to a metal ion, affording distorted trigonal geometry around the central Ag metal ion. The efficient nucleophilic center, i.e., the endocyclic nitrogen of the organic ligand, binds to the silver metal. Ligands are coordinated to adopt cis arrangement, predominantly due to steric reasons. The O(2) and O(3) atoms of the NO3− group further play an important role in such type of ligand arrangement by hydrogen bonding with the NH2 group of ligands. Complex (4) is orthorhombic, P212121, comprising two molecules of 2-amino-3-methylpyridine as ligand coordinated with the metal ion, affording a polymeric structure. The coordination behavior of the ligand is identical to that in complex 2, wherein ring nitrogen is coordinated to the metal center and bridged to another metal ion through an NH2 group. The resulting product is polymeric in nature with the Ag metal in the backbone and ligand as the bridge. Compounds (2–4) were found to be luminescent, while 1 did not show such activity. All compounds were screened for their preliminary biological activities such as antibacterial, antioxidant and enzyme inhibition. Compounds exhibited moderate activity in these tests.

The utilization of heterogeneous catalysts during the production of biodiesel potentially minimize the cost of processing due to the exclusion of the separation step. The (X wt%)Ni–ZrO2 (where X = 10, 25 and 50) catalysts prepared through a hydrothermal process were tested for the production of biodiesel by the transesterification of waste cooking oil (WCO) with methanol. The influences of various reaction parameters were systematically optimized. While the physicochemical characteristics of the as-synthesized catalysts were examined using numerous techniques such as FTIR, XRD, TGA BET, EDX, SEM, and HRTEM. Among all the catalysts, (10 wt%)Ni–ZrO2 exhibited high surface area when compared to the pristine ZrO2, (25 wt%)Ni–ZrO2 and (50 wt%)Ni–ZrO2 nanocatalysts. It may have influenced the catalytic properties of (10 wt%)Ni–ZrO2, which exhibited maximum catalytic activity with a biodiesel production yield of 90.5% under optimal conditions. Such as 15:1 methanol to oil molar ratio, 10 wt% catalysts to oil ratio, 8 h reaction time and 180 °C reaction temperature. Furthermore, the recovered catalyst was efficiently reused in several repeated experiments, demonstrating marginal loss in its activity after multiple cycles (five times).

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.

1,3,4-Oxadiazole moiety is a crucial pharmacophore in many biologically active compounds. In a typical synthesis, probenecid was subjected to a sequence of reactions to obtain a 1,3,4-oxadiazole–phthalimide hybrid (PESMP) in high yields. The NMR (1H and 13C) spectroscopic analysis initially confirmed the structure of PESMP. Further spectral aspects were validated based on a single-crystal XRD analysis. Experimental findings were confirmed afterwards by executing a Hirshfeld surface (HS) analysis and quantum mechanical computations. The HS analysis showed the role of the π⋯π stacking interactions in PESMP. PESMP was found to have a high stability and lower reactivity in terms of global reactivity parameters. α-Amylase inhibition studies revealed that the PESMP was a good inhibitor of α-amylase with an s value of 10.60 ± 0.16 μg/mL compared with that of standard acarbose (IC50 = 8.80 ± 0.21 μg/mL). Molecular docking was also utilized to reveal the binding pose and features of PESMP against the α-amylase enzyme. Via docking computations, the high potency of PESMP and acarbose towards the α-amylase enzyme was unveiled and confirmed by docking scores of −7.4 and −9.4 kcal/mol, respectively. These findings shine a new light on the potential of PESMP compounds as α-amylase inhibitors.

The formation of a C-C bond through Mizoroki-Heck cross-coupling reactions in water with efficient heterogeneous catalysts is a challenging task. In this current study, a highly reduced graphene oxide (HRG) immobilized palladium (Pd) nanoparticle based catalyst (HRG-Py-Pd) is used to catalyze Mizoroki-Heck cross-coupling reactions in water. During the preparation of the catalyst, amino pyrene is used as a smart functionalizing ligand, which offered chemically specific binding sites for the effective and homogeneous nucleation of Pd NPs on the surface of HRG, which significantly enhanced the physical stability and dispersibility of the resulting catalyst in an aqueous medium. Microscopic analysis of the catalyst revealed a uniform distribution of ultrafine Pd NPs on a solid support. The catalytic properties of HRG-Py-Pd are tested towards the Mizoroki-Heck cross-coupling reactions of various aryl halides with acrylic acid in an aqueous medium. Furthermore, the catalytic efficacy of HRG-Py-Pd is also compared with its non-functionalized counterparts such as HRG-Pd and pristine Pd NPs (Pd-NPs). Using the HRG-Py-Pd nanocatalyst, the highest conversion of 99% is achieved in the coupling reaction of 4-bromoanisol and acrylic acid in an aqueous solution in a relatively short period of time (3 h), with less quantity of catalyst (3 mg). Comparatively, pristine Pd NPs delivered lower conversion (∼92%) for the same reaction required a long reaction time and a large amount of catalyst (5.3 mg). Indeed, the conversion of the reaction further decreased to just 40% when 3 mg of Pd-NPs was used which was sufficient to produce 99% conversion in the case of HRG-Py-Pd. On the other hand, HRG-Pd did not deliver any conversion and was ineffective even after using a high amount of catalyst and a longer reaction time. The inability of the HRG-Pd to promote coupling reactions can be attributed to the agglomeration of Pd NPs which reduced the dispersion quality of the catalyst in water. Therefore, the high aqueous stability of HRG-Py-Pd due to smart functionalization can be utilized to perform other organic transformations in water which was otherwise not possible.

New complex compounds (I-III) were synthesized by successive reactions of sodium 1-(2-chlorophenyl)-1H-tetrazole-5-thiolate (NaL1) with cadmium chloride and dimethyl sulfoxide or o-phenanthroline. Successive reactions of sodium 1-(2-methoxyphenyl)-1H-tetrazole-5-thiolate (NaL2) with cadmium chloride and o-phenanthroline gave complexes (IV, V). The structure of the obtained compounds was studied by 1H, 13C NMR, UV–vis spectroscopy and elemental analysis. Moreover, the crystal structure of complexes (I-III/V) was determined by the single crystal X-ray diffraction analysis. The supramolecular assembly was explored through Hirshfeld surface analysis in terms of strong as well as comparatively weak non-covalent interactions. The crystal packing environment of the non-polymeric crystal structures (II/III/V) was further explored by finding the interaction energy between the molecular pairs and energy frameworks. The ligands and the complexes were screened for their bactericidal activity against Staphylococcus aureus and Escherichia coli.

The present investigation deals with the synthesis, characterization and pharmacological evaluation of four cadmium complexes (1–4) with Schiff bases (1L-4L) derived from the substituted amines and aryl aldehydes. Amantadine is reacted with different aryl aldehydes (salicylaldehyde, 3-ethoxysalicylaldehyde and 4-(diethylamino) salicylaldehyde) to prepare Schiff base ligands 1L-3L, while 4L was prepared using 4-methylaniline. The complexes were characterized by elemental analysis, spectroscopic techniques and thermal analysis, and the structure of one of the ligands, 3L was determined by X-ray crystallography. The spectroscopic data indicate that the ligands coordinate with Cd(II) in a bidentate fashion to give octahedral geometry. Single crystal XRD analysis shows that 3L is orthorhombic with the space group P212121. The ligands and their Cd(II) complexes were evaluated for antimicrobial activities, while the complexes were also investigated for inhibition effects towards an enzyme, alkaline phosphatase. The anti-microbial screening results showed that cadmium complex 1 exhibited significant antibacterial potential, particularly against Staphylococcus aureus with respect to the corresponding ligand suggesting that the complexes are more effective than their ligands for antimicrobial activity. In case of alkaline phosphatase inhibition screening, the synthesized cadmium complex 1 was found to maximally inhibit the activity of alkaline phosphatase in comparison to rest of three complexes.

Reaction of the 1,3-diisobutyl thiourea (L) with MX [M = Cu, Ag and X = Cl, NO3] provide polynuclear heteroleptic complexes [Cu3L3Cl3] (1), [Ag2L6](NO3)2 (2) and [Ag6L8Cl4] (3). All complexes were characterized by single crystal X-ray diffraction. The solid-state crystal of these complexes (1–3) were determined by single crystal XRD. Which shows that complex (1) is tri-nuclear with trigonal planer arrangement, complex (2) is binuclear with four membered metalacyclic ring and complex (3) is hexa-nuclear. Complexes (1–3) are tested for their free radical scavenging activity by using 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) showing moderate potential.