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A series of N-dibenzosuberene substituted aroyl selenourea ligands L1–L3 and their Ru(II) (η6-p-cymene) complexes 1–3, [Ru(II) (η6-p-cymene) L] (L = monodentate aroyl selenourea ligand) were synthesized and characterized. The molecular structures of the ligand L3 and complex 3 were confirmed by single-crystal XRD method. The single-crystal XRD study results revealed that aroyl selenourea ligand coordinates with ruthenium via Se neutral monodentate atom. In vitro DNA interaction studies were investigated by UV–Visible and fluorescence spectroscopic methods which showed that the intercalative mode of binding is in the order of 3 &gt; 2 &gt; 1 with the Ru(II) (η6-p-cymene) complexes. The binding affinity of the bovine serum albumin with complexes was calculated using spectroscopic methods. Quantum chemical computations were made using DFT (density functional theory), BL3YP; LANL2DZ basis set in order to determine the frontier molecular orbital parameters and MESP for the newly synthesized complexes. The complexes 1–3 have shown intensive cytotoxicity against the cancer lines HepG-2 and A549 under in vitro conditions. Complex 3 (IC50 = 62 μM) has shown significant cytotoxic activity against HepG-2 compared to cisplatin standard drug. The complexes also examined for their antimicrobial activity. The complex 2 exhibited good activity against B. subtilis (MIC: 13.60 μg/mL), E. coli (MIC: 8.01 μg/mL) and A. flavus (MIC = 15.60 μg/mL), respectively, compared to reference drugs Streptomycin and Ketoconazole. © 2020, Springer Nature B.V.

World University root node

Research on Chemical Intermediates

Synthesis, characterization, in silico and in vitro biological activity studies of Ru(II) (η 6-p-cymene) complexes with novel N-dibenzosuberene substituted aroyl selenourea exhibiting Se type coordination

Journal of Cluster Science

Reaction of the Decaosmium Carbido Cluster [Os<inf>10</inf>(?<inf>6</inf>-C)(CO)<inf>24</inf>]<sup>2?</sup> with Halostibines

Hydrogen (H 2 ) is a clean fuel that can potentially be a future solution for the storage of intermittent renewable energy. However, current H 2 production is mainly dominated by the energy intensive steam reforming reaction, which consumes a fossil fuel, methane, and emits copious amounts of carbon dioxide as one of the byproducts. To address this challenge, we report a molecular catalyst that produces H 2 from aqueous solutions, is composed of affordable, earth-abundant elements such as nickel, and has been incorporated into a system driven by visible light. Under optimized conditions, we observe a turnover number of 3880, among the best for photocatalytic H 2 evolution with nickel complexes from water-methanol solutions. Through nanosecond transient absorption, electron paramagnetic resonance, and UV-vis spectroscopic measurements, and supported by density functional theory calculations, we report a detailed study of this photocatalytic H 2 evolution cycle. We demonstrate that a one-electron reduced, predominantly ligand-centered, reactive Ni intermediate can be accessed under visible light irradiation using triethylamine as the sacrificial electron donor and reductive quencher of the initial photosensitizer excited state. In addition, the computational calculations suggest that the second coordination sphere ether arms can enhance the catalytic activity by promoting proton relay, similar to the mechanism among [FeFe] hydrogenases in nature. Our study can form the basis for future development of H 2 evolution molecular catalysts that incorporate both ligand redox noninnocence and alternative second coordination sphere effects in artificial photosynthetic systems driven by visible light. © 2019 American Chemical Society.

Inorganic Chemistry

Visible Light Driven Hydrogen Evolution by Molecular Nickel Catalysts with Time-Resolved Spectroscopic and DFT Insights

The ruthenacyclic carbamoyl complexes [Ru (2-NHC(O)C5H4N) (CO)2(X) (NCMe)] (X = Cl, Br) (1) and [Ru (2-NHC(O)C5H4N) (CO)2 (2-S-Py)] (2) undergo substitution reactions with organophosphines to afford derivatives which are prone to a redistribution of the phosphine ligand. We have studied these redistribution reactions experimentally and computationally, and proposed an essentially common reaction pathway. The results suggest that the carbamoyl ligand exerts a very strong trans effect. © 2019 Elsevier B.V.

Journal of Organometallic Chemistry

Very strong trans effect in ruthenacyclic carbamoyl complexes leads to ligand redistribution in phosphine derivatives

A route to the synthesis of novel 5,7-diazapentacenes and some preliminary studies on their properties is reported. A single crystal X-ray diffraction study of the dihexyl derivative showed it had formed a dimer during the analysis. The materials possess lower lying frontier orbitals than pentacene and may have potential applications in organic electronic devices. This synthetic method may be applicable to the synthesis of other azaacenes. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chemistry - A European Journal

Synthesis and Electronic Properties of Novel 5,7-Diazapentacene Derivatives

Finding the most effective method for cancer treatment is one of the thought-provoking tasks. Drug delivery by collapsing of metallogel to the cancer cell is an appealing way out. Cancer cells have an acidic environment due to excessive accumulation of lactic acid. In this work, the novel G5 gelator with a strategically free carboxylic acid arm has been designed and fabricated and characterized by several spectroscopic and microscopic techniques. These experiments suggest the formation of an ordered supramolecular gel with clover-leaf-like morphology. Mechanical properties from rheological measurements suggest the viscoelastic nature of the gel. Furthermore, we have obtained crystals of G5 from the pure dimethyl sulfoxide solution, whereas gelation gets induced by addition of water. This G5 gelator loses its gelation capability once the carboxylate is esterified by layering with methanol, which furnished the crystals of Me-G5′ (G5′ = G5-H). Further, the G5 gelator is used for the formation of ruthenium metallogel. Interestingly, we obtained the monomeric species [Ru(G5′)(η6-p-cymene)Cl] [Ru(II)G5] only in confined gel space upon addition of a [Ru2(η6-p-cymene)2Cl4] dimer to G5. The Ru(II)G5 metallogel has an inherent anticancer property with an IC50 value of 10.53 μM for the A549 cancer cell line. Treatment of the Ru(II)G5 metallogel by lactic acid for mimicking the acidic environment of the malignant cell results in collapsing of the gel by releasing the ruthenium metal ion. This released ruthenium ion binds with the lactic acid derivative making the gelator G5 free and producing a new compound Ru(II)L, which has also shown the anticancer property. The molecular docking study revealed that the released G5 could interact with a monocarboxylate transporter to disrupt the lactate transport chain, which might induce apoptosis. Copyright © 2019 American Chemical Society.

ACS Applied Materials and Interfaces

Novel Approach to Generate a Self-Deliverable Ru(II)-Based Anticancer Agent in the Self-Reacting Confined Gel Space

Long-lived room temperature organic phosphorescence is highly useful in biological imaging, electroluminescent devices, information security, and security protection on account of its unique photophysical process and long-lived luminescence. In recent years, pure organic phosphorescent materials that do not contain rare precious metals have received increasing attention. Carbazole and its derivatives have been used to develop room temperature organic phosphorescent materials. However, the effect of carbazolyl groups on the photophysical properties of pure organic phosphors has rarely been reported. In this work, three cyanuric chloride phosphors (CzDCIT, BiCzDT, and TCzT) modified with different numbers of carbazolyl groups were synthesized. Several characterization techniques were employed to reveal distinct crystal forms of CzDCIT, BiCzDT, and TCzT. The single crystal diffraction of CzDCIT and BiCzDT showed not only different crystal packing modes, but also the formation of internal H-aggregation. These three phosphor powders exhibited dual emissions of blue fluorescence and yellow phosphorescence at room temperature, with luminescence lifetimes of 0.16-0.34 s. Theoretical calculations indicated that different numbers of effective intersystem crossing channels between CzDCIT, BiCzDT, or TCzT were responsible for the luminescence lifetimes. After doping the phosphors into the polymer matrix, they exhibited good persistent phosphorescence and high recoverability in multiple compression-grinding cycles. © 2019 American Chemical Society.

Effect of Carbazolyl Groups on Photophysical Properties of Cyanuric Chloride

Five new pincer type Ni(II)-Schiff base complexes of the general formula [NiL1(PPh3)] 1, [NiL2(PPh3)] 2, [NiL3(PPh3)] 3, [NiL4(PPh3)] 4 and [NiL4(4-MePy)] 5 [where H2L1 = 2-(2,3-dihydroxybenzylideneamino)phenol, H2L2 = N-(2,3-dihydroxybenzylidene)benzohydrazide, H2L3 = 2-(2,3-dihydroxybenzylidene)hydrazinecarbothioamide, H2L4 = 5-(diethylamino)-2-(2-hydroxybenzylideneamino)phenol, 4-MePy = 4-Methylpyridine] were synthesized by the reaction of the Ni(OAc)2.4H2O with the corresponding Schiff base ligand in methanol as coloured crystalline solids in high yields. All the five complexes were fully characterized by FT-IR, UV–Vis, 1H NMR, 13C{1H} NMR, 31P{1H} NMR, mass spectrometry and single crystal X-ray diffraction studies. The crystal structures of all five new complexes confirmed the tridentate nature of the pincer type Schiff base ligands (ONO and ONS) and distorted square planar geometry around the metal centre in all cases. The monodentate ligand (triphenylphosphine/4-Methylpyridine) occupied the fourth site at nickel. The catalytic potential of the complexes has been demonstrated in the synthesis of a series of 2-substituted benzimidazoles at room temperature using low catalyst loading (0.5 mol %), and without the use of any additives. All organic products were isolated in high yields (85–96%) and fully characterized by 1H and 13C{1H} NMR studies. © 2019

Synthesis, characterization and single crystal X-ray studies of pincer type Ni(II)-Schiff base complexes: Application in synthesis of 2-substituted benzimidazoles

The development of metallogels widens the span of sensing activity as it opens new opportunities to develop chemosensors through metal-ligand interactions. Herein, a new nitrile-substituted 1,3,5-tricarboxamide-based gelator G4 has been fabricated and shows aggregate-induced enhanced emission (AIEE) after gelation in the presence of water. A dimethylformamide (DMF) solution of the gelator shows rapid crystallization, but addition of water to a DMF solution of gelator G4 leads to gelation at room temperature. In addition, gelator G4 was used for the formation of metallogels, and among them, the cobalt metallogel has been found to be effective for sensing l-tryptophan in the gel state through the quenching of AIEE. Interestingly, the gel is also effective in sensing bovine serum albumin protein at the nanomolar level, which contains an l-tryptophan residue. The limit of detection of Co(II)G4 for selective sensing of tryptophan has been found to be 2.4 × 10-8 M. To the best of our knowledge, there have been no reports to date of a metallogel being utilized to discriminate and selectively sense an amino acid and a protein. The gelation properties of the organic gelator molecule and metallogels have been explored through various spectroscopic tools and physicochemical experiments. © 2019 American Chemical Society.

Cobalt Metallogel Interface for Selectively Sensing l -Tryptophan among Essential Amino Acids

We utilized two organic dications containing, respectively, a pyridinium and an imidazolium core to construct new n = 1 (where n refers to the number of contiguous two-dimensional (2D) inorganic layers, i.e., not separated by organic cations) 2D lead-iodide perovskites 1 and 2. The former material exhibits a (100)- and the latter a very rare 3 × 3 (110)-structural type. Compared with primary ammonium functionality, their constituent ring-centered positive charges have lower charge density. As a result, [PbI 6 ] 4- interoctahedral distortions of the inorganic lattice in 1 and 2 are reduced (Pb-I-Pb bond angles are as high as 166° and 174°, respectively). This results in bathochromically shifted optical features. In addition, the compact nature of the dications produces extremely short lead-iodide sheet separations, with respective iodide-iodide (I···I) distances as small as 4.149 and 4.278 Å. These are among the shortest separations of adjacent lead-iodide layers ever reported for such materials. When crystallized as thin films on top of substrates, the resulting 2D perovskite layers do not adopt a regular growth direction parallel to the surface. Instead, the crystallites grow with no fixed orientation. As a consequence of their proximate inorganic distances and unusual crystallization tendencies, the resulting 2D perovskites exhibit low excitonic activation energies (93.59 and 96.53 meV, respectively), enhanced photoconductivity in solar cells, and unprecedented incident photon-to-current conversion rates of up to 60%. More importantly, mesoporous 2D layered perovskite solar cells with power conversion efficiencies of 1.43 and 1.83% were achieved for 1 and 2, respectively. These are the highest values obtained thus far for pure n = 1 lead-iodide perovskites and more than 20 times higher than those obtained for materials templated by more conventional cations such as phenylethylammonium (0.08%). Copyright © 2019 American Chemical Society.