Crystal Structure Elucidation Research Articles

Two rhodamine-azo based fluorescent probes for recognition of trivalent metal ions: crystal structure elucidation and biological applications.

Two rhodamine and azo based chemosensors (HL1 = (3',6'-bis(ethylamino)-2-((2-hydroxy-3-methoxy-5-(phenyldiazenyl)benzylidene)amino)-2',7'-dimethylspiro[isoindoline-1,9'-xanthen]-3-one) and HL2 = (3',6'-bis(ethylamino)-2-(((2-hydroxy-3-methoxy-5-(p-tolyldiazenyl)benzylidene)amino)-2',7'-dimethylspiro[isoindoline-1,9'-xanthen]-3-one) have been synthesized for colorimetric and fluorometric detection of three trivalent metal ions, Al3+, Cr3+ and Fe3+. The chemosensors have been thoroughly characterized by different spectroscopic techniques and X-ray crystallography. They are non-fluorescent due to the presence of a spirolactam ring. The trivalent metal ions initiate an opening of the spirolactam ring when excited at 490 nm in Britton-Robinson buffer solution (H2O/MeOH 1 : 9 v/v; pH 7.4). The opening of the spirolactam ring increases conjugation within the probe, which is supported by an intense fluorescent pinkish-yellow colouration and an enhancement of the fluorescence intensity of the chemosensors by ∼400 times in the presence of Al3+ and Cr3+ ions and by ∼100 times in the presence of Fe3+ ions. Such a type of enormous fluorescence enhancement is rarely observed in other chemosensors for the detection of trivalent metal ions. A 2 : 1 binding stoichiometry of the probes with the respective ions has been confirmed by Job's plot analysis. Elucidation of the crystal structures of the Al3+ bound chemosensors (1 and 4) also justifies the 2 : 1 binding stoichiometry and the presence of an open spirolactam ring within the chemosensor framework. The limit of detection (LOD) values for both the chemosensors towards the respective metal ions are in the order of ∼10-9 M which supports their application in the biological field. The biocompatibility of the ligands has been studied with the help of the MTT assay. The results show that no significant toxicity was observed up to 100 μM of chemosensor concentration. The capability of our synthesized chemosensors to detect intracellular Al3+, Cr3+ and Fe3+ ions in the cervical cancer cell line HeLa was evaluated with the aid of fluorescence imaging.

Absolute configuration determination of pharmaceutical crystalline powders by MicroED via chiral salt formation.

Microcrystal electron diffraction (MicroED) has established its complementary role alongside X-ray diffraction in crystal structure elucidation. Unfortunately, kinematical refinement of MicroED data lacks the differentiation power to assign the absolute structure solely based on the measured intensities. Here we report a method for absolute configuration determination via MicroED by employing salt formation with chiral counterions.

Crystal structure elucidation and DFT studies of imidazopyridine-pyrazoline derivative

The present work concentrates on the newly synthesized imidazopyridine-pyrazoline derivative. The compound is characterized by LC-MS, Infrared (IR) analysis, and X-ray diffraction. The molecule crystallizes in the monoclinic crystal system with the space group P21/n. The unit cell parameters are: a = 4.8410(12) Å, b = 17.065(4) Å, c = 23.332(7) Å, α = γ = 90°, and β = 92.390° Hirshfeld surface study was carried out to quantify the intermolecular interactions and crystal packing. The geometry optimization was done using the density functional theory (DFT) calculations using B3LYP hybrid functional. Theoretical calculations such as energy gap between the frontier molecular orbitals, molecular electrostatic potential surface and non covalent interactions were studied.

Synthesis, hydrogen bond interactions and crystal structure elucidation of some stable 2H-imidazolium salts

Abstract Reaction of 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (1) with phthalimide, quinazolinedione, thiophenole and 4-pyridinethiole led to the formation of the hydrogen-bonded salts, imidazolium phthalimide (2), imidazolium quinazolinedione (3), imidazolium thiophenolate (4) and imidazolium 4-pyridinethiolate (5), respectively, in good yield. In crystals of 2, the anion is linked to the imidazolium cation by a C–H···O hydrogen bond, while in 3 and 5 C–H···N hydrogen bonds are observed. In 4, the imidazolium ion is linked to the anion by C–H···S hydrogen bonds. In compounds 2, 3 and 5, the interionic hydrogen bonds are close to linearity, while the interionic hydrogen bond angle in 4 is 148.5(9)°.

Synthesis, crystal structure elucidation, Hirshfeld surface analysis, 3D energy frameworks and DFT studies of 2-(4-fluorophenoxy) acetic acid

The compound 2-(4-fluorophenoxy) acetic acid was synthesized by refluxing, 4-fluoro-phenol as a starting material with ethyl chloroacetate in acetone as solvent. The compound crystallizes in the monoclinic crystal system with the space group P21/c. Crystal data for C8H7FO3, a = 13.3087(17) Å, b = 4.9912(6) Å, c = 11.6018(15) Å, β = 104.171(4)°, V = 747.21(16) Å3, Z = 4, T = 293(2) K, μ(CuKα) = 1.142 mm-1, Dcalc = 1.512 g/cm3, 8759 reflections measured (13.72° ≤ 2Θ ≤ 130.62°), 1246 unique (Rint = 0.0528) which were used in all calculations. The final R1 was 0.0458 (>2sigma(I)) and wR2 was 0.1313 (all data). The structure was stabilized by C-H···O and C-H···Cg interactions. The intermolecular interactions in the crystal were studied using Hirshfeld surface analysis. 3D energy frameworks were computed to visualize the packing modes. DFT calculations were performed. The FMOs were studied to estimate the kinetic stability and reactivity of the molecule. The MEP surface was generated to investigate the charge distribution and chemical reactive sites in the molecule.

Crystal structure elucidation, experimental and computational optical properties of novel acceptor-donor-acceptor organic material: A suitable candidate for nonlinear applications

A new organic nonlinear optical (NLO) material, 2-(4-chlorophenoxy)-N'-[(1E)-1-(4-fluorophenyl) ethylidene] acetohydrazide (4CP4FPEA), has been synthesized and single crystals were grown using DMF as solvent. The compound was characterized by 1H NMR and single X-ray diffraction analyses. Analysis of intermolecular interactions was carried out by mapping Hirshfeld surfaces over 2D fingerprint plots, dnorm and curvedness using Crystal Explorer. Open aperture Z-Scan experimental curve showed that the 4CP4FPEA molecule exhibits lower transmittance at the focus at 532 nm wavelength. 4CP4FPEA exhibits good optical limiting behavior at the wavelength 532 nm. Estimated excited state absorption cross-section (σex) and ground state absorption cross-section (σg) are found to be 3.59 × 10−17cm2 and 1.9 × 10−21 cm2 respectively (σg <<< σex) indicating that nonlinear absorption is due to Reverse Saturable Absorption. Semi-empirical calculations were implemented to calculate static and frequency dependent mean polarizability, first-order hyperpolarizability and second-order hyperpolarizability using time-dependent Hartree–Fock (TDHF) method. We have observed enhancement in nonlinear optical property compared to our previous reported molecule 2-(4-chlorophenoxy)-N'-[(1E)-1-(4-methylphenyl) ethylidene] acetohydrazide (4CP4MPEA).

Isolation of isoeleutherol from microwave assisted methanol extract of Eleutherine bulbosa bulbs, its crystal structure elucidation and cytotoxicity evaluation

Different extraction methods (Soxhlet, Serial soxhlet, Cold, and microwave-assisted extraction) were executed for the extraction of phytochemicals from the bulbs of Eleutherine bulbosa Miller (Urban), an important medicinal plant in the family Iridaceae. Among the different methods, most efficient (especially in terms of extraction time) was the microwave-assisted extraction (MAE) using methanol as the extraction solvent. The microwave assisted methanolic extract was subjected to column chromatography and a naphthalene compound, isoeleutherol was isolated. Starting from, about two grams of the crude methanol extract, 21 mg of pure compound (isoeleutherol) was obtained as yellow needle like crystals with an Rf value of 0.53 in TLC. The structural characterization was done by Single crystal X-ray diffraction analysis. The study also tested the cytotoxic activity of the compound against two cancer cell lines (HeLa and MCF-7) and one normal cell (Chang liver cells) line by MTT assay. Results of the cytotoxicity evaluation showed that isoeleutherol has potent activity on both the cancer cell lines with LC 50 values of 35.4 and 23.8 μg/ml against HeLa and MCF-7 cells, respectively. Isoeleutherol exhibitted less cytotoxicity towards normal cells (Chang liver cells). At the highest concentration used (100 μg/ml), 60.99 ± 1.92% normal cells were viable. This is the first report of isolation of a compound from E. bulbosa through microwave-assisted extraction, a faster and environment friendly technique for the phytochemical extraction. The present study also reports detailed structural elucidation of isoeleutherol by X-ray crystallography for the first time.

Supramolecular Enhancement of a Natural 14-3-3 Protein Ligand.

Rational design of protein-protein interaction (PPI) inhibitors is challenging. Connecting a general supramolecular protein binder with a specific peptidic ligand provides a novel conceptual approach. Thus, lysine-specific molecular tweezers were conjugated to a peptide-based 14-3-3 ligand and produced a strong PPI inhibitor with 100-fold elevated protein affinity. X-ray crystal structure elucidation of this supramolecular directed assembly provides unique molecular insight into the binding mode and fully aligns with Molecular Dynamics (MD) simulations. This new supramolecular chemical biology concept opens the path to novel chemical tools for studying PPIs.

Structure Elucidation of Complex Endotaxially Intergrown Lanthanum Barium Oxonitridosilicate Oxides by Combination of Microfocused Synchrotron Radiation and Transmission Electron Microscopy.

Single‐crystalline domains in intergrown microcrystalline material of the new compounds Ba22.5+x La55−x [Si129N240−x O x ]O3:Ce3+ and Ba25.5+x La77−x [Si170N312−x O9+x ]O4:Ce3+ were identified by transmission electron microscopy (TEM). Precise diffraction data from these domains were collected with microfocused synchrotron radiation so that crystal structure elucidation of the complex disordered networks became possible. They are composed of two different interconnected slabs of which one is similar in both compounds, which explains their notorious intergrowth. The distribution of Ba and La is indicated by the analysis of bond‐valence sums and by comparison with isostructural Sr28.5+x La75−x [Si170N312−x O9+x ]O4. Ce3+ doping leads to yellow luminescence. This is a showcase that highlights the discovery and accurate characterization of new compounds relevant for luminescence applications from heterogeneous microcrystalline samples by exploiting the capability of the combination of TEM and diffraction using the latest focusing techniques for synchrotron radiation.

Preface

It was a great pleasure to welcome all the participants from different countries to the 2021 International Conference on Electronic Materials and Information Engineering (EMIE 2021), which was successfully held during April 09-11, 2021 in Xi´an, China. EMIE 2021 provides an enabling platform for Electronic Materials and Information Engineering experts to exchange new ideas and present research results. This conference also promotes the establishing of business or research relations among global partners for future collaboration. We hope that this conference could make significant contribution to the update of knowledge about these latest scientific field.The conference model was divided into two sessions, including oral presentations and keynote speeches. In the first part, some scholars, whose submissions were selected as the excellent papers, were given 15 minutes to perform their oral presentations one by one. Then in the second part, keynote speakers were each allocated 30-45 minutes to hold their speeches. In this conference, we were greatly honored to have invited Professor Alex Lugovskoy from Department of Chemical Engineering, Ariel University as our Conference Chair. There were over 70 experts and scholars in the area of Electronic Materials and Information Engineering representing different famous universities and institutes around the globe to attend the conference.During the conference, we were pleased to invite four distinguished experts to present their insightful speeches. Prof. Fanian Shi, our first keynote speaker, from Shenyang University of Technology. His research interests: Crystal Structure Design and Elucidation; Electromagnetic wave absorbing material; Composite. Prof.Jing Guo, from School of Materials Science and Engineering, Xi’an Jiaotong University. He devoted to electronic ceramics, low temperature sintering, microwave dielectric materials and other related research area. Prof.Yang Yue, from Nankai University. He had outstanding research in intelligent photonics, optical communications and networking, optical interconnect, detection, imaging and display technology, integrated photonics, free-space and fiber optics and other related area. Prof. Xiaoming Zhang, our finale keynote speaker, from Hebei University of Technology. His research area: Topological theory; Electronic materials; 2D materials.The participants of the conference were from most part of the world, with background of either academia or industry, even well-known enterprise. The success and prosperity of the conference is reflected high level of the papers received. The proceedings are a compilation of the accepted papers and represent an interesting outcome of the conference. EMIE 2021 for exchange of research findings, analysis, information, and knowledge in areas which include but are not limited to: Electronic Materials, Information Engineering and other related topics.We would like to acknowledge all of those who supported EMIE 2021. Each individual and institutional help are very important for the success of this conference. Especially we would like to thank the organizing committee for their valuable advices in the organization and helpful peer review of the papers. We sincerely hope that EMIE 2021 will be a forum for excellent discussions that will put forward new ideas and promote collaborative researches. We are sure that the proceedings will serve as an important research source of references and the knowledge, which will lead to not only scientific and engineering progress but also other new products and processes.The Organizing Committee of EMIE 2021List of Committee member are available in this pdf.

X-Ray Crystal Structure Elucidation, DNA Binding, and Molecular Docking Studies of Natural Compounds Isolated from &lt;i&gt;Crateva Religiosa&lt;/i&gt; Leaves: A Biophysical Approach

X-Ray Crystal Structure Elucidation, DNA Binding, and Molecular Docking Studies of Natural Compounds Isolated from &lt;i&gt;Crateva Religiosa&lt;/i&gt; Leaves: A Biophysical Approach

Metal Ion Promiscuity and Structure of 2,3-Dihydroxybenzoic Acid Decarboxylase of Aspergillus oryzae.

Broad substrate tolerance and excellent regioselectivity, as well as independence from sensitive cofactors have established benzoic acid decarboxylases from microbial sources as efficient biocatalysts. Robustness under process conditions makes them particularly attractive for preparative‐scale applications. The divalent metal‐dependent enzymes are capable of catalyzing the reversible non‐oxidative (de)carboxylation of a variety of electron‐rich (hetero)aromatic substrates analogously to the chemical Kolbe‐Schmitt reaction. Elemental mass spectrometry supported by crystal structure elucidation and quantum chemical calculations verified the presence of a catalytically relevant Mg2+ complexed in the active site of 2,3‐dihydroxybenoic acid decarboxylase from Aspergillus oryzae (2,3‐DHBD_Ao). This unique example with respect to the nature of the metal is in contrast to mechanistically related decarboxylases, which generally have Zn2+ or Mn2+ as the catalytically active metal.

A Tetratopic Phosphonic Acid for the Synthesis of Permanently Porous MOFs: Reactor Size-Dependent Product Formation and Crystal Structure Elucidation via Three-Dimensional Electron Diffraction.

Following the strategy of installing porosity in coordination polymers predefined by linker geometry, we employed the new tetratopic linker molecule 1,1,2,2-tetrakis[4-phosphonophenyl]ethylene (H8TPPE) for the synthesis of new porous metal phosphonates. A high-throughput study was carried out using Ni2+ and Co2+ as metal ions, and a very strong influence of the reactor size on the product formation is observed while maintaining the same reaction parameters. Using small autoclaves (V = 250 μL), single crystals of isostructural mononuclear complexes of the composition [Ni(H3DPBP)2(H2O)4] (1) and [Co(H3DPBP)2(H2O)4] (2) are formed. They contain the linker molecule H4DPBP (4,4'-diphosphonobenzophenone), which is formed in situ by oxidation of H8TPPE. Using autoclaves with a volume of V = 2 mL, two new 3D metal-organic frameworks (MOFs) of composition [Ni2(H4TPPE)(H2O)6]·4H2O (CAU-46) and [Co2(H4TPPE)(H2O)4]·3H2O (CAU-47) were isolated in bulk quantities, and their crystal structures were determined from three-dimensional electron diffraction (3D ED) and powder X-ray diffraction data. Using even larger autoclaves (V = 30 mL), another 3D MOF of the composition [Co2(H4TPPE)]·6H2O (Co-CAU-48) was obtained, and a structure model was established via 3D ED measurements. Remarkably, the isostructural compound [Ni2(H4TPPE)]·9H2O (Ni-CAU-48) is only obtained indirectly, i.e., via thermal activation of CAU-46. As the chosen linker geometry leads to the formation of MOFs, topological analyses were carried out, highlighting the different connectivities observed in the three frameworks. Porosity of the compounds was proven via water sorption experiments, resulting in uptakes of 126 mg/g (CAU-46), 105 mg/g (CAU-47), 210 mg/g (Ni-CAU-48), and 109 mg/g (Co-CAU-48).

Synthesis, X-ray crystal structure elucidation and Hirshfeld surface analysis of N-((4-(1H-benzo[d]imidazole-2-yl)phenyl)carbamothioyl)benzamide: investigations for elastase inhibition, antioxidant and DNA binding potentials for biological applications.

The interest in the present study pertains to the development of a new compound based upon a benzimidazole thiourea moiety that has unique properties related to elastase inhibition, free radical scavenging activity and its DNA binding ability. The title compound, N-(4-(1H-benzo[d]imidazol-2-yl)phenyl)-3-benzoyl thiourea (C21H18N4O2SH2O:TUBC), was synthesized by reacting an acid chloride of benzoic acid with potassium thiocyanate (KSCN) along with the subsequent addition of 4-(1H-benzo[d]imidazol-2-yl)benzenamine via a one-pot three-step procedure. The structure of the resulting benzimidazole based thiourea was confirmed by spectroscopic techniques including FTIR, 1H-NMR, 13C-NMR and single crystal X-ray diffraction and further examined by Hirshfeld surface analysis. TUBC was also investigated by using both in silico methodology including molecular docking for elastase inhibition along with quantum chemical studies and in vitro experimental methodology utilizing elastase inhibition and free radical scavenging assay along with DNA binding experiments. Docking results confirmed that TUBC binding was within the active region of elastase. In comparison to the reference drug oleanolic acid, the low IC50 value of TUBC also indicated its high tendency towards elastase inhibition. TUBC scavenged 80% of DPPH˙ radicals which pointed towards its promising antioxidant activity. TUBC–DNA binding by DFT, docking, UV-visible spectroscopy and viscosity measurements revealed TUBC to be a potential drug candidate that binds spontaneously and reversibly with DNA via a mixed binding mode. All theoretical and experimental findings pointed to TUBC as a potential candidate for a variety of biological applications.

Crystal structure of Gig2 protein from Candida albicans provides a structural insight into DUF1479 family oxygenases

Candida albicans, GlcNAc inducible gene 2 (Gig2) is important for its virulence, oxidative stress adaptation and is supposed to be a part of the undefined GlcNAc metabolic network. On the basis of sequence homology, Gig2 is classified as a putative oxidoreductase of DUF1479 family (Domain of Unknown Function) with no reported structure and function. In this work, we have elucidated the crystal structure of Gig2 protein using X-ray crystallography at 1.7 Å resolution. Crystals were improved using successive macro-seeding technique. Structure was solved by molecular replacement using a template (PDBID: 2CSG) with a mere 27% identity with Gig2, followed by manual and automated model building. Gig2 exists as a monomer with a single large DUF1479 domain and is composed of a cupin like double stranded β-helix (DBSH) core fold with Iron (Fe) in the active site. This is the first report of DUF1479 family proteins which identifies and highlights its unique structural features. Crystal structure elucidation, structural comparisons, and docking studies proposes Gig2 as a non-heme Fe (II) containing 2-oxoglutarate dependent oxygenase.

Structure-guided design combined with evolutionary diversity led to the discovery of the xylose-releasing exo-xylanase activity in the glycoside hydrolase family 43.

Rational design is an important tool for sculpting functional and stability properties of proteins and its potential can be much magnified when combined with in vitro and natural evolutionary diversity. Herein, we report the structure-guided design of a xylose-releasing exo-β-1,4-xylanase from an inactive member of glycoside hydrolase family 43 (GH43). Structural analysis revealed a nonconserved substitution (Lys247 ) that results in the disruption of the hydrogen bond network that supports catalysis. The mutation of this residue to a conserved serine restored the catalytic activity and crystal structure elucidation of the mutant confirmed the recovery of the proper orientation of the catalytically relevant histidine. Interestingly, the tailored enzyme can cleave both xylooligosaccharides and xylan, releasing xylose as the main product, being the first xylose-releasing exo-β-1,4-xylanase reported in the GH43 family. This enzyme presents a unique active-site topology when compared with closely related β-xylosidases, which is the absence of a hydrophobic barrier at the positive-subsite region, allowing the accommodation of long substrates. Therefore, the combination of rational design for catalytic activation along with naturally occurring differences in the substrate binding interface led to the discovery of a novel activity within the GH43 family. In addition, these results demonstrate the importance of solvation of the β-propeller hollow for GH43 catalytic function and expand our mechanistic understanding about the diverse modes of action of GH43 members, a key and polyspecific carbohydrate-active enzyme family abundant in most plant cell-wall-degrading microorganisms.

Spergulagenic Acid A: Isolation and single crystal structure elucidation

In the present work, the crystal structure of (3b)-3-acetoxy-30-methoxy-30-oxo-olean-12-en-28-oic acid, (Spergulagenic Acid A) is presented. The compound was isolated from Cecropia telenitida roots, employing semi-pilot scale extraction system and automated flash chromatography device. Vapor diffusion of methanol in chloroform yield suitable crystals for X-ray diffraction. The crystal packing of the Spergulagenic Acid A as methanol solvate is formed by strong hydrogen bonds between the SA-A molecule and the methanol. SA-A as well other pentacyclic triterpenes, present interesting potential biological activities. Inasmuch as biological activity is clearly related to molecular structure, the main goal of the present work was the structural elucidation of this molecule by single crystal X-ray diffraction. To the best of our knowledge, there is no previous crystal structure report in the literature for the titled compound or any other with simultaneous substitution at C2 and C7.

Synthesis, Crystal and Topological Electronic Structures of New Bismuth Tellurohalides Bi2TeBr and Bi3TeBr

Halogen substitution, that is, bromine for iodine, in the series of topological BinTeI (n = 1, 2, 3) materials was conducted in order to explore the impact of anion exchange on topological electronic structure. In this proof-of-concept study, we demonstrate the applicability of the modular view on crystal and electronic structures of new Bi2TeBr and Bi3TeBr compounds. Along with the isostructural telluroiodides, they constitute a family of layered structures that are stacked from two basic building modules, ∞2[Bi2] and ∞2[BiTeX] (X = I, Br). We present solid-state synthesis, thermochemical studies, crystal growth, and crystal-structure elucidation of Bi2TeBr [space group R3̅m (no. 166), a = 433.04(2) pm, c = 5081.6(3) pm] and Bi3TeBr [space group R3m (no. 160), a = 437.68(3) pm, c = 3122.9(3) pm]. First-principles calculations establish the topological nature of Bi2TeBr and Bi3TeBr. General aspects of chemical bonding appear to be similar for BinTeX (X = I, Br) with the same n, so that alternation of the global gap size upon substitution is insignificant. The complex topological inversion proceeds between the states of two distinct modules, ∞2[Bi2] and ∞2[BiTeBr]; thus, the title compounds can be seen as heterostructures built via a modular principle. Furthermore, highly disordered as well as incommensurately modulated ternary phase(s) are documented near the Bi2TeBr composition. Single-crystal X-ray diffraction experiments on BiTeBr and Bi2TeI resolve some discrepancies in prior published work.

Abstract 2665: Bioassay approach isolation and crystal structure elucidation of isoglabratephrin: A prenylated flavonoid from Tephrosia apollinea and its anticancer property

Abstract Cancer is characterized by uncontrolled cell division caused by dysregulation of cell proliferation. Therefore, agents that impair cancer cell proliferation could have potential therapeutic value. Higher plants are considered to be a good source of anticancer agents, and several clinically tested chemotherapeutic agents have been isolated from plants or derived from constituents of plant origin. In the present study, a prenylated flavone (isoglabratephrin) was isolated from aerial parts of Tephrosia apollinea using a bioassay-guided technique. Chemical structure of the isolated compound was elucidated using spectroscopic techniques (NMR, IR, and LC-MC) and confirmed using single crystal X-ray analysis. The antiproliferative effect of isoglabratephrin was tested using three human cancer cell lines (prostate (PC3), pancreatic (PANC-1), and colon (HCT-116) and one normal cell line (human fibroblast). Isoglabratephrin displayed selective inhibitory activity against proliferation of PC3 and PANC-1 cells with median inhibitory concentration values of 20.4 and 26.6μg/ml, respectively. Isoglabratephrin demonstrated pro-apoptotic features, as it induced chromatin dissolution, nuclear condensation, and fragmentation. It also disrupted the mitochondrial membrane potential in the treated cancer cells. Thus, isoglabratephrin could be a new lead for development of cancer chemotherapies to treat human prostate and pancreatic malignancies. Citation Format: Loiy E. Ahmed Hassan, Muhammad Adnan Iqbal, Aman Shah Abdul Majid, Amin M. Abdul Majid, Zarina Thasneem Zainudeen. Bioassay approach isolation and crystal structure elucidation of isoglabratephrin: A prenylated flavonoid from Tephrosia apollinea and its anticancer property [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2665.

π⋯π and hydrogen bonding interactions in the crystal structure of trans-dichloro-tetrakis(1H-indazole-N2)-nickel(II)

A new mononuclear complex of nickel(II), [Ni(1H-Indz)4Cl2] (1), where 1H-Indz is the 1H-Indazole ligand, was synthesized and characterized by elemental analysis, FT-IR spectroscopy and single crystal X-ray structure elucidation. Single crystal X-ray analysis indicates that this complex crystallizes in the triclinic system [a = 6.859(3) Å, b = 12.275(6) Å, c = 18.202(9) Å, α = 97.615(9)°, β= 98.336(9)°, γ= 105.118(9)°] and the asymmetric part of unit cell consists of two crystallographically independent neutral mononuclear Ni(II) complexes. The nickel atom in 1 is six-coordinate, as a trans-[Mn(Cl)2(N)4], with four nitrogen atoms from four 1H-indazole ligands, and the overall geometry around nickel(II) ions is best described as a slightly distorted octahedron. The crystal structure of complex 1 is stabilized by several intermolecular N–H⋯Cl hydrogen bonds, C−H⋯π, and π⋯π interactions.