A phthalocyanine–subphthalocyanine heterodinuclear dimer: comparison of spectroscopic properties with those of homodinuclear dimers of constituting units

X Ray ◽

X Ray Crystallography ◽

A phthalocyanine–subphthalocyanine heterodinuclear dimer has been disclosed for the first time with its unique flat-bowl-shaped structure revealed by X-ray crystallography.

Bis(1-phenyl-1-propyne) complexes of tungsten(II): crystal structures of [WI2(CO)(NCR)(η2-MeC2Ph)2] (R = Me, Et, or Ph)

Canadian Journal of Chemistry ◽

10.1139/v01-028 ◽

2001 ◽

Vol 79 (3) ◽

pp. 263-271

Author(s):

Paul K Baker ◽

Michael GB Drew ◽

Deborah S Evans

Keyword(s):

Carbon Monoxide ◽

Solid State ◽

Crystal Structures ◽

Octahedral Geometry ◽

X Ray ◽

X Ray Crystallography ◽

Alkyne Complexes ◽

Reaction of [WI2(CO)3(NCMe)2] with two equivalents of 1-phenyl-1-propyne (MeC2Ph) in CH2Cl2, and in the absence of light, gave the bis(1-phenyl-1-propyne) complex [WI2(CO)(NCMe)(η2-MeC2Ph)2] (1) in 77% yield. Treatment of equimolar quantities of 1 and NCR (R = Et, i-Pr, t-Bu, Ph) in CH2Cl2 afforded the nitrile-exchanged products, [WI2(CO)(NCR)(η2-MeC2Ph)2] (2-5) (R = Et (2), i-Pr (3), t-Bu (4), Ph (5)). Complexes 1, 2, and 5 were structurally characterized by X-ray crystallography. All three structures have the same pseudo-octahedral geometry, with the equatorial sites being occupied by cis and parallel alkyne groups, which are trans to the cis-iodo groups. The trans carbon monoxide and acetonitrile ligands occupy the axial sites. In structures 1 and 2, the methyl and phenyl substituents of the 1-phenyl-1-propyne ligands are cis to each other, whereas for the bulkier NCPh complex (5), the methyl and phenyl groups are trans to one another. This is the first time that this arrangement has been observed in the solid state in bis(alkyne) complexes of this type.Key words: bis(1-phenyl-1-propyne), carbonyl, nitrile, diiodo, tungsten(II), crystal structures.

Systhesis, Characterization and Spectroscopic Properties of (2E,6E)-2,6-Bis(2,3,4-tri-methoxy-benzylidene)cyclohexanone

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.396-398.2338 ◽

2011 ◽

Vol 396-398 ◽

pp. 2338-2341

Author(s):

Xing Chuan Wei ◽

Zhi Li Liu ◽

Kun Zhang ◽

Zhi Yun Du ◽

Xi Zheng

Keyword(s):

Crystal Structure ◽

Acetic Acid ◽

Hydrogen Bonds ◽

Title Compound ◽

Spectral Studies ◽

Double Bonds ◽

X Ray ◽

Π Interactions ◽

X Ray Crystallography

In this paper, (2E,6E)-2,6-Bis(2,3,4-tri-methoxy -benzylidene)cyclohexanone (omitted as tmbcho) (1) was obtained by the reaction of acetic acid, tetrahydrofuran, cyclohexanone and 2,3,4-tri-methoxy-benzaldehyde. Three non-classic hydrogen bonds were observed in the compound. X-ray crystallography shows that the crystal structure is stabilized by intermolecular C-H•••π interactions and it contains plenty of conjugated double bonds. The title compound was characterized by UV-vis and fluorescent spectral studies.

Unraveling the long-pursued Au144 structure by x-ray crystallography

Science Advances ◽

10.1126/sciadv.aat7259 ◽

2018 ◽

Vol 4 (10) ◽

pp. eaat7259 ◽

Cited By ~ 112

Author(s):

Nan Yan ◽

Nan Xia ◽

Lingwen Liao ◽

Min Zhu ◽

Fengming Jin ◽

...

Keyword(s):

Metal Nanoparticles ◽

Weak Interactions ◽

Gold Nanoclusters ◽

Atomic Level ◽

High Quality ◽

X Ray ◽

X Ray Crystallography ◽

Quantum Size ◽

The transition from nanocluster to nanocrystal is a central issue in nanoscience. The atomic structure determination of metal nanoparticles in the transition size range is challenging and particularly important in understanding the quantum size effect at the atomic level. On the basis of the rationale that the intra- and interparticle weak interactions play critical roles in growing high-quality single crystals of metal nanoparticles, we have reproducibly obtained ideal crystals of Au144(SR)60 and successfully solved its structure by x-ray crystallography (XRC); this structure was theoretically predicted a decade ago and has long been pursued experimentally but without success until now. Here, XRC reveals an interesting Au12 hollow icosahedron in thiolated gold nanoclusters for the first time. The Au–Au bond length, close to that of bulk gold, shows better thermal extensibility than the other Au–Au bond lengths in Au144(SR)60, providing an atomic-level perspective because metal generally shows better thermal extensibility than nonmetal materials. Thus, our work not only reveals the mysterious, long experimentally pursued structure of a transition-sized nanoparticle but also has important implications for the growth of high-quality, single-crystal nanoparticles, as well as for the understanding of the thermal extensibility of metals from the perspective of chemical bonding.

Fragment-Based Screening for Inhibitors of PDE4A Using Enthalpy Arrays and X-ray Crystallography

CrossRef Listing of Deleted DOIs ◽

10.1177/1087057111430987 ◽

2012 ◽

Vol 17 (4) ◽

pp. 469-480 ◽

Cited By ~ 15

Author(s):

Michael I. Recht ◽

Vandana Sridhar ◽

John Badger ◽

Leslie Hernandez ◽

Barbara Chie-Leon ◽

...

Keyword(s):

Titration Calorimetry ◽

Label Free ◽

Lead Discovery ◽

High Resolution Data ◽

Affinity Ligands ◽

X Ray ◽

X Ray Crystallography ◽

Chemical Structures ◽

Fragment Library

Fragment-based screening has typically relied on X-ray or nuclear magnetic resonance methods to identify low-affinity ligands that bind to therapeutic targets. These techniques are expensive in terms of material and time, so it useful to have a higher throughput method to reliably prescreen a fragment library to identify a subset of compounds for structural analysis. Calorimetry provides a label-free method to assay binding and enzymatic activity that is unaffected by the spectroscopic properties of the sample. Conventional microcalorimetry is hampered by requiring large quantities of reagents and long measurement times. Nanocalorimeters can overcome these limitations of conventional isothermal titration calorimetry. Here we have used enthalpy arrays, which are arrays of nanocalorimeters, to perform an enzyme activity-based fragment screen for competitive inhibitors of phosphodiesterase 4A (PDE4A). Several inhibitors with K I <2 mM were identified and moved to X-ray crystallization trials. Although the co-crystals did not yield high-resolution data, evidence of binding was observed, and the chemical structures of the hits were consistent with motifs of known PDE4 inhibitors. This study shows how array calorimetry can be used as a prescreening method for fragment-based lead discovery with enzyme targets and provides a list of candidate fragments for inhibition of PDE4A.

Sesquiterpene Lactones from Inula oculus-christi

Natural Product Communications ◽

10.1177/1934578x1000500402 ◽

2010 ◽

Vol 5 (4) ◽

pp. 1934578X1000500 ◽

Cited By ~ 5

Author(s):

Mahmoud Mosaddegh ◽

Maryam Hamzeloo Moghadam ◽

Saeedeh Ghafari ◽

Farzaneh Naghibi ◽

Seyed Nasser Ostad ◽

...

Keyword(s):

Cytotoxic Activity ◽

Crystal Structures ◽

Spectroscopic Data ◽

Sesquiterpene Lactones ◽

X Ray ◽

X Ray Crystallography ◽

Inula oculus-christi L. (Compositae) extract was chromatographed and three sesquiterpene lactones ergolide, gaillardin and pulchellin C were isolated. The structures of these compounds were determined by analysis of their spectroscopic data, and their crystal structures were defined using X-ray crystallography; the isolation of ergolide and pulchellin C is reported for the first time from this species. These three compounds were evaluated for their in vitro cytotoxic activity against MDBK, MCF7 and WEHI164 cells; ergolide and gaillardin exhibited lower and significantly different IC50 values compared with pulchellin C ( p<0.001).

Mechanochemical Synthesis and Structure of the Tetrahydrate and Mesoporous Anhydrous Metforminium(2+)-N,N’-1,4-Phenylenedioxalamic Acid Cocrystal Salt: The Role of Hydrogen Bonding and N→π* Charge Assisted Interactions

10.20944/preprints202009.0660.v1 ◽

2020 ◽

Author(s):

Sayuri Chong-Canto ◽

Efrén V. García-Báez ◽

Francisco J. Martínez-Martínez ◽

Ángel Ramos-Organillo ◽

Itzia I. Padilla-Martínez

Keyword(s):

Hydrogen Bonding ◽

Mechanochemical Synthesis ◽

Water Molecules ◽

X Ray ◽

X Ray Crystallography ◽

Adsorption Desorption ◽

First Time ◽

Selective Formation ◽

Crystallization From Solution

A new cocrystal salt of metformin, an antidiabetic drug, and N,N’-(1,4-phenylene)dioxalamic acid, was synthesized by mechanochemical synthesis, purified by crystallization from solution and characterized by single X-ray crystallography. The structure revealed a salt-type cocrystal composed of one dicationic metformin unit, two monoanionic units of the acid and four water molecules namely H2Mf(HpOXA)2∙4H2O. X-ray powder, IR, 13C-CPMAS, thermal and BET adsorption-desorption analyses were performed to elucidate the structure of the molecular and supramolecurar structure of the anhydrous microcrystalline mesoporous solid H2Mf(HpOXA)2. The results suggest that their structures, conformation and hydrogen bonding schemes are very similar between them. To the best of our knowledge, the selective formation of the monoanion HpOXA⁻, as well as its structure in the solid, is herein reported for the first time. Regular O(-)∙∙∙C(), O(-)∙∙∙N+ and bifacial O(-)∙∙∙C()∙∙∙O(-) of n→* charge-assisted interactions are herein described in H2MfA cocrystal salts which could be responsible of the interactions of metformin in biologic systems. The results, support the participation of n→* charge-assisted interactions independently, and not just as a short contact imposed by the geometric constraint due to the hydrogen bonding patterns.

Polymorphic G:G mismatches act as hotspots for inducing right-handed Z DNA by DNA intercalation

Nucleic Acids Research ◽

10.1093/nar/gkz653 ◽

2019 ◽

Vol 47 (16) ◽

pp. 8899-8912 ◽

Cited By ~ 1

Author(s):

Roshan Satange ◽

Chien-Ying Chuang ◽

Stephen Neidle ◽

Ming-Hon Hou

Keyword(s):

Actinomycin D ◽

Single Step ◽

Dna Intercalation ◽

Chromomycin A3 ◽

Dna Structures ◽

X Ray ◽

X Ray Crystallography ◽

Dna Mismatches ◽

Z Dna ◽

Abstract DNA mismatches are highly polymorphic and dynamic in nature, albeit poorly characterized structurally. We utilized the antitumour antibiotic CoII(Chro)2 (Chro = chromomycin A3) to stabilize the palindromic duplex d(TTGGCGAA) DNA with two G:G mismatches, allowing X-ray crystallography-based monitoring of mismatch polymorphism. For the first time, the unusual geometry of several G:G mismatches including syn–syn, water mediated anti–syn and syn–syn-like conformations can be simultaneously observed in the crystal structure. The G:G mismatch sites of the d(TTGGCGAA) duplex can also act as a hotspot for the formation of alternative DNA structures with a GC/GA-5′ intercalation site for binding by the GC-selective intercalator actinomycin D (ActiD). Direct intercalation of two ActiD molecules to G:G mismatch sites causes DNA rearrangements, resulting in backbone distortion to form right-handed Z-DNA structures with a single-step sharp kink. Our study provides insights on intercalators-mismatch DNA interactions and a rationale for mismatch interrogation and detection via DNA intercalation.

The potential benefits of using higher X-ray energies for macromolecular crystallography

Journal of Synchrotron Radiation ◽

10.1107/s160057751900612x ◽

2019 ◽

Vol 26 (4) ◽

pp. 922-930 ◽

Cited By ~ 6

Author(s):

Joshua L. Dickerson ◽

Elspeth F. Garman

Keyword(s):

Photon Counting ◽

Incident Beam ◽

Macromolecular Crystallography ◽

Silicon Detectors ◽

X Ray ◽

X Ray Crystallography ◽

Cdte Detector ◽

Potential Benefits ◽

Incident Beam Energy ◽

Using X-ray energies higher than those normally used (5–15 keV) for macromolecular X-ray crystallography (MX) at synchrotron sources can theoretically increase the achievable signal as a function of dose and reduce the rate of radiation damage. In practice, a major stumbling block to the use of higher X-ray energy has been the reduced quantum efficiency of silicon detectors as the X-ray energy increases, but hybrid photon-counting CdTe detectors are optimized for higher X-ray energies, and their performance has been steadily improving. Here the potential advantages of using higher incident beam energy together with a CdTe detector for MX are explored, with a particular focus on the advantages that higher beam energies may have for MX experiments with microbeams or microcrystals. Monte Carlo simulations are presented here which for the first time include the efficiency responses of some available X-ray detectors, as well as the possible escape of photoelectrons from the sample and their entry from surrounding material. The results reveal a `sweet spot' at an incident X-ray energy of 26 keV, and show a greater than factor of two improvement in diffraction efficiency at this energy when using microbeams and microcrystals of 5 µm or less.

Identification and Optimization of PDE10A Inhibitors Using Fragment-Based Screening by Nanocalorimetry and X-ray Crystallography

CrossRef Listing of Deleted DOIs ◽

10.1177/1087057113516493 ◽

2013 ◽

Vol 19 (4) ◽

pp. 497-507 ◽

Cited By ~ 15

Author(s):

Michael I. Recht ◽

Vandana Sridhar ◽

John Badger ◽

Pierre-Yves Bounaud ◽

Cheyenne Logan ◽

...

Keyword(s):

High Resolution ◽

Structural Information ◽

Low Complexity ◽

Titration Calorimetry ◽

Label Free ◽

Lead Discovery ◽

X Ray ◽

X Ray Crystallography ◽

Heavy Atoms

Fragment-based lead discovery (FBLD) is a technique in which small, low-complexity chemical fragments of 6 to 15 heavy atoms are screened for binding to or inhibiting activity of the target. Hits are then linked and/or elaborated into tightly binding ligands, ideally yielding early lead compounds for drug discovery. Calorimetry provides a label-free method to assay binding and enzymatic activity that is unaffected by the spectroscopic properties of the sample. Conventional microcalorimetry is hampered by requiring large quantities of reagents and long measurement times. Nanocalorimeters can overcome these limitations of conventional isothermal titration calorimetry. Here we use enthalpy arrays, which are arrays of nanocalorimeters, to perform an enzyme activity-based fragment screen for competitive inhibitors of phosphodiesterase 10A (PDE10A). Two dozen fragments with KI <2 mM were identified and moved to crystal soaking trials. All soak experiments yielded high-resolution diffraction, with two-thirds of the fragments yielding high-resolution co-crystal structures with PDE10A. The structural information was used to elaborate fragment hits, yielding leads with KI <1 µM. This study shows how array calorimetry can be used as a prescreening method for fragment-based lead discovery with enzyme targets and paired successfully with an X-ray crystallography secondary screen.

Cisplatin binding to human serum albumin: a structural study

Chemical Communications ◽

10.1039/c5cc01751c ◽

2015 ◽

Vol 51 (46) ◽

pp. 9436-9439 ◽

Cited By ~ 73

Author(s):

Giarita Ferraro ◽

Lara Massai ◽

Luigi Messori ◽

Antonello Merlino

Keyword(s):

Human Serum Albumin ◽

Serum Albumin ◽

Human Serum ◽

Crystal Structures ◽

Structural Study ◽

X Ray ◽

X Ray Crystallography ◽

The reaction between cisplatin and human serum albumin (HSA) was investigated by X-ray crystallography and crystal structures of the cisplatin/HSA adduct were eventually solved for the first time.