Geometric, electronic and magnetic structures of S = 19/2 and S = 20/2 thiophene-2-carboxylate functionalized Mn12 single molecule magnets

2015 ◽  
Vol 44 (1) ◽  
pp. 167-175 ◽  
Author(s):  
Jorge H. Rodriguez ◽  
Christopher J. Ziegler
Keyword(s):  
Hydrogen Bonding ◽  
Single Molecule ◽  
Magnetic Moment ◽  
Water Molecules ◽  
Single Molecule Magnets ◽  
Magnetic Structures ◽  
Electronic And Magnetic Structures ◽  
Hydrogen Bonded

Hydrogen bonding of water molecules to Mn4O4 inner cubane of S = 19/2 Mn12 SMM gives rise to geometric and magnetic asymmetries. Two Mn ions hydrogen bonded to water molecules depart from their Mn4+(S = 3/2) states and acquire an incipient Mn3+(S = 4/2) character. The magnetic moment vectors of the cubane Mn ions are inequivalent.

scholarly journals Nanomechanics of negatively supercoiled diaminopurine-substituted DNA

2021 ◽  
Author(s):  
Domenico Salerno ◽  
Francesco Mantegazza ◽  
Valeria Cassina ◽  
Matteo Cristofalo ◽  
Qing Shao ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Single Molecule ◽  
Conformational Dynamics ◽  
Persistence Length ◽  
Base Stacking ◽  
Base Pairs ◽  
Left Handed ◽  
Negative Supercoiling ◽  
Mechanical Dynamics ◽  
Hydrogen Bonded

ABSTRACTSingle molecule experiments have demonstrated a progressive transition from a B- to an L-form helix as DNA is gently stretched and progressively unwound. Since the particular sequence of a DNA segment influences both base stacking and hydrogen bonding, the conformational dynamics of B-to-L transitions should be tunable. To test this idea, DNA with diaminopurine replacing adenine was synthesized to produce linear fragments with triply hydrogen-bonded A:T base pairs. Triple hydrogen bonding stiffened the DNA by 30% flexurally. In addition, DAP-substituted DNA formed plectonemes with larger gyres for both B- and L-form helices. Both unmodified and DAP-substituted DNA transitioned from a B- to an L-helix under physiological conditions of mild tension and unwinding. This transition avoids writhing by DNA stretched and unwound by enzymatic activity. The intramolecular nature and ease of this transition likely prevent cumbersome topological rearrangements in genomic DNA that would require topoisomerase activity to resolve. L-DNA displayed about tenfold lower persistence length indicating it is much more contractile and prone to sharp bends and kinks. However, left-handed DAP DNA was twice as stiff as unmodified L-DNA. Thus, significantly doubly and triply hydrogen bonded segments have very distinct mechanical dynamics at physiological levels of negative supercoiling and tension.

scholarly journals Synthesis, Structural Characterization and Ligand-Enhanced Photo-Induced Color-Changing Behavior of Two Hydrogen-Bonded Ho(III)-Squarate Supramolecular Compounds

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1369 ◽  
Author(s):  
Wang ◽  
Ke ◽  
Feng ◽  
Ho ◽  
Chang ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Uv Light ◽  
Squaric Acid ◽  
Water Molecules ◽  
Light Illumination ◽  
Supramolecular Architecture ◽  
Bridging Ligands ◽  
Coordination Modes ◽  
Oxygen Atoms ◽  
Hydrogen Bonded

Two coordination polymers (CPs) with chemical formulas, [Ho2(C4O4)2(C2O4)(H2O)8]·4H2O (1) and [Ho(C4O4)1.5(H2O)3] (2), (C4O42− = dianion of squaric acid, C2O42− = oxalate), have been synthesized and their structures were determined by single-crystal X-ray diffractometer (XRD). In compound 1, the coordination environment of Ho(III) ion is eight-coordinate bonded to eight oxygen atoms from two squarate, one oxalate ligands and four water molecules. The squarates and oxalates both act as bridging ligands with 1,2-bis-monodentate and bis-chelating coordination modes, respectively, connecting the Ho(III) ions to form a one-dimensional (1D) ladder-like framework. Adjacent ladders are interlinked via O–HO hydrogen bonding interaction to form a hydrogen-bonded two-dimensional (2D) layered framework and then arranged orderly in an AAA manner to construct its three-dimensional (3D) supramolecular architecture. In compound 2, the coordination geometry of Ho(III) is square-antiprismatic eight coordinate bonded to eight oxygen atoms from five squarate ligands and three water molecules. The squarates act as bridging ligands with two coordination modes, 1,2,3-trismonodentate and 1,2-bis-monodentate, connecting the Ho(III) ions to form a 2D bi-layered framework. Adjacent 2D frameworks are then parallel stacked in an AAA manner to construct its 3D supramolecular architecture. Hydrogen bonding interactions between the squarate ligands and coordinated water molecules in 1 and 2 both play important roles on the construction of their 3D supramolecular assembly. Compounds 1 and 2 both show remarkable ligand-enhanced photo-induced color-changing behavior, with their pink crystals immediately turning to yellow crystals under UV light illumination.

More examples of the 15-crown-5...H2O—M—OH2...15-crown-5 motif, M = Al3+, Cr3+ and Pd2+

2010 ◽  
Vol 66 (2) ◽  
pp. 213-221 ◽  
Author(s):  
Maxime A. Siegler ◽  
Jacob H. Prewitt ◽  
Steven P. Kelley ◽  
Sean Parkin ◽  
John P. Selegue ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Water Molecule ◽  
Lattice Water Molecule ◽  
Literature Survey ◽  
The Other ◽  
Water Molecules ◽  
Lattice Water ◽  
Hydrogen Bonding Pattern ◽  
Hydrogen Bonded

Five structures of co-crystals grown from aqueous solutions equimolar in 15-crown-5 (or 15C5) and [M(H2O)6](NO3) n , M = Al3+, Cr3+ and Pd2+, are reported. The hydrogen-bonding patterns in all are similar: metal complexes including the fragment trans-H2O—M—OH2 alternate with 15C5 molecules, to which they are hydrogen bonded, to form stacks. A literature survey shows that this hydrogen-bonding pattern is very common. In each of the two polymorphs of the compound [Al(H2O)6](NO3)3·15C5·4H2O there are two independent cations; one forms hydrogen bonds directly to the 15C5 molecules adjacent in the stack, while the other cation is hydrogen-bonded to two water molecules that act as spacers in the stack. These stacks are then crosslinked by hydrogen bonds formed by the three nitrate counterions and the three lattice water molecules. The hydrogen-bonded stacks in [Cr(H2O)5(NO3)](NO3)2·1.5(15C5)·H2O are discrete rather than infinite; each unit contains two Cr3+ complex cations and three 15C5 molecules. These units are again crosslinked by the uncoordinated nitrate ions and a lattice water molecule. In [Pd(H2O)2(NO3)2]·15C5 the infinite stacks are electrically neutral and are not crosslinked. In [Pd(H2O)2(NO3)2]·2(15C5)·2H2O·2HNO3 a discrete, uncharged unit containing one Pd complex and two 15C5 molecules is `capped off' at either end by a lattice water molecule and an included nitric acid molecule. In all five structures the infinite stacks or discrete units form an array that is at least approximately hexagonal.

Channel- and layer-type anionic host structures in inclusion compounds of urea, tetraalkylammonium terephthalate/trimesate and water

2000 ◽  
Vol 56 (1) ◽  
pp. 142-154 ◽  
Author(s):  
Feng Xue ◽  
Thomas C. W. Mak
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Three Dimensional ◽  
Directed Assembly ◽  
Water Molecules ◽  
Triclinic Space Group ◽  
Dimensional Network ◽  
Graph Set ◽  
Host Lattices ◽  
Hydrogen Bonded

New crystalline adducts of tetraalkylammonium terephthalate/trimesate with urea and water molecules result from hydrogen-bond directed assembly of complementary acceptors and donors, and the anionic host lattices are described using the graph-set notation to identify distinct hydrogen-bonding motifs and patterns. Tetra-n-butylammonium terephthalate–urea–water (1/6/2), C46H104N14O12 (1), triclinic, space group P1¯, a = 8.390 (2), b = 9.894 (2), c = 18.908 (3) Å, α = 105.06 (2), β = 94.91 (1), γ = 93.82 (2)°, Z = 1, is composed of hydrogen-bonded terephthalate–urea layers, which are intersected by urea layers to generate a three-dimensional network containing large channels for accommodation of the cations. Tetraethylammonium terephthalate–urea–water (1/1/5), C25H58N4O10 (2), triclinic, P1¯, a = 9.432 (1), b = 12.601 (1), c = 14.804 (1) Å, α = 79.98 (1), β = 79.20 (1), γ = 84.18 (1)°, Z = 2, has cations sandwiched between hydrogen-bonded anionic layers. Tetraethylammonium trimesate–urea–water (1/2/7.5), C35H86N7O15.5 (3), triclinic, P1¯, a = 13.250 (1), b = 14.034 (1), c = 15.260 (1) Å, α = 72.46 (1), β = 78.32 (1), γ = 66.95 (1)°, Z = 2, manifests a layer-type structure analogous to that of (2). Tetra-n-propylammonium hydrogen trimesate–urea–water (1/2/5), C35H78N6O13 (4), orthorhombic, Pna21, a = 16.467 (3), b = 33.109 (6), c = 8.344 (1) Å, Z = 4, features hydrogen trimesate helices in a three-dimensional host architecture containing nanoscale channels each filled by a double column of cations.

The Hydrate of Hexafluorophosphoric Acid

1972 ◽  
Vol 50 (21) ◽  
pp. 3515-3520 ◽  
Author(s):  
D. W. Davidson ◽  
S. K. Garg
Keyword(s):  
Hydrogen Bonding ◽  
Chemical Analysis ◽  
Resonance Line ◽  
Water Molecules ◽  
Rigid Lattice ◽  
Proton Diffusion ◽  
Rapid Proton ◽  
Hydrogen Bonded

HPF6 is said to form a hexahydrate of a unique clathrate structure in which [Formula: see text] ions occupy truncated-octahedral cages in a framework of hydrogen-bonded water molecules. N.m.r. studies show, however, that appreciable quantities of HF are incorporated in the lattice and that the composition is more properly [Formula: see text], a result supported by chemical analysis. H3O+ and HF appear to be distributed over the lattice sites previously assigned to water molecules so as to involve all H atoms in the hydrogen bonding. The 1H resonance line is narrowed by rapid proton diffusion down to 150 °K. The 19F line of encaged [Formula: see text] is narrowed by rotation above 75 °K and reaches the rigid-lattice shape only below 25 °K.

Raman and infrared spectroscopic study of the vivianite-group phosphates vivianite, baricite and bobierrite

2002 ◽  
Vol 66 (6) ◽  
pp. 1063-1073 ◽  
Author(s):  
R. L. Frost ◽  
W. Martens ◽  
P. A. Williams ◽  
J. T. Kloprogge
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bonding ◽  
Water Molecules ◽  
Infrared Spectroscopic Study ◽  
Tetrahedral Symmetry ◽  
Phosphate Anions ◽  
Stretching Vibrations ◽  
Bending Modes ◽  
Ir Bands ◽  
Hydrogen Bonded

Abstract The molecular structure of the three vivianite-structure, compositionally related phosphate minerals vivianite, baricite and bobierrite of formula M32+(PO4)2.8H2O where M is Fe or Mg, has been assessed using a combination of Raman and infrared (IR) spectroscopy. The Raman spectra of the hydroxyl-stretching region are complex with overlapping broad bands. Hydroxyl stretching vibrations are identified at 3460, 3281, 3104 and 3012 cm−1 for vivianite. The high wavenumber band is attributed to the presence of FeOH groups. This complexity is reflected in the water HOH-bending modes where a strong IR band centred around 1660 cm−1 is found. Such a band reflects the strong hydrogen bonding of the water molecules to the phosphate anions in adjacent layers. Spectra show three distinct OH-bending bands fromstrongly hydrogen-bonded, weakly hydrogen bonded water and non-hydrogen bonded water. The Raman phosphate PO-stretching region shows strong similarity between the three minerals. In the IR spectra, complexity exists with multiple antisymmetric stretching vibrations observed, due to the reduced tetrahedral symmetry. This loss of degeneracy is also reflected in the bending modes. Strong IR bands around 800 cm−1 are attributed to water librational modes. The spectra of the three minerals display similarities due to their compositions and crystal structures, but sufficient subtle differences exist for the spectra to be useful in distinguishing the species.

First Principle Calculations of the Magnetic Structures of 3d Transition Metals Doped GaN

2007 ◽  
Vol 124-126 ◽  
pp. 847-850 ◽  
Author(s):  
Seung Cheol Lee ◽  
Kwang Real Lee ◽  
Kyu Hwan Lee
Keyword(s):  
Transition Metals ◽  
Magnetic Moment ◽  
Magnetic Phase ◽  
Magnetic Moments ◽  
Transition Element ◽  
First Principle ◽  
Magnetic Structures ◽  
First Principle Calculations ◽  
Electronic And Magnetic Structures ◽  
Mn Doped

First principle calculations were performed on the electronic and magnetic structures of the transition metals doped GaN. Seven elements in 3d transition metals from V to Cu were used as a dopant. Magnetic phase was stable compared to non-magnetic phase for all transition metals doped GaN. Total magnetic moments followed Hund’s rule to maximize the magnetic moment. Transition element projected magnetic moments showed that most of magnetic moments were concentrated on transition metals in the cases of V, Cr, and Mn doped GaN, which could not be used for DMS. Since Fe and Ni doped GaNs are intrinsic insulators, Fe and Ni doped GaNs could not be used for DMS materials unless additional dopants are introduced. The most probable candidates for DMS applications were predicted to be Co or Cu doped GaNs, respectively.

scholarly journals Hydrogen-bonding patterns in 2,2-bis(4-methylphenyl)hexafluoropropane pyridinium and ethylenediammonium salt crystals

2020 ◽  
Vol 76 (5) ◽  
pp. 742-746 ◽  
Author(s):  
Haruki Sugiyama
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Three Dimensional ◽  
Water Molecules ◽  
Space Group ◽  
One Dimensional ◽  
Salt Crystals ◽  
Bonding Patterns ◽  
Hydrogen Bonded

The crystal structures of two salt crystals of 2,2-bis(4-methylphenyl)hexafluoropropane (Bmphfp) with amines, namely, dipyridinium 4,4′-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)dibenzoate 4,4′-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)dibenzoic acid, 2C5H6N+·C17H8F6O4 2−·C17H10F6O4, (1), and a monohydrated ethylenediammonium salt ethane-1,2-diaminium 4,4′-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)dibenzoate monohydrate, C2H10N2 2+·C17H8F6O4 2−·H2O, (2), are reported. Compounds 1 and 2 crystallize, respectively, in space group P21/c with Z′ = 2 and in space group Pbca with Z′ = 1. The crystals of compound 1 contain neutral and anionic Bmphfp molecules, and form a one-dimensional hydrogen-bonded chain motif. The crystals of compound 2 contain anionic Bmphfp molecules, which form a complex three-dimensional hydrogen-bonded network with the ethylenediamine and water molecules.

Alkylammonium lead halides. Part 1. Isolated PbI64− ions in (CH3NH3)4PbI6•2H2O

1987 ◽  
Vol 65 (5) ◽  
pp. 1042-1046 ◽  
Author(s):  
Beverly R. Vincent ◽  
Katherine N. Robertson ◽  
T. Stanley Cameron ◽  
Osvald Knop
Keyword(s):  
Hydrogen Bonding ◽  
Three Dimensional ◽  
Water Molecules ◽  
Bond Lengths ◽  
Type Lattice ◽  
Hydrogen Bonded

The yellow (CH3NH3)4PbI6•2H2O(P21/n, a = 10.421(3) Å, b = 11.334(2) Å, c = 10.668(2) Å, β = 91.73(2)°, Z = 2) contains isolated PbI64− octahedra, CH3NH3+ cations of two types and H2O molecules. The cations and the water molecules are hydrogen-bonded to form [Formula: see text] units arranged in centrosymmtric [Formula: see text] pairs; the centres of these composite units and the Pb atoms form a distorted NaCl-type lattice. The Pb—I bond lengths in the PbI64− anions are compared with those in [Pb(II)I6]ε complexes containing shared I atoms and the effect of the sharing on the bond lengths is discussed. A scheme is proposed for the extensive three-dimensional hydrogen bonding in the structure.

scholarly journals Conformational and structural stability of the single molecule and hydrogen bonded clusters of para aminobenzoic acid in the gas and solution phases

CrystEngComm ◽  
2018 ◽  
Vol 20 (46) ◽  
pp. 7543-7555 ◽  
Author(s):  
Ian Rosbottom ◽  
Dimitrios Toroz ◽  
Robert B. Hammond ◽  
Kevin J. Roberts
Keyword(s):  
Hydrogen Bonding ◽  
Ab Initio ◽  
Structural Stability ◽  
Single Molecule ◽  
Building Blocks ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Aminobenzoic Acid ◽  
Cluster Stability ◽  
Hydrogen Bonded

The structures of α- and β-para aminobenzoic acid are deconstructed into their hydrogen bonding molecular structural building blocks, where they are analysed usingab initioquantum mechanical calculations of their conformation and cluster stability in solution.

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