Chirale Erkennung bei Tris(diimin)-Metallkomplexen, 10. Vergleich der intermolekularen Wechselwirkungs- und Packungsmuster in der Reihe [Cr(bpy)3]n+(PF6)n (n = 0 – 3) / Chiral Recognition among Tris(diimine)-metal Complexes, 10. Comparison of Intermolecular Interactions and Packing Patterns in the Series [Cr(bpy)3]n+(PF6)n (n = 0–3)

2004 ◽  
Vol 59 (9) ◽  
pp. 1015-1025 ◽  
Author(s):  
Josef Breu ◽  
Andrea Zwicknagel
Keyword(s):  
Crystalline State ◽  
Chiral Recognition ◽  
Oxidation States ◽  
Structural Motif ◽  
Inorganic Salts ◽  
Central Metal ◽  
Interaction Patterns ◽  
Two Dimensional ◽  
Molecular Salts ◽  
Madelung Energy

Due to their conformational rigidity, the corrugated, chiral molecular structure, and the variability in the central metal and its oxidation state, [M(bpy)3]n+ complexes are particularly well suited to study chiral recognition and to identify intermolecular interaction patterns in the crystalline state. For [Cr(bpy)3]n+(PF6)n (n=0 - 3) four oxidation states are readily accessible which allows to investigate the influence of the cation/anion ratio on the observed packing patterns.The crystal structures of all four oxidation states are governed by so-called ‘π-π-interactions’. Apparently, in molecular salts the Madelung energy is less important as compared to classical inorganic salts.Interestingly, [Cr(bpy)3](PF6) and [Cr(bpy)3](PF6)2 comprise the same homochiral layers. However, while the former crystallises as true racemate, the latter spontaneously resolves into a conglomerate. This two-dimensional building block of homochiral layers is the most popular structural motif in this class of compounds which has been observed in a great variety of racemic and homochiral stackings.

scholarly journals Weak C—H...X(X= O, N) hydrogen bonds in the crystal structure of dihydroberberine

2014 ◽  
Vol 70 (4) ◽  
pp. 388-391 ◽  
Author(s):  
Subramanya Pingali ◽  
James P. Donahue ◽  
Florastina Payton-Stewart
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Crystalline State ◽  
Ring System ◽  
Reduced Form ◽  
Two Dimensional ◽  
Partial Saturation ◽  
Type C

Dihydroberberine (systematic name: 9,10-dimethoxy-6,8-dihydro-5H-1,3-dioxolo[4,5-g]isoquinolino[3,2-a]isoquinoline), C20H19NO4, a reduced form of pharmacologically important berberine, crystallizes from ethanol without interstitial solvent. The molecule shows a dihedral angle of 27.94 (5)° between the two arene rings at the ends of the molecule, owing to the partial saturation of the inner quinolizine ring system. Although lacking classical O—H or N—H donors, the packing in the crystalline state is clearly governed by C—H...N and C—H...O hydrogen bonds involving the two acetal-type C—H bonds of the 1,3-dioxole ring. Each dihydroberberine molecule is engaged in four hydrogen bonds with neighbouring molecules, twice as donor and twice as acceptor, thus forming a two-dimensional sheet network that lies parallel to the (100) plane.

Central-metal effect on intramolecular vibrational energy transfer of M(CO)5Br (M = Mn, Re) probed by two-dimensional infrared spectroscopy

2018 ◽  
Vol 20 (5) ◽  
pp. 3637-3647 ◽  
Author(s):  
Fan Yang ◽  
Xueqian Dong ◽  
Minjun Feng ◽  
Juan Zhao ◽  
Jianping Wang
Keyword(s):  
Energy Transfer ◽  
Infrared Spectroscopy ◽  
Vibrational Energy ◽  
Central Metal ◽  
Two Dimensional ◽  
Vibrational Energy Transfer ◽  
Vibrational Coupling ◽  
Two Dimensional Infrared Spectroscopy ◽  
Metal Effect

Central-metal effect on IVR time correlates with the vibrational coupling between the two involved modes.

Oligosiloxanediols as building blocks for supramolecular chemistry: hydrogen-bonded adducts with amines form supramolecular structures in zero, one and two dimensions

2000 ◽  
Vol 56 (2) ◽  
pp. 273-286 ◽  
Author(s):  
Brian O'Leary ◽  
Trevor R. Spalding ◽  
George Ferguson ◽  
Christopher Glidewell
Keyword(s):  
Hydrogen Bonds ◽  
Supramolecular Chemistry ◽  
Building Blocks ◽  
Two Dimensions ◽  
Supramolecular Structures ◽  
Structural Motif ◽  
Two Dimensional ◽  
The Third ◽  
A Chain ◽  
Hydrogen Bonded

The structure of 1,1,3,3,5,5-hexaphenyltrisiloxane-1,5-diol–pyrazine (4/1), (C36H32O4Si3)4·C4H4N2 (1), contains finite centrosymmetric aggregates; the diol units form dimers, by means of O—H...O hydrogen bonds, and pairs of such dimers are linked to the pyrazine by means of O—H...N hydrogen bonds. In 1,1,3,3,5,5-hexaphenyltrisiloxane-1,5-diol–pyridine (2/3), (C36H32O4Si3)2·(C5H5N)3 (2), the diol units are linked into centrosymmetric pairs by means of disordered O—H...O hydrogen bonds: two of the three pyridine molecules are linked to the diol dimer by means of ordered O—H...N hydrogen bonds, while the third pyridine unit, which is disordered across a centre of inversion, links the diol dimers into a C 3 3(9) chain by means of O—H...N and C—H...O hydrogen bonds. In 1,1,3,3-tetraphenyldisiloxane-1,3-diol–hexamethylenetetramine (1/1), (C24H22O3Si2)·C6H12N4 (3), the diol acts as a double donor and the hexamethylenetetramine acts as a double acceptor in ordered O—H...N hydrogen bonds and the structure consists of C 2 2(10) chains of alternating diol and amine units. In 1,1,3,3-tetraphenyldisiloxane-1,3-diol–2,2′-bipyridyl (1/1), C24H22O3Si2·C10H8N2 (4), there are two independent diol molecules, both lying across centres of inversion and therefore both containing linear Si—O—Si groups: each diol acts as a double donor of hydrogen bonds and the unique 2,2′-bipyridyl molecule acts as a double acceptor, thus forming C 2 2(11) chains of alternating diol and amine units. The structural motif in 1,1,3,3-tetraphenyldisiloxane-1,3-diol–pyrazine (2/1), (C24H22O3Si2)2·C4H4N2 (5), is a chain-of-rings: pairs of diol molecules are linked by O—H...O hydrogen bonds into centrosymmetric R 2 2(12) dimers and these dimers are linked into C 2 2(13) chains by means of O—H...N hydrogen bonds to the pyrazine units. 1,1,3,3-Tetraphenyldisiloxane-1,3-diol–pyridine (1/1), C24H22O3Si2·C5H5N (6), and 1,1,3,3-tetraphenyldisiloxane-1,3-diol–pyrimidine (1/1), C24H22O3Si2·C4H4N2 (7), are isomorphous: in each compound the amine unit is disordered across a centre of inversion. The diol molecules form C(6) chains, by means of disordered O—H...O hydrogen bonds, and these chains are linked into two-dimensional nets built from R 6 6(26) rings, by a combination of O—H...N and C—H...O hydrogen bonds.

Variable-Temperature Fourier Transform Infrared Spectroscopic Investigations of Poly(3-Hydroxyalkanoates) and Perturbation-Correlation Moving-Window Two-Dimensional Correlation Analysis. Part I: Study of Non-Annealed and Annealed Poly(3-Hydroxybutyrate) Homopolymer

2009 ◽  
Vol 63 (9) ◽  
pp. 1027-1033 ◽  
Author(s):  
Miriam Unger ◽  
Shigeaki Morita ◽  
Harumi Sato ◽  
Yukihiro Ozaki ◽  
Heinz W. Siesler
Keyword(s):  
Fourier Transform ◽  
Correlation Analysis ◽  
Crystalline State ◽  
Variable Temperature ◽  
Fourier Transform Infrared ◽  
Melting Behavior ◽  
Correlation Spectroscopy ◽  
Moving Window ◽  
Two Dimensional ◽  
Ft Ir

Generalized two-dimensional correlation spectroscopy (2DCOS) and perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy were applied to explore the melting behavior of non-annealed and annealed poly(3-hydroxybutyrate) (PHB) homopolymer as studied by variable-temperature Fourier transform infrared (FT-IR) spectroscopy. The absorption band of the C=O stretching vibration was employed to investigate the structural changes during the heating process (30–200 °C). Non-annealed PHB showed a recrystallization process in the temperature range 30–120 °C. In the asynchronous 2D correlation spectrum we clearly captured the existence of two components in the crystallinity-sensitive wing of the C=O stretching mode: a well-ordered crystalline state at lower wavenumbers (1718 cm−1) and a less ordered crystalline state at higher wavenumbers (1724 cm−1). These crystallinity-sensitive bands at 1718 and 1724 cm−1, which are not readily detectable in the one-dimensional (1D) FT-IR spectra, share asynchronous cross-peaks with bands at around 1737 and 1747 cm−1 assignable to the C=O stretching absorptions due to the amorphous components. In the case of the melting process of non-annealed PHB in the temperature range 120–200 °C, it is helpful to use the PCMW2D correlation analysis, which indicates the recrystallization between 40 and 110 °C by the shift of the C=O stretching band from 1726 cm−1 to 1722 cm−1 and the sharp change to the broad amorphous C=O stretching absorption at 1747 cm−1 at the melting temperature of PHB around 190 °C. For an annealed sample of PHB only the melting behavior was observed in the PCMW2D correlation analysis by the sharp transition from the crystalline to the amorphous C=O stretching band.

Surfactant-Assisted Hydrothermal Synthesis of Multilayered Flower-Like BiOBr with Enhanced Visible Light Photocatalytic Activity

2012 ◽  
Vol 476-478 ◽  
pp. 1541-1546 ◽  
Author(s):  
Yan Ming Cao ◽  
Fu Min Wang ◽  
Zhi Fang Jia ◽  
Ning Liu
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Three Dimensional ◽  
Inorganic Salts ◽  
Layer By Layer ◽  
Two Dimensional ◽  
Visible Light Photocatalytic Activity ◽  
Pvp K30 ◽  
Surfactant Assisted ◽  
Visible Light Photocatalytic

A novel multilayered flower-like structure of BiOBr was fabricated by mild and facile polyvinylpyrrolidone (PVP) K30-assisted hydrothermal method using stable, less toxic inorganic salts Bi(NO3)3•5H2O and NaBr as the starting materials. Such three-dimensional (3D) BiOBr assemblies were constructed layer-by-layer from a large number of two-dimensional (2D) nanoplates. Rhodamine B (RhB) photocatalytic degradation experiments showed that the BiOBr flowers exhibited higher visible-light photocatalytic activity than that of irregular BiOBr nanoplates. Therefore, the resulting flower-like BiOBr are very promising photocatalysts for the treatment of organic pollutants

Two-dimensional metal–organic frameworks with high oxidation states for efficient electrocatalytic urea oxidation

2017 ◽  
Vol 53 (79) ◽  
pp. 10906-10909 ◽  
Author(s):  
Dongdong Zhu ◽  
Chunxian Guo ◽  
Jinlong Liu ◽  
Liang Wang ◽  
Yi Du ◽  
...  
Keyword(s):  
Oxidation Reaction ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Organic Ligand ◽  
Oxidation States ◽  
Two Dimensional ◽  
Benzenedicarboxylic Acid ◽  
High Oxidation ◽  
Metal Organic ◽  
Nickel Species

A two-dimensional metal–organic framework comprising nickel species and an organic ligand of benzenedicarboxylic acid is fabricated and explored as an electrocatalyst for urea oxidation reaction.

Stereochemistry of heterobinuclear Pt-M complexes

2017 ◽  
Vol 37 (3-4) ◽  
pp. 131-146 ◽  
Author(s):  
Milan Melnik ◽  
Peter Mikus
Keyword(s):  
Structural Parameters ◽  
The Other ◽  
Oxidation States ◽  
Central Metal ◽  
Metal Atoms ◽  
Square Planar ◽  
Coordination Spheres

AbstractIn this review, the structural parameters of almost 30 isomers of heterobinuclear Pt-M (M=Sn, Tl, Cu, Ag, Ti, W, Cr, Fe, Co, Ni, Mn, Pd, or Rh) complexes are summarized and analyzed. There are three types of isomers: distortion (by far the prevailing type), polymerization, and mixed isomers. On the basis of Pt-M distance, there are two groups of complexes: one in which the Pt-M bond distances are <3.0 Å (M=Sn, Tl, W, Cr, Mn, Ni, or Pd) and the other one in which the Pt-M separations are >3.0 Å (M=Cu, Ag, Ti, W, Fe, Co, or Rh). Platinum atoms exist in two oxidation states: +2 and +4. The former by far prevails with a square-planar arrangement with varying degrees of distortion. The Pt(IV) atoms are six-coordinated. The inner coordination spheres about M atoms range from two-coordinated (AgNCl) to sandwiched (FeC10). There is wide variety of donor atoms (ligands) (H, OL, NL, CL, BL, Cl, SL, PL, Br, or I) that build up the respective inner coordination spheres about central metal atoms.

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