Crystal and Electronic Structures of Hydrogen-Bonded 2,5-Diamino-3,6-dihydroxy-p-benzoquinone

2006 ◽  
Vol 6 (1) ◽  
pp. 70-74 ◽  
Author(s):  
Tomoyuki Akutagawa ◽  
Takayoshi Nakamura
Keyword(s):  
Electronic Structures ◽  
Hydrogen Bonded

Geometric and Electronic Structures of Phenoxyl Radicals Hydrogen Bonded to Neutral and Cationic Partners

2012 ◽  
Vol 18 (17) ◽  
pp. 5416-5429 ◽  
Author(s):  
Maylis Orio ◽  
Olivier Jarjayes ◽  
Benoit Baptiste ◽  
Christian Philouze ◽  
Carole Duboc ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Phenoxyl Radicals ◽  
Hydrogen Bonded

2-Amino-6-methoxy-4-(4-methylanilino)-5-nitrosopyrimidine and ethylN-[4-(adamantan-1-ylamino)-2-amino-5-nitrosopyrimidin-6-yl]-3-aminopropionate: polarized electronic structures and hydrogen-bonded supramolecular assembly in one and two dimensions

2012 ◽  
Vol 68 (5) ◽  
pp. o199-o203 ◽  
Author(s):  
Andrés F. Yépes ◽  
Alirio Palma ◽  
Antonio Marchal ◽  
Justo Cobo ◽  
Christopher Glidewell
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Electronic Structures ◽  
Supramolecular Assembly ◽  
Two Dimensions ◽  
A Chain ◽  
Hydrogen Bonded

In both 2-amino-6-methoxy-4-(4-methylanilino)-5-nitrosopyrimidine, C12H13N5O2, (I), and ethylN-[4-(1-adamantylamino)-2-amino-5-nitrosopyrimidin-6-yl]-3-aminopropionate, C19H28N6O3, (II), the nitrosopyrimidine unit is planar and the bond distances provide evidence for significant polarization of the electronic structures. In (II), the ethoxycarbonyl fragment of the molecule is disordered over two sets of sites with occupancies of 0.910 (4) and 0.090 (4). In the molecules of both compounds, there is an intramolecular N—H...O hydrogen bond. The molecules of (I) are linked into a chain of rings by a combination of N—H...O and C—H...O hydrogen bonds, while the molecules of (II) are linked by a two-centre N—H...N hydrogen bond and a three-centre N—H...(N,O) hydrogen bond to form sheets containing four distinct types of ring.

Geometric and Electronic Structures of Hydrogen-Bonded Warren Truss Networks Comprising Planar Triamide Molecules on Graphite (0001)

2013 ◽  
Vol 117 (19) ◽  
pp. 9652-9662 ◽  
Author(s):  
Shunya Yamazaki ◽  
Yusuke Sueyoshi ◽  
Keiji Matsumoto ◽  
Motoki Tsuboi ◽  
Hiroyuki Ozaki ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Hydrogen Bonded

N 6-Substituted 2-amino-4-chloro-5-formylpyrimidines: puckered versus planar pyrimidine rings, and hydrogen-bonded aggregation in zero, one, two and three dimensions

2008 ◽  
Vol 64 (5) ◽  
pp. 596-609 ◽  
Author(s):  
Justo Cobo ◽  
Jorge Trilleras ◽  
Jairo Quiroga ◽  
Antonio Marchal ◽  
Manuel Nogueras ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Electronic Structures ◽  
Negative Charge ◽  
Positive Charge ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Framework Structure ◽  
Molecular Electronic ◽  
Twist Boat ◽  
Hydrogen Bonded

The structures of 12 new N 6-substituted 2-amino-4-chloro-5-formylpyrimidines, where the N 6 substituent is of the type NHR or NR 1 R 2, have been determined. The intramolecular dimensions provide strong evidence for the development of polarized, charge-separated molecular-electronic structures, with the positive charge delocalized over the two exocyclic amino N atoms and with negative charge on the formyl O atom. This polarization appears to be independent of the significant puckering, in seven of the compounds, of the pyrimidine rings from planarity towards boat, twist-boat or screw-boat conformations. In 11 of the compounds studied here, N—H...N hydrogen bonds link pairs of molecules into centrosymmetric R_2^2(8) dimer units, and their overall crystal structures are determined by the patterns of hydrogen bonds by which these units are further linked. Examples are reported in which no further hydrogen bonding occurs; in which the R_2^2(8) dimers are linked into chains of rings, or into sheets; and in which sheets are formed by the π-stacking of hydrogen-bonded chains of rings. In the sole structure lacking the R_2^2(8) dimer motif, N—H...O and N—H...N hydrogen bonds cooperate to generate a three-dimensional framework structure.

scholarly journals All high-spin (S = 2) iron(ii) hemes are NOT alike

2015 ◽  
Vol 44 (42) ◽  
pp. 18301-18310 ◽  
Author(s):  
Chuanjiang Hu ◽  
Charles E. Schulz ◽  
W. Robert Scheidt
Keyword(s):  
High Spin ◽  
Electronic Structures ◽  
High Spin Iron ◽  
Hydrogen Bonded

High spin iron(ii) porphyrinates ligated by imidazole, hydrogen-bonded imidazole, and imidazolate are found to display two distinct electronic structures.

The Nature of Oxide Surfaces: Topographic and Electronic Structure

1993 ◽  
Vol 51 ◽  
pp. 966-967
Author(s):  
Dawn A. Bonnell ◽  
Yong Liang
Keyword(s):  
Transition Metal Oxides ◽  
Electronic Structures ◽  
Recent Progress ◽  
Spatial Localization ◽  
Level Of Detail ◽  
Scanning Tunneling ◽  
Oxide Surfaces ◽  
Tunneling Microscopy ◽  
Considerable Effort ◽  
Complete Understanding

Recent progress in the application of scanning tunneling microscopy (STM) and tunneling spectroscopy (STS) to oxide surfaces has allowed issues of image formation mechanism and spatial resolution limitations to be addressed. As the STM analyses of oxide surfaces continues, it is becoming clear that the geometric and electronic structures of these surfaces are intrinsically complex. Since STM requires conductivity, the oxides in question are transition metal oxides that accommodate aliovalent dopants or nonstoichiometry to produce mobile carriers. To date, considerable effort has been directed toward probing the structures and reactivities of ZnO polar and nonpolar surfaces, TiO2 (110) and (001) surfaces and the SrTiO3 (001) surface, with a view towards integrating these results with the vast amount of previous surface analysis (LEED and photoemission) to build a more complete understanding of these surfaces. However, the spatial localization of the STM/STS provides a level of detail that leads to conclusions somewhat different from those made earlier.

An Unnatural Amino Acid that Mimics a Tripeptide β-Strand and Forms β-Sheetlike Hydrogen-Bonded Dimers [J. Am. Chem. Soc.2000,122, 7654-7661]. 

2001 ◽  
Vol 123 (7) ◽  
pp. 1545-1546
Author(s):  
James S. Nowick ◽  
De Michael Chung ◽  
Kalyani Maitra ◽  
Santanu Maitra ◽  
Kimberly D. Stigers ◽  
...  
Keyword(s):  
Amino Acid ◽  
Unnatural Amino Acid ◽  
Hydrogen Bonded
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