Search results for "CONDENSED MATTER"

Spin-Transition in [Fe(II)(2,6-Bis-(Benzimidazol-2′-yl)pyridine)2] (CIO4)2: Hysteresis Effect Dependent on the Matrix

1999

Abstract Far-Infrared spectroscopical investigation of the spin-crossover in [Fe(II)(2,6-bis-(benzimidazol-2′-yl)-pyridine)2] (CIO4)2 exhibits a hysteresis in both CsI and polyethylene matrices within temperature cycles between 100K and 520K. The hysteresis broadening is dependent on the matrix and bigger in CsI. This can be explained due to polarity and hydrogen bonding. Two low spin vibrations, LS1 at 437 cm−1 and LS2 at 424cm−1, are observed. On heating from 100K to 520K: during LS1 decreases, the LS2 raises temporarily, until both LS1 and LS2 disappear; for the HS only one raising species was observed. This gives raise to assume two different sub-lattices.

Diethylammonium hydrogen oxalate

2006

The structure of the title compound, C4H12N+·C2HO4−, consists of discrete oxalate monoanions and diethyl­ammonium cations. The N atom lies on a crystallographic twofold rotation axis and the oxalate ion is centrosymmetric. The oxalate monoanions are present as hydrogen-bonded linear chains. Conformationally extended diethyl­ammonium cations link the linear chains through three–centre N–H⋯O hydrogen bonds.

[5,10,15,20-Tetrakis(4-tert-butylphenyl)-porphyrinato-κ4N] zinc(II) toluene solvate

2007

The structure of the title compound, [Zn(C60H60N4)]·C7H8, represents a typical clathrate containing a host mol­ecule of [5,10,15,20-tetra­kis(4-tert-butyl­phen­yl)­porphyrin­ato]­zinc(II) and a toluene guest mol­ecule. The Zn atom occupies an inversion center and exhibits ideal square-planar coordination, while the porphyrin group remains perfectly flat. The toluene mol­ecule lies on an inversion center and is disordered.

An AM1 study on π-facial selectivity in Diels-Alder reactions of 2-aza-1, 3-dienes with azodienophiles

1994

Abstract A theoretical study of the π-facial selectivity in Diels-Alder reactions of chloro derivatives of 2-aza-1,3-dienes with azodienophiles has been carried out using the semiempirical AM1 method. Three transition structures for the model reaction of the diene 3 with the dienophile 4 were located. The Diels-Alder reaction of the non-substituted 2-aza-1,3-diene 6 with the trans -diimide was studied. All transition structures located show an important asynchronicity and the calculations reveal the presence of stereoelectronic effects. The predicted stereoselectivity is in agreement with the experimental evidence.

4-Chloro-1,1-diphenyl-3-(1-pyrrolyl)-2-azabuta-1,3-diene

2002

The title compound, C19H15ClN2, is the sole stable product resulting from nucleophilic attack of the sodium salt of pyrrole on 4,4-di­chloro-1,1-di­phenyl-2-aza­buta-1,3-diene. The mech­an­ism of its formation is briefly discussed.

2,3,4,5,6-Pentabromophenyl phenyl ether

2002

The title compound, C12H5Br5O, belongs to a group of flame retardants known as polybrominated di­phenyl ethers (PBDE). Salient features of the packing are stabilization due to intermolecular Br⋯Br contacts in the ab plane and aromatic intermolecular contacts along the c direction.

Interactions of different hydrocolloids with milk proteins

2020

Abstract To control rheological properties and accomplish perfect sensory properties and mouthfeel, polysaccharides are added to milk-based beverages. However, in contrast to expectations, it is often found that adding low concentrations of xanthan gum or guar gum to milk provokes phase separations of unclear physical origin. From this observation, questions arise regarding the interaction of added polysaccharides and the proteins present in milk – caseins and whey proteins. The focus of this study is to investigate such systems and to understand the basic interactions of caseins and whey proteins with different hydrocolloids. The hydrocolloids used in this study are xanthan gum, guar gum, …

Hierarchical halogen bonding induces polymorphism

2009

Co-crystals of 1-iodo-3,5-dinitrobenzene and 1,4-diazabicyclo[2.2.2]octane manifest either two strong or one strong and one weak intermolecular 2 : 1 halogen bond (XB) motifs in polymorphic structures I and II, respectively, whereas weaker XB-donor 4,4-bipyridine just forms 1 : 1 structure III with one strong halogen bond.

3-(4-Fluorophenyl)-4-(4-pyridyl)quinolin-2(1H)-one

2006

The title compound, C20H13FN2O, has the quinolin-2(1H)-one unit in the lactam form. The mol­ecules form rows along the b axis via N—H⋯N hydrogen bonds

Amorphous polyphosphate nanoparticles: application of the morphogenetically active inorganic polymer for personalized tissue regeneration

2019