نتایج جستجو برای: halogen π
تعداد نتایج: 37828 فیلتر نتایج به سال:
Halogens produced by ocean biological and photochemical processes reach the tropical tropopause layer (TTL), where cold temperatures and the prevailing low ozone abundances favor the diurnal photochemical enhancement of halogen atoms. Under these conditions atomic bromine and iodine are modeled to be the dominant inorganic halogen species in the sunlit TTL, surpassing the abundance of the commo...
The formation of two-dimensional halogen-bonded layers of 4,4'-bipyridyl and 1,4-diiodotetrafluorobenzene was observed on a graphite surface at sub-monolayer coverage using synchrotron X-ray diffraction; the use of the diffraction technique enabled, for the first time, the measurement of I···N halogen bonding distances in a two-dimensional cocrystal and the identification of the halogen bonding...
background: one of the first‑line assessment tools for fetal surveillance is nonstress test (nst), although it is limited by a high rate of false‑nonreactive results. this study was performed to investigate if external stimulation from vibroacoustic and halogen light could help in provoking fetal responsiveness and altering nst results. materials and methods: this is a clinical trial. sampling ...
CHAL336 Benchmark Set: How Well Do Quantum-Chemical Methods Describe Chalcogen-Bonding Interactions?
We present the CHAL336 benchmark set-the most comprehensive database for assessment of chalcogen-bonding (CB) interactions. After careful selection suitable systems and identification three high-level reference methods, set comprises 336 dimers each consisting up to 49 atoms covers both σ- π-hole interactions across four categories: chalcogen-chalcogen, chalcogen-π, chalcogen-halogen, chalcogen...
ترکیب پلیمری {(c10h9n2)[mn(c7h3no4)2].(c10h8n2).6h2o}n از واکنش منگنز(ii) نیترات شش آبه با پیریدین-2، 3- دی کربوکسیک اسید(py-2,3-dch2) و 4،َ4- بی پیریدین (4,4´-bipy)، با نسبت مولی 1:2:4 تهیه شد. سیستم بلوری این کمپلکس مونوکلینیک با گروه فضایی p21/n و چهار مولکول در سلول واحد میباشد. ابعاد سلول واحد åa = 22.2099(15) ، åb = 6.6599(4) ، å c = 23.5921(16) و β = 104.014(3) ° هستند. مقدار r نهای...
There has recently been an increasing interest in controlling macromolecular conformations and interactions through halogen bonding. Halogen bonds are favorable electrostatic interactions between polarized, electropositive chlorine, bromine, or iodine atoms and electronegative atoms such as oxygen or nitrogen. These interactions have been likened to hydrogen bonds in terms of their favored acce...
The calculated properties of substituted carboranes such as dipole moment, polarisability, the magnitude of the σ-hole and the desolvation free energy are compared with these properties in comparable aromatic and cyclic aliphatic organic compounds. Dispersion and charge transfer energies are similar. However, the predicted strength of the halogen bonds with the same electron donor (based on the...
Trends in the properties of normal valent and multivalent halogen-oxygen bonding are examined for the isomers of the halogen polyoxide families of the types (YXO2) and (YXO3), Y = Cl, Br, I, H, CH(3), X = Cl, Br, I. A qualitative model is formulated on the relationship between the X-O bond distance variations, the ionic character of the bonding, and the degree of halogen valence. The relative s...
Background and Aim: Halogen lamp is the commonly used light source for composite photo polymerization. Recently, high power halogen lamps, LED and plasma arc are introduced for improving the polymerization. The aim of this study was to investigate the effect of conventional and high power halogen lamps and LED light curing unit on degree of conversion of two different composite resins.Materials...
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