نتایج جستجو برای: halogen
تعداد نتایج: 4763 فیلتر نتایج به سال:
In this paper, the effect of halogen compounds on tetrahedrozoline with nanosized fullerene was investigated. First, the structures of Tetrahydrozoline on a fully vectorized nanoclay were optimized with halogen compounds on carbon 69 (R-X: X = F, Cl, Br; R = C60-Tetrahydrozoline-C69-). Then orbital calculations were performed using NBO technique, and structural parameters and bipolar moments of...
The aim of this study was to evaluate the degree of conversion (DC) of two lingual retainer adhesives, Transbond Lingual Retainer (TLR) and Light Cure Retainer (LCR), cured with a fast halogen light, a plasma arc light and a light-emitting diode (LED) at various curing times. A conventional halogen light served as the control. One hundred adhesive samples (five per group) were cured for 5, 10 o...
The interactions between the two CX3 groups in perhalogenated ethanes, X3C–CX3 are studied, with X3C–CX3 = H3C–CH3, F3C–CF3, F3C–CCl3, and Cl3C–CCl3. Utilising the recently developed method for revealing non-covalent interactions in molecular systems by Johnson et al. [1], a previously overlooked non-covalent interaction between halogens attached to opposite carbon atoms is unearthed. Further i...
A new approach towards highly enantioselective halogen-bonding catalysis has been developed. In order to circumvent the intrinsic issues of halogen-bond (XB) nature and consequent unresolved limitations in asymmetric catalysis, fine-tuned halogen--halogen interactions between substrate XB-donor were designed pre-organize catalyst’s cavity boost enantiocontrol. The present strategy exploits both...
Two bistable halogen and hydrogen bonding-naphthalene diimide [2]rotaxanes have been prepared and the system incorporating a halogen bond donor anion recognition site is demonstrated to exhibit superior anion induced translational motion of the macrocyclic wheel component relative to the hydrogen bonding analogue. Proton NMR spectroscopy is used to estimate the percentage occupancies of the mac...
The formation of a halogen bonded self-assembled co-crystal physisorbed monolayer containing N···Br interactions is reported for the first time. The co-crystal monolayer is identified experimentally by synchrotron X-ray diffraction and the structure determined. Density functional theory (DFT) calculations are also employed to assess the magnitudes of the different interactions in the layer. Sig...
The influence of halogen substituents on the catalytic oxidation of 2,4,6-trihalogenated phenols (TrXPs) by iron(III)-porphyrin/KHSO₅ catalytic systems was investigated. Iron(III)-5,10,15,20-tetrakis(p-hydroxyphenyl)porphyrin (FeTHP) and its supported variants were employed, where the supported catalysts were synthesized by introducing FeTHP into hydroquinone-derived humic acids via formaldehyd...
The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is n...
Halogen bonding, due to its directionality and tunable strength, is being increasingly utilized in self-assembling materials and crystal engineering. Using density functional theory (DFT) and molecular mechanics (OPLS/CM1Ax) calculations, multiply halogen bonded complexes of brominated imidazole and pyridine are investigated along with their potential in construction of self-assembling architec...
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