Long-Range 31P-31P Spin Coupling Constants in the 31P NMR Spectra of Phosphite Triesters

Abstract

Data are presented on the magnitudes of ⁵ J _pp and ⁶ J _PP spin-spin coupling constants in the ³¹P NMR spectra of a variety of novel polyphosphite triesters.     

Modelling interaction between ammonia and nitric oxide molecules and aquaporins

Aquaporin is a family of small membrane-proteins that are capable of transporting nano-sized materials. In the present paper, we investigate the structure of these channels and provide information about the mechanism of individual molecules being encapsulated into aquaglyceroporin (GlpF) and aquaporin-1 (AQP1) channels by calculating the potential energy. In particular, we presents a mathematical model to determine the total potential energy for the interaction of the ammonia and nitric oxide molecules and different aquaporin channels which we assume to have a symmetrical cylindrical structure. We propose to describe these interactions in two steps. Firstly, we model the nitrogen atom as a discrete point and secondly, we model the three hydrogen atoms on the surface of a sphere of a certain radius. Then, we find the total potential energy by summing these interactions. Next, by considering the nitric oxide molecule as two discrete atoms uniformly distributed interacting with GlpF and AQP1 channels then gathering all pairs of interaction to determine the potential energy. Our results show that the ammonia and nitric oxide molecules can be encapsulated into both GlpF and AQP1 channels.     

Palladium‐Catalyzed Synthesis of Ammonium Sulfinates from Aryl Halides and a Sulfur Dioxide Surrogate: A Gas‐ and Reductant‐Free Process

Sulfonyl‐derived functional groups populate a broad range of useful molecules and materials, and despite a variety of preparative methods being available, processes which introduce the most basic sulfonyl building block, sulfur dioxide, using catalytic methods, are rare. Described herein is a simple reaction system consisting of the sulfur dioxide surrogate DABSO, triethylamine, and a palladium(0) catalyst for effective convertion of a broad range of aryl and heteroaryl halides into the corresponding ammonium sulfinates. Key features of this gas‐ and reductant‐free reaction include the low loadings of palladium (1 mol %) and ligand (1.5 mol %) which can be employed, and the use of isopropyl alcohol as both a solvent and formal reductant. The ammonium sulfinate products are converted in situ into a variety of sulfonyl‐containing functional groups, including sulfones, sulfonyl chlorides, and sulfonamides.     

Liquid chromatography-mass spectrometry identification of imidacloprid photolysis products

Photolysis of imidacloprid by near ultraviolet (UV) radiation was investigated using reversed phase liquid chromatography (RPLC) and liquid chromatography-electrospray ionization/mass spectrometry (LC-ESI/MS) operated in the positive ion mode. The decomposition of imidacloprid by near UV light is first order with a half life of 10.18 h. Photo-degradation products of imidacloprid identified in this study included imidacloprid urea, imidacloprid olefin, and imidacloprid desnitro. A degradation pathway is proposed for imidacloprid from an examination of the product decay curves obtained in this monitoring study which was performed in a batch test mode.     

Analysis of diverse direct arylation polymerization (DArP) conditions toward the efficient synthesis of polymers converging with stille polymers in organic solar cells

Despite the emergence of direct arylation polymerization (DArP) as an alternative method to traditional cross‐coupling routes like Stille polymerization, the exploration of DArP polymers in practical applications like polymer solar cells (PSCs) is limited. DArP polymers tend to have a reputation for being marginally inferior to Stille counterparts due to the increased presence of defects that result from unwanted side reactions in direct arylation, such as unselective C‐H bond activation and homocoupling. We report ten DArP protocols across the three major classes of DArP to generate poly[(2,5‐bis(2‐hexyldecyloxy)phenylene)‐alt‐(4,7‐di(thiophen‐2‐yl)benzo[c][1,2,5]thiadiazole)] (PPDTBT). Through evaluation of the method and resulting photophysical and electronic properties, we show not all DArP methods are suitable for generating device‐quality alternating copolymers. When DArP PPDTBT was synthesized in superheated THF with Cs₂CO₃, neodecanoic acid, and P(o‐anisyl)₃, it generated polymers of exceptional quality that performed comparably to Stille counterparts in both roll coated ITO‐free and spin‐coated ITO devices. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2907–2918     

An optimal<Emphasis Type="Italic">L</Emphasis><Superscript><Emphasis Type="Italic">p</Emphasis></Superscript>-bound on the Krein spectral shift function

Let ξ_A,B be the Krein spectral shift function for a pair of operatorsA, B, with C =A-B trace class. We establish the bound

Non-Uniformity and Generalised Sacks Splitting

We show that there do not exist computable functions f ₁(e, i), f ₂(e, i), g ₁(e, i), g ₂(e, i) such that for all e, i ∈ ω, (1) $ {\left( {W_{{f_{1} {\left( {e,i} \right)}}} - W_{{f_{2} {\left( {e,i} \right)}}} } \right)} \leqslant _{{\rm T}} {\left( {W_{e} - W_{i} } \right)}; $ (2) $ {\left( {W_{{g_{1} {\left( {e,i} \right)}}} - W_{{g_{2} {\left( {e,i} \right)}}} } \right)} \leqslant _{{\rm T}} {\left( {W_{e} - W_{i} } \right)}; $ (3) $ {\left( {W_{e} - W_{i} } \right)} \not\leqslant _{{\rm T}} {\left( {W_{{f_{1} {\left( {e,i} \right)}}} - W_{{f_{2} {\left( {e,i} \right)}}} } \right)} \oplus {\left( {W_{{g_{1} {\left( {e,i} \right)}}} - W_{{g_{2} {\left( {e,i} \right)}}} } \right)}; $ (4) $ {\left( {W_{e} - W_{i} } \right)} \not\leqslant _{{\rm T}} {\left( {W_{{f_{1} {\left( {e,i} \right)}}} - W_{{f_{2} {\left( {e,i} \right)}}} } \right)}{\text{unless}}{\left( {W_{e} - W_{i} } \right)} \leqslant _{{\rm T}} {\emptyset};{\text{and}} $ (5) $ {\left( {W_{e} - W_{i} } \right)} \leqslant _{{\rm T}} {\left( {W_{{g_{1} {\left( {e,i} \right)}}} - W_{{g_{2} {\left( {e,i} \right)}}} } \right)}{\text{unless}}{\left( {W_{e} - W_{i} } \right)} \leqslant _{{\rm T}} {\emptyset}. $ It follows that the splitting theorems of Sacks and Cooper cannot be combined uniformly.     

Pd asymmetric allylic alkylation (AAA). A powerful synthetic tool

Palladium catalyzed asymmetric allylic alkylations represent a challenging problem because the mechanism of the reaction places the chiral environment distal to the bond breaking or making events responsible for the asymmetric induction. Furthermore, unlike virtually every other asymmetric process, many strategies can be employed for introduction of asymmetry and many different types of bonds can be formed. While over 100 different ligands have been designed, a family of ligands derived from 2-diphenylphosphinobenzoic or 1-naphthoic acid and chiral scalemic diamines have been successful in inducing excellent enantioselectivity by five different enantiodiscriminating events. These methods have already provided practical strategies towards numerous biological targets--some of which are adenosine and its enantiomer, aflatoxin B, aristeromycin, calanolide A and B, carbovir, cyclophellitol, ethambutol, galanthamine, mannostatin, neplanocin, phyllanthocin, sphingofungins E and F, tetraponaines, vigabatrin, and valienamine.