The difluoromethylene (CF2) group in aliphatic chains : synthesis and conformational preference of palmitic acids and nonadecane containing CF2 groups

Funding: ERC Advanced Investigator Grant (D.O'H).The syntheses of palmitic acids and a nonadecane are reported with CF2 groups located 1,3 or 1,4 to each other along the aliphatic chain. Specifically 8,8,10,10- and 8,8,11,11-tetrafluorohexadecanoic acids (6b and 6c) are prepared as well as the singly modified analogue 8,8-difluorohexadecanoic acid (6a). Also 8,8,11,11-tetrafluorononadecane (27) is prepared as a pure hydrocarbon containing a 1,4-di-CF2 motif. The modified palmitic acids are characterized by differential scanning calorimetry (DSC) to determine melting points and phase behaviour relative to palmitic acid (62.5 degrees C). It emerges that 6c, with the CF2 groups placed 1,4- to each other, has a significantly higher melting point (89.9 degrees C) when compared to the other analogues and palmitic acid itself. It is a crystalline compound and the structure reveals an extended anti-zig-zag chain. Similarly 8,8,11,11-tetrafluorononadecane (27) adopts an extended anti-zig-zag structure. This is rationalized by dipolar relaxation between the two CF2 groups placed 1,4 to each other in the extended anti-zig-zag chain and suggests a design modification for long chain aliphatics which can introduce conformational stability.Publisher PDFPublisher PDFPeer reviewe

The vicinal difluoro motif : the synthesis and conformation of erythro- and threo-diastereoisomers of 1,2-difluorodiphenylethanes, 2,3-difluorosuccinic acids and their derivatives

Background: It is well established that vicinal fluorines (RCHF-CHFR) prefer to adopt a gauche rather than an anti conformation when placed along aliphatic chains. This has been particularly recognised for 1,2-difluoroethane and extends to 2,3-difluorobutane and longer alkyl chains. It follows in these latter cases that if erythro and threo vicinal difluorinated stereoisomers are compared, they will adopt different overall conformations if the fluorines prefer to be gauche in each case. This concept is explored in this paper with erythro- and threo- diastereoisomers of 2,3-difluorosuccinates. Results: A synthetic route to 2,3-difluorosuccinates has been developed through erythro- and threo- 1,2-difluoro-1,2-diphenylethane which involved the oxidation of the aryl rings to generate the corresponding 2,3- difluorosuccinic acids. Ester and amide derivatives of the erythro- and threo- 2,3-difluorosuccinic acids were then prepared. The solid and solution state conformation of these compounds was assessed by X-ray crystallography and NMR. Ab initio calculations were also carried out to model the conformation of erythro- and threo- 1,2-difluoro-1,2-diphenylethane as these differed from the 2,3-difluorosuccinates. Conclusion: In general the overall chain conformations of the 2,3-difluorosuccinates diastereoisomers were found to be influenced by the fluorine gauche effect. The study highlights the prospects of utilising the vicinal difluorine motif (RCHF-CHFR) as a tool for influencing the conformation of performance organic molecules and particularly tuning conformation by selecting specific diastereoisomers (erythro or threo).Publisher PDFPeer reviewe

4-Chlorobenzyl chloride

The X-ray structure of the title compound has been determined for the first time. Its molecular structure is in good agreement with those previously determined for similar benzyl halides and the angles between the ring–Cl bonds in adjacent molecules show values in good agreement with an early Zeeman quadrupole spectroscopy study.Publisher PDFPeer reviewe

5-Amino-3-methyl-1,2,4-thiadiazole

An improved procedure for isolation of 5-amino-3-methyl-1,2,4-thiadiazole in pure form on a multi-gram scale without chromatography is reported. Its 1H and 13C NMR and IR data are presented and previously published erroneous data corrected. The molecular structure is confirmed by X-ray diffraction which shows layers consisting of an elaborate two-dimensional hydrogen bonded network of moleculesPublisher PDFPublisher PDFPeer reviewe

Asymmetric synthesis of tri- and tetrasubstituted trifluoromethyl dihydropyranones from alpha-aroyloxyaldehydes via NHC redox catalysis

We thank the Royal Society for a University Research Fellowship (A.D.S.), and the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) ERC Grant Agreement No. 279850 (A.T.D.).The asymmetric synthesis of tri- and tetrasubstituted trifluoromethyl dihydropyranones via an NHC-catalyzed redox process, introducing methyl, benzyl, and aryl substituents to the C(5) position, is presented. Their substrate-controlled derivatization into δ-lactones and cyclic hemiacetals containing stereogenic trifluoromethyl groups is also described.PostprintPeer reviewe

cis-Dichloridobis(dimethoxy­phenyl­phosphine)palladium(II)

The title compound, [PdCl2(C8H11O2P)2], has a comparable structure to those of related palladium dichloride complexes containing trimethyl phosphinite and methyl diphenyl phosphinite. The Pd atom is located on a crystallographic twofold rotation axis: thus, there is just one half-mol­ecule in the asymmetric unit. The structure is isomorphous with the platinum analogue cis-[PtCl2{P(OMe)2Ph}2]

OrganiZational communication and organiSational communication: Binaries and the fragments of a field

In this paper, I employ personal narrative to help cast light on connections and tensions between organiZational communication research, as produced in the United States, and organiSational communication research, as produced in Aotearoa New Zealand. I address the issue by highlighting three sets of differences between these bodies of research: canonical, institutional and theoretical. I then unpack how these differences are apparent in my own university before sketching out three ways in which we might productively use such tensions to achieve radical engagement, and critique disciplinary others, identities, and locations

Thermally activated delayed fluorescence and high-contrast mechanochromism of anthrone-based donor-acceptor systems

Funding: This project was funded by the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement no. 891606 (TADFNIR). The authors thank the Engineering and Physical Sciences Research Council for funding (EP/P010482/1).The development of materials that emit in the deep red to near-infrared region of the spectrum has attracted significant attention on account of their potential as optical sensing and imaging reagents in biology. We report herein the synthesis and optoelectronic characterization of four anthraquinone-based emitters T-tBuCz-AQ, T-MeOCz-AQ, C-tBuCz-AQ, and C-MeOCz-AQ, and two pyrazoloanthrone-based emitters tBuCz-PA and DMAC-PA. Depending on the donor, these compounds emit between 640-750 nm in the neat film, while the emission of the 10 wt% doped films in PMMA are blue-shifted to between 600-700 nm and have low photoluminescence quantum yields of between 2.6-6.6%. Of these compounds, T-tBuCz-AQ, T-MeOCz-AQ, and C-tBuCz-AQ exhibited thermally activated delayed fluorescence in 10 wt% doped films in PMMA, while the crystals of T-tBuCz-AQ also showed TADF. Compound tBuCz-PA showed highcontrast and reversible PL response upon mechanical grinding and hexane fuming.Publisher PDFPeer reviewe

2,6-exo-8,10-exo-4-Butyl-9-oxa-4-azatetracyclo[5.3.1.02,6.08,10]undecane-3,5-dione

The title epoxide was obtained by spontaneous epoxidation of the corresponding unsaturated imide in air or by peracid oxidation. Unambiguous assignment of the 1H and 13C NMR spectra is achieved by comparison between analogous compounds and its X-ray structure confirms the exo,exo-configuration.Publisher PDFPeer reviewe

Structure and NMR spectra of bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylic acid and its anhydride

Two of the three published sets of 1H and 13C NMR data for bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylic anhydride have been found to actually be those of the corresponding diacid. The NMR spectroscopic distinction between these two compounds is clarified and 1JC–H values are reported for the anhydride, the diacid and a related diester. The X-ray structure of the diacid has been determined and features chains of molecules involving both intra- and inter-molecular hydrogen bonding.PostprintPeer reviewe