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AbstractHerein, we describe an improved method to synthesise mono-, di- and tetra-cyanocalix[4]arene and report their crystal structure determinations. We also report our attempts to further functionalise the cyanocalix[4]arenes into dithiadiazolyl-calix[4]arenes, and propose a hypothesis as to why the cyano group on a calix[4]arene is an extremely challenging group to modify. 相似文献
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Richard I. Thomson Dr. Christopher M. Pask Dr. Gareth O. Lloyd Prof. Masaki Mito Prof. Jeremy M. Rawson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(28):8629-8633
The structure of the canted antiferromagnet β‐p‐NCC6F4CNSSN ( 1 ) was determined from synchrotron powder‐diffraction studies in the pressure range 0–21.6 kbar. Radical 1 crystallizes in the orthorhombic space group Fdd2, but undergoes an asymmetric contraction of the unit‐cell size with increasing pressure. At the molecular level, this contraction of the unit cell is simultaneously accommodated by: 1) an increase in twist angle between aryl and heterocyclic rings; and 2) a shortening of the intermolecular S ??? N contacts, which propagate the magnetic‐exchange pathway. DFT calculations based on the structures in this pressure range revealed an increase in the magnetic‐exchange interaction (J) with increasing pressure, and an excellent correlation was observed between J and the magnetic‐ordering temperature, which increased from 36 K at ambient pressure up to 70 K at 16 kbar. 相似文献
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A series of liquid-crystalline materials based on 4-substituted cyanobiphenyls, RC(6)H(4)C(6)H(4)CN (R = C(5)H(11), C(6)H(13), C(7)H(15), C(8)H(17) and C(12)H(25), commonly referred to as 5CB, 6CB, 7CB, 8CB and 12CB, respectively) were functionalised to give the corresponding dithiadiazolyl organic radicals RC(6)H(4)C(6)H(4)CNSSN(*) (compounds 1(*), 2(*), 3(*), 4(*) and 5(*), respectively). EPR spectra of n-C(12)H(25)C(6)H(4)C(6)H(4)CNSSN(*) (5(*)) reveal that it adopts a dimeric diamagnetic structure in the solid state with a small number of paramagnetic defect sites. Variable temperature electron paramagnetic resonance (EPR) studies reveal a thermally activated rotation about the molecular long axis at temperatures above 314 K. The energy barrier to rotation about the phenylene-dithiadiazolyl bond was estimated as 25 kJ mol(-1) using density functional theory (DFT). At elevated temperatures thermal annealing was also observed, quenching the sample's paramagnetism. 相似文献
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Nadia T. Stephaniuk Mitchell A. Nascimento Dr. Sahar Nikoo Dr. Elodie Heyer Lara K. Watanabe Dr. Jeremy M. Rawson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(15):e202103846
Cocrystallization of the dithiadiazolyl (DTDA) radicals p-XC6F4CNSSN (X=F, Cl, Br, I, CN) with TEMPO afforded the 2 : 1 cocrystals [p-XC6F4CNSSN]2[TEMPO] ( 1 – 5 ) whose structures all reflect a common S4⋅⋅⋅O supramolecular motif. The nature of this interaction was probed by DFT calculations (M06/aug-cc-pVDZ) on 1 which revealed that the enthalpy of formation of the [C6F5CNSSN]2[TEMPO] supramolecular motif from [C6F5CNSSN]2 and TEMPO is substantial (−54.0 kJ mol−1). Electronic structure calculations revealed a TEMPO-based doublet S= configuration as the ground state with limited spin density on the DTDA rings (2.4 %). The corresponding spin quartet state is +78.9 kJ mol−1 higher in energy. An atoms-in-molecules analysis reveals four bond critical points (BCPs) between the TEMPO O and the DTDA S atoms as well as additional BCPs between selected DTDA S atoms and methyl H atoms of the TEMPO molecule. Herein, the structures of 2 – 5 are considered within the context of a hierarchical view of competing and complementary intermolecular interactions; in particular, the established supramolecular CN⋅⋅⋅S−S synthon is sacrificed in order to form the new S4⋅⋅⋅O interaction. 相似文献
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Christine M. Aherne Arthur J. Banister Thomas G. Hibbert Anthony W. Luke Jeremy M. Rawson 《Polyhedron》1997,16(24):172-4245
A series of aryl-substituted 1,2,3,5-dithiadiazolylium cations (I) and 1,3,2,4-dithiadiazolylium cations (II) were prepared as their hexafluoroarsenate(V) salts using standard methods. Electrochemical studies on I and II showed reversible one-electron reductions. The half-wave reduction potentials for a series of meta-substituted derivatives of both I and II exhibited a linear free energy relationship with the Hammett parameter, σm. The small value of the reaction constant, , for both meta and para-derivatives indicates that electronic effects are small and in the case of the ortho-derivatives of II, steric effects dominate the redox process. Reduction of the 1,2,3,5-dithiadiazolylium cations, as their chloride salts, yielded the corresponding dithiadiazolyl radicals (III). 相似文献
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Arthur J. Banister Andrei S. Batsanov Owen G. Dawe Judith A. K. Howard John E. Davies Jeremy M. Rawson 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):553-556
The solid state structures of a series of difluorophenyl dithiadiazolyl radicals are presented and the packing described in terms of S...F, S...S, F...F secondary interactions. 相似文献
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Delia A. Haynes Eric J. L. McInnes Jack Passmore Jeremy M. Rawson 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4-5):869-873
Condensation of CF3C(═NH)NH2 with SCl2 yielded the dithiadiazolylium salt, [CF3CNSSN]Cl which could be reduced to [CF3CNSSN]2 with Zn/Cu couple in SO2. [CF3CNSSN]2 is a diamagnetic dimer in the solid state but melts at 308 K to give a paramagnetic liquid. On cooling the radical enters a metastable state before immediately re-solidifying below 295 K. The thermal hysteresis was probed by EPR spectroscopy. Metastable samples spontaneously solidified after an induction period, typically between ca. 5 and 30 min, consistent with the variable time necessary to form a seed crystal from which crystallization can occur. 相似文献
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