Azine

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform

Jason A C Clyburne - One of the best experts on this subject based on the ideXlab platform.

  • Azines: conjugation stoppers or conjugation switches
    Journal of Materials Chemistry, 2007
    Co-Authors: Christine Mcloughlin, Jason A C Clyburne, Noham Weinberg
    Abstract:

    The results of B3LYP/6-31G* calculations on Azines and their diene analogues indicate that the Azine linkage supports conjugation between the CN double bonds, although in competition with the conjugation between the CN double bonds and lone pairs of nitrogen atoms. This additional conjugation mode significantly alters the appearance of the conjugation effects. The opportunities arising from this ability of Azine molecules to switch between two types of conjugation are explored in the context of their potential applications as optical and mechano-optical molecular devices.

  • Azines possessing strong push–pull donors/acceptors
    Chemical Communications, 2004
    Co-Authors: Dharinee D. Choytun, Lisa D. Langlois, Thomas P. Johansson, Gary W. Leach, Noham Weinberg, Charles L B Macdonald, Jason A C Clyburne
    Abstract:

    Azines (R2CN–NCR2) are 2,3-diaza analogues of 1,3-butadiene. In this report we show that strong polarisation of the Azine imparts structural features consistent with delocalization within the Azine fragment; NLO properties for the Azines are also reported.

  • Azines possessing strong push-pull donors/acceptors
    Chemical communications (Cambridge England), 2004
    Co-Authors: Dharinee D. Choytun, Lisa D. Langlois, Thomas P. Johansson, Gary W. Leach, Noham Weinberg, Charles L B Macdonald, Jason A C Clyburne
    Abstract:

    Azines (R2CN–NCR2) are 2,3-diaza analogues of 1,3-butadiene. In this report we show that strong polarisation of the Azine imparts structural features consistent with delocalization within the Azine fragment; NLO properties for the Azines are also reported.

Aijun Tong - One of the best experts on this subject based on the ideXlab platform.

Rainer Glaser - One of the best experts on this subject based on the ideXlab platform.

  • The Azine bridge as a conjugation stopper: an NMR spectroscopic study of electron delocalization in acetophenone Azines.
    Journal of Organic Chemistry, 2002
    Co-Authors: Michael Lewis, Rainer Glaser
    Abstract:

    Dipole parallel-alignment of organic molecular crystals of Azines has been achieved with a design that was based on the hypothesis that the Azine bridge is a conjugation stopper. This hypothesis has now been tested in detail, and 1H and 13C NMR spectroscopic data of symmetric and unsymmetric acetophenone Azines are presented in support of this design concept. Previous structural, ab initio, and electrochemical studies have shown that the Azine bridge largely inhibits through-conjugation in molecules with the general structure DPhC(Me)N−NC(Me)PhA, where D is a donor group and A is an acceptor group. NMR spectroscopy is an excellent tool to probe the degree of conjugation through the Azine bridge. The NMR results reported here for nine symmetrical and 18 unsymmetrical Azines show in a compelling fashion that the hypothesis holds. Varying the donor group does not change the chemical shifts of the aromatic hydrogen and carbon atoms on the acceptor-substituted phenyl ring. Likewise, varying the acceptor group ...

  • The crystal structure of 4-iodoacetophenone Azine
    Journal of Chemical Crystallography, 1999
    Co-Authors: Michael Lewis, Charles L. Barnes, Rainer Glaser
    Abstract:

    4-Iodoacetophenone Azine crystallizes in the space group Pbcn with cell parametersa = 34.5187(19), b = 7.2638(4), and c = 6.3736(3) A. The Azine shows a gauche conformation with regard to the N—N bond and the phenyl rings are twisted in a way that leads to the largest possible twist between the benzene rings of each Azine. This Azine conformation allows for intermolecular arene–arene T-contacts between pairs of benzene rings and these double-T contacts involve only molecules within the same layer. All Azines are perfectly colinear within each layer and this results in a quadrilateral kite-shaped arrangement of iodine atoms at the interface of each layer. The iodine-iodine distances within each layer are 4.5 and 5.1 A, and the three unique angles of the kite-shaped quadrilaterals are 97.1, 76.9, and 88.8°. The iodine atoms in adjacent layers pack such that atoms of one layer fill the square interstices of the next layer. The distances between iodine atoms in adjacent layers are 4.5 and 4.1 A. The C—I bonds are not orthogonal to the I-planes and the direction of the molecules in adjacent layers causes a deviation of about 40° from colinearity

  • Conjugation in Azines. Stereochemical analysis of benzoylformate Azines in the solid state, in solution, and in the gas phase
    Journal of Organic Chemistry, 1993
    Co-Authors: Rainer Glaser, Grace Shiahuy Chen, Charles L. Barnes
    Abstract:

    The stereochemistry of benzoylformate Azines 3 was studied in the solid state (X-rays, IR), in solution ( 1 H-, 13 C-, and 15 N-NMR), and in the gas phase (ab initio theory). Benzoylformate Azines are excellent systems to study phenyl conjugation because the ester substituent is electron-withdrawing and in a conformation that impedes π backdonation thereby causing the Azine-C to be highly electron-defficient and an excellent potential acceptor for π-donation. The X-ray structure of ethyl benzoylformate Azine (3a) is reported and compared to the crystallographic record. Azines 3 assume the N-N s-trans conformation and the Z,Z configuration

Dharinee D. Choytun - One of the best experts on this subject based on the ideXlab platform.

  • Azines possessing strong push–pull donors/acceptors
    Chemical Communications, 2004
    Co-Authors: Dharinee D. Choytun, Lisa D. Langlois, Thomas P. Johansson, Gary W. Leach, Noham Weinberg, Charles L B Macdonald, Jason A C Clyburne
    Abstract:

    Azines (R2CN–NCR2) are 2,3-diaza analogues of 1,3-butadiene. In this report we show that strong polarisation of the Azine imparts structural features consistent with delocalization within the Azine fragment; NLO properties for the Azines are also reported.

  • Azines possessing strong push-pull donors/acceptors
    Chemical communications (Cambridge England), 2004
    Co-Authors: Dharinee D. Choytun, Lisa D. Langlois, Thomas P. Johansson, Gary W. Leach, Noham Weinberg, Charles L B Macdonald, Jason A C Clyburne
    Abstract:

    Azines (R2CN–NCR2) are 2,3-diaza analogues of 1,3-butadiene. In this report we show that strong polarisation of the Azine imparts structural features consistent with delocalization within the Azine fragment; NLO properties for the Azines are also reported.

Prasad V. Bharatam - One of the best experts on this subject based on the ideXlab platform.

  • Azine-Hydrazone Tautomerism of Guanylhydrazones: Evidence for the Preference Toward the Azine Tautomer
    Journal of Organic Chemistry, 2016
    Co-Authors: Sumit S. Chourasiya, Ashok Ramakrishnan, Deepika Kathuria, Sham Shridhar Nikam, Sadhika Khullar, Sanjay K Mandal, Asit K Chakraborti, Prasad V. Bharatam
    Abstract:

    Guanylhydrazones have been known for a long time and have wide applications in organic synthesis, medicinal chemistry, and material science; however, little attention has been paid toward their electronic and structural properties. Quantum chemical analysis on several therapeutically important guanylhydrazones indicated that all of them prefer the Azine tautomeric state (by about 3–12 kcal/mol). A set of simple and conjugated Azines were designed using quantum chemical methods, whose tautomeric preference toward the Azine tautomer is in the range of 3–8 kcal/mol. Twenty new Azines were synthesized and isolated in their neutral state. Variable temperature NMR study suggests existence of the Azine tautomer even at higher temperatures with no traces of the hydrazone tautomer. The crystal structures of two representative compounds confirmed that the title compounds prefer to exist in their Azine tautomeric form.

  • Azine or hydrazone? The dilemma in amidinohydrazones
    RSC Advances, 2015
    Co-Authors: Ashok Ramakrishnan, Sumit S. Chourasiya, Prasad V. Bharatam
    Abstract:

    Azines belong to an important class of compounds that are found to have numerous applications in medicinal chemistry. Hydrazones are related to Azines and are more widely known compounds that carry many biochemical applications. Hydrazones with appropriate substituents can show Azine–hydrazone tautomerism. There are many cases in which Azines are wrongly considered to be hydrazones. In this article, we report the tautomeric energy differences of Azine and hydrazone and provide the structural details of amidinohydrazones, which prefer Azine structure rather than that of hydrazone structure, an important example being the anti-hypertensive drug, guanabenz. The importance of appropriate tautomeric representation of guanabenz has been established in terms of its molecular interactions with a known enzyme.