- Naphthoquinones as covalent reversible inhibitors of cysteine proteases—studies on inhibition mechanism and kinetics
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The facile synthesis and detailed investigation of a class of highly potent protease inhibitors based on 1,4‐naphthoquinones with a dipeptidic recognition motif (HN‐L‐Phe‐L‐Leu‐OR) in the 2‐position and an electron‐withdrawing group (EWG) in the 3‐positio
- Barthels, Fabian,Distler, Ute,Engel, Volker,Engels, Bernd,Hellmich, Ute A.,Johe, Patrick,Klein, Philipp,Le, Thien Anh,Opatz, Till,Schirmeister, Tanja,Schmid, Paul,Tenzer, Stefan,Wagner, Annika
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- A spectrophotometric study of molecular complexes of 2,3-dicyano-1,4-naphthoquinone
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Molecular complexes of 2,3-dicyano-1,4-naphthoquinone with various aromatic anilines were studied spectrophotometrically in dichloromethane solvent at different temperatures.All these complexes show a new broad charge-transfer band in the visible region of the electromagnetic spectrum.All the donors are known to form strong 1:1 complexes with the acceptor and their stoichiometry was unaffected by the variation of temperature over a small interval.The thermodynamic and spectroscopic parameters were evaluated.The order of donor strength followed the sequence: 2,5-dimethylaniline>2,3-dimethylaniline>N,N-dimethylaniline>p-toluidine>o-toluidine>m-toluidine>N-methylaniline>aniline.
- Budni, M. L.,Jayadevappa, E. S.
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- Studies on charge-transfer complexes of 2,3-dicyano-1,4-naphthoquinone with some ring and N-substituted anilines
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The charge-transfer complexes (CT-complexes) between 2,3-dicyano-1,4- naphthoquinone (DCNQ) and some aromatic anilines, both ring and N-substituted, were studied spectrophotometrically in three chlorinated solvents, viz. chloroform, dichloromethane, and 1,2-dichloroethane at different temperatures. All the donors are known to form stable 1:1 stoichiometric complexes with DCNQ and their stoichiometry was unaffected by the variation of temperature over the studied range. The change in polarity of the solvent also doesn't affect the stoichiometry of the complexes. The determined formation constant values are in the range of 0.49-10.8 dm3 mol-1, the highest is for the N-benzylaniline and the lowest is for o-chloroaniline. The effect of functional groups on the aniline moiety towards the strength and its electron releasing property has been discussed. The ΔH, ΔS, and ΔG values are all negative, so the studied complexes are reasonably stable and exothermic in nature. The ionization potentials of the donors were determined using the charge-transfer (CT) absorption bands of the complexes. The dissociation energies (W) of the charge-transfer excited state for the CT-complexes were also determined and are found to be constant. Springer-Verlag 2004.
- Neelgund, Gururaj M.,Budni
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- 7. Tetrazinodiheteroarene: 'Charge -Transfer'-Komplexbildung mit Akzeptorverbindungen
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The formation of charge-transfer complexes and radical-ion pairs of donor compounds 1-6 with acceptor compounds 7-12 has been investigated by means of VIS/NIR-spectrospcopic methods.The equilibrium constants KCT (up to 1100M-1) for the donor/acceptor couple dipyridotetrazine (2)/ethylenetetracarbonitrile (11) and spectra of the CT complexes have been determined in 1,2-dichloroethane solution at 25 deg C.Results are discussed in relation to known CT-complex properties and to voltammetric redox-potentials E1/2.
- Hellrung, Bruno,Balli, Heinz
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