Photochemical reactions of charge-transfer complexes. The irradiation of the charge-transfer complexes between 1,4-, 1,5-, and 2,3-dimethoxynaphthalenes and 1,2-dicyanoethylenes

1980 ◽  
Vol 58 (9) ◽  
pp. 918-927 ◽  
Author(s):  
P. C. Wong ◽  
D. R. Arnold
Keyword(s):  
Charge Transfer ◽  
Triplet State ◽  
Ion Pair ◽  
Photochemical Reactions ◽  
Association Constants ◽  
Charge Transfer Complexes ◽  
Polar Solvents ◽  
Photostationary State ◽  
Ct Complex ◽  
Ct Complexes

The first part of this paper describes the experimental search for a donor which would complex preferentially one of the isomers of 1,2-dicyanoethylene. This involved measuring the association constants (KcDA) of the charge-transfer (ct) complexes of several dimethoxynaphthalenes (DMN) with maleonitrile (MN) and fumaronitrile (FN). From the measured KcDA, we found that MN complexes more strongly than FN with 1,4- and 1,5-DMN but that FN complexes more strongly with 2,3-DMN than does MN. These results are explained in terms of more than one favourable geometry for the ct complexes, since the donors are relatively large compared to the acceptors.Irradiation of the ct complexes between 1,4-, 1,5-, or 2,3-DMN and 1,2-dicyanoethylene led to isomerization of the olefins. The photostationary state depends on the absorption spectra of the ct complexes formed between the donor and the isomeric olefins. From spectroscopic and photo-CIDNP studies, we find evidence that the isomerization in polar solvents takes place via the triplet state of the olefin. The triplet is formed from the radical ion pair resulting after excitation of the ct complex.

Photochemical reactions of charge-transfer complexes. IV. The orientation effects of charge-transfer complexes: theory and experiment

1981 ◽  
Vol 59 (6) ◽  
pp. 982-989 ◽  
Author(s):  
Po Cheong Wong ◽  
Donald R. Arnold
Keyword(s):  
Charge Transfer ◽  
Chloroform Solution ◽  
Photochemical Reactions ◽  
Dominant Factor ◽  
Charge Transfer Complexes ◽  
Molecular Orbital Calculations ◽  
Complex Stability ◽  
Orientation Effects ◽  
Ct Complexes ◽  
Good Agreement

In paper number III of this series (2) ab initio and PCILO molecular orbital calculations for the four π–π* charge-transfer (ct) complexes formed between maleonitrile (MN) and fumaronitrile (FN), and cis (CS) and trans-1,2-dimethoxyethylene (TR) were reported. This paper reports the ct transition absorption characteristics and association constants of these complexes as a function of temperature. From this data the heats of formation of the complexes are determined and these experimental results are then compared with the theoretical values; good agreement is obtained. The order of complex stability (−ΔHθ (kcal mol)) measured in chloroform solution is: MN−TR(0.55) < FN−TR(0.65) < MN−CS(0.78) < FN−CS(1.25).We reach the conclusion that, for these complexes, orientation effects of the substituents are quite small in magnitude and that the dominant factor influencing complex stability follows the redox potential difference. The structures of the complexes are discussed in view of these results.

scholarly journals Charge Transfer Complexes of Ketotifen with 2,3-Dichloro-5,6-dicyano-p-benzoquinone and 7,7,8,8-Tetracyanoquodimethane: Spectroscopic Characterization Studies

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2039
Author(s):  
Gamal A. E. Mostafa ◽  
Ahmed Bakheit ◽  
Najla AlMasoud ◽  
Haitham AlRabiah
Keyword(s):  
Charge Transfer ◽  
Spectroscopic Characterization ◽  
Molar Ratio ◽  
Charge Transfer Complexes ◽  
Physical Parameters ◽  
Spectrophotometric Methods ◽  
Theoretical Approaches ◽  
The Stability ◽  
Ct Complexes

The reactions of ketotifen fumarate (KT) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π acceptors to form charge transfer (CT) complexes were evaluated in this study. Experimental and theoretical approaches, including density function theory (DFT), were used to obtain the comprehensive, reliable, and accurate structure elucidation of the developed CT complexes. The CT complexes (KT-DDQ and KT-TCNQ) were monitored at 485 and 843 nm, respectively, and the calibration curve ranged from 10 to 100 ppm for KT-DDQ and 2.5 to 40 ppm for KT-TCNQ. The spectrophotometric methods were validated for the determination of KT, and the stability of the CT complexes was assessed by studying the corresponding spectroscopic physical parameters. The molar ratio of KT:DDQ and KT:TCNQ was estimated at 1:1 using Job’s method, which was compatible with the results obtained using the Benesi–Hildebrand equation. Using these complexes, the quantitative determination of KT in its dosage form was successful.

scholarly journals Charge-transfer complexes of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone with amino molecules in polar solvents

2015 ◽  
Vol 149 ◽  
pp. 75-82 ◽  
Author(s):  
Silvia Berto ◽  
Enrico Chiavazza ◽  
Valentina Ribotta ◽  
Pier Giuseppe Daniele ◽  
Claudia Barolo ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Charge Transfer Complexes ◽  
Polar Solvents

Chemical behavior of charge-transfer complexes. VII. Solvolysis of alkyl arenesulfonate donors in the presence of aromatic acceptors

1978 ◽  
Vol 56 (4) ◽  
pp. 585-590 ◽  
Author(s):  
Allan K. Colter ◽  
Robert E. C. Turkos
Keyword(s):  
Acetic Acid ◽  
Charge Transfer ◽  
Kinetic Data ◽  
Association Constants ◽  
Charge Transfer Complexes ◽  
Chemical Behavior ◽  
Measurable Rate ◽  
Leaving Groups

Rates of solvolysis of several ethyl and 2-propyl arenesulfonates having π donor leaving groups were measured in the absence of accepter and in the presence of the π acceptors 1,3,5-trinitrobenzene (TNB) and 2,4,7-trinitrofluorenone (TNF). With four of the nine combinations investigated, added accepter produced small but measurable rate enhancements. Ester–TNF 1:1 association constants were measured spectrophotometrically at 20, 30, and 40 °C in acetic acid for 2-propyl 4-methoxy-1-naphthalenesulfonate (3b), 4,8-dimethoxy-1-naphthalenesulfonate (4), 3,7-dimethyl-1-naphthalenesulfonate (5), and 1-pyrenesulfonate (6). From the equilibrium and kinetic data, the reactivity of the 1:1 ester–TNF complex relative to that of the uncomplexed ester (kc/ku) in acetolysis at 85.73 °C was estimated to be lessthan 4.2 and 1.4 for 3b and 4, respectively, 4.4 ± 2.0 for 5, and 2.8 ± 0.4 for 6. The value of kc/ku for 6 determined from analysis of the kinetic data alone is 2.7 ± 0.8.

One-dimensionality and neutral-to-ionic transition of some mixed-stack charge-transfer complexes

2002 ◽  
Vol 12 (9) ◽  
pp. 357-360
Author(s):  
M. Buron ◽  
E. Collet ◽  
M. H. Lemée-Cailleau ◽  
H. Cailleau ◽  
T. Luty ◽  
...  
Keyword(s):  
Phase Transition ◽  
Charge Transfer ◽  
Charge Transfer Complexes ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
Giant Dielectric ◽  
Ionic Transition ◽  
The One ◽  
Ct Complexes ◽  
Dimerization Process

Mixed-stack charge-transfer (CT) complexes undergoing the neutral-ionic (N-I) phase transition are molecular materials formed of stacks where electron donor (D) and acceptor (A) molecules regularly alternate. In the N phase, the CT is low and molecules are situated on inversion centers, while in the I phase, the increase of CT is accompanied by a lattice distortion (dimerization process and symmetry breaking). The one-dimensional (1D) architecture triggers the chain multistability by stabilizing lattice-relaxed (LR)-CT excitations ...D° A° D° A° $(D^+A^-)(D^+A^-)(D^+A^-)$ Do A" D° A° D°... These 1D nano-scale objects are at the heart of the equilibrium N-I phase transition and govern the fascinating physical properties such as giant dielectric response or photo-induced phase transformations. In this contribution, the 1D character of these critical excitations will be demonstrated by direct observation using high resolution X-Ray diffraction.

Charge Transfer Complexes of N-Arylcarbamates with π-Acceptors

1987 ◽  
Vol 42 (3) ◽  
pp. 284-288 ◽  
Author(s):  
Aboul-fetouh E. Mourad
Keyword(s):  
Charge Transfer ◽  
Electron Density ◽  
Nmr Spectra ◽  
Charge Transfer Complexes ◽  
H Nmr ◽  
Ct Complexes

The charge-transfer (CT) complexes of some N-arylcarbamates as donors with a number of π-acceptors have been studied spectrophotometrically. The Lewis basicities of the N-arylcarbamates as well as the types of interactions are discussed. The 1H-NMR spectra of some CT complexes with both 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) and 7,7,8,8 tetracyanoquinodimethane (TCNQ) indicate a decrease of the electron density on the donor part of the complex.

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