Conductometric Studies of Molecular Complexes of Charge Transfer Type Formed between Aza-Aromatics and Haloanils

1993 ◽  
Vol 58 (4) ◽  
pp. 783-790 ◽  
Author(s):  
Harbhajan S. Randhawa ◽  
Rajni Lakhani
Keyword(s):  
Electrical Conductivity ◽  
Charge Transfer ◽  
Ionization Potential ◽  
Equilibrium Constant ◽  
Molecular Complex ◽  
Molecular Interaction ◽  
Lone Pair ◽  
Molecular Complexes ◽  
Nitrogen Ring ◽  
Ct Complexes

Electrical conductivity technique has been employed to investigate the molecular interaction of aza-aromatics viz. pyridine, α-pikoline, β-picoline and γ-picoline with haloanils, namely chloranil, bromanil and fluranil. The stoichiometry of the charge transfer (CT) complexes has been established and molar conductivities of the complexes determined employing the method of Gutmann and Keyzer. A model has been proposed for determining the equilibrium constant (K) of 1 : 1 molecular complexes of CT type by conductometric measurements. The model involves the assumption: 1/σ = [(1 + K c0A)/qdK c0A] (1/c0D) + (1/qd c0A), where σ is the conductivity of the molecular complex, qd is the extent of depolarization of the complex, c0A) and c0D) are the initial concentrations of the acceptors and donors, respectively. The values of K and qd follows the expected trend of the conductometric parameters determined by the method of Gutmann and Keyzer as well as ionization potential of donors, thereby substantiating the validity of the model proposed. The observed and theoretical values of thermodynamic parameters for the aza-aromatic-chloranil systems that the interaction of aza-aromatics with haloanils is occurring through the lone pair of nitrogen ring.

Estimation of the fraction of dative structure in molecular complexes using Hammett ρ values

1979 ◽  
Vol 57 (12) ◽  
pp. 1418-1420
Author(s):  
Bo-Long Poh
Keyword(s):  
Charge Transfer ◽  
Ionization Potential ◽  
Molecular Complex ◽  
Physical Interpretation ◽  
Molecular Complexes ◽  
Transfer Energy ◽  
Simple Method ◽  
Charge Transfer Energy

A simple method of estimating the fraction of dative structure in molecular complexes using Hammett ρ values is given. A physical interpretation of the parameter m in the equation, hν = mID + n, relating the charge-transfer energy, hν, of a molecular complex and the ionization potential, ID, of the donor is given.

Charge Transfer Molecular Complexes of 4-(Dimethylamino)pyridine with Some Conventional and Unconventional Acceptors Involving Fluoroarenes

2006 ◽  
Vol 71 (9) ◽  
pp. 1359-1370 ◽  
Author(s):  
Usama M. Rabie
Keyword(s):  
Charge Transfer ◽  
Nmr Spectra ◽  
Molecular Complexes ◽  
Outer Sphere ◽  
Formation Constants ◽  
Stoichiometric Ratio ◽  
Spectral Bands ◽  
Elemental Analyses ◽  
Ct Complexes ◽  
Solid Complexes

Charge transfer (CT) complexes of 4-(dimethylamino)pyridine (DMAP) with iodine as a typical σ-type acceptor and with typical π-type acceptor, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), have been synthesized and characterized. Octafluorotoluene (OFT), octafluoronaphthalene (OFN), perfluorophenanthrene (PFP), and 2,3,5,6-tetrafluoropyridine-4-carbonitrile (TFP) were also used as acceptors for interaction with DMAP. Properties of such CT complexes were investigated by UV/VIS and IR spectra, and elemental analyses of the isolated complexes. The systems DMAP-iodine and DMAP-DDQ are characterized by formation of triiodide ions (I3-) and DDQ•- anion radicals, respectively, which is proposed to occur via initial formation of outer-sphere CT complexes. The systems (DMAP-OFT, DMAP-OFN, DMAP-PFP and DMAP-TFP) are characterized by the appearance of new UV/VIS spectral bands assigned as CT bands; they also furnished the corresponding solid complexes with the stoichiometric ratio 1:1. 1H and 19F NMR spectra were used on confirming the formation of the DMAP-PFP CT complexes. The formation constants (KCT) and molar absorption coefficients (εCT) of the latter complex were obtained.

Molecular Complexes of Cyclophanes, Part XVII Charge-Transfer Complexes of [2.2]- and [2.2.2]Paracyclophane-carbamates with π-Acceptors

1987 ◽  
Vol 42 (9) ◽  
pp. 1147-1152 ◽  
Author(s):  
Aboul-fetouh E. Mourad ◽  
Verena Lehne
Keyword(s):  
Charge Transfer ◽  
Functional Group ◽  
Lone Pair ◽  
Molecular Complexes ◽  
Charge Transfer Complexes ◽  
Electronic Interactions ◽  
H Nmr ◽  
Ct Complex ◽  
Nitrogen Lone Pair ◽  
Lone Pair Electrons

Charge-transfer (CT) complexation between some [2.2]- and [2.2.2]paracyclophane-carbamates as donors with 2,3-dichloro-5.6-dicyanobenzoquinone (DDO ) as well as tetracyanoethylene (TCNE) as π-acceptors has been evidenced by VIS. 1H NMR and IR spectroscopy. The site of interaction in the two different donor systems was determined. The results reveal no contribution of the nitrogen lone pair electrons of the carbamate functional group in the CT complexation. and the interaction is mainly of π-π* type. In addition, the existence of the transannular electronic interactions in [2.2]paracyclophane derivatives is responsible for CT complex formation.

Electron-Donating Radialenes. Potential Donors for Molecular Organic (Super) Conductors and Ferromagnets

1989 ◽  
Vol 173 ◽  
Author(s):  
Z. Yoshida ◽  
T. Sugimoto ◽  
Y. Misaki
Keyword(s):  
Electrical Conductivity ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Charge Transfer ◽  
Single Crystals ◽  
Temperature Change ◽  
Radical Cation ◽  
Electrical Conductivities ◽  
New Type ◽  
Ct Complexes

ABSTRACTThe electron-donating [n]radialenes (n=3,4,5) were prepared with the aim of developing both new type of organic (super)conductors and unprecedented organic/molecular ferromagnets. The charge-transfer (CT) complexes of 1,3-dithiole[4]radialene with TCNQ and of 1,3-benzodithiole-[4]radialene with TCNQF4 and DDQ showed comparatively high electrical conductivities in compressed pellets. The single crystals of PF6 and CIO4 salts of 1,3-benzodithiole[4]radialene radical cation revealed temperature change of electrical conductivity characteristic of a semiconductor. The magnetic properties of the bis(trifluoroacetate)salt of thioxanthene[3]-radialene dication and of the CT complexes of 1,3-benzodithiole[5]-radialene with DDQ, TCNQF4, and hexacyanohexamethylenecyclopropane, were also investigated from the ESR and/or magnetic susceptibility measurements.

Evidence for molecular complexes in the mechanism of additions of iodine mono-chloride to alkenes

1984 ◽  
Vol 62 (11) ◽  
pp. 2526-2534 ◽  
Author(s):  
George H. Sçhmid ◽  
James W. Gordon
Keyword(s):  
Absorption Band ◽  
Equilibrium Constant ◽  
Molecular Complex ◽  
Molecular Complexes ◽  
Electrophilic Addition ◽  
Reaction Coordinate ◽  
Rate Law ◽  
Rate Determining Step ◽  
Enthalpy Changes ◽  
Enthalpy Of Activation

Immediately upon mixing ICls and 2,3-dimethyl-2-butene in CCl4 at 25 °C a new absorption band due to an alkene–ICl molecular complex appears at 295 ± 5 nm and decreases rapidly with time. The rate law under conditions of (alkene)0 [Formula: see text] (ICl)0 for the electrophilic addition of ICl to 2,3-dimethyl-2-butene, E- and Z-2-butene, and E- and Z-1-phenylpropene is −d(ICl)/dt = kexpt(alkene)(ICl)3/{1 + kAD(alkene)}3 where KAD is the equilibrium constant for the formation of a 1:1 alkene–ICl molecular complex. The addition of ICl to the Z and E isomers of 2-butene and 1-phenylpropene occurs by anti-stereospecific addition. The negative enthalpy of activation for the addition of ICl to 2,3-dimethyl-2-butene is evidence that one or more complexes are involved on the reaction coordinate prior to the rate-determining step. On the basis of analysis of the enthalpy changes during the reaction, it is proposed that both a 1:1 and a 1:2 alkene–ICl molecular complex is involved in the mechanism prior to the rate-determining step.

Molecular Complexes of Cyclophanes, Part XVI On the Donor Properties of Polynuclear Paracyclophanes and their Sulfur Analogues

1987 ◽  
Vol 42 (9) ◽  
pp. 1142-1146 ◽  
Author(s):  
Aboul-fetouh E. Mourad ◽  
Joachim Hucker ◽  
Henning Hopf
Keyword(s):  
Charge Transfer ◽  
Infrared Spectra ◽  
Molecular Complexes ◽  
Electron Donors ◽  
Effect Of Temperature ◽  
H Nmr ◽  
High Basicity ◽  
The Stability ◽  
Ct Complexes

Visible, 1H NMR and infrared spectra of the charge-transfer (CT) complexes of polynuclear- [2.2]paracyclophanes and their sulfur analogues as electron donors with 2,3-dichloro-5.6-dicyanobenzoquinone (DDQ ), tetracyanoethylene (TCNE) and 9-dicyanom ethylene-2,4,7-trinitrofluorene (DTF) as π-acceptors have been measured. The data indicate an unexpected high basicity of the polynuclear hydrocarbons relative to their sulfur analogues. The types of CT interactions as well as different factors governing the stability of the CT complexes studied are discussed. The effect of temperature on the CT complexes studied are discussed. The effect of temperature on the CT complexes with TCNE is reported.

Topography and electrical conductivity of films of molecular complexes of zinc(II)tetra-tert-butylphthalocyanine with electron-donating ligands

2008 ◽  
Vol 12 (10) ◽  
pp. 1118-1122 ◽  
Author(s):  
Natalia Sh. Lebedeva ◽  
Elena A. Malkova ◽  
Shushanna R. Melkonyn ◽  
Mihail I. Fedorov ◽  
Sergey V. Maslennikov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Complex Formation ◽  
Molecular Complex ◽  
Molecular Complexes ◽  
Specific Electrical Conductivity ◽  
Polymorphous Modification ◽  
Molecular Complex Formation

Topography and specific electrical conductivity of films of molecular complexes of zinc(II)tetra-tert-butylphthalocyanine ( Zn (t- Bu )4 Pc ) with electron-donating ligands and films of pure α-polymorphous modification of zinc(II)tetra-tert-butylphthalocyanine have been studied. It has been found that the specific electrical conductivity increases from 30 to 3.5 × 105 times upon molecular complex formation of Zn (t- Bu )4 Pc with ligands.

scholarly journals Polymer Optical Waveguide Sensor Based on Fe-Amino-Triazole Complex Molecular Switches

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 195
Author(s):  
Muhammad Shaukat Khan ◽  
Hunain Farooq ◽  
Christopher Wittmund ◽  
Stephen Klimke ◽  
Roland Lachmayer ◽  
...  
Keyword(s):  
Molecular Complex ◽  
Electromagnetic Interference ◽  
Optical Power ◽  
Uv Curing ◽  
Molecular Complexes ◽  
Core Material ◽  
Absorption Bands ◽  
Electronic Temperature ◽  
Polymer Waveguide ◽  
Temperature Detection

We report on a polymer-waveguide-based temperature sensing system relying on switchable molecular complexes. The polymer waveguide cladding is fabricated using a maskless lithographic optical system and replicated onto polymer material (i.e., PMMA) using a hot embossing device. An iron-amino-triazole molecular complex material (i.e., [Fe(Htrz)2.85(NH2-trz)0.15](ClO4)2) is used to sense changes in ambient temperature. For this purpose, the core of the waveguide is filled with a mixture of core material (NOA68), and the molecular complex using doctor blading and UV curing is applied for solidification. The absorption spectrum of the molecular complex in the UV/VIS light range features two prominent absorption bands in the low-spin state. As temperature approaches room temperature, a spin-crossover transition occurs, and the molecular complex changes its color (i.e. spectral properties) from violet-pink to white. The measurement of the optical power transmitted through the waveguide as a function of temperature exhibits a memory effect with a hysteresis width of approx. 12 °C and sensitivity of 0.08 mW/°C. This enables optical rather than electronic temperature detection in environments where electromagnetic interference might influence the measurements.

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