Ultrasonic velocity (U), density (r) and viscosity (h) were measured in n-hexane solutions containing iodine (acceptor) and benzene, naphthalene, biphenyl or anthracene (donor) at various equimolar concentrations at 303K. The acoustical parameters such as adiabatic compressibility (k), free length (Lf), internal pressure ( pi) and molecular interaction parameter (c) are evaluated. The variation in acoustical parameters with concentration confirms the formation of donor-acceptor complex between iodine and the four arenes. The stability constant (K) and Gibbs free energy of formation ( DGo) values are reported for the Charge transfer (CT) complexes.

A spectrophotometric study concerning the interaction between Trimethoprim (TMP), Sulfamethoxazole (SFMx), as n-donor and 2, 3-dichloro-5, 6- dicyano-P-benzoquinine (DDQ) and chloranilic acid (CA) as p-acceptor were been performed at 25oC. The results of interaction of CA and DDQwith TMP indicate the formation of a 1: 1, 1: 2, Charge transfer complexes through non equilibrium reactions. In the case of SFMx, the formation of 1: 2 (SFMx/DDQ, SFMx /CA) Charge-transfer complexes is confirmed. The formation constants of the equilibrium step were evaluated from the computer fitting of the absorbance-mole ratio data. Also, this study was carried out to simultaneously determine quantitatively TMP in Cotrimoxazole.The complexes of TMP with DDQ and chloranilic acid absorbed maximally in 512 and 585, respectively.

Lithium and oxygen interaction plays a cornerstone role in lithium ion and lithium air batteries and lithium based technologies. In this way, oxidation and reduction of neutral and Charged lithium is the key process in its application as power source and sustainable energies. Since both oxidation and reduction are based on Charge transfer in molecular scale, they can be analyzed via electronic structure changes. Two types of fragmentations for Charged complexes were suggested, in which the positive Charge was located on either lithium or oxygen fragment. Deformation density analysis is a recently developed technique for identification of different intermolecular interactions in the context of quantum chemical language. In this analysis, the molecular orbitals of isolated fragments were employed to build non-interacting and anti-symmetrized fragments and the corresponding density matrices to find deformation density matrix of each one. In the present study, two types of deformation density including kinetic energy pressure and relaxation analyses were accomplished for lithium and oxygen interaction at B3LYP/6-311+G* theoretical level. Electronic deformation orbitals responsible for Charge transfer were identified with respect to their eigenvalues. The results showed how these two competed with each other in neutral and Charged complexes with different fragmentations.

The color developing reaction between ambrisentan and 2, 3-dichloro-5, 6-dicyano-1, 4- benzoquinone (DDQ) or 2, 5-dichloro-3, 6-dihydroxy-1, 4-benzoquinone (CLA) was successfully employed in the development of two simple and sensitive spectrophotometric methods (M1 and M2) for the determination of ambrisentan in its pharmaceutical dosage forms.The methods are based on the Charge transfer reaction of ambrisentan with DDQ (M1) or CLA (M2), to give colored radical anions. The colored products are measured at 560 nmin methanol and at 520 nm in acetonitrile for the methods M1 and M2, respectively. Under the optimized reaction conditions, Beer’s law is obeyed in the range of 5-50 mg ml-1 for both the methods. The limit of detection, limit of quantification, molar absorptivity and Sandell’s sensitivity were also reported for both the methods. Intra- and inter-day precision and accuracy of the methods were satisfactory. The proposed method was successfully applied to the quantification of ambrisentan in its tablet dosage forms with good accuracy and precision.