Charge transfer complex formation between 8-hydroxyquinoline as the electron donor and citric acid as the electron acceptor has been studied spectrophotometrically in ethanol and methanol solvents at room temperature. Absorption band due to charge transfer complex formation was observed near 320 and 325？nm in ethanol and methanol, respectively. The stoichiometric ratio of the complex has been found 3？:？1 by using Job’s and conductometric titration methods. Benesi-Hildebrand equation has been applied to estimate the formation constant and molecular extinction coefficient. It was found that the value of formation constant was larger in ethanol than in methanol. The physical parameters, ionization potential, and standard free energy change of the formed complex were determined and evaluated in the ethanol and methanol solvents. 1. Introduction Mulliken also showed that the charge transfer interactions within a molecular complex consisting of an electron donor (ED) and an electron acceptor (EA) involved a resonance with a transfer of charge from ED to EA [1, 2]. Charge-transfer complexes result from a donor-acceptor mechanism of Lewis acid-base reaction between two or more different chemical constituents. The formation of electron-donor acceptor (EDA) complexes can be rapidly assessed for its validity as a simple quantitative analytical method for many drug substances which can act as electron donors. Charge transfer complexes have been studied exclusively due to their wide application as ion sensors in the field of environmental science and in the determination of drugs based on the charge-transfer (CT) complexes formed with electron acceptors [3–5]. They also can be used as organic semiconductors photo catalysts, dendrimers, and in the studying of redox processes [6]. More recently, attention has been given to the isolation and investigation of physical properties of some CT-complexes in the solid states. Some of these complexes show interesting electrical conductivity properties and have found applications in many forms of electronics and solar cells [7]. Charge transfer complexation is currently to achieve the great importance in biochemical, bioelectrochemical energy transfer process, biological systems, and drug-receptor binding mechanism, for examples, drug action, enzyme catalysis, and ion transfers through lipophilic membranes [8]. Recently, many studies have been widely reported about the rapid interactions between different kinds of drugs and related compounds as donors like morpholine, norfloxacin, ciprofloxacin, and sulfadoxine, with several
References
[1]
R. S. Mulliken, “Structures of complexes formed by halogen molecules with aromatic and with oxygenated solvents,” Journal of the American Chemical Society, vol. 72, no. 1, pp. 600–608, 1950.
[2]
M. S. Refat, M. Y. El-Sayed, A. M. A. Adam, H. A. Saad, and H. H. Eldaroti, “Charge transfer complexes as a semiconductor models: outline of spectroscopic studies on electron donor-acceptor complexes of hexane-1,6-diol with different -acceptors,” International Journal of Electrochemical Science, vol. 8, no. 3, pp. 4234–4259, 2013.
[3]
M. S. Refat, H. A. Didamony, K. M. A. El-Nour, I. Grabchev, L. El-Zayat, and A. M. A. Adam, “Spectroscopic characterizations on the N,N'-bis-alkyl derivatives of 1,4,6,8-naphthalenediimide charge-transfer complexes,” Arabian Journal of Chemistry, vol. 4, no. 1, pp. 83–97, 2011.
[4]
I. M. Khan, A. Naeem, and A. Ahmad, “Semiquantitative determination of some nitrogen compounds by the formation of charge-transfer complexes of diphenylamine with p-dimethylaminobenzaldehyde by capillary solid-state spot-tests,” Chinese Chemical Letters, vol. 21, no. 6, pp. 720–724, 2010.
[5]
D. Wu, L. Zhao, X. Liu et al., “Photon-driven charge transfer and photocatalysis of p-aminothiophenol in metal nanogaps: A DFT study of SERS,” Chemical Communications, vol. 47, no. 9, pp. 2520–2522, 2011.
[6]
I. M. Khan and A. S. N. Ahmad, “Spectroscopic studies of multiple charge transfer complexes of 8-hydroxyquinoline with acceptor p-Nitrophenol in different solvents at room temperature,” Canadian Journal of Analytical Sciences and Spectroscopy, vol. 54, no. 1, pp. 31–37, 2009.
[7]
M. S. Refat, S. A. El-Korashy, I. M. El-Deen, and S. M. El-Sayed, “Charge-transfer complexes of sulfamethoxazole drug with different classes of acceptors,” Journal of Molecular Structure, vol. 980, no. 1–3, pp. 124–136, 2010.
[8]
A. M. A. Adam, M. Salman, T. Sharshar, and M. S. Refat, “Chemical and physical studies on the reaction mechanism of charge-transfer complexes between narcotic drugs and electronic acceptors,” International Journal of Electrochemical Science, vol. 8, no. 1, pp. 1274–1294, 2013.
[9]
M. S. Refat, L. A. El-Zayat, and O. Z. Ye？ilel, “Spectroscopic characterization of charge-transfer complexes of morpholine with chloranilic and picric acids in organic media: crystal structure of bis(morpholinium 2,4,6-trinitrocyclohexanolate),” Spectrochimica Acta A: Molecular and Biomolecular Spectroscopy, vol. 75, no. 2, pp. 745–752, 2010.
[10]
I. M. Khan and A. Ahmad, “Spectrophotometric and spectroscopic studies of complexation of 8-hydroxyquinoline with acceptor metadinitrobenzene in different polar solvents,” Spectrochimica Acta A: Molecular and Biomolecular Spectroscopy, vol. 73, no. 5, pp. 966–971, 2009.
[11]
S. Amirah, M. M. AL-Attas, H. Maram, and T. Basha, “Spectrophotometric and conductimetric studies of charge transfer complexes of some pyrimidine derivatives with chloranilic acid as π-acceptor in methanol,” World Journal of Chemistry, vol. 2, pp. 16–24, 2007.
[12]
I. A. Mansour, “Spectral and electrical conductance studies of charge-transfer complexes derived from 6-aminoindazole schiff bases and chloro-p-benzoquinone derivatives,” Chemical Papers, vol. 59, no. 3, pp. 174–177, 2005.
[13]
F. S. Mooney and J. G. Heathcote, “Lack of proteolytic digestion in the causation of pernicious anaemia,” The Lancet, vol. 2, no. 7512, pp. 397–399, 1967.
[14]
L. R. Naik and N. N. Math, “Photo physical properties of 8-hydroxy quinoline,” Indian Journal of Pure and Applied Physics, vol. 43, no. 10, pp. 743–749, 2005.
[15]
A. A. Ibrahim, “Spectrophotometric studies of charge transfer complex of 8-hydroxyquinoline with 1, 4-benzoquinone,” African Journal of Pure and Applied Chemistry, vol. 5, no. 16, pp. 507–514, 2011.
[16]
P. Job, Advanced Physicochemical Experimental, Pitman, London, UK, 1964.
[17]
O. M. Al-Shuja'A, A. O. Obeid, and A. G. El-Shekeil, “Spectral, thermal and dc electrical conductivity of charge transfer complex formed between 5,7-dimethyl-1-oxo-2-phenyl-1H-pyrazolo [1,2-α]pyrazol-4- ium-3-olate and iodine,” Journal of Macromolecular Science, vol. 48, no. 5, pp. 355–364, 2011.
[18]
F. Yakuphanoglu and M. Arslan, “Determination of electrical conduction mechanism and optical band gap of a new charge transfer complex,” Solid State Communications, vol. 132, no. 3-4, pp. 229–234, 2004.
[19]
F. Doaa, E. H. Baamer, E. L. Mossalamy, S. Salih, and A. L. Juaid, “Spectrophotometric and kinetic studies of charge transfer complexes of pantoprazole with chloranilic acid and DDQ as π-acceptors,” in Proceedings of the 2nd International Conference on Chemical, Environmental and Biological Sciences, pp. 17–18, 2013.
[20]
H. A. Benesi and J. H. Hildebrand, “A spectrophotometric investigation of the interaction of iodine with aromatic hydrocarbons,” Journal of the American Chemical Society, vol. 71, no. 8, pp. 2703–2707, 1949.
[21]
K. M. Al-Ahmary, M. M. Habeeb, and E. A. Al-Solmy, “Spectroscopic and thermodynamic studies on charge transfer complex formation between 2-aminopyridine and 2,5-dihydroxy-p-benzoquinone,” Journal of Solution Chemistry, vol. 39, no. 9, pp. 1264–1277, 2010.
[22]
R. M. Alghanmi, “Spectrophotometric study of charge transfer complex between 2,6-diaminopyridine and 2,5-dihydroxy-p-benzoquinone,” Physics and Chemistry of Liquids, vol. 51, no. 3, pp. 365–380, 2013.
[23]
G. G. Aloisi and S. Pignataro, “Molecular complexes of substituted thiophens with σ and π acceptors. Charge transfer spectra and ionization potentials of the donors,” Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases, vol. 69, pp. 534–539, 1973.
[24]
A. N. J. Martin and A. Swarbrick, Cammarata, Physical Pharmacy, Lee and Febiger, Philadelphia, Pa, USA, 3rd edition, 1969.
[25]
E. Nour, S. Y. Alqaradawi, A. Mostafa, E. Shams, and H. S. Bazzi, “Synthesis, characterization and spectroscopic structural studies of charge-transfer complexes of 1,4,8,11-tetraazacyclotetradecane-5,7-dione with iodine, TCNE and DDQ,” Journal of Molecular Structure, vol. 980, no. 1–3, pp. 218–224, 2010.
