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Biguanides [HN=C(NR)=NH] constitute an important family of molecules used as drugs in the treatment of diabetes. When R 1 =R 2 =R 3 =R 4 =H the molecule is named simply "biguanide". The five nitrogen atoms are potential coordination sites. Several experimental works published in literature show that in complex state, therapeutic properties of the active molecules increase considerably. In fact, the chlorine atom, a preferred substitute in pharmacy, improves the effectiveness of these drugs by increasing their activities and also by reducing their side effects. Recent experiments with Zinc complexes on diabetic animals have been very successful. In the present work a theoretical study of the coordination of N-chlorine derivatives of Ndeprotonated tautomer of biguanide has been carried out. The aim is to determine, among the five nitrogen and chlorine atoms, the site most favorable to the coordination of these ligands. This determination is based on some coordination indicators. François et al.; IRJPAC, 21(2): 10-25, 2020; Article no.IRJPAC.54821 11 The calculations were performed by the DFT / B3LYP method in the 6-31G (d, p) orbital basis set with the Gaussian 09 and Gaussian 03 software. The DCENT-QSAR program was also used. The results of the various calculations revealed the imine nitrogen atoms as the most favorable coordination sites in the studied N-chlorosubstituted derivatives of N-deprotonated tautomeric biguanide. Complexes of these ligands with Zn (II) were modelled. The chlorine atom proved unfavorable to coordination. Original Research Article

IntroductionGiven the dizzying growth in global energy needs and the surge in crude oil prices, the diversification of energy sources and, above all, the use of renewable sources of energy that respects the environment are increasingly emerging as the best alternative to curbing the crisis [1]. Among the renewable energy sources the solar energy, practically inexhaustible, is by far the most available natural source of energy, clean and accessible at every point of the earth's surface [1,2]. It can therefore be an excellent solution to the problem of energy supply in the world and especially in the sunny geographical areas of the globe.The 99% of the photovoltaic cells produced today in the world, to tame and to use the solar energy, are based on silicon, material of which the growing demand in the electronic field raises the problem of its availability. Moreover, the production of this material requires truly polluting and costly purification processes which make it impossible for ordinary people to acquire and use silicon-based solar panels as a source of energy [1]. This is why, worldwide, research teams are working to find other materials with interesting semiconductor properties. In this stride, organic molecules or polymers are increasingly explored and used as semiconductor materials in the design of photovoltaic cells. However, in this scientific endeavor, one of the challenges still remains the improvement of the electrical conversion efficiency of these organic semiconductors [1][2][3]. The semiconducting properties of organic materials come from the alternation of single and double covalent bonds in their molecular structures [1][2][3][4][5]. This electronic conjugation which favors the delocalisation and the circulation of the electronic charges can then constitute a first criterion for the selection of the molecules likely to be involved in the design of an organic photovoltaic cell. The photovoltaic effect is a phenomenon which consists in generating electricity by absorption and conversion of light energy into electrical energy. An organic solar cell consists of a layer of photoactive organic materials sandwiched between two electrodes [1,2]:i. The active layer consists, on the one hand, of electrondonating organic molecules (D), possessing a low ionization potential and permitting the transport of holes, and, on the other hand, of organic electron accepting molecules (A), having a high electron affinity and enabling the electron transport. AbstractPolyacetylens noted PA, with general formulae ( )are organic compounds with double conjugated bonds. They are the thirst polymers conducting characters which, after doping, were highlighted. Indeed, the semiconducting character of an organic material resides in the alternation of single and double covalent bonds; the π bonds electrons, in these conditions, are able to be delocalization. That delocalisation assures the transport of charges. The substitution derivatives of these compounds may exhibit better conduction capabilities. Since AP and their der...