Murat Saracoglu

Inhibition Effects of Amides on the Corrosion of Copper in 1.0 M HCl: Theoretical and Experimental Studies

Abstract The corrosion inhibition effects of benzamide (BA) and 4-aminobenzenesulfonamide (ABSA) for copper in 1.0 M hydrochloric acid (HCl) solution were investigated using potentiodynamic polarization, cyclic voltammetry (CV), and potentiostatic current-time curves. The Langmuir adsorption isotherms of the inhibitors were used to explain the adsorption behavior. In addition, surface analysis of copper was investigated using scanning electron microscopy (SEM). The results showed that the inhibition efficiency of ABSA was much better than those of BA. The theoretical study on the corrosion inhibition efficiencies for neutral and protonated forms of the BA and ABSA molecules were performed using density functional theory (DFT) and MP2 method in gas and water phases.

The Investigation of Structure-Activity Relationships of Tacrine Analogues: Electronic-Topological Method

In this study we investigated the structure-activity relationships by using the Electron- Topological Method (ETM) for a class of AChE inhibitors related to tacrine (9-amino-1,2,3,4-tetrahydroacridine) and 11 H-Indeno-[1,2-b]-quinolin-10-ylamine that tetracyclic tacrine analogues, a drug currently in use for the treatment of the AD. Molecular fragments being specific for active and inactive compounds were revealed by using ETM. The result of testing showed the high ability of ETM in predicting the activity and inactivity in investigated series.

Inhibition Performance and Adsorptive Behavior of Three Amino Acids on Cold-Rolled Steel in 1.0 M HCl—Chemical, Electrochemical, and Morphological Studies

Three selected amino acids, namely, serine (Ser), threonine (Thr), and glutamine (Glu), were tested as corrosion inhibitors for cold-rolled steel (CRS) in 1.0 M hydrochloric acid (HCl) solutions at different temperatures (283 K to 333 K). Chemical (weight loss) and electrochemical (Tafel polarization) methods were used in this study. Electrochemical frequency modulation (EFM), a non-destructive corrosion measurement technique that can directly give values of corrosion current without prior knowledge of Tafel constants, was also used. Experimental corrosion rates determined by the Tafel extrapolation method were compared with those obtained using the EFM technique and the weight-loss method. Morphologies of the corroded and the inhibited surfaces were studied by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM). Tafel plots showed that the three tested amino acids act as mixed-type inhibitors. The three tested amino acids appeared to function through adsorption following the Tem...

ETM-ANN Approach Application for Thiobenzamide and Quinolizidine Derivatives

The structure anti-influenza activity relationships of thiobenzamide and quinolizidine derivatives, being influenza fusion inhibitors, have been investigated using the electronic-topological method (ETM) and artificial neural network (ANN) method. Molecular fragments specific for active compounds and breaks of activity were calculated for influenza fusion inhibitors by applying the ETM. QSAR descriptors such as molecular weight, EHOMO, ELUMO, ΔE, chemical potential, softness, electrophilicity index, dipole moment, and so forth were calculated, and it was found to give good statistical qualities (classified correctly 92%, or 48 compounds from 52 in training set, and 69% or 9 compounds from 13 in the external test set). By using multiple linear regression, several QSAR models were performed with the help of calculated descriptors and the compounds activity data. Among the obtained QSAR models, statistically the most significant one is the one of skeleton 1 with R2 = 0.999.

Investigation of Structure-Activity Relationship Between Chemical Structure and CCR5 Anti HIV-1 Activity in a Class of 1-[N-(Methyl)-N- (Phenylsulfonyl)Amino]-2-(Phenyl)-4-[4-(Substituted)Piperidin-1-yl]Butane Derivatives: The Electronic-Topological Approach

The relationship between chemical structure and CCR5 anti HIV-1 activity was investigated in the series of 1-[N-(Methyl)-N-(phenylsulfonyl)amino]-2-(phenyl)-4-[4-(substituted) piperidin-1-yl]butanes derivatives including 114 molecules by using the Electron-Topological Method (ETM). In the frameworks of this approach, its input data were taken as the results of conformational and quantum-mechanical calculations. Conformational analysis and quantum-chemical calculations were carried out for each molecule. Then molecular fragments being specific for active molecules and non-active molecules were revealed by using ETM. The result of testing showed the high ability of ETM in predicting the activity and inactivity investigated series. In order to classify and to develop a model for those molecules, cluster and discriminant analyses are conducted. First, cluster analysis is implemented in order to classify similar molecules into the groups. Then, discriminant analysis is used to construct models including descriptors. By doing so, two obtained discriminant functions segregate those molecules into three different groups by using the descriptors called EHOMO, Dipole Moment and SEZPE.

The structure-AChE inhibitory activity relationships study in a series of pyridazine analogues.

The structure-activity relationships (SAR) are investigated by means of the Electronic-Topological Method (ETM) followed by the Neural Networks application (ETM-NN) for a class of anti-cholinesterase inhibitors (AChE, 53 molecules) being pyridazine derivatives. AChE activities of the series were measured in IC(50) units, and relative to the activity levels, the series was partitioned into classes of active and inactive compounds. Based on pharmacophores and antipharmacophores calculated by the ETM-software as sub-matrices containing important spatial and electronic characteristics, a system for the activity prognostication is developed. Input data for the ETM were taken as the results of conformational and quantum-mechanics calculations. To predict the activity, we used one of the most well known neural networks, namely, the feed-forward neural networks (FFNNs) trained with the back propagation algorithm. The supervised learning was performed using a variant of FFNN known as the Associative Neural Networks (ASNN). The result of the testing revealed that the high ETMs ability of predicting both activity and inactivity of potential AChE inhibitors. Analysis of HOMOs for the compounds containing Ph1 and APh1 has shown that atoms with the highest values of the atomic orbital coefficients are mainly those atoms that enter into the pharmacophores. Thus, the set of pharmacophores and antipharmacophores found as the result of this study forms a basis for a system of the anti-cholinesterase activity prediction.

ETM and ANN study for polysubstituted 2H-pyran-2-ones.

The structure glutamate pyruvate transaminase (GPT), glutamate oxaloacetate transaminase (GOT), acid phosphatase (ACP), alkaline phosphatase (ALP) and glutamate dehydrogenase (GlDH) activity relationships of 2H-pyran-2- ones polysubstitutes being a new class of hepatoprotective agents have been investigated by means of the Electronic- Topological Method (ETM) and two Statistical Analysis. Molecular fragments specific for active compounds were calculated for 2H-pyran-2-ones polysubstitutes by applying the ETM. QSAR descriptors such as molecular weight, EHOMO, ELUMO, ΔE, chemical potential, softness, electrophilicity index, dipole moment, etc were calculated. In order to examine the relationship between independent and dependent variables, both Partial Least Squares Regression and ANNs are employed to determine the relationship since the data set consists of highly nonlinearity and multicolinearity. It is observed that ANN has surpassed both PLS2 and PLS1 in terms of better modeling and validation.

Quantum Chemical Calculations for some Isatin Thiosemicarbazones

Derivatives of isatin are reported to be present in mammalian tissues and body fluids (Casas et al., 1996; Agrawal & Sartorelli, 1978; Casas et al., 1994; Medvedev et al., 1998; Boon, 1997; Pandeya & Dimmock, 1993; Rodriguez-Arguelles et al., 1999; Casas et al., 2000) and possess antibacterial (Daisley & Shah, 1984), antifungal (Piscopo et al., 1987), and anti-HIV (Pandeya et al., 1998, 1999) activities. N-methylisatin--4’, 4’ – diethylthiosemicarbazone were also reported to have activity against the viruses such as cytomegalo and moloney leukemia viruses (Sherman et al., 1980; Ronen et al., 1987). With the help of combinatorial method, the cytotoxicity and antiviral activities of isaitin--thiosemicarbazones against the vaccine virus and cowpox virus-infected human cells were evaluated (Pirrung et al., 2005).