Bulgarian Chemical Communications, Volume 50, Special Issue-I, 2018

Pages 4-4
Download PDF (179 KB)


An investigation of the pH effect on the particlesize and zeta potentials of poly (ethylene glycol) and poly ethylene-block-poly(ethyleneglycol) with various molecular weights
Original Research Article
Pages 5 – 11
D. Sakar Dasdan, G. Tosun, Y. Karahan
Download PDF (628 KB)

The aim of this study is to investigate the effect of the polyethylene (PE) segments on the charge and particle size of poly(ethylene glycol). For this purpose, in this current work, to compare the charge and particle size of poly(ethylene glycol) and PEG co-polymerized with PE segments polyethylene-block-poly(ethylene glycol) (PE-b-PEG) which is surfactant, emulsifier for coatings, ceramics, mold release agent and thickening with different molecular weights have been examined by Zeta Potential Analyzer. Zeta potential, mobility, and particle size of PEG and PE-b-PEG systems were determined by using the Zeta Potential Analyzer in water as a function of pHs..


Controlled release of donepezil hydrochloride from PEG-DA hydrogels
Original Research Article
Pages 12 – 17
S. Senol, E. Akyol
Download PDF (824 KB)

Aim of the research work is to create a controlled-release system through the preparation and characterization of hydrogels based on polyethylene glycol diacrylate (PEG-DA). To determine the influence of photo-initiators on the drug release behavior of the resulting hydrogels, three different photo-initiators 2,2-dimethoxy-2-phenyl-acetophenone (Irgacure 651), 1-hydroxycyclohexyl phenyl ketone (Irgacure 184) and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959) were used. In addition, hydroxyapatite (Hap) was employed to modify PEG-DA hydrogels. Fourier transform infrared (FT-IR) spectroscopy and digital microscopy were used for characterizing the prepared hydrogels. Swelling ratios and release behaviors of the prepared hydrogels under different conditions were investigated. Drug release studies were performed at pH 1.2, 6.8 and 7.4.


Particle size prediction of copolymer-drug conjugate using partial least squares regression
Original Research Article
Pages 18 – 24
F. Noyan Tekeli, D. Sakar Dasdan, G. Karakus
Download PDF (809 KB)

Particle size of the copolymers and the associated polydispersity are among the most important factors affecting biopharmaceutical behavior in a wide variety of therapeutic applications. Particle size provides valuable properties of particles or molecules in liquid medium. This characteristic directly affects bioavailability, dissolution and immunotoxicity. Predicting particle size will often skip many preliminary studies that are necessary to optimize formulations. In this work, the particle size of copolymer-drug conjugates was tried to be predicted using partial least squares regression (PLSR). The aim of this article is to construct a mathematical model for predicting the particle size of the copolymer-drug conjugate produced by a preferred pharmaceutical polymer. PLSR is a method that involves a combination of principal component analysis and multiple regression analysis for building predictive models when the factors are many and highly collinear. In the present study, to calculate the particle size of the copolymer-drug conjugate, we used the zeta potential and the particle size of the copolymer and drug, and different pH values as inputs.


An entry to the synthesis of uleine-type alkaloids by Fischer indole synthesis reactions: FT-IR, NMR spectroscopy and computational study of the substituted carbazole compound
Original Research Article
Pages 25 – 37
G. Serdaroglu, N. Uludag
Download PDF (953 KB)

An efficient and straightforward method for the synthesis of 2-(2,3,4,9-tetrahydro-1H-carbazole-2-yl)acetonitrile by Fischer reaction of phenylhydrazine hydrochloride acid and 2-(3-oxocyclohexyl)acetonitrile in presence of ethanol is reported. Mild reaction conditions, good yields of products, short reaction times, and operational simplicity are the advantages of this procedure. PES scan was performed to determine the stable conformers of the studied compound in the gas phase at B3LYP/6-31G(d,p) level of the theory.The1H and 1C NMR chemical shifts for each stable conformer of the studied compound were observed and simulated by the DFT method in both gas and water phases. Also, the recorded FT-IR spectrum of the studied compound wascompared with the simulated vibrational modes for each stable conformer. NBO was employed to predict the important intra-molecular interactions contributing to the lowering of the molecular stabilization energy of each stable conformer. FMO analysis and MEP diagrams were performed to predict the physicochemical and quantum chemical parameters to estimate the chemical reactivity behavior and reactive sites of each stable conformer.


Mechanism of the electron-exchange reactions between mixed ligand Fe(III) complexes and cyano complex of Fe(II)
Original Research Article
Pages 38 – 44
Rozina Khattak, Muhammad Sufaid Khan, Iftikhar Imam Naqvi
Download PDF (517 KB)

Our interest was to study the reactions of those mixed ligand complexes of Fe(III), where cyanide plays its role as a ligand. We synthesized the mixed ligand complexes of Fe(III) with diimine and cyanide as ligands to form octahedral geometry with high stability. We adopted previously cited procedures with improvements. The synthesized complexes, [FeIII(phen/bpy)2(CN)2]+ were reduced by the hexacyano complex of Fe(II) that is well-known for its high stability and octahedral geometry. The reduction was performed in aqueous medium at constant ionic strength of 0.06. The progress of the reactions was monitored spectrophotometrically by measuring the formation of [FeII(phen/bpy)2(CN)2], i.e., the increase in absorbance with time. We found that the reduction of the mixed ligand Fe(III) complexes takes place in two phases. The first phase, when the Fe(III) complex is reduced to the neutral Fe(II) complex followsing zeroth order kinetics. The second phase was observed to be the rate-determining or slow step in the reduction of each complex, and the electron-exchange took place by an overall second order kinetics. In order to refine our results and to differentiate between the species which were taking part in the rate-determining step (slow step) and those which were taking part in the fast step, we studied the effect of protons and ionic strength on the rate constants in aqueous medium. We proposed an outer-sphere mechanism for the electron-exchange between Fe(III) and Fe(II) complexes.


Possible reaction pathways of the acetamiprid molecule according to the DFT calculation method
Original Research Article
Pages 45 – 52
B. Eren, Y. Yalcin Gurkan
Download PDF (1015 KB)

Acetamiprid, the major active ingredient of some pesticides, is a subclass of the neonicotinoid group and is used especially against whitefly, aphididae, leaf bugs, potato bugs which affect products such as cotton, tobacco, potato, tomato, nut, citrus, planted in greenhouses and fields. Quantum chemical calculations of density functional theory (DFT) were used to investigate the structural and physical characteristics of acetamiprid. The analysis was made on the probable reaction path of acetamiprid molecule with OH radicals. The calculation of the optimized geometry and the geometric optimization for determination of the lowest energy status were made by the Gauss View 5 and the Gaussian 09 program. Activation energy for the probable reaction paths was calculated and its most stable states from the thermodynamic perspective were determined for the different phases. The aim of this study is to estimate the degradation mechanism of acetamiprid molecule in gaseous phase, in ethanol and water as polar solvents, and in chloroform as a partially polar solvent, all of which were analysed through the conductor-like screening solvation model (COSMO) as the solvation model. The probable reaction path of the activation energy was calculated, and its most stable state in the thermodynamic frame was determined for these phases.


Investigation of in vitro salt stress on peroxidase enzyme of Amsonia orientalis and purification of peroxidase from non-stressed and salt-stressed plants
Original Research Article
Pages 53 – 59
Y. Duman, M. Yilmaz
Download PDF (568 KB)

In this study, we focused on in vitro salt stress on peroxidase (POD) enzyme activity change of Amsonia orientalis. The plant was subjected to 25, 50, 75, 100, 125 and 150 mM NaCl salinity for 30 days. Change of POD activity was observed by spectrophotometric and activity staining assays. Our findings indicated that POD activity didn’t dramatically change especially when plant was exposed to high salinity. The specific activity of POD of non-stressed plant was calculated as 0.74 (U/mg), while the highest specific activity was seen at 50 mM NaCl and the lowest specific activity at 150 mM NaCl as 0.87 (U/mg) and 0.54 (U/mg), respectively. For further analysis of salt stress effect on POD activity, the enzyme was purified from non-stressed and 50 mM salt-stressed A. orientalis. Similar purification profiles were observed for non-stressed and 50 mM salt-stressed plant at 4.570-fold purification with 8% yield and at 4.10-fold purification with 7% yield. The molecular weights of purified enzymes from both extracts were determined by electrophoretic methods as 59 kDa. These results suggest that POD is a strong defensive enzyme against salinity due to non-change of its activity especially in 50 mM NaCl by monitoring POD activity in crude and purified extracts.


Inhibition effect of polyacrylic acid and its mixture with potassium iodide on mild steel corrosion in acid solution
Original Research Article
Pages 60 – 67
I. Dehri, G. Sigircik, A. Sari, M. Erbil
Download PDF (979 KB)

The synergistic inhibition effect of polyacrylic acid and iodide ions was studied against mild steel corrosion in 0.5 M HCl solution. Potentiodynamic and electrochemical impedance spectroscopy measurements were realized in order to examine the corrosion process. In addition, the effect of long exposure period on inhibition efficiency was investigated. Surface morphology of steel was investigated by scanning electron microscopy technique. The obtained consequences revealed that mixture of polyacrylic acid and potassium iodide exhibited enhanced inhibition efficiency for mild steel corrosion because of synergistic effect.