A statistical comparative study between the functions of alcohols and thiols using quantum chemistry methods

Using the QSAR method, the present work aims to comparatively study the relationship between solubility (data from literature) and several physical and chemical parameters (computationally calculated) for two classes of analogue compounds, i.e. alcohols and their corresponding thiols. The obtained results show that there are significant differences between the ways in which solubility can be computationally determined for these two classes

Qsar analysis of toxicity for a series of aromatic compounds

Aromatic compounds are particularly interesting to scientists due to environmental and human health concerns. QSAR models are increasingly used to investigate the relationship between the toxicity of a pollutant and its structural properties, on the assumption that pollutants similar in structure and physicochemical properties are likely to be similar in toxicity. Based on the above mentioned, this paper investigates the relationship between electron affinity, ionization potential, and the toxicity of some aromatic compounds. Correlation and linear regression are used as QSAR analysis methods

Non-ambient FTIR study of thermally treated seashells

A large quantity of waste seashells (millions of tons) is discarded annually after mollusc consumption, which becomes a problem for the environment worldwide as these shells are a habitat for microbes which could turn into a public health issue [1]. On the other hand, waste shell biomaterials need a small amount of energy for recycling and processing into useful products for various applications. Calcium carbonate is essential in biomineralization, where it is the primary constituent of mollusc shells, crustacean cuticles, corals etc. In its pure form, it occurs naturally, under normal temperature and pressure conditions, in three anhydrous crystalline forms, namely calcite, aragonite and vaterite [2]. At high pressures, two further forms, namely calcite II and calcite III, are formed. The most stable form of calcium carbonate at atmospheric pressure and room temperature is calcite. The presence of both calcite and aragonite is very frequent in biologically produced calcium carbonate minerals. Though aragonite is metastable in aqueous solution, it can nucleate [3]. Aragonite is found in the nacre of the shells of bivalve molluscs, which provide a protection for these animals [4]. From the study of the marine bivalve species Mercenaria mercenaria and Crassostrea gigas, Weiner et al. [5] have shown that amorphous calcium carbonate is a precursor phase of aragonite. The present study, which is part of our efforts to convert seashells into useful products like hydroxyapatite, investigates the temperature influence on the calcite and aragonite in a processed shell sample by using Fourier-transform infrared spectroscopy (FTIR)

A spectroscopic and semiempirical quantum chemical study of copper (II) phthalocyaninate

Copper(II) phthalocyaninate (CuPc) was studied using both the PM3 and PM7 semiempirical molecular orbital methods, and the results were compared with its XRD, FTIR and Raman experimental properties

Hydrothermal synthesis of hydroxyapatite with tartaric acid

The hydrothermal synthesis of hydroxyapatite (HA) with addition of tartaric acid (TA) is presented in the paper. The role of tartaric acid is to form a complex with the Ca ions and to help in tailoring the crystallization behavior of hydroxyapatite. A comparison is made between two situations: one is characterized by the addition of tartaric acid after the precipitation of hydroxyapatite, and the other is defined by tartaric acid being added to the Ca precursor, followed by the addition of the P precursor. The crystalline particles resulted were studied by means of XRD, FTIR, SEM and TEM, and it was concluded that they consist in hexagonal lamellar crystals with lengths < 200 nm and widths < 50 nm. The difference between the two cases is that the crystallinity degree, the uniformity in crystal dimensions and the aspect ratio are higher when TA was added before the precipitation rather than to the precipitated HA. The dimensions of the achieved crystals are similar to the mineral grains found in the hard tissues of the human body

A spectrophotometrical analitic method elaboration for tinidazole’s quantity determination from tablets

The main inconvenience of analytical determination of Tinidazole in pharmaceutical formulations consists in presence of ingredients, frequently with unknown identity. In order to overcome the complications of methods based on selective separations, a spectrophotometrical method for Tinidazole assay was performed and tested. By appropriate derivatization of the analythe, a photometrically estimable Schiff base is obtained, with absorptionin the visible region where the interference of ingredients is negligible. The linearity of analytic signal was checked out in methanol solution in the 2–14 mg/l concentration domain. The method exhibit a good reproducibility: in a 8-fold repetition the main standard deviation is 0.38 % of the average of individual values

Solvatochromism in Diketopyrrolopyrrole Derivatives: Experimental and Computational Studies

A series of seven thiophen-substituted diketopyrrolopyrrole derivatives were synthesised and their solution absorption spectra characterised in a range of solvents of varying polarity. The absorption spectra of these diketopyrrolopyrrole derivatives exhibited significant negative solvatochromism. The behaviour is consistent with results of time-dependent density-functional theory calculations of excitation energies. Calculated electronic structures suggest that there is significant charge transfer between the electron-donating thiophen substituents and the diketopyrrolopyrrole core but that the magnitude of this charge shift is reduced in the excited state compared with the ground state. The resulting reduction in polarity of the excited state accounts for the negative solvatochromism observed. The implications of the results for the potential application of diketopyrrolopyrrole compounds as photovoltaic materials are considered