Synthesis and reactions of the thioamide derivatives of methyl vinyl ketone

The reaction of isothiocyanates with in situ generated carbanions of α,β‐unsaturated ketones yielded α,β‐unsaturated keto thioamides which in the reaction with acids or bases cyclized to give 2,6‐disubstituted thiopyran‐4‐ones and in the reaction with α‐bromoesters gave thiazolidin‐4‐one derivatives. The thiopyran‐4‐ones reacted with α,β‐unsaturated aldehydes to yield tetrahydrothiopyran[2,3‐b]pyridin‐4‐ones, while thioanilides were formed in the reaction with phenyl isothiocyanate.     

Comprehensive Evaluation of Late Season Peach Varieties (Prunus persica L.): Fruit Nutritional Quality and Phytochemicals

Peaches are one of the most preferred seasonal fruits, and a reliable source of nutrients. They possess biologically active substances that largely differ among varieties. Hence, revealing the potential of several late season peaches is of present interest. Three commonly consumed varieties (“Flat Queen”; “Evmolpiya”; “Morsiani 90”) were studied in terms of nutritive and phytochemical content, as well as antioxidant activity with the use of reliable spectrophotometric and High Performance Liquid Chromatographic (HPLC) methods. An analysis of the soil was also made. The phytochemical data were subjected to principal component analysis in order to evaluate their relationship. The “Morsiani 90” variety had the highest minerals concentration (2349.03 mg/kg fw), total carbohydrates (16.21 g/100 g fw), and α-tocopherol (395.75 µg/100 g fresh weight (fw)). Similar amounts of TDF (approx. 3 g/100 g fw) were reported for all three varieties. “Flat Queen’s” peel extract was the richest in monomeric anthocyanins (2279.33 µg cyanidin-3-glucoside (C3GE)/100 g fw). The “Morsiani 90” variety extracts had the highest antioxidant potential, defined by 2,2-diphenil-1-picrylhydrazyl (DPPH), ferric-reducing antioxidant power (FRAP) and cupric ion-reducing antioxidant capacity (CUPRAC) assays.     

Modeling toxicity by using supervised kohonen neural networks

Counterprogation neural network is shown to be a powerful and suitable tool for the investigation of toxicity. This study mined a data set of 568 chemicals. Two hundred eighty-two objects were used as the training set and 286 as the test set. The final model developed presents high performances on the data set R(2) = 0.83 (R(2) = 0.97 on the training set, R(2) = 0.59 on the test set). This technique distinguishes itself also for the ability to give to the expert two-dimensional maps suitable for the study of the distribution/clustering of the data and the identification of outliers.     

Application of microextraction by packed sorbent to isolation of psychotropic drugs from human serum

A method of microextraction by packed sorbent (MEPS) followed by liquid chromatography with diode array detection has been developed and optimized for the extraction of six tricyclic antidepressants (amitriptyline, nortriptyline, imipramine, desipramine, doxepin, nordoxepin) from human serum. The optimal parameters of MEPS extraction (type of sorbent, volume of sample, composition, and volume of washing and elution solutions) for these drugs in spiked samples were defined. The developed MEPS procedure was validated and then successfully applied to the analysis of serum reference material. The limit of detection (0.02–0.05 μg/mL), intraday (2.7–8.8%) and interday (4.4–11.6%) precision (RSD), and the accuracy of the assay (94.5–108.8%) at three concentration levels—0.2, 0.5, and 0.8 μg/mL—were estimated. The accuracy of the method was evaluated by the analysis of certified reference material. Moreover, the validated procedure was compared with the solid-phase extraction technique. Finally, microextraction by packed sorbent was assessed as a suitable tool in forensic and clinical methods for serum sample preparations.     

Investigations on the interaction of dichloroaluminum carboxylates with Lewis bases and water: an efficient road toward oxo- and hydroxoaluminum carboxylate complexes

A series of dichloroaluminum carboxylates [Cl(2)Al(O(2)CR)](2) (were R = Ph (1a), (t)Bu (1b), CHCH(2) (1c) and C(11)H(23) (1d)) were prepared and extended investigations on their structure and reactivity toward various Lewis bases and H(2)O performed. Compounds [Cl(2)Al(O(2)CR)](2) and their adducts with Lewis bases show a large structural variety, featuring both molecular and ionic forms with different coordination numbers of the metal center and various coordination modes of the carboxylate ligand. Upon addition of a Lewis base of moderate strength the molecular form [Cl(2)Al(O(2)CR)](2) equilibrates with new ionic forms. In the presences of 4-methylpyridine the six-coordinate Lewis acid-base adducts [Cl(2)Al(λ(2)-O(2)CR)(py-Me)(2)] [R = Ph (3a), (t)Bu (3b)] with a chelating carboxylate ligand were formed. The reactions of 1a, 1b, and 1d with 0.33 equiv of H(2)O in THF-toluene solution lead to oxo carboxylates [(Al(3)O)(O(2)CR)(6)(THF)(3)] [AlCl(4)] [where R = Ph (4a(THF)), (t)Bu (4b(THF)), and C(11)H(23) (4d(THF))] in high yield. The similar reaction of 1c in tetrahydrofuran (THF) afforded the chloro(hydroxo)aluminum acrylate [(ClAl)(2)(OH)(O(2)CC(2)H(3))(2) (THF)(4)][AlCl(4)] (5), while the hydrolysis of 1b in MeCN lead to the hydroxoaluminum carboxylate [Al(2)(OH)(O(2)C(t)Bu)(2)(MeCN)(6)][AlCl(4))(3)] (6). All compounds were characterized by elemental analysis, (1)H, (27)Al NMR, and IR spectroscopy, and the molecular structure of 1a, 3a, 3b, 4a(THF), 4b(THF), 4b(py-Me'), 5, and 6 were determined by single-crystal X-ray diffraction. The study provides a platform for testing transformations of secondary building units in Al-Metal-Organic Frameworks toward H(2)O and neutral donor ligands.     

Collagen Hydrolysate Prepared from Chicken By-Product as a Functional Polymer in Cosmetic Formulation

Chicken stomachs can be processed into collagen hydrolysate usable in cosmetic products. The aim of the study was to verify the effects of a carbopol gel formulation enriched with 1.0% (w/w) chicken hydrolysate on the properties of the skin in the periorbital area after regular application twice a day for eight weeks in volunteers ageed 50 ± 9 years. Skin hydration, transepidermal water loss (TEWL), skin elasticity and skin relief were evaluated. Overall, skin hydration increased by 11.82% and 9.45%, TEWL decreased by 25.70% and 17.80% (always reported for the right and left area). Generally, there was an increase in skin elasticity, a decrease in skin roughness, as the resonance times decreased by 85%. The average reduction of wrinkles was 35.40% on the right and 41.20% on the left. For all results, it can be seen that the longer the cosmetic gel formulation is applied, the better the results. Due to the positive effect on the quality and functionality of the skin, it is possible to apply the cosmetic gel formulation in the periorbital area. The advantage of the product with chicken collagen hydrolysate is also the biocompatibility with the skin and the biodegradability of the formulation.     

Naphthazarin Derivatives in the Light of Intra- and Intermolecular Forces

Our long-term investigations have been devoted the characterization of intramolecular hydrogen bonds in cyclic compounds. Our previous work covers naphthazarin, the parent compound of two systems discussed in the current work: 2,3-dimethylnaphthazarin (1) and 2,3-dimethoxy-6-methylnaphthazarin (2). Intramolecular hydrogen bonds and substituent effects in these compounds were analyzed on the basis of Density Functional Theory (DFT), Møller–Plesset second-order perturbation theory (MP2), Coupled Clusters with Singles and Doubles (CCSD) and Car-Parrinello Molecular Dynamics (CPMD). The simulations were carried out in the gas and crystalline phases. The nuclear quantum effects were incorporated a posteriori using the snapshots taken from ab initio trajectories. Further, they were used to solve a vibrational Schrödinger equation. The proton reaction path was studied using B3LYP, ωB97XD and PBE functionals with a 6-311++G(2d,2p) basis set. Two energy minima (deep and shallow) were found, indicating that the proton transfer phenomena could occur in the electronic ground state. Next, the electronic structure and topology were examined in the molecular and proton transferred (PT) forms. The Atoms In Molecules (AIM) theory was employed for this purpose. It was found that the hydrogen bond is stronger in the proton transferred (PT) forms. In order to estimate the dimers’ stabilization and forces responsible for it, the Symmetry-Adapted Perturbation Theory (SAPT) was applied. The energy decomposition revealed that dispersion is the primary factor stabilizing the dimeric forms and crystal structure of both compounds. The CPMD results showed that the proton transfer phenomena occurred in both studied compounds, as well as in both phases. In the case of compound 2, the proton transfer events are more frequent in the solid state, indicating an influence of the environmental effects on the bridged proton dynamics. Finally, the vibrational signatures were computed for both compounds using the CPMD trajectories. The Fourier transformation of the autocorrelation function of atomic velocity was applied to obtain the power spectra. The IR spectra show very broad absorption regions between 700 cm−1–1700 cm−1 and 2300 cm−1–3400 cm−1 in the gas phase and 600 cm−1–1800 cm−1 and 2200 cm−1–3400 cm−1 in the solid state for compound 1. The absorption regions for compound 2 were found as follows: 700 cm−1–1700 cm−1 and 2300 cm−1–3300 cm−1 for the gas phase and one broad absorption region in the solid state between 700 cm−1 and 3100 cm−1. The obtained spectroscopic features confirmed a strong mobility of the bridged protons. The inclusion of nuclear quantum effects showed a stronger delocalization of the bridged protons.     

Vibrational studies of the solid imidazole and pyridine adducts of metal(II) saccharinates. III. Zn(II) and Hg(II) imidazole saccharinates

Adducts of bis(o-sulfobenzimidato)zinc(II) and mercury(II) with imidazole are synthesized for the first time and their mid-infrared vibrational spectra at ambient conditions and at 77 K are coupled with the earlier spectra-structural inferences to predict aspects of the respective solid-state structures. The spectrum of the H2O-matrix isolated OD fundamentals in the hydrated zinc compound is also investigated. The structure of the latter adduct contrasts the octahedral isostructural tetrad of mixed imidazole-saccharinates [M(H2O)2(C3H4N2)4](C7H4NO3S)2 [M = Mn(II), Fe(II), Co(II) and Ni(II)] in that it bears only a single crystallographic type of hydrogen bonded C2v water molecules and at least two structurally different o-sulfobenzimidate ligands, some of them likely utilized in a bridging fashion. The rotation and the partial ionic character of a pair of N-monodentate o-sulfobenzimidato ligands placed about 212-214 pm from the metal accommodates another pair of imidazole molecules in the tetrahedral arrangement around the metal in the neutral unhydrous mercury complex.     

Trimethylsilyl fluorosulfonyldifluoroacetate (TFDA): a new, highly efficient difluorocarbene reagent

TFDA is readily prepared from the reaction of fluorosulfonyldifluoroacetic acid with trimethylsilyl chloride, and it is a very effective and efficient source of difluorocarbene for use in addition reactions to alkenes of a broad scope of reactivities. Acid-sensitive substrates may require an additional purification step involving treatment of the distilled TFDA with sufficient Et₃N to remove the acid impurity. Other trialkylsilyl fluorosulfonyldifluoroacetates can also be prepared, and they have been found to have reactivities similar to TFDA. The triethyl derivative, TEFDA is more convenient to prepare in a pure state and has similar reactivity to TFDA. Thus, it may prove to be a superior reagent.