Vibrational spectroscopic study of brazilin and brazilein,the main constituents of brazilwood from Brazil

In this work, the vibrational spectra (FT-Raman and infrared spectra) of brazilin, the major component of brazilwood Caesalpinia echinata (from Bahia, Brazil), and brazilein, the oxidised pigment, are investigated. The FT-Raman spectra of the compounds show different patterns in the carbonyl stretching region, where brazilein presents a Raman feature at 1697 cm⁻¹ that is tentatively assigned to a coupled vibrational mode described by CO and aromatic CC stretching. Infrared measurements are used to support this assignment. The spectral region between 1700 and 1500 cm⁻¹ is also proposed as a fingerprint for brazilin and brazilein. Comparisons with some quinones and polyalcohols as parent molecules and other deep red resin pigments such as “dragon’s blood” are undertaken to assist the vibrational assignment. As a test of the spectroscopic protocol for the identification of these pigments in natural brazilwoods, an 80-year-old archival specimen of Caesalpinia echinata was analysed non-destructively and the feature of brazilein shown from the Raman spectrum.     

Effect of Spirulina (Arthrospira platensis) Supplementation on Physical and Chemical Properties of Semolina (Triticum durum) Based Fresh Pasta

Taking into account that many advantages have been associated with the consumption of spirulina (microalgae) in terms of antioxidant capacity, anticancer, anti-inflammatory, and anti-aging activities, the study focuses on spirulina supplementation of semolina-based pasta. Fresh pasta was prepared by mixing semolina flour (Triticum durum) with an addition of 3, 5, 7, and 10% (w/w) of spirulina (Arthrospira platensis) powder. Physicochemical and nutritional analyses were done on raw materials, and on fresh pasta before and after cooking. Sensorial analysis was done shortly after cooking pastas. Spirulina had a high content of protein (71.34%), with all the essential amino acids, a high total fiber (8.45%), as well as ash content (5.93%), which significantly increased the nutritional value of the obtained fresh pasta. Supplemented pastas have a significantly better amino acid profile and higher total fiber content (up to 2.99 g/100 g d.m.) than the control sample. Moreover, the addition of spirulina had a significant effect on the pasta’s color, weight gain, and cooking loss after being cooked. The addition of spirulina also affected the scores obtained for the individual parameters (texture, color, flavor, taste, and overall acceptability) of the sensory evaluation.     

Calculated ro-vibrational spectrum of 7Li+3 and 7Li2 6Li+

Calculated ro-vibrational energy levels (J ⩽ 4) and transition intensities are presented for the two most abundant isotopomers of Li⁺₃. The calculations use the recent ab initio potential energy surface of Searles et al. (Spectrochim. Acta 43A, 699 (1987); 44A, 505 (1988); 44A, 985 (1988)). The rotational levels of the ground state and vibrational fundamentals are given in terms of parameterised Hamiltonians due to Watson retaining terms to fourth-order. The small splitting of the degenerate ν₂ mode in the mixed isotopomer leads to strong Coriolis coupling between the ν₂ and ν₃ in ⁷Li₂ ⁶Li⁺.     

Some novel liquid crystalline derivatives of 4-carboxyphthalimide

A series of novel esters of 4-carboxyphthalimides has been prepared. Differential scanning calorimetry and polarizing optical microscopy studies reveal that N-substituted 4-cholesteryloxycarboxyphthalimides exhibit a chiral nematic (cholesteric) phase in the range 120-205°C. Unexpectedly, esters containing well-known mesogenic groups such as 4-cyano- or 4-methoxy-phenyl do not form liquid crystal phases.     

钇对苯甲酸芳香体系的效应钇在镧系元素中的位置

钇对苯甲酸芳香体系的效应加以研究并与碱和碱土金属以及若干过渡金属和有毒的重金属的效应相比较。钇与镧系元素相似,具有稳定苯甲酸体系的效应。芳香体系的微扰作用随着金属离子势的减小而增大。红外谱带强度的详细分析表示钇的位置是在铒与铥之间。芳香环谱带的相对强度和频率对于镧系元素原子序数的依赖关系表明双-双效应的存在。     

Microwave spectrum and conformation of n-propyltrifluorosilane

The conformational properties of gaseous n-propyltrifluorosilane (CH₃CH₂CH₂SiF₃) have been investigated by microwave spectroscopy and high-level quantum chemical calculations. The microwave spectrum was investigated in the 20–62 GHz spectral range at a temperature of −78 °C. The spectra of the ground vibrational state and three vibrationally excited states of one conformer having an antiperiplanar conformation of the C–C–C–Si chain of atoms were assigned. No evidence for the existence of the synclinal (gauche) conformer was seen in the microwave spectrum. It is concluded that the synclinal form is at least 3.5 kJ/mol less stable than the antiperiplanar conformer in the gas phase. Density functional theory calculations have been performed for the system mainly to predict the effects of centrifugal distortion. The G3 quantum chemical method has been used to test the ability of this method to predict the energy difference between the synclinal and antiperiplanar conformers.     

Synthesis and absolute configuration of two diastereoisomeric (1R,2S,3R)-and (1S,2S,3R)-2-amino-1-(2-furyl)-1,3-butandiols

The synthesis of (1R, 2S, 3R) and (1S, 2S, 3R)-2-(N-benzoylamino)-1-(2-furyl)-1, 3-butandiols (15) and (16) from D-threonine is described. The assignment of absolute configuration of the newly formed asymmetric center at C-1 was based on the ¹H-NMR spectra of O-isopropylidene derivatives 17 and 18.     

Synthesis of S-(28a-homobetulin-28a-yl) thiophosphate,thiophosphonate, and thiophosphinate

A concise synthesis of thiophosphate, phenylthiophosphonate, and diphenylthiophosphinate esters bearing a 28a-homolupane residue is reported. The new triterpenes were obtained from the readily available 3-O-acetylichopanol by a nucleophilic substitution of the corresponding mesylate with thiocyanate ion followed by a Michaelis–Arbuzov reaction. These results open the way to new lupane-type derivatives having a thiophosphorus moiety at the lupane core as potential anticancer compounds. Additionally, the cytotoxic activities of the new homolupane compounds were evaluated in vitro.     

The relationship between chemical structure and antimicrobial activity of selected nicotinates, p-iodobenzoates, picolinates and isonicotinates

Alkaline metal, calcium and magnesium p-iodobenzoates and alkaline metal nicotinates, as well as sodium and potassium picolinic and isonicotinates were investigated by means of their antimicrobial and chemical properties. The quality estimation of the influence of metal cation coordinated to the carboxylic anion of the series of studied compounds on their antimicrobial activity as well as on the vibrational structure of whole complex in water solution was done. The changes in antimicrobial properties and in charge distribution of the complex along the position of nitrogen atom in the aromatic ring in sodium and potassium complexes were investigated. The analysis of influence of iodine substituent in para position on the change of electronic charge distribution of carboxylate anion and aromatic ring was done. The relationship between electronic properties estimated by vibrational spectroscopy and antimicrobial activity of studied complexes was investigated.