Spectrophotometric studies on some nitrosonaphthols

1018-1021The UV and visible absorption spectra of some nitrosonaphthol derivatives have been studied in organic solvents of varying polarities. The dependence of the band shift on the nature of substituent, dielectric effect and specific solvation has been studied. The absorption spectra have also been studied in buffer solutions of varying pH values and the acid dissociation constants of the different ionisable groups have been determined using the half-height and the modified limiting absorbance methods. It is found that the nitroso substituent leads to a decrease in ionisation constants of the naphthalenic OH group

Simultaneous determination of paracetamol and tramadol in pharmaceutical tablets by derivative UV-Vis absorption spectrophotometry

A comparative study of the use of first derivative zero order crossing spectra for the resolution of Paracetamol and Tramadol hydrochloride in mixtures has been achieved showing the success of the first derivative method in resolving and quantifying both compounds. Using the first derivative, rather than the second derivative, results in improved signal to noise ratio. The absorption spectra of prepared mixtures were scanned in the range of 200-500 nm. The linear concentration ranges were 25-112 and 6-48 µg mL-1 for paracetamol and Tramadol hydrochloride, respectively. The method has been successfully used for prediction of concentrations of both compounds in mixtures with good selectivity, high sensitivity and extremely low relative error. Statistical comparison was performed using t-test at 95% confidence level. There was no significant statistical difference between the results obtained by the first derivative method and the accepted values for both compounds. Also, the percentage errors were very low which adds to the merits of our work in terms of both sensitivity and accuracy

Electrical properties of organic light emitting diodes with post fabrication heat and electric field treatments

The current work presents post-fabrication heat treatment and a combined external electric field-heat post-fabrication treatments for organic light emitting diodes (OLEDs). The devices were fabricated in the same run with a standard device without annealing for comparison, with an identical structure of ITO/PVK/Rhodamine B/Pb. After depositing the Rhodamine B layer on the PVK film, the samples were thermally annealed at different temperatures before depositing Pb. Some of the samples were thermally annealed without any external electric field while others were treated by an external electric field during heating. It is found that the annealing temperature of PVK/Rhodamine B layers increases the turn-on voltage of the device. On the other hand, in the electric field-heat treatment, the turn-on voltage is observed to decrease and the maximum current density of the device is dramatically enhanced

Thermoelectricity Based on Cuo as a Semiconducting Material

In this paper, thermoelectricity based on copper(II) oxide CuO as semiconducting material is explored. The electrical properties of the samples were studied under different temperature gradients and pressures. Moreover, the effect of baking temperature was also investigated. CuO prepared using decomposition of Cu(NO3)2 as well as CuO nanopowder prepared using microwave-assisted synthesis technique were investigated and their results were compared. It was found that the current density can be enhanced with increasing the pressing pressure of the sample and when the sample undergoes a baking process. Moreover, it was found that the current density can be considerably enhanced with increasing the temperature gradient between the two ends of the sample. The CuO prepared using microwave-assisted synthesis technique was found to exhibit much better results over those of the CuO prepared using decomposition of Cu(NO3)2

Synthesis and biological assessment of new benzothiazolopyridine and benzothiazolyl- triazole derivatives as antioxidant and antibacterial agents

ABSTRACT. A novel series of benzothiazolopyridine derivatives was synthesized via interaction of -2-(benzothiazol-2-yl)-3-(4-chlorophenyl)acrylonitrile (2) with a diverse of commercially available reagents (indandione, thiobarbituric acid, and malononitrile). Moreover, a novel group of benzothiazole linked substituted 1,2,3-triazole derivatives were synthesized by exploring the chemical behavior of 5-benzothiazolyl-2-(4-chlorophenyl)-triazol-4-amine through refluxing in glacial acetic acid, condensation with phthalic anhydride, and cyanoacetylation reactions. All newly synthetized compounds have been tested for their antioxidant and antibacterial activities compared with ascorbic acid and Ampicillin as reference drugs, respectively. The benzothiazolo- pyridopyrimidine compound 6 was found the most potent antioxidant agent with IC50 = 0.015 mg/mL compared to the results of ascorbic acid (IC50 = 0.022 mg/mL). The investigated compounds showed no antibacterial properties against Gram-negative bacterial species, Pseudomonas aeruginosa and Escherichia coli. Benzothiazolopyridine derivative 5 displayed the best growth inhibition against Gram-positive bacteria, Staphylococcus aureus and Bacillus cereus with inhibition zones 24 and 20 mm, respectively.   KEY WORDS: Benzothiazole, Pyridobenzothiazole, 1,2,3-Triazole, Naphtharidine, Antioxidant   Bull. Chem. Soc. Ethiop. 2022, 36(2), 451-463.                                                              DOI: https://dx.doi.org/10.4314/bcse.v36i2.17                                                     &nbsp