Dyeing of Polyester Fabric with Natural Colorants Extracted from Mahogany (Swieteniamahagoni) Seed Pods

Polyester fabric is usually dyed with disperse dyes which has severe limitations specially toxicity and environmental issues. The aim of the present research is to introduce an ecofriendly dyeing process for polyester fabric with natural dyes. The natural colorants were extracted from mahogany seed pods using the simple acid boiling method. The spectroscopic analysis of the crude extract was carried out by UV and IR spectra of the extracted dyes and illuminated the presence of natural tannins as coloring materials in the crude extract. 10g fabric was dyed in 200cc extracted solution at 130⁰C for 60 minutes in exhaust dyeing method followed by neutralization and soaping. Finally, a light brown dyed fabric was obtained. The dyed fabric exhibited color strength in terms of k/s value of 0.63 (λmax 360nm), lightness of 80.565 and chromaticity value of 12.002 CIE units. Different samples were dyed by fluctuating the dyeing period. The dyeing traits of the dyed materials were judged in terms of their color strength and fatness properties. All testes were carried out following the ISO standards. From the results, it is lucid that the dyed fabric showed acceptable color fastness properties in case of all fastness except color fastness to light. It is observed that dyeing time had profound influence on the color strength (k/s value) of the dyed material. The k/s value increases with the increase of dyeing period up to 120 minutes. The maximum color strength (0.76) was noted for the fabric. The shorter dyeing time produces lighter samples and the longer dyeing time produced colorful samples. Journal of Engineering Science 11(1), 2020, 37-42

Preparation and Characterization of a Complex of Paeonol and Hydroxypropyl-β-cyclodextrin

Purpose: To improve the solubility of paeonol in water by complexing with hydroxypropyl-β-cyclodextrin (HP-β-CD) and also to characterize the physicochemical properties of the complex.Methods: The complex of paeonol and HP-β-CD was prepared by freeze-drying method. Its physicochemical properties were studied by phase-solubility method, ultraviolet-visible spectrometry (UV), infrared spectrometry (IR), scanning electron microscopy (SEM), x-ray diffractometry (XRD) and thermogravimetric/differential scanning calorimetry (TG/DSC).Results: The phase-solubility results showed that paeonol formed a 1:1 stoichiometric complex with HP-β-CD while UV and IR spectra suggested that HP-β-CD and paeonol in the complex interacted by a non-covalent bond. SEM and XRD indicate that the heat stability of paeonol was significantly improved by complexing with HP-β-CD.Conclusion: Paeonol can be efficiently complexed with HP-β-CD to form a complex by freeze-drying method. The aqueous solubility and heat stability of paeonol is significantly improved by complexation HP-β-CD.Keywords: Paeonol, Hydroxypropyl-β-cyclodextrin, Complexation, Aqueous solubility, Heat stability

Photolysis study of fluorinated ketones under natural sunlight conditions

UV and IR spectra of CF3COCH3 and CF3COC2H5 are provided, with photolysis being their dominant fate in the atmosphere.

The UV and IR Comparative Spectrophotometric Study of Some Saturated and Lacunary Polyoxometalates

Objectives: The polyoxometalates are a class of inorganic compounds with controllable shapes and sizes, and with excellent properties that make them attractive for various applications. This study is aimed at the comparative UV and IR spectra of Keggin type polyoxometalates. Methods: Compounds under (UV and IR) investigations were divided into several groups to highlight similarities between compounds or classes of compounds for the same category. There are four types of saturated Keggin structures and six lacunar compounds included in this study. The study begins with the UV investigations on aqueous solutions with 10-5 M concentration for these compounds. IR spectra were recorded as KBr pressed pellets. Results: The UV spectras presents large strong peaks between 185-195 nm corresponding to W = Od bonds, between 251-268 nm for W-O-W bridge bonds, depending on heteroatom types (As, Sb). The unsaturated cryptand ligand having Co2+ coordinated presents the most intense peak, due to the involvement of oxygen atoms from terminal W = Od coordinative bonds with high electronic densities in coordination of W-O-Co bond. The IR spectra present many peaks that are associated as follows: for terminal bonds W = Od, 955-970 cm-1; for W-OW bridging bonds, 790-910 cm-1; for W-O-As/Sb bonds to heteroatom, 690-760 cm-1. Vibrations of the bonds between heteroatoms and oxygen (As/Sb-O) appear around 620-660 cm-1. Conclusions: Similarities appear from the recorded spectra, between compounds of the same class, by category association. Very fine displacements of peaks that occur explain the influence of heteroatoms, addenda atoms or coordinated cations.

Supramolecular Assembly of Functional Cholesteryl Substituted Luminol Derivative in Organized Molecular Films

Functional luminol derivative with cholesteryl substituted group has been designed and synthesized from the reaction of the corresponding precursor cholesteryl chloroformate with luminol. This compound can be spread on water surface to form stable monolayer. It has been found that UV and IR spectra confirmed the characteristic aromatic segment, imide group and cholesteryl substituted group. In addition, the CD spectra also showed positive CD signals, which may be attributed to the chiral cholesteryl substituted groups. AFM investigation indicated some aggregated domains with the averaged height about 3.6  0.2 nm appeared. This suggested an organized structure of double molecules may be fabricated in the transferred LB films. The present results have demonstrated that the interfacial properties of luminol derivative can be modified by changing proper substituted groups of luminol, which show potential application in functional material fields such as ECL sensor.

Interconversion of Nitrenes, Carbenes, and Nitrile Ylides by Ring Expansion, Ring Opening, Ring Contraction, and Ring Closure: 3-Quinolylnitrene, 2-Quinoxalylcarbene, and 3-Quinolylcarbene

Photolysis of 3-azidoquinoline 6 in an Ar matrix generates 3-quinolylnitrene 7, which is characterized by its electron spin resonance (ESR), UV, and IR spectra in Ar matrices. Nitrene 7 undergoes ring opening to a nitrile ylide 19, also characterized by its UV and IR spectra. A subsequent 1,7-hydrogen shift in the ylide 19 affords 3-(2-isocyanophenyl)ketenimine 20. Matrix photolysis of 1,2,3-triazolo[1,5-c]quinoxaline 26 generates 4-diazomethylquinazoline 27, followed by 4-quinazolylcarbene 28, which is characterized by ESR and IR spectroscopy. Further photolysis of carbene 28 slowly generates ketenimine 20, thus suggesting that ylide 19 is formed initially. Flash vacuum thermolysis (FVT) of both 6 and 26 affords 3-cyanoindole 22 in high yield, thereby indicating that carbene 28 and nitrene 7 enter the same energy surface. Matrix photolysis of 3-quinolyldiazomethane 30 generates 3-quinolylcarbene 31, which on photolysis at >500 nm reacts with N2 to regenerate diazo compound 30. Photolysis of 30 in the presence of CO generates a ketene (34). 3-Quinolylcarbene 31 cyclizes on photolysis at >500 nm to 5-aza-2,3-benzobicyclo[4.1.0]hepta-2,4,7-triene 32. Both 31 and 32 are characterized by their IR and UV spectra. FVT of 30 yields a mixture of 2- and 3-cyanoindenes via a carbene–carbene–nitrene rearrangement 31 → 2-quinolylcarbene 39 → 1-naphthylnitrene 43. The reaction mechanisms are supported by density functional theory calculations of the energies and spectra of all relevant ground and transition state structures at the B3LYP/6–31G* level.