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The depolymerization of natural biomass-based lignin is a definitive challenge, as it involves the integral breakdown of complex and wellconstructed natural structures. A sustainable method called ‘ionoSolv pretreatment’ employs ionic liquids in biomass processing. In this study, Bronsted acidic IL (BAIL); 1-methyl-3-(3-sulfopropyl)-imidazolium chloride, [C3SO3HMIM]Cl was synthesized and commendably used to both assist the depolymerization of lignin under mild reaction conditions as well as to benefit from the commercially valuable vanillin. About 68% degree of depolymerization (DD) of lignin was achieved under optimized conditions (120 °C, 60 min), yielding ca. 43% of tetrahydrofuran (THF) soluble products. The influence of BAIL on the depolymerization was investigated using chromatographic (gas chromatography-mass spectrometry, gel permeation chromatography, and high performance liquid chromatography (HPLC) and spectroscopic techniques (Fourier transform infrared). The HPLC analysis of the depolymerized lignin detected the clear presence of 12% of vanillin was obtained from 2 wt.% of rice husk’s lignin. [ABSTRACT FROM AUTHOR]

Feather keratin is a biomass generated in excess from various livestock industries. With appropriate processing, it holds potential as a green source for degradable biopolymer that could potentially replace current fossil fuel based materials. Several processing methods have been developed, but the use of ultrasonication has not been explored. In this study, we focus on (i) comparing and optimizing the dissolution process of turkey feather keratin through sonication and conventional processes, and (ii) generating a biodegradable polymer material, as a value added product, from the dissolved keratin that could be used in packaging and other applications. Sonication of feather keratin in pure ionic liquids (ILs) and a mixture containing ILs and different co-solvents was conducted under different applied acoustic power levels. It was found that ultrasonic irradiation significantly improved the rate of dissolution of feather keratin as compared to the conventional method, from about 2 h to less than 20 min. The amount of ILs needed was also reduced by introducing a suitable co-solvent. The keratin was then regenerated, analyzed and characterized using various methods. This material holds the potential to be reused in various appliances. [ABSTRACT FROM AUTHOR]

[Display omitted] • New red emitters based on ring-opened rhodamine derivatives (CR1 and CR2) were synthesized and characterized. • Single novel mixture CR2:CG:CB produced pure white light emission with CIE coordinates of (0.32, 0.33). • White light mechanism proposed a highly efficient FRET system from spectral overlap integral and Förster distance. • RGB emitters exhibit good thermal stability and efficient charge transfer from electrochemical and DFT studies. The mixture of red, green, and blue (RGB) organic fluorophores in a single blend is becoming more relevant to produce metal-free, low cost and color tunable white light emission. Herein we describe the combination of pure organic molecules based on the coumarin and rhodamine frameworks that generated broad or multi-band emission in both solution and solid forms. The derivatives of coumarin (CB), furocoumarin (CG) and rhodamine (CR1 and CR2) were synthesized and characterized using 1H NMR, 13C NMR, FTIR and ESI-MS spectroscopic techniques. The "closed-form" of the synthesized rhodamines have been further elucidated with the single crystal X-ray analysis. Their photophysical, thermal stability and electrochemical properties have been investigated, accompanied by DFT calculations to assess the plausible mechanism responsible for white light along with their eminent characteristics. Single mixture of ethanol-solubilized CR2 : CG : CB in the ratio of 3:10:3 showed extremely pure white light fluorescence with CIE coordinates of (0.32, 0.33) when excited at 360 nm while CR1 : CG : CB revealed almost pure white light (0.27, 0.32) in the ratio of 1:2:1 when excited at a much longer wavelength (λ ex = 395 nm). The results obtained are very encouraging in such a way that only minimal proportions of the blue and green fluorophores are required in the single mixture for a highly efficient FRET system when combined with the newly synthesized rhodamine derivatives. The ratio differences can be down to 30–42 % as compared to white light mixture with the commercial red R640. Furthermore, all of the synthesized RGB components exhibit reasonably good thermal stability with onset of decomposition above 210 °C, endowing their suitability for general applications of optoelectronic devices. The HOMO-LUMO energy band gaps from the cyclic voltammetry and geometrical optimized structures of the ground state are generally in nice agreement. White light emission was also generated when the polymer mixtures containing each RGB emitters was coated on a commercial UV-LED, demonstrating potential low cost and purely organic device set-up. [ABSTRACT FROM AUTHOR]

Coconut shell, a natural biopolymer, is available in high amounts as waste in many countries. It could potentially be a crucial renewable source of raw materials for the carbon fiber industry. In this study, a series of aprotic ionic liquids, [Bmim][Ace], [Bmim]Cl, [Emim][Ace], and [Emim]Cl, were used in the dissolution and regeneration process of coconut shell. The results indicate that the dissolution of coconut shell (up to 70 mg of coconut shell per g of solvent) can occur in aprotic ionic liquids under a nitrogen atmosphere at 110 °C (6 h) and 150 °C (2 h). The extraction efficiency was greatly influenced by temperature, time, particle size, and types of cations and anions in the ionic liquids. At 150 °C, 10% regenerated lignin was obtained in [Emim][Ace], which was higher compared with [Emim]Cl, [Bmim][Ace], and [Bmim]Cl. The recyclability of the ionic liquids during the dissolution process (up to four times) was also scrutinized. The structure and properties of the untreated coconut shell and regenerated lignin were characterized by Fourier transform infra-red (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) analysis, and proton nuclear magnetic resonance (1H NMR). [ABSTRACT FROM AUTHOR]

A series of furocoumarins (4a-h) was synthesized via a multi-component reaction and characterized by FTIR, 1H NMR, 13C NMR and ESI-MS. Compound 4g was further characterized with single-crystal X-ray diffraction for the molecular packing and interaction analysis. The photophysical and photochemical properties of the series have been experimentally and theoretically investigated, focusing on the absorption and fluorescence properties in solvents of varying polarity. Geometry optimization, HOMO-LUMO energy gap, NBO analyses and potential nonlinear optical (NLO) responses for all furocoumarins (4a-h) have been computed using DFT/TD-DFT method. The experimental results reveal that absorption and fluorescence of furocoumarins are highly sensitive to the solvent polarity and inter or intramolecular interactions. Furocoumarin exhibits strong solvatochromism through the intramolecular charge transfer (ICT) process, large Stokes shift up to 142 nm in polar solvents, long emission wavelength up to 520 nm in polar protic solvent through large polarization and relative high quantum efficiencies up to 94% in DMSO. Compound 4h exhibits Stokes shift value of 197 nm in toluene. The charge transfer character was correlated with the Lippert-Mataga and McRae plots while the effect of substituents on the fluorescence quantum yield was described by the Hammett plot. Based on the theoretical computations, furocoumarins with strong electron donating substituents (4b and 4d) possess high frequency-dependent first order hyperpolarizabilities, β in the range of 21.32–27.34 × 10−30 esu, suggesting their possible use in the NLO application. Fluorescence quenching in 4c , 4g and 4h were caused by site-specific hydrogen bonding strengthening and molecular packing that led to the formation of excimer species. This work will be valuable for the exploitation of ICT and solvatochromic effects and future molecular engineering of organic materials for practical utilities endowing low cost, facile and greener approach. [Display omitted] • A series of furocoumarins (4a-h) was synthesized through a one-pot synthesis and characterized. • Strong solvatochromism was observed through the Lippert-Mataga and McRae methods. • Hammett plot depicted high fluorescence quantum yield (up to 94%) for derivative with strong electron donating group. • Furocoumarins undergo ICT mechanism which is responsible for the red-shifted emission and large Stokes shift. [ABSTRACT FROM AUTHOR]

Wool keratin, a natural biopolymer, is potentially an important renewable source of raw materials for the polyamide plastics industry. Large quantities of non-spinnable and short fibers of wool are discarded globally and hence are available as low value waste materials. In this study, we have investigated different solvents, including ionic liquids and deep eutectic mixtures, for the dissolution and processing of wool. The results show that substantial dissolution of wool (up to 475 mg wool per gram of solvent) can be obtained in the 1-allyl-3-methylimidazolium dicyanamide [AMIM][dca] ionic liquid at 130 °C. Our studies also indicated enhanced dissolution (an additional 50-100 mg g-1) of wool upon the addition of a reducing agent to the ionic liquids. Water insoluble fractions (20-40%) were obtained on the addition of water to the dissolved wool. This regenerated fraction was characterized for structural and chemical changes and found to contain a larger fraction of β-sheets and random coils than the starting material. The water soluble fraction was characterised and the results indicated the presence of fragments of low molecular weight polypeptide chains. [ABSTRACT FROM AUTHOR]

Keratin from various livestock industries is currently a waste material that has potential as a source of polyamide polymers that could replace fossil fuel derived materials if processing methods can be developed. In this work we have investigated methods for the dissolution and regeneration of keratin. Dissolution of keratin (from turkey feather) in ionic liquids was conducted under nitrogen at 130 °C for 10 hours. It was found that [BMIM]Cl, [AMIM]Cl and [choline][thioglycolate] could dissolve turkey feather keratin without addition of solvent or other chemicals. A significant percentage of solubility was obtained, up to 45% by weight. A water insoluble fraction was recovered by addition of water to the solution (∼50%). The structure and properties of this regenerated, water insoluble fraction were investigated. Compared to the starting material, the regenerated keratin shows structural changes rather than chemical changes within the polypeptide chains. The remaining fraction, consisting of water soluble fragments, was characterised by gel electrophoresis. [ABSTRACT FROM AUTHOR]

• BAILs were used as a medium solvent to dissolve rice husk and depolymerize the lignin. • 78 % of regenerated lignin was effectively extracted from rice husk by [C 3 SO 3 HMIM]Cl. • Acidic properties of BAILs improve the delignification process. • [C 3 SO 3 HMIM][HSO 4 ] was successfully depolymerized the lignin into low molecular weight aromatic products. Lignocellulosic agricultural waste, like rice husk, is generated abundantly from rice milling industries. It is no longer mere waste but has become a treasure trove of outstanding potentials for sustainable environment growth. In this study, a series of Bronsted acidic ionic liquids (BAILs) were synthesized, characterized and used as a medium solvent to dissolve rice husk. Fractionation of rice husk into lignin, cellulose and hemicellulose was successfully achieved after 6 h of stirring at 100 °C. About 78 % and 53 % of the regenerated lignin were effectively extracted from rice husk by 1-methyl-3-(3-sulfopropyl)-imidazolium chloride, [C 3 SO 3 HMIM]Cl and 1-methyl-3-(3-sulfopropyl)-imidazolium acetate, [C 3 SO 3 HMIM][Ace] respectively, while 1-methyl-3-(3-sulfopropyl)-imidazolium hydrogen sulfate, [C 3 SO 3 HMIM][HSO 4 ] only extracted 11 % (based on the original rice husk). The regenerated lignin and cellulose were characterized using FTIR and TGA. Among the BAILs, [C 3 SO 3 HMIM]Cl was found to be a good medium solvent to extract lignin from rice husk and could be recycled up to four times. The regenerated lignin was further depolymerized using the synthesized BAILs at 120 °C (1 h) to generate low molecular weight aromatic products, which were analysed using gas chromatography-mass spectrometry (GC–MS). During depolymerization process, [C 3 SO 3 HMIM][HSO 4 ] was identified as an excellent solvent to depolymerize the lignin into low molecular weight aromatic products. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) are renowned for their unique properties with numerous and growing applications in various fields and industries. Although several methods are available to prepare CDs, low conversion yield, tedious purification processes and poor color purity remain major drawbacks. To address these issues, a cooling stage for full protonation prior to direct heating has been developed. This innovative method produces high-color purity solid-state CDs with a conversion yield of up to 99.5% in less than 6 min. The CDs synthesized by this method exhibited a highly crystalline structure, as confirmed by HRTEM, Raman and XRD analyses. In addition, the emission profile of the CDs could be effectively tuned by reducing the amount of concentrated sulfuric acid, resulting in a shift of the emission from 484 to 650 nm. The high-color purity of the CDs is postulated to be due to the solvent cage effect. Overall, this study presents a simple, efficient and rapid method for the preparation of high-quality CDs with excellent color purity and crystallinity. [ABSTRACT FROM AUTHOR]

There is much interest in the use of deoxyribonucleic acid (DNA) for applications in the field of molecular electronics and biosensors because of its unique self-assembling behaviour. Studying its sequence-specific electronic properties is one such analysis that could be employed as a tool for understanding mechanisms of charge transfer for integration into DNA-based devices. Although known to be reasonably stable in aqueous solution, environmental factors can affect the helical structure, resulting in significantly attenuated electronic profile. DNA molecules are also not stable when stored for long periods in solution form at room temperature prompting many interests for solvents in which DNA structures exhibit long-term stability. Ionic liquid (IL), 1-butyl-3-methylimidazolium acetate ([BMIM][Ace]), is a potential solvent that ensures long-term stability of DNA. Therefore, in this work, the effect of IL on basidiomycetes DNAs integrated within an aluminium (Al)–indium tin oxide (ITO) Schottky junction was investigated. Significant improvement in the rectifying profiles was observed for DNA dissolved in [BMIM][Ace] (IL/DNA) compared to DNA in aqueous solution (aq/DNA) without the addition of IL when stored at different temperatures and time intervals. In general, the junction structure exhibited insulating behaviour when DNA was stored at room temperature for three months. This results in loss of its structure and stability for long periods of use at room temperature. Meanwhile, IL sample itself (control) shows a linear conductive profile. Furthermore, different solid-state parameters calculated allow us to understand the charge transfer mechanism in DNA molecules as a function of IL. [ABSTRACT FROM AUTHOR]