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Lignin is a promising alternative to fossil resources for the production of fuels, biocomposites and value-added chemicals. To better utilize this kind of natural resource, it is still necessary to develop efficient lignin solvents. As such, 13 kinds of novel lignin solvents have been developed, in this work, by the addition of water into bio-derived choline carboxylate ionic liquids (ILs). The solubility of lignin has been determined at 25 °C as a function of IL contents. The effect of the anionic structure of the ILs on lignin solubility is systematically examined. It is found that among these solvents, six types of ILs exhibit highly efficient capacity for lignin dissolution at room temperature. The solubility of lignin increases with increasing alkyl chain length in the carboxylate anions, and a substitution of H in carboxylate anions by the OH or NH2 group as well as the use of choline di-/tri-carboxylates leads to the decrease of lignin solubility, or even makes the lignin insoluble in the solvents. From NMR measurements, these results have been explained by the strong hydration of the carboxyl group of the anions and the possible interaction of alkyl chains of the anions and cations with lignin. In addition, the dissolved lignin can be regenerated by addition of additional water, and no chemical reaction takes place during the dissolution and regeneration processes. [ABSTRACT FROM AUTHOR]

Carboxylate-anion-based imidazolium ionic liquids (ILs)are powerfulsolvents for cellulose and lignin. However, little is known abouttheir fundamental physicochemical properties. In this work, 1-butyl-3-methylimidazoliumcarboxylate ILs 1-butyl-3-methylimidazolium formate ([C4mim][HCOO]), acetate ([C4mim][CH3COO]), propionate([C4mim][CH3CH2COO]), and butyrate([C4mim][CH3(CH2)2COO]),in which the alkyl chain length in the anions is being varied in contrastto the more usual studies where alkyl chain length in the cationsis varied, have been synthesized and their densities and surface tensionshave been determined experimentally at different temperatures. Byusing these data, the molar volume, isobaric expansivity, standardentropy, lattice energy, surface excess entropy, vaporization enthalpy,and Hildebrand solubility parameter have been estimated for theseILs. From the analysis of structure–property relationship,the effect of alkyl chain length in the anions on these physicochemicalproperties of the ILs has been assessed and the dissolution of celluloseand lignin in these ILs has been discussed. Such knowledge is expectedto be useful for understanding the nature of this class of solventfor the dissolution of biomacromolecules. [ABSTRACT FROM AUTHOR]

Abstract A series of zinc(II) coordination complexes, formulated as {[Zn (dbim) 1.5 (m-H 2 adica)] n ·2H 2 O} n (1), [Zn (dbim) (H 2 adi)] n (2), [Zn (dbim) (m-H 2 bdc)] n (3), [Zn 0.5 (dbim) 0.5 (p-H 2 bdc) 0.5 ] n (4), [Zn (dbim) (H 2 sdba)] n (5) and [Zn (dbim) 0.5 (H 2 atda)] n (6) (dbim = 1-(4-((2,5-dimethyl-3a H -benzo [ d ]imidazole-1 (7a H)-yl)methyl)benzyl)-3a,7a-dihydro-2,5-dimethyl-1 H -benzo [ d ]imidazole, m -H 2 adica = 1,3-adamantanedicarboxylic acid, H 2 adi = adipic acid, m -H 2 bdc = 1,3-benzenedicarboxylic acid, p -H 2 bdc = 1,4-benzenedicarboxylic acid, H 2 sdba = 4,4′-sulfonyldibenzoic acid, H 2 atda = 1,3-adamantanediacetic acid), have been obtained by hydrothermal reactions. Complex 1 features a 1D step-like chain. Complex 2 , 3 and 4 exhibits a 4-connected 2D topology with a point symbol of 44·62, severally, while complex 5 possesses a 4-connected 2D topology with the point symbol of (3·43·52) (44·62). Complex 6 is a 1D chain structure. Additionally, complexes 1 – 6 present different photoluminescence behaviors in the solid state. Graphical abstract Six 1D/2D architectures can be constructed from zinc(II) salts and the N-heterocycle ligand dbim. Moreover, 1 – 6 show good fluorescence properties. Image 1 Highlights • Six 1D/2D architectures were constructed from zinc(II) salts, the N-heterocycle ligand dbim and different multidentate O-donor organic aromatic carboxylate ligands. • The dbim ligand and various carboxylate coligands exert a profound influence on the formation of holistic structures of the ultima complexes. • These complexes show good fluorescence properties. [ABSTRACT FROM AUTHOR]

In the present work, seven 1-allyl-3-methylimizodalium carboxylate ionic liquids (ILs), including 1-allyl-3-methylimizodalium formate [Amim][HCOO], acetate [Amim][CH 3 COO], propionate [Amim][CH 3 CH 2 COO], butyrate [Amim][CH 3 (CH 2 ) 2 COO], glycollate [Amim][HOCH 2 COO], lactate [Amim][CH 3 CHOHCOO]) and benzoate [Amim][C 6 H 5 COO], have been synthesized and characterized. Density ( ρ ) and conductivity ( σ ) have been determined experimentally for these ILs at 298.15 K and atmospheric pressure. Then molar volume ( V m ), standard entropy ( S °), lattice energy ( U POT ) and molar conductivity ( Λ ) of the ILs have been derived from the density and conductivity data. Ionicity of the ILs has been estimated using the Walden plot. Meanwhile, how anionic structure of the ILs affects the volumetric and conductivity properties of 1-allyl-3-methylimidazolium carboxylate ILs has been discussed from the analysis of structure–property relationship. [ABSTRACT FROM AUTHOR]

The development of highly efficient cellulose solvents is imperative to the effective utilization of cellulose. In this work, ionic liquids (ILs) with the same 1-allyl-3-methylimidazolium cation ([Amim] + ) but different carboxylate anions, such as formate ([HCOO] − ), acetate ([CH 3 COO] − ), propionate ([CH 3 CH 2 COO] − ), butyrate ([CH 3 CH 2 CH 2 COO] − ), glycollate ([HOCH2COO] − ), lactate ([CH 3 CHOHCOO] − ) and benzoate ([C 6 H 5 COO] − ) were synthesized, and their thermal properties and viscosities were determined. Then these ILs were used to investigate the effect of anion structure on solubility of cellulose in the ILs. It was shown that the viscosity and cellulose solubility depended strongly on the anion structure of the ILs. For example, at 30 °C solubility of cellulose in [Amim][CH 3 CH 2 COO] was as high as 19.0%, whereas cellulose was not soluble in [Amim][HOCH 2 COO], [Amim][CH 3 CHOHCOO] and [Amim][C 6 H 5 COO]. In addition, solvatochromic UV/vis probe and 13 C NMR measurements were performed to demonstrate dissolution mechanism of cellulose in the ILs. The results suggested that although cations of the ILs have un-negligible contribution to the highly efficient dissolution of cellulose, hydrogen bonding interactions of anions of the ILs with cellulose is predominant. [ABSTRACT FROM AUTHOR]

Inthis work, four 1-butyl-3-methylimidazolium carboxylate ionicliquids (ILs) with different substituent groups in anions, including1-butyl-3-methylimidazolium glycollate [C4mim][HOCH2COO], 1-butyl-3-methylimidazolium lactate [C4mim][CH3CHOHCOO], 1-butyl-3-methylimidazolium benzoate [C4mim][C6H5COO], and 1-butyl-3-methylimidazoliumglycinate [C4mim][H2NCH2COO], havebeen synthesized and characterized. Their densities (ρ) andsurface tensions (γ) have been determined experimentally inthe temperature range of (298.15 to 343.15) K. By using thermodynamicand empirical equations, molar volume (Vm), isobaric expansivity (αp), standardentropy (S°), lattice energy (UPOT), surface excess entropy (Ss), vaporization enthalpy (ΔlgHm0) and Hildebrand solubility parameter(δH) of these ILs have been derived from densityand surface tension data. The effects of substituent groups in carboxylateanions on densities and surface tensions of these ILs have been assessedfrom the analysis of the structure–property relationship. [ABSTRACT FROM AUTHOR]