The structure of the complex of cellulose I with ethylenediamine by X-ray crystallography and cross-polarization/magic angle spinning 13C nuclear magnetic resonance

X-ray crystallographic and cross-polarization/magic angle spinning ¹³C nuclear magnetic resonance techniques have been used to study an ethylenediamine (EDA)-cellulose I complex, a transient structure in the cellulose I to cellulose III_I conversion. The crystal structure (space group P2 ₁ ; a = 4.546 Å, b = 11.330 Å, c = 10.368 Å and γ = 94.017°) corresponds to a one-chain unit cell with one glucosyl residue in the asymmetric unit, a gt conformation for the hydroxymethyl group, and one EDA molecule per glucosyl residue. Unusually, there are no O–H···O hydrogen bonds between the cellulose chains; the chains are arranged in hydrophobic stacks, stabilized by hydrogen bonds to the amine groups of bridging EDA molecules. This new structure is an example of a complex in which the cellulose chains are isolated from each other, and provides a number of insights into the structural pathway followed during the conversion of cellulose I to cellulose III_I through EDA treatment.     

Cellulose nanocrystals obtained from microcrystalline cellulose by p-toluene sulfonic acid hydrolysis,NaOH and ethylenediamine treatment

Cellulose nanocrystals (CNCs) were first isolated from microcrystalline cellulose (MCC) by p-toluene sulfonic acid (p-TsOH) hydrolysis. Cellulose II nanocrystal (CNC II) and cellulose III nanocrystal (CNC III) were then formed by swelling the obtained cellulose I nanocrystal (CNC I) in concentrated sodium hydroxide solutions and ethylenediamine (EDA) respectively. The properties of CNC I, CNC II and CNC III were subjected to comprehensive characterization by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The results indicated that CNC I, CNC II and CNC III obtained in this research had high crystallinity index and good thermal stability. The degradation temperatures of the resulted CNC I, CNC II and CNC III were 300 °C, 275 °C and 242 °C, respectively. No ester bonds were found in the resulting CNCs. CNCs prepared in this research also had large aspect ratio and high negative zeta potential.

     

Cellulose gel and aerogel from LiCl/DMSO solution

Recently-discovered lignocellulosic solvent, 8%(w/w) lithium chloride/dimethyl sulfoxide (LiCl/DMSO), was found to dissolve cellulose of varied crystal forms and degree of polymerization. Cellulose samples could be activated for dissolution by complexation with ethylenediamine (EDA), giving EDA contents of 20–23% (w/w) in the complex irrespective of the cellulose type. The cellulose solution gave well-resolved ¹³C NMR spectrum, confirming molecular dispersion. Cellulose could be coagulated by ethanol to give translucent cellulose gels, which could be converted to highly porous aerogels via solvent exchange drying. Nitrogen adsorption analysis gave their specific surface areas of 190–213 m²/g, with typical mesopore sizes of 10–60 nm. Scanning electron microscopy revealed the network structure of aerogel composed of relatively straight fibril segments, approx. 20 nm wide and 100–1,000 nm long. X-ray diffraction showed that the material is poorly crystalline cellulose II.     

Water-soluble pillar[4]arene[1]quinone: Synthesis,host-guest property and application in the fluorescence turn-on sensing of ethylenediamine in aqueous solution,organic solvent and air

Water-soluble pillar[5]arenes are a class of typical macrocycles and have aroused tremendous attention for its easy to modify, abundant host-guest properties and extensive applications. However, up to now, all the reported water-soluble pillar[5]arenes acted as the host molecules, whereas they failed to be postsynthetically modified, which seriously impeded the development of the pillar[5]arene-based supramolecular chemistry. In this work, a new water-soluble pillar[5]arene, pillar[4]arene[1]quinone, was designed and synthsized with eight quaternary ammonium groups as well as a quinone units. Such a new water-soluble pillar[4]arene[1]quinone was capable of forming 1:1 stable complex with sodium 1-octanesulfonate in aqueous solution. Since the 1,4-quinone unit of WP[4]Q[1] could react with ethylenediamine (EDA) to form a conjugated quinoxaline structure, so pillar[4]arene[1]quinone could apply to the facile fluorescence turn-on sensing of EDA in aqueous solution, organic solvent and air.     

Reactions of some ortho and para halogenated aromatic nitriles with ethylenediamine: selective synthesis of imidazolines

The reaction of ethylenediamine (EDA) with ortho and/or para halogenated benzonitriles did not lead to the imidazolines expected: a competitive aromatic nucleophilic substitution (S_NAr) was observed instead. The selective synthesis of these imidazolines was performed by nucleophilic addition of EDA to thiobenzamide derivatives. The difference in reactivity between the nitrile and thioamide derivatives was estimated by a frontier orbital approach at the RHF/6-31G** level which predicted a greater reactivity of substituted thiobenzamides towards the nucleophilic addition of EDA.     

Co(II)-exchanged montmorillonite with ethylenediamine,trimethyl- and tetramethyl-ethylenediamine and their thermal decomposition

The influence of different steric properties of ethylenediamine (EDA), trimethylenediamine (TrMeEDA) and tetraethylenediamine (TeMeEDA) on the type of interactions with Co(II)-exchanged montmorillonite and thermal decomposition of these materials were studied. The results of X-ray diffraction (XRD), thermogravimetry (TG), derivative thermogravimetry (DTG) and spectral analysis shows that the studied ethylenediamines are intercalated into the interlayer space of montmorillonite. Thermal decomposition at 20–500 °C of studied samples with EDA proceeds in three steps (the release of chemosorbed amines, coordinated EDA and dehydroxylation) while the sample with TrMeEDA and TeMeEDA in five steps (also release the protonated forms). The effect of different steric properties of individual diamines is evident.     

Phase-transfer catalyst-induced changes in the absorption and fluorescence behavior of some electron donor-acceptor molecules.

The quaternary ammonium salts find extensive use in a variety of chemical applications as surfactants and phase-transfer catalysts. Even though the interaction of the surfactants with various systems has been studied rather extensively, very little information is available on how the phase-transfer catalysts (PTC) interact with the dipolar systems in nonpolar media and how/whether these solubilizing agents affect the properties of the dissolved molecules. In this paper, the interaction of several tetraalkylammonium salts, commonly used as PTC, with a number of electron donor-acceptor (EDA) systems has been studied by absorption and fluorescence spectroscopy. The phase-transfer catalysts have been found to affect both the absorption and fluorescence properties of the EDA systems. The spectral changes of the EDA molecules induced by the tetraalkylammonium salts suggest the formation of an 1:1 complex between the two in nonpolar media. An electrostatic interaction between the phase-transfer catalysts (which exist as ion pairs in nonpolar media) and the dipolar molecules is shown to be the driving force for the formation of the complex. The dependence of the formation constant of the complex on the polarity of the media suggests a charge-transfer nature of the complex. It is shown that the anionic component of the salts serves as a source of electron to the positive end of the dipolar molecule, while the tetraalkylammonium cation, besides helping solubilization of its anionic counterpart in the nonpolar media, serves neutralizing the negative charge at the acceptor end of the EDA molecule. In effect, a cooperative influence of the cationic and anionic components of the PTC enhances the charge separation within the dipolar fluorophores. On the basis of the PTC-induced changes in the photophysical behavior of the EDA molecules, a possible structure for the 1:1 complex has been proposed. It has been concluded that a phase-transfer catalyst should not be treated as an innocuous substance that merely helps transfer of a polar substance from a polar to a nonpolar environment. Instead, it is demonstrated that the association of a PTC with a dipolar species can significantly change various properties of the latter.     

CesA protein is included in the terminal complex of <Emphasis Type="Italic">Acetobacter</Emphasis>

Cellulose is a major biopolymer on the earth that is produced by cellulose synthase in the cell membrane of living organisms. Cellulose synthase is a hetero-subunit complex composed of several different protein subunits, and is visualized as a supermolecular complex called a “terminal complex” by electron microscopy. Such supermolecular organization of an enzyme complex is believed to be important for the fiber formation or crystallization of cellulose microfibrils in cellulose biosynthesis. In the case of the cellulose-producing bacterium Acetobacter, it is hypothesized that the enzyme complex includes at least six subunits given its genetic constitution. However, to date, only three of these molecules have been experimentally confirmed as the subunits included in the terminal complex: CesB, CesD, and ccp2. In this study, we used fluorescence immuno-microscopy to show that CesA protein, the catalytic subunit, is included in the terminal complex of Acetobacter. Furthermore we discuss the obtained microscopic data for improving our understanding of the molecular organization of the bacterial cellulose synthase complex.     

Supramolecular complex induced by the binding of sodium dodecyl sulfate to PAMAM dendrimers

Isothermal titration calorimetry (ITC) and dynamic light scattering (DLS) were employed to study the spontaneous supramolecular complexation of amine terminated PAMAM dendrimer (G3[EDA] PAMAM-NH2) induced by the binding of an anionic surfactant, sodium dodecyl sulfate (SDS). At pHor=10, the electrostatic binding ceased because the deprotonated PAMAM dendrimer was uncharged, and hence the surfactant-induced supramolecular assembly could not be formed.     

Electron donor-acceptor interactions in ethanol-CO2 mixtures: an ab initio molecular dynamics study of supercritical carbon dioxide

The nature of interactions between ethanol and carbon dioxide has been characterized using simulations via the Car-Parrinello molecular dynamics (CPMD) method. Optimized geometries and energetics of free-standing ethanol-CO2 clusters exhibit evidence for a relatively more stable electron donor-acceptor (EDA) complex between these two species rather than a hydrogen-bonded configuration. This fact has also been confirmed by the higher formation rate of the EDA complex in supercritical carbon dioxide-ethanol mixtures. The probability density distribution of CO2 molecules around ethanol in the supercritical state shows two high probability regions along the direction of the lone pairs on the oxygen atom of ethanol. The EDA interaction between ethanol and CO2 as well as that between CO2 molecules themselves leads to significant deviations from linearity in the geometry of the CO2 molecule. The vibrational spectra of carbon dioxide obtained from the atomic velocity correlation functions in the bulk system as well as from isolated complexes show splitting of the nu2 bending mode that arises largely from CO2-CO2 interactions, with ethanol contributing only marginally because of its low concentration in the present study. The stretching frequency of the hydroxyl group of ethanol is shifted to lower frequencies in the bulk mixture when compared to its gas-phase value, in agreement with experiments.     

Resonance Raman scattering of the tetracyanoethylene—hexamethylbenzene electron donor/acceptor complex

The Raman spectrum of the tetracyanoethylene—hexamethylbenzene EDA complex was recorded using seven lines of an Ar laser and one from a Kr laser. By comparison with spectra recorded of the donor and acceptor molecules separately, it was found that some of the lines of the complex were up to 393 time stronger than the corresponding lines of an uncomplexed molecule.     

Room temperature solution studies of complexation between o-chloranil and a series of anilines by spectrophotometric method.

Electron donor-acceptor (EDA) complex formation between o-chloranil and a series of anilines has been studied in CCl4 medium. In all the cases, EDA complexes are formed instantaneously on mixing the donor and acceptor solutions. N,N-dimethylaniline and N,N-dimethyl-p-toluidine form stable EDA complexes with o-chloranil while the other complexes decay slowly into secondary products. The kinetics of all these reactions has been studied by UV-VIS absorption spectrophotometric method and the rate constants of the reactions and formation constants of the EDA complexes have been determined. The charge transfer (CT) transition energies of the complexes are found to change systematically with change in the number and position of the methyl groups in the donor molecules (methylanilines). From an analysis of this variation, the electron affinity of o-chloranil has been found to be 2.54 eV. A perturbational inductive effect Hückel parameter hMe has been found from this trend and the value obtained (-0.27) is very close to that (-0.3) obtained by Lepley (J. Am. Chem. Soc., 86 (1964) 2545) from a study of tetracyano ethylene (TCNE)-methylbenzene complexes.     

How the geometrical model for plant cell wall formation enables the production of a random texture

Cellulose synthase (CESA) molecules are the building blocks and catalytic centers of the CESA complex. The study of mutants in Arabidopsis has led to insight into the structure of these nanomachines. Inside the plasma membrane, the CESA molecules are arranged in complexes, which, apart from the CESA molecules proper, contain other, mostly unidentified, proteins. We developed a theory in which CESA density, together with distance between cellulose microfibrils (CMFs) being deposited and cell geometry, determines wall texture. We have shown earlier how this theory is able to explain the production of axial, helical, helicoid and crossed-polylamellate textures. In the present article we extend this theory to random wall textures.     

Dielectric studies of binary mixtures of n -propyl alcohol and ethylenediamine

Dielectric constant (ε’) and dielectric loss (ε") of n-propyl alcohol (PA), ethylenediamine (EDA) and their binary mixtures, for different mole fractions of ethylenediamine have been experimentally measured at 11.15 GHz microwave frequency. Values of density (ρ), viscosity (η) and square refractive index (n _D ² ) of binary mixtures as well as those of pure liquids are reported. Excess square refractive index, viscosity and activation energy of viscous flow have also been estimated. These parameters have been used to explain the formation of complexes in the system.     

Removal of anionic dyes with glycidyl methacrylate-grafted polyethylene terephthalate (PET) fibers modified with ethylenediamine

Research on Chemical Intermediates - In this work, the epoxy groups of poly (ethylene terephthalate) PET copolymers grafted with glycidyl methacrylate (GMA) were modified with ethylenediamine (EDA)...     

Specific features of the structure of a lanthanum nitrate complex with ethylenediamine

Anhydrous lanthanum nitrate and its complexes with one and two ethylenediamine molecules are calculated by the ab initio B3LYP/LANL2DZ quantum-chemical method. An ethylenediamine molecule is shown to coordinate preferentially through one amino group, and a hydrogen bond is formed between the coordinated amino and nitrato groups. An ethylenediamine complex of lanthanum nitrate is synthesized, and its composition and thermal stability are determined. The IR spectra of the ethylenediamine complex of lanthanum nitrate confirm the presence of the intramolecular hydrogen bond in this complex.     

Dissolution of cellulose in ethylene diamine/salt solvent systems

Investigation of the dissolution of cellulose in Ethylene Diamine (EDA)/Potassium thiocyanate (KSCN) solutions by infrared spectroscopy (FTIR) and thermal analysis (DSC) indicated that changes to the solvent during freeze thaw cycling of mixtures was consistent with increased interaction between cellulose and solvent. Thermal transitions in the system, however, occurred at temperatures outside the range used in thermal cycling to promote dissolution. Further exploration of the dissolution and mixing process indicated that mixing was the limiting step in solution formation. The dissolution of two types of cellulose with different molecular weights (Degree of Polymerization (DP)=210 and >1000) was studied using EDA/KSCN solution as the solvent. The solubility and the dissolution rate of cellulose depended on both the solvent composition and cellulose molecular weight. Cellulose could dissolve faster in the solvent with lower salt concentration but the highest cellulose concentration was obtained in the solvent with 30~35% KSCN. Rheological measurements showed that cellulose solutions exhibited viscous solution behavior at low KSCN concentration but primarily elastic behavior at high salt concentration.     

Visible Light-Induced Metal-Free Fluoroalkylations

Fluoroalkylation is a crucial synthetic process that enables the modification of molecules with fluoroalkyl groups, which can enhance the properties of compounds and have potential applications in medicine and materials science. The utilization of visible light-induced, metal-free methods is of particular importance as it provides an environmentally friendly alternative to traditional methods and eliminates the potential risks associated with metal-catalyst toxicity. This Account describes our studies on visible light-induced, metal-free fluoroalkylation processes, which include the use of organic photocatalysts or EDA complexes. We have utilized organophotocatalysts such as Nile red, tri(9-anthryl)borane, and an indole-based tetracyclic complex, as well as catalyst-free EDA chemistry through photoactive halogen bond formation or an unconventional transient ternary complex formation with nucleophilic fluoroalkyl source. A variety of π-systems including arenes/heteroarenes, alkenes, and alkynes have been successfully fluoroalkylated under the developed reaction conditions.     

Determination of ionic liquids solvent properties using an unusual probe: the electron donor-acceptor complex between 4,4'-bis(dimethylamino)-benzophenone and tetracyanoethene

Michler's ketone (MK) and tetracyanoethene (TCNE) may be used as a UV-vis probe to investigate the solvent properties of ionic liquids (ILs). In molecular solvents, MK and TCNE give an electron donor-acceptor (EDA) complex, a zwitterionic species or a radical ion pair, depending on the aprotic or protic nature of the solvent and on its ionizing power. In agreement with the behavior observed in aprotic solvents, only the EDA complex was detected in ILs bearing low donor anions (beta < 0.7). The formation constant determined in [bmim][Tf(2)N] (K(c) = 5.6 (0.5) M(-1)) is similar to that measured in 1,2-dichloroethane at 25 degrees C. The visible absorption maximum (nu(max,CTC)) of the EDA complex is quantitatively described by a multiple correlation using the Kamlet-Taft pi, beta, and alpha parameters of the solvents. The H-bond donating capacity of ILs is not sufficient to determine the transformation of the EDA complex into the zwitterionic species, but the Kamlet-Taft alpha parameter seems to affect the position of the absorption band. The high ionization power of ILs, moreover, favors the slow dissociation of the EDA complex into its corresponding radical ion pair; this behavior generally characterizes highly polar and highly ionizing protic solvents, such as TFE and HFI. Finally, since the formation of the EDA complex is strongly affected by the presence of impurities, traces of nucleophiles (chloride or amines) or water may be easily detected through the change of the solution color.     

Cellulose Functionalization via ATRP Grafting of Glycidyl Methacrylate for Cr（VI） Adsorption

Cellulose was first grafted with glycidyl methacrylate （GMA） in an ionic liquid via atom transfer radical polymerization （ATRP） and then the introduced epoxy groups were reacted with ethanediamine （EDA） to obtain an amino adsorbent. The grafting copolymer and the obtained adsorbent were characterized by FTIR, aH NMR, TEM and SEM. The results showed that the grafted copolymers had grafted polymer chains with well-controlled molecu- lar weight and polydispersity, the polymerization was a controlled system. The cellulose adsorbent had numerous micropores on the surface and showed high performance for Cr（VI） adsorption. The adsorption behavior was pH dependent and the sorption equilibrium was achieved within 2 h on the adsorbent.