Theoretical studies on molecular and structures of mono- and binuclear chromium carbazole derivatives for optoelectronics

Mechanism of interaction between ascorbic acid and soil iron-containing minerals for peroxydisulfate activation and organophosphorus flame retardant degradation

Soil constituents may play an important role in peroxydisulfate (PDS)-based oxidation of organic contaminants in soil. Iron-containing minerals (Fe-minerals) have been found to promote PDS activation for organics degradation. Our study found that ascorbic acid (H2A) could enhance PDS activation by soil Fe-minerals for triphenyl phosphate (TPHP) degradation. Determination and characterization analyses of Fe fractions showed that H2A could induce the reductive dissolution of solid Fe-minerals and the increasing of oxygen vacancies/hydroxyl groups content on Fe-minerals surface. The increasing of divalent Fe (Fe(II)) accelerated PDS activation to generate reactive oxygen species (ROS). Electron paramagnetic resonance (EPR) and quenching studies showed that sulfate radicals (SO4•-) and hydroxyl radicals (HO•) contributed significantly to TPHP degradation. The composition and content of Fe-minerals and soil organic matter (SOM) markedly influenced ROS transformations. Surface-bond and structural Fe played the main role in the production of Fe(II) in reaction system. The high-concentration SOM could result in ROS consumption and degradation inhibition. Density functional theory (DFT) studies revealed that H2A is preferentially adsorbed at α-Fe2O3(012) surface through Fe-O-C bridges rather than hydrogen bonds. After absorption, H atoms on H2A may further be migrated to adjacent O atoms on the α-Fe2O3(012) surface. With the transformation of H atoms to the α-Fe2O3(012) surface, the Fe-O-C bridge is broken and one electron is transferred from the O to Fe atom, inducing the reduction of trivalent Fe (Fe(III)) atom. MS/MS2 analysis, HPLC analysis, and toxicity assessment demonstrated that TPHP was transformed to less toxic 4-hydroxyphenyl diphenyl phosphate (OH-TPHP), diphenyl hydrogen phosphate (DPHP), and phenyl phosphate (PHP) through phenol-cleavage and hydroxylation processes, and even be mineralized in reaction system.

Assembly of a Fluorescent Chiral Photonic Crystal Membrane and Its Sensitive Responses to Multiple Signals Induced by Small Molecules

Chiral liquid crystal materials that are responsive to environmental stimuli are in demand. A chiral photonic crystal membrane based on cellulose nanocrystals (CNCs) was prepared by molecule assembly in the present work. A fluorescent molecule containing a cationic group, [N-(3-N-benzyl-N,N-dimethylpropyl ammonium chloride)-1,8-naphthalimide]hydrazine, was assembled on the surface of the CNCs. The new chiral photonic crystal membrane possesses supersensitive multiresponses to small molecules, such as water and formaldehyde molecules. The appearance, liquid crystal texture, fluorescence, and color of the chiral membrane have sensitive changes induced by small molecules. By increasing RH from 30 to 100%, the reflectance peak of the membrane red-shifted from 498 to 736 nm. In particular, the iridescent texture and fingerprint structure of the membrane could change markedly under trace amounts of formaldehyde, and the chiral membrane can form an extremely sensitive off-on fluorescence switch. The relationship between the fluorescence intensity and the trace concentration of formaldehyde satisfied the linear equation with the association coefficient of 0.9997. The changes in fluorescence and color are visible to the naked eye, and the membrane can quantitatively recognize trace formaldehyde at a molecular level in a humid environment. The mechanism by which the fluorescence switch operates was investigated using density functional theory at the B3LYP/6-31G(d) level. The membrane has potential for use in the fields of advanced functional materials and biomaterials.

Use of Ethylenediaminetetraacetic Acid as a Scavenger for Chromium from “Wet Blue” Leather Waste: Thermodynamic and Kinetics Parameters

One serious consequence of the current consumer society is the transformation of the environment into a waste receptacle arising from human activities. Because of the potential toxic effects of chromium solid waste containing this metal there are grounds for serious concern for the tanning and leather processing industry. The application of tannery waste as organic fertilizer has led to extensive contamination by chromium in agricultural areas and may cause the accumulation of this metal in soils and plants. This work evaluated the extraction of Cr+3and Cr+6contained in solid waste from the leather industry through density functional theory (DFT) calculations. The Gibbs free energy calculations reveal that the chelator ethylenediaminetetraacetic acid (EDTA) forms more stable complexes with metal ions of chromium compared with the structures of the complexes [Cr(NTA)(H2O)2] and [Cr-collagen], the latter used to simulate the protein bound chrome leather.

1,4-Dibut-oxy-2,5-bis-{(Z)-2-[4-(9H-carbazol-9-yl)phen-yl]ethen-yl}benzene

The title compound, C(54)H(48)N(2)O(2), lies about an inversion centre. The carbazole ring system makes dihedral angles of 58.43 (7) and 88.96 (7)°, respectively, with the adjacent and central benzene rings. The dihedral angle between the two benzene rings is 52.01 (8)°. In the crystal, mol-ecules are linked by pairs of C-H⋯O inter-actions, forming a tape along the a axis. The methyl group is disordered over two sets of sites with occupancies of 0.63 (3) and 0.37 (3).