Synthesis and NMR spectral assignments of novel nitrogen and sulfur heterocyclic compounds

Degradation of urea-formaldehyde resin residues by a hydrothermal oxidation method into recyclable small molecular organics

Urea-formaldehyde (UF) resin residues and the related product wastes as organic hazardous wastes are difficult to be biodegraded or recycled. In this research, a hydrothermal oxidation method using hydrogen peroxide (H₂O₂) solution has been developed for the degradation and recycling of UF resin residues. The effects of solution concentration, temperature, and time on the degradation efficiency and products of UF resin residues were studied. Under optimal conditions, i.e., 140 °C and 5 wt% H₂O₂ solution, over 75% of UF resin residues was degraded after 3 h. The degradation efficiency is much higher than that of the traditional hydrothermal treatment or acid hydrolysis method. In addition, results from Fourier transform infrared spectroscopy (FTIR), gas chromatography-mass spectroscopy (GC-MS), nuclear magnetic resonance spectroscopy (NMR), and X-ray diffraction (XRD) confirmed that H₂O₂ solution degrades UF resin residues to low molecular compounds, such as alcohols, methylal, and amides. This research provides a novel and high-efficient hydrothermal oxidization process for the degradation of UF resin residues, which might be a promising environmentally friendly and low-cost method for the disposal and recycling of industrial UF resin residues.

Controllable Synthesis of 1, 3, 5-tris (1H-benzo[d]imidazole-2-yl) Benzene-Based MOFs

The growing interest in metal–organic frameworks (MOFs) in both industrial and scientific circles has increased in the last twenty years, owing to their crystallinity, structural versatility, and controlled porosity. In this study, we present three novel MOFs obtained from the 1, 3, 5-tris (1H-benzo[d]imidazole-2-yl) benzene (TIBM) organic linker. The formed TIBM crystal powders were characterized by scanning electron microscopy (SEM) to estimate the morphology of the particles, powder X-ray diffraction (XRD) to confirm the crystal structure, Brunauer–Emmett–Teller (BET) method for structural analysis, and thermogravimetric measurements to examine the thermal stability. The TIBM-Cu MOF showed excellent CO2 (3.60 mmol/g) adsorption capacity at 1 bar and 298 K, because of the open Cu site, compared to TIBM-Cr (1.6 mmol/g) and TIBM-Al (2.1 mmol/g). Additionally, due to the high porosity (0.3–1.5 nm), TIBM-Cu MOF showed a considerable CO2/N2 selectivity (53) compared to TIBM-Al (35) and TIBM-Cr (10).

Evidence for Electron Transfer between Graphene and Non-Covalently Bound π-Systems

Hybridizing graphene and molecules possess a high potential for developing materials for new applications. However, new methods to characterize such hybrids must be developed. Herein, the wet-chemical non-covalent functionalization of graphene with cationic π-systems is presented and the interaction between graphene and the molecules is characterized in detail. A series of tricationic benzimidazolium salts with various steric demand and counterions was synthesized, characterized and used for the fabrication of graphene hybrids. Subsequently, the doping effects were studied. The molecules are adsorbed onto graphene and studied by Raman spectroscopy, XPS as well as ToF-SIMS. The charged π-systems show a p-doping effect on the underlying graphene. Consequently, the tricationic molecules are reduced through a partial electron transfer process from graphene, a process which is accompanied by the loss of counterions. DFT calculations support this hypothesis and the strong p-doping could be confirmed in fabricated monolayer graphene/hybrid FET devices. The results are the basis to develop sensor applications, which are based on analyte/molecule interactions and effects on doping.

Easily Accessible Thermotropic Hydrogen-Bonded Columnar Discotic Liquid Crystals from Fatty Acid- Tris-Benzoimidazolyl Benzene Complexes

We report the formation of easily accessible hydrogen-bonded columnar discotic liquid crystals (LCs) based on tris-benzoimidazolyl benzene (TBIB) and commercially available fatty acids. By increasing the length of the fatty acid, the temperature range of liquid crystallinity was tuned. Introducing double bonds in octadecanoic acid lowered the crystallization temperature and increased the temperature range of the mesophase. Surprisingly, dimerized linoleic acid also forms an LC phase. When using branched aliphatic acids with the branching point close to the acid moiety, the mesophase was lost, whereas phosphonic acid or benzenesulfonic acid derivatives did have a mesophase, showing that the generality of this approach extends beyond carboxylic acids as the hydrogen-bond donor. Furthermore, a polymerizable LC phase was obtained from mixtures of TBIB with a methacrylate-bearing fatty acid, providing an approach for the fabrication of nanoporous polymer films if the methacrylate groups are polymerized. Finally, the higher solubility of methyl-TBIB was used to suppress phase separation in stoichiometric mixtures of the template molecule with fatty acids.

Activation of -N=CH- bond in a Schiff base by divalent nickel monitored by NMR evidence

The Schiff base, 2-salicylidene-4-aminophenyl benzimidazole in ethanol undergoes activation of -N=CH- bond by Ni(2+) in the presence of ammonia or primary alkyl amine to produce nickel complexes of the formula Ni{o-C(6)H(4)(O)CH NR}(2) . n H(2)O [R  =  H, Me; n  =  0; R  =  Et, n =  0.5] and 4-aminophenyl benzimidazole. The products have been identified by elemental analysis, magnetic susceptibility measurements and IR, ESR, mass and extensive NMR spectral studies. The possible mechanism for the activation of -N=CH- bond has also been proposed.