Efficient and Reusable Silica Gel Supported Metal Ionic Liquid Catalysts for Palmitic Acid Esterification to Biodiesel

A series of silica gel (SG) supported metal ionic liquid catalysts (x[Bmim]Cl-CrCl3/SG) were synthesized and exploited for the esterification of palmitic acid (PA) with methanol (ML) to produce biodiesel efficiently. The 10%[Bmim]Cl-CrCl3/SG catalyst with high surface area and desirable acidity exhibited the best catalytic performance and reusability after six consecutive running cycles. Based on the response surface analysis, the optimal reaction conditions were obtained as follows: methanol/acid mole ratio = 11:1 mol/mol, catalyst amount = 5.3 wt%, reaction time = 65 min, as well as reaction temperature = 373 K, reaching to a biodiesel yield of 96.1%. Further kinetic studies demonstrated that the esterification of PA with ML obeyed 1.41 order kinetics for acid concentration with the activation energy of 16.88 kJ/mol

Performance Evaluation of Coating Materials Containing Perlite-Volcanic Lava Stone-Carrot Pulp Ternary System

Cellulose in the fibrous structure, which is the main structural component in the cell wall of plants, was formed by the combination of three thousand or more glucose molecules and was a natural polymer synthesized by many living microorganisms. In this study, it was aimed to observe the performance of carrot pulp physically added to water-based coating to increase the viscosity of the coatings. In addition, volcanic lava stone (red pumice stone) and perlite stone were added to the coating to improve its properties that heat transfer, adhesion, hydrophobicity, corrosion resistance. The effect of cellulose-based material on the viscosity of the coating was determined using the Design Expert Optimization Method. In this experimental design method, the experimental set was created to be “carrot pulp, volcanic lava stone, and perlite stone” and additives was added as 0-6% by weight of the coating. By using this method, the most suitable process parameters were determined, and the effects of the additives added to the coating were examined, comparatively. As a result, it was found that cellulose derived organic additives and other additives improved the various properties of coating and could be evaluated for industrial coatings.

Palladium Catalyzed Synthesis of Phenylquinoxaline-Alkyne Derivatives via Sonogashira Cross Coupling Reaction

Transition metals mediated cross coupling methodologies provide an extremely powerful versatile pathway in organic syntheses undoubtedly, a facile route for syntheses and derivatization of biologically important heterocycles from easily available precursors. Sonogashira coupling reaction, a leading method to Csp-Csp2 bond formation is one of the most important and rapid pathways to couple aryl/vinyl halides with terminal alkynes. Current research study deals with the synthesis of alkyne substituted quinoxaline derivatives. The quinoxalines class of aromatic heterocycles exhibits a wide variety of important biological potencies. Palladium catalyzed cross coupling process provided an effective synthetic practice for the synthesis of alkyne derivatives of quinoxaline. Vareity of terminal alkynes were coupled with 2-(4-bromophenyl)quinoxaline under optimized conditions for Sonogashira reaction, affording alkyne substituted quinoxaline derivatives in high yields. The optimized reaction conditions for coupling of range of terminal alkyne with quinoxaline basic core render this process significant for designing of medicinally interesting precursors.

DNA Interaction and Biological Activities of Heteroleptic Palladium (II) Complexes

The manuscript describes the binding of DNA as well as biological studies of some mixed ligand dithiocarbamate Palladium (II) complexes (1-5). The observed compounds are of general formulae [PdCl(DT)(PR3)]. The dithiocarbamate “DT” and “PR3” groups are varied among the studied complexes as DT = bis[(2-methoxyethyl) dithiocarbamate)] (1 and 2), dibutyl dithiocarbamate (4 and 5), bis[(2-ethyl) hexyl dithiocarbamate)] (3); PR3 = triphenyl phosphine (1), benzy diphenyl phosphine (2), diphenyl-tert-butyl phpsphine (3), diphenyl-p-tolyl phosphine (4) and diphenyl-2-methoxy phenyl phosphine (5). The synthesized complexes were screened for DNA binding study via (UV Visible spectrophotometry and Viscometery) and biological activities such as anti-bacterial and anti-fungal, Molinspiration calculations and antioxidant potencies stimulated by hydrogen peroxide in human blood lymphocytes. In case of drug DNA interaction, complexes showed some sort of interaction with DNA solution. Almost all the complexes exhibited moderate antifungal and antibacterial behavior (against Gram positive and negative bacterial strains). The Molinspiration calculation study revealed that the said Pd (II) mixed complexes are biologically significant drugs having adequate molecular properties regarding drug likeness, except the log P values of complexes 3-5 because some structural adjustments must be done for enhancement of their bioavailability and hydrophilic nature. Regarding the antioxidant potential of complexes 1, 2 and 4, the H2O2 treatment of complexes violently decreased the action of antioxidant enzymes, superoxide dismutase and catalase and enhanced the level of thiobarbituric acid-reacting substances. Under experimental conditions, we conclude that all complexes act as anti-mutagens as they significantly suppress H2O2-induced oxidative damage at non-genotoxic concentrations.

Selective Removal of Hg2+ Ions from Water Using New Functionalized Silica Resin: Equilibrium, Thermodynamics and Kinetic Modeling Studies

In current study, the diphenylaminomethylcalix[4]arene (3) was synthesized and immobilized onto silica surface to prepare a selective, regenerable and stable resin-4. The synthesized resin-4 has been characterized by FT-IR spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX) and Brunauer-Emmett-Teller (BET) techniques. To check the adsorption capacity of resin-4, the batch and column adsorption methodology were applied and it has observed that the resin-4 was selectively removed Hg2+ ions under the optimized parameters. The maximum adsorption capacity was obtained at pH 9 using 25 mg/L of resin-4. Under the optimal conditions, different equilibrium, kinetic and thermodynamic models were applied to experimental data. The results show that adsorption mechanism is chemical in nature following Langmuir model with good correlation coefficient (R2=0.999) and having 712.098 (mmol/g) adsorption capacity. The energy of calculated from D-R model suggests the ion exchange nature of the adsorption phenomenon. Dynamic adsorption experiments were conducted using Thomas model. The maximum solid phase concentration (qo) was 7.5 and rate constant was found to be 0.176 with (R2=0.938) for Hg2+ ions. The kinetic study describes that the adsorption mechanism follows pseudo second order (R2=0.999). The thermodynamic parameters such as ∆H (0.032 KJ/mol) and ∆S (0.127 KJ/mol /K) and ∆G (-5.747,-6.306, -7.027 KJ/mol) shows that the adsorption of Hg2+ ion is endothermic and spontaneous. The reusability of resin-4 was also checked and it has observed that the after 15 cycle only 1.2 % adsorption reduces. Moreover, the resin-4 was applied on real wastewater samples obtained from local industrial zone of Karachi, Sindh-Pakistan.

Spatial Structure of the Acth-(6-9)-PGP Molecule

The spatial structure of ACTH-(6-9)-PGP molecule has been investigated using theoretical conformational analysis method. Amino acid sequence of the N-terminal pentapeptide fragment of His-Phe-Arg-Trp-Pro of this molecule conforms to the fragment 6-9 of ACTH hormone. Calculations of conformational states of this molecule are carried out regarding nonvalent, electrostatic and torsional interactions and the energy of hydrogen bonds. The spatial structure of the His-Phe-Arg-Trp-Pro-Gly-Pro molecule was estimated on the low–energy conformations of the N-terminal tetrapeptide fragment His-Phe-Arg-Trp and C-terminal tripeptide fragment Pro-Gly-Pro of this molecule. It is shown that the spatial structure of heptapeptide molecule can be presented by 11 low-energy forms of the main chain. The low–energy conformations of this molecule, the values of dihedral angles of the backbone and side chains of the amino acid residues were founded and the energies of intra- and inter-residual interactions were determined.

Functionalization of Cellulose Paper by Coating Nano Metal-Organic Frameworks for Use as Photochromic Material

The cellulose paper-based functional materials modified by Zn-NDI and Cu-NDI were prepared by the coating method. The chemical structures were characterized by FTIR, XRD, UV-vis and SEM, and the photochromic properties of the composite functional materials were studied. The results showed that Zn-NDI and Cu-NDI were successfully prepared and retained on the surface of copy paper, the wavelength of photochromic reaction is between 300-400 nm of MOFs materials. Optical analysis confirmed that the NDI/paper, Zn-NDI/paper and Cu-NDI/paper changed from tan to wheat, light green to olive, and dark tan to brown after 60 seconds of exposure to hernia light irradiations, the MOFs coated paper returned to its original color when it was placed in the dark for 4 hours. The above results indicated that the prepared Zn-NDI and Cu-NDI coated paper composites exhibited excellent photochromic ability and had potential applications in the field of anti-counterfeiting packaging materials.

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

Mesoporous Silica Nanoparticles Supported Atomically Precise Palladium Nanoclusters Catalyzed Aerobic Oxidation of Alcohols in Water

The first mesoporous silica nanoparticles (MSNs) supported atomically precise palladium nanoclusters catalyzed alcohol oxidation reactions in water have been achieved. The catalysts was synthesized with simple impregnation method and well characterized by TEM, FT-IR, XPS anddiffuse reflectance optical spectrum and the results proved that the Pd nanoclustersimmobilized into the pores of MSNs.The as-prepared catalyst show excellent activity for the alcohol oxidation reactions with high yield under extremely mild aqueous conditions utilizes 1 atmosphere of molecular oxygen as sole oxidant. The features of clean system, gram-scale oxidation and easy recovery catalyst make this method cost effectively and environmentally benign.

Electric Field Controlled Separation and Capture of CO2 over S-Doped Graphene: A First-Principles Calculation

The selective adsorption and capture of CO2 from post-combustion gases carries huge significance for the reduction of greenhouse effect. In this research, the computations of density functional are performed to investigate the CO2 selective adsorption of S-doped graphene in thrall to applied electric field (E-F). Introducing the applied E-F, the adsorption between S-doped graphene and CO2 is strong chemisorption, and CO2 can be effectively captured. Removing the applied E-F, the adsorption restores to physisorption and CO2 is easily desorbed. Therefore, the CO2 seize and clearing can be realized merely by controlling the E-F. Besides, the adsorption energy of N2 (H2O) on S-decorated graphene is positive when introduce the applied E-F. The results demonstrated that S-doped graphene can selectively adsorb CO2 from the post-combustion gases by controlling the E-F.