Mazidah Mamat

Investigation of crystal structure influence on spectroscopic and photoluminescent properties of terbium-picrate triethylene glycol complex.

The [Tb(Pic)(2)(H(2)O)(EO3)](Pic)·0.5(EO3) complex, for which EO3 and Pic stand for triethylene glycol and picrate anion, respectively, was successfully prepared and characterized. The Tb(III) complex was crystallized in triclinic structure with space group P1¯. The Tb(III) ion was coordinated to nine oxygen atoms from one EO3 ligand, one water molecule, and two Pic anions. The photoluminescent (PL) spectrum of the complex displayed characteristic narrow bands arising from intraconfigurational transitions of the Tb(III) ion. The strongest emission was centred at 544 nm ((5)D(4)→(7)F(5)), which was responsible for the green emission. The short acyclic chain length of the EO3 ligand, lanthanide contraction, and a bulky picrate anion affected the PL intensity, coordination environment around the Tb(III) ion, and crystal structure of the inner-sphere [Tb(Pic)(2)(H(2)O)(EO3)](+) moiety. The unique crystal structure in the Tb complex contained a half mole of triethylene glycol solvated. The complex had a high thermal stability due to the role of π-π stacking interactions of the Pic anions. The appearance of an emission from the ligands suggests that the photoluminescence of ligands cannot be quenched by coordination to the Tb(III) ion in its complex, so the intramolecular energy transfer process from the triplet state of the ligands (T(1)(L)) to the resonant emissive energy level of Tb(III) is not effective.

Layered hydroxide anion exchanger and their applications related to pesticides: a brief review

Abstract Layered double hydroxides and layered hydroxide salts have generated enormous excitement in the inorganic field due to their potential to act as versatile host materials in fabricating novel host–guest layered materials. The ability of the layered hydroxide anion exchanger to be incorporated with a wide range of guest ions enable them to be exploited in various applications related to pesticides. This review sums up the different methods of preparing layered hydroxide anion exchanger, summarises the types of anion intercalated into these layered hydroxide anion exchanger based on their respective systems, and elucidates their potential applications in pesticide-related fields.

Preparation and characterisation of novel paddy cultivation herbicide nanocomposite from zinc/aluminium layered double hydroxide and quinclorac anion

Abstract Zn/Al-layered double hydroxide-quinclorac (Zn/Al-LDH-QC) nanocomposite has been synthesised via co-precipitation method. The versatility of the Zn/Al-LDH enables this host material to be intercalated with quinclorac (QC), a type of auxin agonist herbicide that was widely used in paddy cultivation. The PXRD analysis shows that the basal spacing of the Zn/Al-LDH-QC nanocomposite expanded in the range of 15.8–16.7 Å (from 8.8 Å in Zn/Al-LDH), therefore indicating the successful intercalation of QC into the interlayer gallery of Zn/Al-LDH. The intercalation was also proven from the FTIR and elemental analysis. The thermogravimetric analysis conducted using TGA/DTG shows that the Zn/Al-LDH-QC exhibits better thermal stability compared to the pure QC herbicide. Based on the results collected from the ICP-OES, CHNS analyser, and TGA/DTG, the chemical formula of Zn/Al-LDH-QC was proposed as [Zn0.75Al0.25(OH)2][C9H4Cl2NCOO]− 0.250.90H2O. This study shows that the Zn/Al-LDH has potential to be used as a host material for herbicide in paddy cultivation sector.

Behavior of Layered Double Hydroxides Having Different Divalent Transition Metal Groups

The layered double hydroxides (LDHs) with different divalent transition metal groups and nitrate as a counter anion were investigated. Three d-block divalent metals namely cobalt (Co), nickel (Ni) and copper (Cu) were selected. The cobalt/aluminium (CoAN)-, nickel/aluminium (NiAN)- and copper/aluminium (CuAN)-layered double hydroxides were successfully synthesized via co-precipitation method. All the obtained LDHs were characterized by PXRD, FT-IR, ICP-OES, CHNS and TGA/DTG analysis. Interestingly, behavior of the LDHs was dependent on the size of divalent cations. PXRD showed the basal spacing decrease in the order NiAN (0.88nm)> CuAN (0.87nm) > CoAN (0.74nm), and in a linear correlation with the increasing radii of the divalent cations. Similar trend is observed for the weight loss of LDHs, where NiAN has the highest weight loss (53%), followed by CuAN (43%) and CoAN (34%). Further elemental analysis showed the content of trivalent metal cations, nitrate anions and water molecules in the LDHs decrease with the increasing radii.

Scrutinizing the consequence of surface modification on membrane stability and resistivity towards fouling

Membrane fouling due to the interactions of solutes and the membrane surface are the object of intensive studies. Appointing to this crucial issues, methods for the improvement of membrane antifouling characteristics have been developed. In this work, the polyethersulfone ultrafiltration (PES-UF) membrane surface has been modified by the pre-adsorption of myoglobin. Ultrafiltration (UF) experiments of lyszoyme were performed using native PES-UF and myoglobin coated PES-UF membrane. Membrane resistance towards fouling was measured by calculating the flux recovery ratio (FRR) and each membrane was analyzed for the degree of hydrophilicity using contact angle measurements. Results were further verified by the UF of lysozyme and the degree of transmission for both coated and uncoated membranes were compared. Findings obtained showed that the myoglobin modified membranes gave higher flux recovery ratio and a superior hydrophilicity attributes as contrast to the PES-UF membrane of unmodified surface. An increased in the transmission of lysozyme with an optimum percentage of 96.31% was also attained for the myoglobin modified PES-UF membrane, indicates that, the surface modified membranes potentially show a better ability towards protein fractionation. Such enhancement might be contributes by the introduction of myoglobin coating. Thus, it can be concluded that, this proprietary surface coating has successfully enhanced the hydrophilic features of the modified PES-UF membrane, making it more invincible to fouling than the native PES-UF membrane. The excellent flux recovery property of these myoglobin coated PES-UF membranes signifies that this surface modified membrane could be regenerated and used repeatedly for several runs. Hence, the membrane surface treatment method proposed in this research may have facile implications for the manufacturing of high flux and fouling endurance UF membrane.