Keywords : 5
In Situ Polymerization Of The Metal-organic Framework 5 (MOF-5) By The Use Of Maghnite-H+ As A Green Solid Catalyst
Advanced Materials Letters,
2015, Volume 6, Issue 3, Pages 271-277
Metal-organic framework MOF-5 [Zn4O(BDC)3, BDC : 1,4 benzenedicarboxylic] is a microporous material with a large specific surface area and high porosity formed by benzenedicaroboxylic acid as organic ligand and zinc nitrate hexahydrate as metal ion . This material is mainly used in the field of automobile industry as a container for storing hydrogen (alternative fuel) and for the environmental preservation by trapping CO2 (greenhouse gas emissions). The present study shows the synthesis of this material using a clay called Maghnite-H+ as catalytic support in order to enhance the yield which increases from 35% to 63% and improve the thermal stability of MOF-5. Maghnite-H+ is a montmorillonite sheet silicate clay, exchanged with protons, it is an efficient catalyst for polymerization of many vinylic and heterocyclic monomers. The structure of resulting products is characterized and established by Magic Angle Spinning Nuclear Magnetic Resonance ( 13 C MAS NMR). 27 Al MAS NMR and 29 Si MAS NMR results show that there are interactions between the chains of MOF-5 and the silicate surface or aluminum of Maghnite-H + . Fourier Transform Infrared spectroscopy (FTIR) is also used to confirm the structure of these products showing that there is a complete deprotonation of benzenedicaroboxylic acid. The X-Ray Diffraction (XRD) allows to study the morphology of the obtained compounds and reveals the formation of a partially exfoliated/partially intercalated structure. Thermal stability is studied by Thermogravimetric Analysis (TGA) and shows an enhanced thermal stability for MOF-5/Mag-H + with a gain of 40°C.
Advanced Materials Letters,
2012, Volume 3, Issue 6, Pages 487-492
Low molecular weight chitosan (LMWC) exhibits higher water solubility and produces nanoparticles of fairly low particle size. However, poor drug loading and shorter circulation time in body limits its application in preparation of nanoparticles. Acylation of LMWC ensures extended circulation of nanoparticles in body and hence enhanced bioavailability of the drug. We therefore synthesized the acylated LMWC using palmitoyl chloride and confirmed its synthesis by FTIR and NMR spectroscopy. The nanoparticles of LMWC and low molecular weight palmitoyl chitosan (LMWPC) were prepared by miniemulsion and chemical crosslinking method using glutaraldehyde and 5-fluorouracil (5FU) as a model drug. The nanoparticles were evaluated for particle size, zeta potential, morphology, drug loading and drug release. TEM analysis revealed nanosize and spherical nature of the particles. The palmitoyl chain of LMWPC increased particle size from 83.2±2.5 nm to 93.4±3.2 nm whereas zeta potential of nanoparticles decreased from 12.5±2.2 mV to 4.2±1.1 mV due to diminished amino groups of LMWPC as a result of acylation. The drug loading in nanoparticles was increased from 13.8±0.95% to 30.2±1.9%. LMWC showed 80±2.08% as maximum drug released in 10 h while only 52.3±2.14% was released in 24 h for LMWPC. Hence, LMWPC nanoparticles ensure increased drug loading capacity and sustained drug release profile without significant change in particle size.