Immobilization of metalloporphyrin on functionalized nanoporous silica

SBA-15 nanoporous silica were prepared cooperation assembly of tetraethylorthosilicate precursor in the presence of poly (ethylene glycol)–block- poly (propylene glycol)–block- poly (ethylene glycol) copolymer surfactant and functionalized with (3-aminopropyl) triethoxysilane (APTES) via sol-gel reaction to obtain APTES-SBA-15. Tetra-(p-chlorophenyl) porphyrin (TClPP) was synthesized using slightly modified Alder- Longo method and zinc(II) was inserted into the TClPP using zinc acetate as source of zinc. The existance of zinc metal in porphyrin was confirmed by the appearance of Soret band and Q band in UV- vis spectra. Zn(II)-TClPP was also characterized using FTIR and NMR spectroscopy .With the aid of amino functionalized on surface of SBA-15, it can be used as support for immobilization of metalloporphyrin producing APTES-SBA-15-Zn(II)-TClPP that can used as heterogenous catalysis in various reactions. The formation of this material was confirmed by characterization by using FTIR spectroscopy, XRD and BET adsorption

Synthesis of supramolecular self-assembled benzene-1,3,5- tricarboxamides and their liquid crystalline properties

Supramolecular self-assembly of soft matter have received many attention for various applications such as liquid crystals, sensors, catalysts, and optics due to its precise control and easily tunable characteristics. Particularly, benzene-1,3,5-tricarboxamides (BTAs) as p- stacked organic motif were recognized for formation of liquid crystals materials; however, these BTAs were only reported bearing different short alkyl or aromatic side chains in order to have liquid crystalline properties. Herein, self-assemblies of BTAs (CRNH-BTA, where R = 10, 12, 14, 16, and 18) via hydrogen bonding interactions have been demonstrated as mesophase liquid crystalline materials by simply tuning its long hydrophobic alkyl chains attached to amide. Series of BTAs were synthesized by a Schotten-Baumann reaction using 1,3,5-benzenetricarbonyl trichloride with respected alkyl amides in the presence of triethylamine in dry tetrahydrofuran (THF) under an inert condition for overnight. Nuclear magnetic resonance (NMR), matrix-assisted laser desorption/ionization time-of-flight mass (MALDI-TOF-MS) and Fourier transform infrared spectroscopy (FT–IR) have proved the successful isolation of the hydrophobic BTAs using column chromatography as powdery solids. Scanning electron microscope (SEM) measurements showed self-assembled aggregation of a tape-like morphology with different aspect to ratio lengths corresponding to different alkyl side-chains lengths. Likewise, FT–IR spectra showed vibration bands at 1540 and 1719 cm-1 due to formation of N-H and C=O bondings, respectively, corresponding to the presence of hydrogen bonding interactions for all BTAs. Moreover, polarized optical microscopy (POM) showed spehrulitic-like texture upon isotropic melts at 140 ºC monitored for 20 hours of C12NH-BTA, strongly supports the characteristics of discotic liquid crystals for BTAs. In addition, differential scanning calorimetry (DSC) thermograms showed that longer alkyl side-chains shortened mesophase ranges due to the presence of higher steric hindrance of the alkyl amide chains

Fabrication of high quality mesoporous silica/gold film nanocomposites: calcination versus thermal hydrogen reduction

High quality mesoporous silica is an important nanomaterial in confinement of metal nanoparticles for potential applications as catalysts, sensors, and opto-electronic devices. Herein we report that high quality mesoporous silica/gold film nanocomposites with an interpore distance of 4.1 nm were successfully fabricated as transparent thin film by an amphiphilic trinuclear gold(I) pyrazolate complex that act as both a template in sol-gel synthesis and as a metal source in formation of gold nanoparticles (AuNPs). In contrast to the calcined thin films at 250 and 450C for 3 h, diffraction peak of d100 and transmission electron microscope (TEM) images showed high quality of mesoporous silica/gold film nanocomposites after thermal hydrogen reduction in the temperature range between 190 and 250C for 2 h. Nevertheless, both methods indicated formation of AuNPs as proved by the presence of diffraction peak at 2 = 38.20, surface plasmon resonance (SPR) peak between 500 to 580 nm, and spherical shape of TEM images

Trinuclear copper (I) pyrazolate complexes for vapochromic sensing of aromatic volatile organic compounds

Vapochromism using optical chemosensors of d10 group metal complexes have a great potential for sensing different kinds of volatile organic compounds (VOCs) by vapor-triggered color and luminescence changes. Since organic aromatic vapors are mainly hazardous and carcinogenic to human health and environment, it is interesting challenge to develop the low-cost vapochromic chemosensors with high sensing capability. On the other hands, inorganic complexes and materials have been found to change their color and luminescence properties by modifying molecular structures. However, there is no study on, the relationship of molecular structures for chemosensors of VOCs such as aromatic vapors. Therefore, we report systematic study on by using supramolecular assembly of a weak metal-metal interaction, optical response of trinuclear copper(I) pyrazolate complexes ([Cu3Pz3]) for vapochromic chemosensors of benzene, toluene and hexafluorobenzene. The [Cu3Pz3] complexes have been successfully synthesized from 3,5-dimethyl (complex A), 3,5-trifluoromethyl (complex B), 3,5-diphenyl (complex C) and 4-(3,5-dimethoxybenzyl)-3,5-dimethyl (complex D) pyrazole ligands as a solid powder. The resulting complexes showed color emission in the range from red to green upon exposure to a UV hand lamp (254 nm) in dark room, which were in good agreement with emission spectra upon excitation at 280 nm; 590 nm (complex A), 570 nm (complex B), 614 nm (complex D) and upon excitation at 321 nm for emission at 642 nm (complex C). The sensing capability of all [Cu3Pz3] complexes with different molecular side-chains showed different phenomena depending on the types of aromatic solvents. In contrast to no response of complex A upon exposure to VOCs, complexes B and C showed gradually quenching of the intensity due to cleavage of Cu(I)-Cu(I) interaction. Interestingly, complex D showed blue shifting of its emission center due to enhancement of the metal-metal distance

Studies on the activity of phosphotungstic acid (HPW) supported on porous kaolin and effects on the catalytic activity

Kaolin is an abundant clay mineral and chemically natural hydrous aluminosilicate with the 1:1 type layered structure. In this work mesoporous material derived from raw kaolin was obtained using starch as organic template. The surface area of the kaolin derived porous clay heterostructure (PCH) has increased remarkably from 15 to 756 m2g-1 with pore volume of 0.65cm3g-1. The FTIR spectra after pyridine adsorption showed that both raw kaolin and PCH was synthesized by a wet impregnation method. HPW incorporated into PCH significantly increased the surface acidity by forming mainly Bronsted acidities in acylation of anisole is demonstrated by varying the amount of Lewis and Bronsted acid sites

Application of X-raydiffraction for Characterization of Cds / Polymer and Stability of Cds/aptms-al-mcm-4 Nanocomposites

The haracterization of Cadmium Sulfide (CdS) nanoparticles on CdS/Polymer nanocomposite and stability ofAl-MCM-41 mesoporous structure in CdS / APTMS-Al-MCM-41 nanocomposite were carried out using X-ray diffraction techniques. The polymer used is poly (Steren-divinilbenzen) sulfonated [SO3H-P (S-DVB)]. The presence of nano-particles of CdS in CdS/SO3H-P (S-DVB) is indicated by the peak width at diffractogram at position 2θ = 26.40°; 43.75° and 52.00° corresponding to the pattern of CdS nano diffractogram cubic form(111), (220) and (311). Meanwhile the stability of diffractogram of CdS/APTMS-Al-MCM-41 nanocomposites was observed of a sharp peak at 2θ = 2,1° (100) and a series weak peaks at 2θ = 3,7° (110); 4,3° (200); 5,5° (210) that it\u27s shown of diffactogram pattern of Al-MCM-41 as a host matrix of CdS/APTMS-Al-MCM-41

The effect of oxygen and nitrogen functional groups on the electrochemical performance of ordered carbon

Ordered carbon (OC) has been synthesised via replication strategy by using Santa Barbara Amorphous (SBA)-15 as a template. The successful replication process has been proven by nitrogen adsorption-desorption analyzer and transmission electron microscopy (TEM). The OC showed well-aligned mesopore system, similar to the SBA-15 template. The oxygen and nitrogen functional groups introduced were identified by X-ray photoelectron spectroscopy (XPS). Electrochemical performance of the oxygen containing OC (OC-O), nitrogen containing OC (OC-N), and oxygen nitrogen containing OC (OC-ON) was then evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) using a three electrode system in 1M KOH aqueous electrolyte. The OC-O, OC-N, and OC-ON showed significant increment in specific capacitance, CS and exhibited good capacitance retention (CR, %) over high scan rate and current density

Structural, porosity and morphological changes of montmorillonite derived porous clay heterostructures prepared by the starch gel template method

Clay minerals are natural hydrous aluminosilicate and possess a layered silicate structure that can be found in a number of soils. Montmorillonite (MMT) is one of the clay minerals have a surface area of 191 m²g.¹ and has been used as a catalyst and adsorbent. However, their efficient use is limited due to low thermal stability and lack of porosity1-3. In this work, mesoporous materials derived from raw MMTwere obtained using the starch gel template method. Porous heterostructures (PCHs) were prepared by intercalation of cationic potato starch and hydrolysed potato starch as template, dodecylamine as co-template and tetraethylorthosilicate (TEOS) as silica pillar into the interlayer space of MMT. The effects of starch loading and aging temperature on changes of the structure, porosity and morphology of MMT in the formation of PCHswere investigated. The MMT derived PCHswas characterized by means of XRD, N2 adsorption-desorption, pyridine adsorption, FESEM and FTIR spectroscopy. The XRD and FESEM analyses of the PCHs prepared using cationic and hydrolyzed starchshowed a significant disordering of the MMT layer arrangement after treatment with the starch gel template. However, results of the nitrogen adsorption measurement showed the surface area has increased remarkably as high as 1000 m²g.¹ with average pore diameters of 3.4 – 3.8 nm and pore volumesof 0.70 to 0.87 cm3g-1. Furthermore, the structural integrity of PCHs deteriorated slightly with increasing temperature but the porosity was maintained until up to 900 .C. The FTIR spectra after pyridine adsorption showed thatboth raw MMT and PCHspossessed mainly strong Lewis acid sites. The acidity properties and high surface area of PCHsmake them useful as potential heterogeneous catalyst for the transformation of bulky organics

Supramolecular hydrogen bonding interactions of self-assembled mixed-hydrophobic/hydrophilic benzene-1,3,5-tricarboxamides for sensing nitrobenzene

Supramolecular self-assembly of weak non-covalent hydrogen, metal-metal, and interactions have been developed for molecular recognition due to its easy to control and tune precisely. Moreover, nitrobenzene (NB) have been reported to penetrate skins rapidly, cause formation of methemoglobin on acute exposure, and used as explosive compounds in the bomb for terrorist activities. In recent years, benzene-1,3,5-tricarboxamides (BTAs) self-assembled to form nanofiber; however, there is no report on the use of its hydrogen bondings for sensing this hazardous NB. Herein we report, self-assemblies via hydrogen bonding interactions as a chemosensor of NB by using mixed-hydrophobic/hydrophilic version of BTAs. Hydrophobic BTA as a white powder solid showed self-assembly with a tape-like morphology, while hydrophilic BTA as an oily liquid formed less order characteristic of self-assemblies, thus suggesting the competitive intramolecular hydrogen bonding with amphiphilic prope - Both chemosensors BTAs, showed disappearances of N H vibrational peaks at 3233 and 1540 cm-1 and appearance of a new peak at 1478 cm-1 for nitroso (N N=O) upon addition of NB. These sensing capabilities was found to strongly depend on the anisotropic behavior of the self-assembled BTAs where highly ordered hydrophobic BTA with more rigid side chain has better N N=O formation compared to hydrophilic BTA. Interestingly, mixing of both BTAs at equal molar ratio give a stable suspension indicating the formation of organogel with tape-like morphology due to -so-hydrophobic/hydrophilic BTAs organogel turned to liquid upon addition of NB, suggesting improvement of sensing capability and breaking of hydrogen bonding or disassembly. The optimization of sensing capability parameters will be discussed in details later