DSpace Collection:http://localhost:8080/xmlui/handle/123456789/17612024-03-29T03:35:35Z2024-03-29T03:35:35ZNanoassembling of Thixotropically Reversible Alumino-siloxane Hybrid Gels to Hierarchically Porous Aerogel FrameworkLinsha, VMohamed, A PAnanthakumar, Shttp://localhost:8080/xmlui/handle/123456789/47972024-03-01T07:51:17Z2015-01-01T00:00:00ZTitle: Nanoassembling of Thixotropically Reversible Alumino-siloxane Hybrid Gels to Hierarchically Porous Aerogel Framework
Authors: Linsha, V; Mohamed, A P; Ananthakumar, S
Abstract: This work describes a versatile strategy for the formation of thixotropically reversible alumino-siloxane
hybrid gel suitable for the fabrication of open-porous aerogel like framework. Aminated alumino-siloxane gel was synthesized by pH controlled sol–gel assisted co-condensation of hydrolyzed aluminum isopropoxide with 3-aminopropyltrimethoxy silane. A rare reversible thixotropic flow behavior was noticed
for the first time in aminated alumino-siloxane hybrid gel. The hybrid gel was used for preparation of
hydrogel microspheres via gel granulation technique. The hydrogel microspheres derived from thixotropic gel showed an open porous network with intercommunicated structure. It was then converted to
aerogel microspheres, without the collapse of the transient hybrid porous network by ambient pressure
drying technique. The porous framework was tailored to hierarchical domains containing meso/macro
porosity, with a dense array of functional amine on internal porous framework. The textural properties
of the hybrid alumino-siloxane aerogel microspheres have been characterized by SEM, TEM, FTIR and
N2 gas adsorption/desorption analysis and the results are discussed. Hybrid aerogel microspheres exhibit
2–3 times superior properties in terms of surface area and pore features compared to their xerogel counterparts. Thus, open porous aerogel microsphere derived from thixotropic gel could be a new media for
controlling host–guest interactions especially when it is intended to be used in adsorption, separation
and catalysis/catalyst support.2015-01-01T00:00:00ZNear-IR Squaraine Dye-loaded Gated Periodic Mesoporous Organosilica for Photo-oxidation of Phenol in a Continuous-flow DeviceBorah, PSreejith, SAnees, PMenon, N VKang, Y JAjayaghosh, AZhao, Y Lhttp://localhost:8080/xmlui/handle/123456789/47952024-02-29T10:29:35Z2015-09-04T00:00:00ZTitle: Near-IR Squaraine Dye-loaded Gated Periodic Mesoporous Organosilica for Photo-oxidation of Phenol in a Continuous-flow Device
Authors: Borah, P; Sreejith, S; Anees, P; Menon, N V; Kang, Y J; Ajayaghosh, A; Zhao, Y L
Abstract: Periodic mesoporous organosilica (PMO) has been widely used for the fabrication of a variety of catalytically active materials. We report the preparation of novel photo-responsive PMO with azobenzene-gated pores. Upon activation, the azobenzene gate undergoes trans-cis isomerization, which allows an unsymmetrical near-infrared squaraine dye (Sq) to enter into the pores. The gate closure by cis-trans isomerization of the azobenzene unit leads to the safe loading of the monomeric dye inside the pores. The dye-loaded and azobenzene-gated PMO (Sq-azo@PMO) exhibits excellent generation of reactive oxygen species upon excitation at 664 nm, which can be effectively used for the oxidation of phenol into benzoquinone in aqueous solution. Furthermore, Sq-azo@PMO as the catalyst was placed inside a custom-built, continuous-flow device to carry out the photo-oxidation of phenol to benzoquinone in the presence of 664-nm light. By using the device, about 23% production of benzoquinone with 100% selectivity was achieved. The current research presents a prototype of transforming heterogeneous catalysts toward practical use.2015-09-04T00:00:00ZOne Step Green Synthesis Of Carbon Quantum Dots and Its Application Towards The Bioelectroanalytical and Biolabeling StudiesShereema, R MSankar, VRaghu, K GRao, T PShankar, S Shttp://localhost:8080/xmlui/handle/123456789/47942024-02-29T10:28:37Z2015-11-10T00:00:00ZTitle: One Step Green Synthesis Of Carbon Quantum Dots and Its Application Towards The Bioelectroanalytical and Biolabeling Studies
Authors: Shereema, R M; Sankar, V; Raghu, K G; Rao, T P; Shankar, S S
Abstract: A green luminescent carbon quantum dots were prepared from maltose by Microwave assisted method
followed by passivation with NaOH (pH = 7.4). The TEM measurement confirmed the average size of
prepared carbon quantum dots to be 2 nm. Surface characterization such as XPS, FTIR and Raman
spectroscopy confirm that the functional groups (C=O, C-OH) were attached on the surface of sp2
hybridized carbon. Electrochemical characterization studies on carbon paste electrode (CPE) revealed
that the synthesized carbon quantum dots showed higher electrocatalytic property, conductivity and
surface area. Therefore, herein we report the synthesized carbon quantum dots could find its applicability
as an electrochemical sensor for the detection of neurotransmitter, dopamine. Cyclic voltammetry and
differential pulse voltammetry (DPV) was employed for the detection of DA in presence of common
interferences like UA, and AA with carbon quantum dots modified carbon paste electrode. The developed
sensor was effectively applied for the real sample analysis with satisfactory results. Moreover, biological
studies in He La cell lines proclaimed that the cell viability was unaffected (100% viability) on incubation
with the carbon dots. Significant cellular uptake as revealed by fluorescence imaging makes them
suitable for cell labeling studies.2015-11-10T00:00:00ZAchieving Visible Light Excitation in Carbazole-based Eu3+–β-diketonate Complexes via Molecular EngineeringFrancis, BHeering, CFreire, R OReddy, M L PJaniak, Chttp://localhost:8080/xmlui/handle/123456789/47932024-02-29T09:56:57Z2015-01-01T00:00:00ZTitle: Achieving Visible Light Excitation in Carbazole-based Eu3+–β-diketonate Complexes via Molecular Engineering
Authors: Francis, B; Heering, C; Freire, R O; Reddy, M L P; Janiak, C
Abstract: Herein, we present the synthesis, characterization and photophysical properties of a series of Eu3+
complexes prepared with novel carbazole-based fluorinated b-diketones, namely, 4,4,5,5,5-pentafluoro3-hydroxy-1-(9-phenyl-9H-carbazol-2-yl)pent-2-en-1-one (L1) and 4,4,5,5,5-pentafluoro-3-hydroxy-1-
(9-(4-methoxyphenyl)-9H-carbazol-2-yl)pent-2-en-1-one (L2) as primary ligands and a bidentate
phosphine oxide molecule, 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene oxide (DDXPO) as
ancillary ligand. Using the Sparkle/PM3 model the molecular geometries of the designed complexes are
optimized and the luminescent parameters are calculated by the LUMPAC software. The results
demonstrated that suitably expanded p-conjugation in the developed Eu3+–carbazole based bdiketonate complexes dramatically red-shifted the excitation maximum to the visible region (lex,max ¼
420 nm) with an impressive quantum yield (34–42%). The triplet state energy levels of L1 and L2 in the
complexes are higher than that of the lowest excited level of Eu3+ ion, 5
D0, so the photoluminescence
mechanism of the Eu3+ complexes was proposed as a ligand-sensitized luminescence process. The
predicted luminescent parameters from the Sparkle/PM3 structures are in agreement with the
experimental data, which shows the efficacy of the theoretical models adopted in the present study.2015-01-01T00:00:00Z