01623nas a2200193 4500008004100000022001400041245014900055210006900204260011000273300001400383490000700397520078300404100002301187700001901210700002001229700002201249700003001271856012801301 2010 eng d a1144-054600aClicking molecular hooks on silica nanoparticles to immobilize catalytically important metal complexes: the case of gold catalyst immobilization0 aClicking molecular hooks on silica nanoparticles to immobilize c aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcAUG a2662-26700 v343 a

Gold mediated reactions have emerged as one of the best choices for affecting a variety of chemical transformations with a wide range of functional group tolerance. Application of such transformations to industrial processes necessitates immobilization of the Au ions into a matrix for easy separation of the catalyst after reaction. We report the synthesis and characterization of silica nanoparticles in which Au(III) has been immobilized through a 1,2,3-triazole linkage using an alkynalated picolinic acid exploiting ``click chemistry''. The Au( III) immobilized silica nanoparticle has been thoroughly characterized using FT-IR, C-13 CP MAS NMR and XPS. The utility of these particles as an easily separable catalyst for the Hashmi phenol synthesis is also reported.

1 aGanai, Anal, Kumar1 aBhardwaj, Rima1 aHotha, Srinivas1 aGupta, Sayam, Sen1 aPrasad, Bhagavatula L. V. uhttps://library.ncl.res.in/content/clicking-molecular-hooks-silica-nanoparticles-immobilize-catalytically-important-metal-001933nas a2200193 4500008004100000022001400041245010500055210006900160260007100229300001600300490000800316520117500324100001901499700002001518700002301538700003001561700002201591856012601613 2011 eng d a1932-744700aFunctionalization of SBA-15 mesoporous materials using ``thiol-ene click'' michael addition reaction0 aFunctionalization of SBA15 mesoporous materials using thiolene c a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcSEP a17774-177810 v1153 a

Methacrylate-labeled SBA-15 has been successfully synthesized from calcined SBA-15 and commercially available 3-trichlorosilyl propylmethacrylate. This material undergoes efficient thiol-ene ``click reaction'' with a variety of both thiol and disulfide-containing substrates in aqueous and organic media. The products were thoroughly characterized by a variety of analytical techniques including multinuclear (C-13, Si-29) solid-state NMR, TG-DTA, and nitrogen adsorption desorption studies. Disulfide-containing substrates in which the TCEP-mediated reduction of the disulfide bond and its subsequent addition to the methacrylate group anchored in SBA-15 in one-pot were used to synthesize a silica-protein hybrid material composed of biotin-labeled SBA-15 and streptavidin. Electrochemically active material was synthesized from the reaction of ferrocene-containing thiol and the methacrylate-labeled SBA-15. The ease of synthesis for the methacrylate-labeled SBA-15 material together with its ability to undergo efficient chemoselective thiol-ene reaction would make it a very attractive platform for the development of covalently anchored enzymes and sensors.

1 aKumari, Sushma1 aMalvi, Bharmana1 aGanai, Anal, Kumar1 aPillai, Vijayamohanan, K.1 aGupta, Sayam, Sen uhttps://library.ncl.res.in/content/functionalization-sba-15-mesoporous-materials-using-thiol-ene-click-michael-addition-001917nas a2200241 4500008004100000022001400041245014500055210006900200260007100269300001400340490000700354520100900361653001401370653001601384653001701400653001801417653001501435100002501450700002301475700002201498700002701520856012801547 2011 eng d a0897-475600aSelf-standing three-dimensional networks of nanoparticles with controllable morphology by dynamic templating of surfactant hexagonal domains0 aSelfstanding threedimensional networks of nanoparticles with con a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAPR a1448-14550 v233 a

Assembly of nanoparticles into free-standing three-dimensional networks has implications for a wide range of applications. We show that dynamic templating of surfactant hexagonal domains is a facile technique to organize nanoparticles into a network of particulate strands. Dispersed particles (> 10 nm), independent of particle chemistry, assemble into networks, when the surfactant matrix cools into the hexagonal phase. We demonstrate assembly of inorganic, polymeric, and protein nanoparticles into networks. Where particle assembly is reversible, particles are coated with polymers that are subsequently cross-linked to stabilize the networks after surfactant removal. This technique involves near ambient temperatures and a benign water wash for template removal. The network mesh size can be varied from submicrometers to tens of micrometers by controlling the cooling rate. Particle networks can be flow-oriented prior to cross-linking, and interpenetrating networks can also be formed.

10ahexagonal10amacroporous10ananoparticle10aself assembly10asurfactant1 aSharma, Kamendra, P.1 aGanai, Anal, Kumar1 aGupta, Sayam, Sen1 aKumaraswamy, Guruswamy uhttps://library.ncl.res.in/content/self-standing-three-dimensional-networks-nanoparticles-controllable-morphology-dynamic-001259nas a2200205 4500008004100000022001400041245011400055210006900169260011000238300001400348490000700362520041800369100002300787700001900810700002500829700002100854700002700875700002200902856012900924 2012 eng d a1359-734500aSynthesis of functional hybrid silica scaffolds with controllable hierarchical porosity by dynamic templating0 aSynthesis of functional hybrid silica scaffolds with controllabl aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcMAR a5292-52940 v483 a

We report a facile one-pot synthesis of hierarchically porous scaffolds, with independent control over nanoparticle mesoporosity and scaffold macroporosity. Our technique combines the chemistry of mesoporous silica nanoparticles with the control afforded by dynamic templating of surfactant mesophases. These materials are readily functionalizable and allow controllable spatial variation in macroporosity.

1 aGanai, Anal, Kumar1 aKumari, Sushma1 aSharma, Kamendra, P.1 aPanda, Chakadola1 aKumaraswamy, Guruswamy1 aGupta, Sayam, Sen uhttps://library.ncl.res.in/content/synthesis-functional-hybrid-silica-scaffolds-controllable-hierarchical-porosity-dynamic-001581nas a2200193 4500008004100000022001400041245007100055210006700126260011000193300001400303490000600317520085700323100002301180700001901203700002001222700002201242700003001264856009301294 2013 eng d a2046-206900aDevelopment of a multifunctional catalyst for a ``relay'' reaction0 aDevelopment of a multifunctional catalyst for a relay reaction aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcDEC a2186-21910 v33 a

In the area of catalysis, nanoparticles and enzymes are two of the most important systems. By amalgamating the two, we present here proof of the concept that it is possible to prepare a multifunctional catalyst that can carry out a ``relay'' reaction. The catalyst consists of a surface bound enzyme on a metal(core)-silica(shell) nanoparticle architecture. Here the enzyme catalyzes the 1st reaction and the metal nanoparticles act as a catalyst for the 2nd reaction of the product from the 1st reaction. In particular, we have studied the catalytic activity of glucosidase grafted Au@mSiO(2) on 4-nitrophenyl-beta-glucopyranoside, where glucosidase will catalyse the 1st step to generate 4-nitrophenol, which acts as a substrate for the next reduction step which is catalysed by the Au nanoparticles present inside the mesoporous silica shell.

1 aGanai, Anal, Kumar1 aShinde, Pravin1 aDhar, Basab, B.1 aGupta, Sayam, Sen1 aPrasad, Bhagavatula L. V. uhttps://library.ncl.res.in/content/development-multifunctional-catalyst-relay-reaction-001822nas a2200193 4500008004100000022001400041245011000055210006900165260007100234300001600305490000800321520104600329100002501375700002301400700001701423700003001440700002701470856013101497 2013 eng d a1520-610600aExclusion from hexagonal mesophase surfactant domains drives end-to-end enchainment of rod-like particles0 aExclusion from hexagonal mesophase surfactant domains drives end a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT a12661-126680 v1173 a

Anisotropic rod-like particles assemble end-to-end when the surfactant/water matrix in which they are dispersed is cooled from the isotropic to the lyotropic hexagonal phase. We demonstrate the formation of such end-to-end assemblies for gold nanorods, which are tens of nanometers in size, as well as for micrometer-sized ellipsoidal polystyrene particles. In both cases, the particles are well-dispersed in the low-viscosity surfactant/water phase above the isotropic-H-1 transition temperature. On cooling into the H-1 phase, mesophase domains form and the particles are expelled to the isotropic phase. As the H-1 domains grow and finally impinge, the particles are localized at the domain boundaries where they reorient and assemble end-to-end. Remarkably, we observe the formation of end-to-end assemblies of gold nanorods even for volume fractions as low as 2 x 10(-6) in the initially dispersed state. The extent of particle ``enchainment'' increases with the particle concentration and with the aspect ratio of the particles.

1 aSharma, Kamendra, P.1 aGanai, Anal, Kumar1 aSen, Debasis1 aPrasad, Bhagavatula L. V.1 aKumaraswamy, Guruswamy uhttps://library.ncl.res.in/content/exclusion-hexagonal-mesophase-surfactant-domains-drives-end-end-enchainment-rod-particles-0