@article { ISI:000283495200040, title = {Clicking molecular hooks on silica nanoparticles to immobilize catalytically important metal complexes: the case of gold catalyst immobilization}, journal = {New Journal of Chemistry}, volume = {34}, number = {11}, year = {2010}, month = {AUG}, pages = {2662-2670}, publisher = {ROYAL SOC CHEMISTRY}, type = {Article}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

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 {\textquoteleft}{\textquoteleft}click chemistry{\textquoteright}{\textquoteright}. 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.

}, issn = {1144-0546}, doi = {10.1039/c0nj00292e}, author = {Ganai, Anal Kumar and Bhardwaj, Rima and Hotha, Srinivas and Sen Gupta, Sayam and Bhagavatula L. V. Prasad} } @article { ISI:000294701600022, title = {Functionalization of SBA-15 mesoporous materials using {\textquoteleft}{\textquoteleft}thiol-ene click{\textquoteright}{\textquoteright} michael addition reaction}, journal = {Journal of Physical Chemistry C }, volume = {115}, number = {36}, year = {2011}, month = {SEP}, pages = {17774-17781}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Methacrylate-labeled SBA-15 has been successfully synthesized from calcined SBA-15 and commercially available 3-trichlorosilyl propylmethacrylate. This material undergoes efficient thiol-ene {\textquoteleft}{\textquoteleft}click reaction{\textquoteright}{\textquoteright} 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.

}, issn = {1932-7447}, doi = {10.1021/jp2056442}, author = {Kumari, Sushma and Malvi, Bharmana and Ganai, Anal Kumar and Pillai, Vijayamohanan K. and Sen Gupta, Sayam} } @article { ISI:000288291400015, title = {Self-standing three-dimensional networks of nanoparticles with controllable morphology by dynamic templating of surfactant hexagonal domains}, journal = {Chemistry of Materials}, volume = {23}, number = {6}, year = {2011}, month = {APR}, pages = {1448-1455}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

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.

}, keywords = {hexagonal, macroporous, nanoparticle, self assembly, surfactant}, issn = {0897-4756}, doi = {10.1021/cm102945x}, author = {Sharma, Kamendra P. and Ganai, Anal Kumar and Sen Gupta, Sayam and Kumaraswamy, Guruswamy} } @article { ISI:000303442500017, title = {Synthesis of functional hybrid silica scaffolds with controllable hierarchical porosity by dynamic templating}, journal = {Chemical Communications}, volume = {48}, number = {43}, year = {2012}, month = {MAR}, pages = {5292-5294}, publisher = {ROYAL SOC CHEMISTRY}, type = {Article}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

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.

}, issn = {1359-7345}, doi = {10.1039/c2cc30885a}, author = {Ganai, Anal Kumar and Kumari, Sushma and Sharma, Kamendra P. and Panda, Chakadola and Kumaraswamy, Guruswamy and Sen Gupta, Sayam} } @article { ISI:000313812400012, title = {Development of a multifunctional catalyst for a {\textquoteleft}{\textquoteleft}relay{\textquoteright}{\textquoteright} reaction}, journal = {RSC Advances}, volume = {3}, number = {7}, year = {2013}, month = {DEC}, pages = {2186-2191}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

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 {\textquoteleft}{\textquoteleft}relay{\textquoteright}{\textquoteright} 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.

}, issn = {2046-2069}, doi = {10.1039/c2ra22829g}, author = {Ganai, Anal Kumar and Shinde, Pravin and Dhar, Basab B. and Sen Gupta, Sayam and Bhagavatula L. V. Prasad} } @article { ISI:000326126000033, title = {Exclusion from hexagonal mesophase surfactant domains drives end-to-end enchainment of rod-like particles}, journal = {Journal of Physical Chemistry B}, volume = {117}, number = {41}, year = {2013}, month = {OCT}, pages = {12661-12668}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

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 {\textquoteleft}{\textquoteleft}enchainment{\textquoteright}{\textquoteright} increases with the particle concentration and with the aspect ratio of the particles.

}, issn = {1520-6106}, doi = {10.1021/jp407403a}, author = {Sharma, Kamendra P. and Ganai, Anal Kumar and Sen, Debasis and Bhagavatula L. V. Prasad and Kumaraswamy, Guruswamy} }