The development of new methods to synthesize nanometric metal catalysts has always been an import... more The development of new methods to synthesize nanometric metal catalysts has always been an important and prerequisite step in advanced catalysis. Herein, we design a stable nitrogen ligated Pt complex for the straightforward synthesis by carbonization of uniformly sized atomic and sub-nanometric Pt catalysts supported on mesoporous silica. During the carbonization of the Pt precursor into active Pt species, the nitrogen-containing ligand directed the decomposition in a controlled fashion to maintain uniform sizes of the Pt species. The nitrogen ligand had a key role to stabilize the single Pt atoms on a weak anchoring support like silica. The Pt catalysts exhibited remarkable activities in the hydrogenation of common organic functional groups with turnover frequencies higher than in previous studies. By a simple post-synthetic treatment, we could selectively remove the Pt nanoparticles to obtain a mixture of single atoms and nanoclusters, extending the applicability of the present m...
Decreasing fossil fuel resources has forced the mankind to explore alternative sources to make up... more Decreasing fossil fuel resources has forced the mankind to explore alternative sources to make up the gap between energy demand and its production. Lignocellulosic biomass is currently considered as one of the best solutions for this consequence, since it is highly abundant and has no competition with food crops. This chapter discloses some efficient catalytic approaches for the conversion of lignocellulose feedstocks into liquid hydrocarbon fuels via deoxygenation processes. Different catalytic factors of nanomaterials including composition, functionalities, and effect of catalyst support in the deoxygenation process are critically discussed.
Angewandte Chemie (International ed. in English), Jul 30, 2016
In coordination chemistry, catalytically active metal complexes in a zero- or low-valent state of... more In coordination chemistry, catalytically active metal complexes in a zero- or low-valent state often adopt four-coordinate square-planar or tetrahedral geometry. By applying this principle, we have developed a stable Pt1 single-atom catalyst with a high Pt loading (close to 1 wt %) on phosphomolybdic acid(PMA)-modified active carbon. This was achieved by anchoring Pt on the four-fold hollow sites on PMA. Each Pt atom is stabilized by four oxygen atoms in a distorted square-planar geometry, with Pt slightly protruding from the oxygen planar surface. Pt is positively charged, absorbs hydrogen easily, and exhibits excellent performance in the hydrogenation of nitrobenzene and cyclohexanone. It is likely that the system described here can be extended to a number of stable SACs with superior catalytic activities.
Chemical communications (Cambridge, England), Jan 29, 2016
Nano-scale metal particles have huge potential due to their wide range of diverse catalytic appli... more Nano-scale metal particles have huge potential due to their wide range of diverse catalytic applications. Recently, they have found numerous applications in the field of biomass conversion. The proposed contribution is aimed at providing a brief account of remarkable recent findings and advances in the design of metal-based nanocatalysts for biomass valorization. We have discussed the rational control of the size, shape, composition and surface properties of nano-scale metal catalysts. Following that, the interplay between various structural parameters and the catalytic properties in the transformation of cellulose, chitin, lignin and lipids has been critically discussed.
High acidity titanium phosphate (TiP) material was synthesized by a reaction between commercial T... more High acidity titanium phosphate (TiP) material was synthesized by a reaction between commercial TiO2 and H3PO4 under reflux condition. The synthesized material was characterized by FTIR, XRD and TEM; a probable formula was derived by thermogravimetric, elemental and XRD analysis. NH3-TPD measurement confirmed the exceptional high acidity of the material. The catalytic efficiency of the TiP material was tested against the dehydration of various sugars for the production of an important building block molecule, 5-hydroxymethylfurfural (HMF) in a biphasic water/THF solvent system. The Lewis and Brønsted acidic nature of TiP material helps the isomerisation of glucose to fructose followed by an excellent conversion into HMF. Good recyclability of the catalyst can be attributed to its high stability and water-tolerant acidic properties.
ABSTRACT Benzimidazole derivatives have attracted a significant attention in recent years because... more ABSTRACT Benzimidazole derivatives have attracted a significant attention in recent years because of their medicinal applications as antiviral, antiulcer, antifungal, antihypertensive, anticancer, and antihistamine compounds. The one-pot synthesis of benzimidazole derivatives via oxidative condensation of aromatic aldehydes with o-phenylenediamines under mild conditions was successfully accomplished using a cobalt(II) supported on mesoporous silica-type material. The supported cobalt catalyst could be easily recovered after reaction completion and reused seven times with an excellent durability and without any noticeable loss in activity. Graphical Abstract
ABSTRACT The synthesis of fine chemicals from the platform molecules obtained through the degrada... more ABSTRACT The synthesis of fine chemicals from the platform molecules obtained through the degradation of the cellulosic and lignocellulosic biomass is a most widely envisioned approach toward the implementation of renewable feedstocks for fuels and chemicals. Significant advances have been made in the synthesis of furan-based polyester building block 2,5-furandicarboxylic acid (FDCA) and related compounds such as 2,5-bis(hydroxymethyl)furan and 2,5-bis(hydroxymethyl)tetrahydrofuran from biomass-derived 5-hydroxymethylfurfural (HMF) by using homogeneous and nanoparticulate catalysts. This review provides a survey of selective aerobic oxidation of HMF to give FDCA as the end-product. The article highlights the fundamental aspects of preferring nanoparticulate catalysts over the conventional supported metal catalysts for the synthesis of FDCA with high selectivity. Another objective of the review is to discuss how efficiently the HMF-platform produces biofuels, including gasoline blendstock 2,5-dimethylfuran (DMF), 5-ethoxymethylfurfural (EMF), and ethyl levulinate (EL), which are competitive of existing liquid fuels.
We have synthesized a furan-based acetylating agent, 2,5-bisacetoxymethylfuran (BAMF) from carboh... more We have synthesized a furan-based acetylating agent, 2,5-bisacetoxymethylfuran (BAMF) from carbohydrate derived 5-hydroxymethylfurfural (HMF) and studied its acetylation activity with amines and cytochrome c. The results show that BAMF can modify proteins in biological conditions without affecting their structure and function. The modification of cytochrome c with BAMF occurred through the reduction of heme center, but there was no change in the coordination property of iron and the tertiary structure of cytochrome c. Further analysis using MALDI-TOF-MS spectrometer suggests that BAMF selectively targeted lysine amino acid of cytochrome c under our experimental conditions. Kinetics study revealed that the modification of cytochrome c with BAMF took place at faster rates than aspirin.
The current review article summarizes the recent advances of SACs in the biomass conversion proce... more The current review article summarizes the recent advances of SACs in the biomass conversion process. A detailed and fundamental discussion is made from the aspects of unique activity, reaction mechanism, and industrial implications of SACs.
The development of new methods to synthesize nanometric metal catalysts has always been an import... more The development of new methods to synthesize nanometric metal catalysts has always been an important and prerequisite step in advanced catalysis. Herein, we design a stable nitrogen ligated Pt complex for the straightforward synthesis by carbonization of uniformly sized atomic and sub-nanometric Pt catalysts supported on mesoporous silica. During the carbonization of the Pt precursor into active Pt species, the nitrogen-containing ligand directed the decomposition in a controlled fashion to maintain uniform sizes of the Pt species. The nitrogen ligand had a key role to stabilize the single Pt atoms on a weak anchoring support like silica. The Pt catalysts exhibited remarkable activities in the hydrogenation of common organic functional groups with turnover frequencies higher than in previous studies. By a simple post-synthetic treatment, we could selectively remove the Pt nanoparticles to obtain a mixture of single atoms and nanoclusters, extending the applicability of the present m...
Decreasing fossil fuel resources has forced the mankind to explore alternative sources to make up... more Decreasing fossil fuel resources has forced the mankind to explore alternative sources to make up the gap between energy demand and its production. Lignocellulosic biomass is currently considered as one of the best solutions for this consequence, since it is highly abundant and has no competition with food crops. This chapter discloses some efficient catalytic approaches for the conversion of lignocellulose feedstocks into liquid hydrocarbon fuels via deoxygenation processes. Different catalytic factors of nanomaterials including composition, functionalities, and effect of catalyst support in the deoxygenation process are critically discussed.
Angewandte Chemie (International ed. in English), Jul 30, 2016
In coordination chemistry, catalytically active metal complexes in a zero- or low-valent state of... more In coordination chemistry, catalytically active metal complexes in a zero- or low-valent state often adopt four-coordinate square-planar or tetrahedral geometry. By applying this principle, we have developed a stable Pt1 single-atom catalyst with a high Pt loading (close to 1 wt %) on phosphomolybdic acid(PMA)-modified active carbon. This was achieved by anchoring Pt on the four-fold hollow sites on PMA. Each Pt atom is stabilized by four oxygen atoms in a distorted square-planar geometry, with Pt slightly protruding from the oxygen planar surface. Pt is positively charged, absorbs hydrogen easily, and exhibits excellent performance in the hydrogenation of nitrobenzene and cyclohexanone. It is likely that the system described here can be extended to a number of stable SACs with superior catalytic activities.
Chemical communications (Cambridge, England), Jan 29, 2016
Nano-scale metal particles have huge potential due to their wide range of diverse catalytic appli... more Nano-scale metal particles have huge potential due to their wide range of diverse catalytic applications. Recently, they have found numerous applications in the field of biomass conversion. The proposed contribution is aimed at providing a brief account of remarkable recent findings and advances in the design of metal-based nanocatalysts for biomass valorization. We have discussed the rational control of the size, shape, composition and surface properties of nano-scale metal catalysts. Following that, the interplay between various structural parameters and the catalytic properties in the transformation of cellulose, chitin, lignin and lipids has been critically discussed.
High acidity titanium phosphate (TiP) material was synthesized by a reaction between commercial T... more High acidity titanium phosphate (TiP) material was synthesized by a reaction between commercial TiO2 and H3PO4 under reflux condition. The synthesized material was characterized by FTIR, XRD and TEM; a probable formula was derived by thermogravimetric, elemental and XRD analysis. NH3-TPD measurement confirmed the exceptional high acidity of the material. The catalytic efficiency of the TiP material was tested against the dehydration of various sugars for the production of an important building block molecule, 5-hydroxymethylfurfural (HMF) in a biphasic water/THF solvent system. The Lewis and Brønsted acidic nature of TiP material helps the isomerisation of glucose to fructose followed by an excellent conversion into HMF. Good recyclability of the catalyst can be attributed to its high stability and water-tolerant acidic properties.
ABSTRACT Benzimidazole derivatives have attracted a significant attention in recent years because... more ABSTRACT Benzimidazole derivatives have attracted a significant attention in recent years because of their medicinal applications as antiviral, antiulcer, antifungal, antihypertensive, anticancer, and antihistamine compounds. The one-pot synthesis of benzimidazole derivatives via oxidative condensation of aromatic aldehydes with o-phenylenediamines under mild conditions was successfully accomplished using a cobalt(II) supported on mesoporous silica-type material. The supported cobalt catalyst could be easily recovered after reaction completion and reused seven times with an excellent durability and without any noticeable loss in activity. Graphical Abstract
ABSTRACT The synthesis of fine chemicals from the platform molecules obtained through the degrada... more ABSTRACT The synthesis of fine chemicals from the platform molecules obtained through the degradation of the cellulosic and lignocellulosic biomass is a most widely envisioned approach toward the implementation of renewable feedstocks for fuels and chemicals. Significant advances have been made in the synthesis of furan-based polyester building block 2,5-furandicarboxylic acid (FDCA) and related compounds such as 2,5-bis(hydroxymethyl)furan and 2,5-bis(hydroxymethyl)tetrahydrofuran from biomass-derived 5-hydroxymethylfurfural (HMF) by using homogeneous and nanoparticulate catalysts. This review provides a survey of selective aerobic oxidation of HMF to give FDCA as the end-product. The article highlights the fundamental aspects of preferring nanoparticulate catalysts over the conventional supported metal catalysts for the synthesis of FDCA with high selectivity. Another objective of the review is to discuss how efficiently the HMF-platform produces biofuels, including gasoline blendstock 2,5-dimethylfuran (DMF), 5-ethoxymethylfurfural (EMF), and ethyl levulinate (EL), which are competitive of existing liquid fuels.
We have synthesized a furan-based acetylating agent, 2,5-bisacetoxymethylfuran (BAMF) from carboh... more We have synthesized a furan-based acetylating agent, 2,5-bisacetoxymethylfuran (BAMF) from carbohydrate derived 5-hydroxymethylfurfural (HMF) and studied its acetylation activity with amines and cytochrome c. The results show that BAMF can modify proteins in biological conditions without affecting their structure and function. The modification of cytochrome c with BAMF occurred through the reduction of heme center, but there was no change in the coordination property of iron and the tertiary structure of cytochrome c. Further analysis using MALDI-TOF-MS spectrometer suggests that BAMF selectively targeted lysine amino acid of cytochrome c under our experimental conditions. Kinetics study revealed that the modification of cytochrome c with BAMF took place at faster rates than aspirin.
The current review article summarizes the recent advances of SACs in the biomass conversion proce... more The current review article summarizes the recent advances of SACs in the biomass conversion process. A detailed and fundamental discussion is made from the aspects of unique activity, reaction mechanism, and industrial implications of SACs.
Uploads
Papers by Sudipta De