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Mishra K, Acharjee D, Das A, Ghosh S. Subpicosecond Hot Hole Transfer in a Graphene Quantum Dot Composite with High Efficiency. J Phys Chem Lett 2022; 13:606-613. [PMID: 35019662 DOI: 10.1021/acs.jpclett.1c03530] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Extraction of hot carriers is of prime importance because of its potential to overcome the energy loss that limits the efficiency of an optoelectronic device. Employing a femtosecond upconversion setup, herein we report a few picoseconds carrier cooling time of colloidal graphene quantum dots (GQDs) is at least an order of magnitude slower compared to that in its bulk form. A slower carrier cooling time of GQDs compared to that of the other semiconductor quantum dots and their bulk materials is indeed a coveted property of GQDs that would allow one easy harvesting of high energy species employing a suitable molecular system as shown in this study. A subpicosecond hot hole transfer time scale has been achieved in a GQD-molecular system composite with high transfer efficiency. Our finding suggests a dramatic enhancement of the efficiency of GQD based optoelectronic devices can possibly be a reality.
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Affiliation(s)
- Krishna Mishra
- School of Chemical Sciences, National Institute of Science Education and Research, Homi Bhabha National Institute (HBNI), Khurda 752050, Odisha, India
| | - Debopam Acharjee
- School of Chemical Sciences, National Institute of Science Education and Research, Homi Bhabha National Institute (HBNI), Khurda 752050, Odisha, India
| | - Ayendrila Das
- School of Chemical Sciences, National Institute of Science Education and Research, Homi Bhabha National Institute (HBNI), Khurda 752050, Odisha, India
| | - Subhadip Ghosh
- School of Chemical Sciences, National Institute of Science Education and Research, Homi Bhabha National Institute (HBNI), Khurda 752050, Odisha, India
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2
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Moharkar S, Dhamole PB. Sugaring-out extraction of erythromycin from fermentation broth. KOREAN J CHEM ENG 2021; 38:90-97. [PMID: 33432252 PMCID: PMC7787404 DOI: 10.1007/s11814-020-0680-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/14/2020] [Accepted: 09/18/2020] [Indexed: 12/27/2022]
Abstract
This study reports the sugaring-out extraction of erythromycin from fermentation broth using acetonitrile (ACN) as solvent and glucose as a mass separating agent. Different process parameters-glucose concentration, temperature, ACN/water ratio and pH-were optimized to achieve maximum extraction of erythromycin. 88% (w/w) of erythromycin was extracted from the model system with following optimized conditions: glucose 156.3 g/L; temperature 4 °C; ACN/water ratio 1 and pH 8.3. Further, the effect of typical fermentation media components (starch, soybean flour, CaCO3, NaCl and (NH4)2SO4) on sugaring out extraction of erythromycin was also investigated. Starch, soybean flour and CaCO3 were observed to affect erythromycin extraction only at higher concentration. Removal of suspended solids from simulated as well as real broth prior to extraction enhanced the extraction efficiency (from 72% to 87%). Sugaring out extraction of erythromycin was found to be more effective than salting out extraction. Also, higher partition coefficient was achieved in the present work than other reported methods using carbohydrates as mass separating agent. Further, it was found that the antimicrobial activity of erythromycin was preserved during sugaring out extraction of erythromycin.
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Affiliation(s)
- Sharayu Moharkar
- Department of Chemical Engineering, Visvesvaraya National Institute of Technology, Nagpur, Maharashtra, India
| | - Pradip Babanrao Dhamole
- Department of Chemical Engineering, Visvesvaraya National Institute of Technology, Nagpur, Maharashtra, India
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Nagasaka M, Yuzawa H, Kosugi N. Microheterogeneity in Aqueous Acetonitrile Solution Probed by Soft X-ray Absorption Spectroscopy. J Phys Chem B 2020; 124:1259-1265. [PMID: 31990199 DOI: 10.1021/acs.jpcb.0c00551] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chemical processes in solution are influenced by microheterogeneity (MH), where two liquids seem to be mixed in a macroscopic scale but are microscopically inhomogeneous. We have investigated one of the simplest MH systems, aqueous acetonitrile solution, using soft X-ray absorption spectroscopy (XAS). Molecular interactions of acetonitrile were revealed by C and N K-edge XAS at different concentrations, and those of solvent water were separately revealed by O K-edge XAS. The energy shift of the C≡N π* peak at the C K-edge shows three characteristic concentration regions and a phase-transition-like behavior between them. By comparing the energy shifts in XAS spectra with ab initio quantum chemical inner-shell calculations, we have determined local structures of acetonitrile-water mixtures in three concentration regions and found that the dipole interaction between acetonitrile and water is the key structure to emerge the MH state in the middle concentration region.
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Affiliation(s)
- Masanari Nagasaka
- Institute for Molecular Science , Myodaiji, Okazaki 444-8585 , Japan.,SOKENDAI (The Graduate University for Advanced Studies) , Myodaiji, Okazaki 444-8585 , Japan
| | - Hayato Yuzawa
- Institute for Molecular Science , Myodaiji, Okazaki 444-8585 , Japan
| | - Nobuhiro Kosugi
- Institute for Molecular Science , Myodaiji, Okazaki 444-8585 , Japan.,SOKENDAI (The Graduate University for Advanced Studies) , Myodaiji, Okazaki 444-8585 , Japan
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Mishra K, Koley S, Ghosh S. Ground-State Heterogeneity along with Fluorescent Byproducts Causes Excitation-Dependent Fluorescence and Time-Dependent Spectral Migration in Citric Acid-Derived Carbon Dots. J Phys Chem Lett 2019; 10:335-345. [PMID: 30607959 DOI: 10.1021/acs.jpclett.8b03803] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The integrity of fluorescent carbon dot (FCD) emission deserves its highest appreciation when sample purification is performed with extreme care. Several controversial phenomena of FCD fluorescence including excitation-dependent emission, spectral migration with time, and thereby violation of the Kasha-Vavilov rule, which sparked intense debate during recent reports, disappeared when we rigorously purified the as-synthesized FCD sample. Purification was performed by first visual silica column chromatography (observing the emissions under UV illumination) and subsequently prolonged membrane dialysis. Most of the surprising phenomena of FCD fluorescence reported earlier apparently arose from ground-state spectral heterogeneity of FCD sample containing a large amount of fluorescent impurities (mostly polymeric or oligomeric in nature). Observation of our ensemble spectroscopic measurements, albeit nicely matched with recent reports based on single-particle experiments, differed largely from that of other ensemble measurements. Our results reconciled a number of long-standing controversies on FCD emission mostly by emphasizing the urgency of sample purification with more scientific rigor.
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Affiliation(s)
- Krishna Mishra
- School of Chemical Sciences , National Institute of Science Education and Research, Homi Bhabha National Institute (HBNI) , Khurda 752050 , Odisha India
| | - Somnath Koley
- School of Chemical Sciences , National Institute of Science Education and Research, Homi Bhabha National Institute (HBNI) , Khurda 752050 , Odisha India
| | - Subhadip Ghosh
- School of Chemical Sciences , National Institute of Science Education and Research, Homi Bhabha National Institute (HBNI) , Khurda 752050 , Odisha India
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Model-Free Estimation of Energy-Transfer Timescales in a Closely Emitting CdSe/ZnS Quantum Dot and Rhodamine 6G FRET Couple. Chem Asian J 2018; 13:3296-3303. [DOI: 10.1002/asia.201801272] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Indexed: 12/28/2022]
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Panda MR, Koley S, Mishra K, Ghosh S. Probing of Reorganization Dynamics within the Different Phases of Themotropic Liquid Crystals. ChemistrySelect 2018. [DOI: 10.1002/slct.201702944] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Manas Ranjan Panda
- School of Chemical Sciences; National Institute of Science Education and Research, HBNI; Khurda - 752050, Odisha India
| | - Somnath Koley
- School of Chemical Sciences; National Institute of Science Education and Research, HBNI; Khurda - 752050, Odisha India
| | - Krishna Mishra
- School of Chemical Sciences; National Institute of Science Education and Research, HBNI; Khurda - 752050, Odisha India
| | - Subhadip Ghosh
- School of Chemical Sciences; National Institute of Science Education and Research, HBNI; Khurda - 752050, Odisha India
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Koley S, Panda MR, Bharadwaj K, Ghosh S. Spectroscopic and Calorimetric Studies of Molecular Recognitions in a Dendrimer-Surfactant Complex. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:817-825. [PMID: 28505448 DOI: 10.1021/acs.langmuir.7b01081] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Molecular recognitions, causing supramolecular complex formation between a hyperbranched polymer molecule (polyamidoamine (PAMAM) dendrimer generation 3) with oppositely charged surfactant sodium dodecyl sulfate (SDS) in aqueous solution, were studied by using various spectroscopic techniques and calorimetric titration of heat change measurements. Spectroscopic measurements were performed using dynamic Stokes shift (DSS), rotational anisotropy decay, and translational diffusion of a fluorescent probe molecule coumarin 153 (C153) noncovalently attached to the dendrimer-surfactant complex. All these studies unanimously confirm that the critical aggregation concentration (CAC) of SDS falls to ∼0.8 mM (from its critical micelle concentration (CMC) ∼ 8 mM) in the presence of ∼0.2 mM dendrimer. Further studies of isothermal titration calorimetry (ITC) measurement show that the CAC of SDS in the presence of dendrimer remains invariant to the dendrimer concentration. Complexation reaction between SDS and dendrimer is highly exothermic in nature. A maximum heat release (ΔH∼ -6.6 kJ/mol of SDS binding) was observed at a SDS-to-dendrimer mole ratio of ∼3-5; where up to 3 to 5 SDS molecules were encapsulated by one dendrimer molecule to form dendrimer-SDS encapsulation complex. When negatively charged SDS was replaced with a positively charged surfactant dodecyl-trimethylammonium-bromide (DTAB), we found that the DTAB hardly interacted with positively charged dendrimer due to the charge-charge repulsions.
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Affiliation(s)
- Somnath Koley
- School of Chemical Sciences, National Institute of Science Education and Research, HBNI , Khurda-752050, Odisha, India
| | - Manas Ranjan Panda
- School of Chemical Sciences, National Institute of Science Education and Research, HBNI , Khurda-752050, Odisha, India
| | - Kiran Bharadwaj
- School of Chemical Sciences, National Institute of Science Education and Research, HBNI , Khurda-752050, Odisha, India
| | - Subhadip Ghosh
- School of Chemical Sciences, National Institute of Science Education and Research, HBNI , Khurda-752050, Odisha, India
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Koley S, Ghosh S. Encapsulation and Residency of a Hydrophobic Dye within the Water-Filled Interior of a PAMAM Dendrimer Molecule. J Phys Chem B 2017; 121:1930-1940. [DOI: 10.1021/acs.jpcb.6b10176] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Somnath Koley
- School of Chemical Sciences, National Institute of Science Education and Research, HBNI, Khurda 752050, Odisha, India
| | - Subhadip Ghosh
- School of Chemical Sciences, National Institute of Science Education and Research, HBNI, Khurda 752050, Odisha, India
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Dutta Choudhury S, Pal H. Intriguing Tautomerism of Lumichrome in Binary Aqueous Solvent Mixtures: Implications for Probing Microenvironments. J Phys Chem B 2016; 120:11970-11977. [DOI: 10.1021/acs.jpcb.6b08777] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Haridas Pal
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
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Koley S, Ghosh S. A deeper insight into an intriguing acetonitrile–water binary mixture: synergistic effect, dynamic Stokes shift, fluorescence correlation spectroscopy, and NMR studies. Phys Chem Chem Phys 2016; 18:32308-32318. [DOI: 10.1039/c6cp05024g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An insight study reveals the strong synergistic solvation behaviours from reporter dye molecules within the acetonitrile (ACN)–water (WT) binary mixture.
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Affiliation(s)
- Somnath Koley
- School of Chemical Sciences
- National Institute of Science Education and Research
- HBNI
- Bhubaneswar 751005
- India
| | - Subhadip Ghosh
- School of Chemical Sciences
- National Institute of Science Education and Research
- HBNI
- Bhubaneswar 751005
- India
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