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Prakash S, Patra B, Sahu S, Mishra AK. One-step synthesis of orange-red emissive carbon dots: photophysical insight into their excitation wavelength-independent and dependent luminescence. Phys Chem Chem Phys 2024; 26:16309-16319. [PMID: 38804891 DOI: 10.1039/d4cp00919c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
A low-temperature method was developed to synthesize orange-red luminescence phosphor-doped carbon dots (CDs) without complicated purification procedures. These CDs showed excitation wavelength-independent narrow emission (photo-luminescence quantum yield, Φf ∼ 12 to 22%) with single exponential time-resolved decay in weakly polar/non-polar solvents, indicating the presence of one kind of chromophore. In contrast, the same CDs showed excitation wavelength-dependent broad emission (Φf ∼ 1 to 8%) with multi-exponential fluorescence decay in polar solvents. These CDs exhibited poor solubility in polar solvents, resulting in CD aggregates contributed by excitation wavelength-dependent weak luminescence. The CDs embedded in polymethyl methacrylate (PMMA) polymer film displayed bright orange-red fluorescence under UV 365 nm illumination, indicating their potential application in solid-state luminescence. Further, an analytical method was developed for the naked-eye detection of trifluoracetic acid (red emission) and triethylamine (green emission) under UV 365 nm illumination with reversible two switch-mode luminescence. Additionally, this efficient orange-red luminescence of CDs was utilized for possible bioimaging applications with negligible cytotoxicity in 3T3 mouse fibroblast cells.
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Affiliation(s)
- Swayam Prakash
- Department of Chemistry, IIT Madras, Chennai-600036, India.
| | - Bamadeb Patra
- Department of Biotechnology, IIT Madras, Chennai-600036, India.
| | - Saugata Sahu
- Department of Chemistry, IIT Madras, Chennai-600036, India.
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Shukla A, Biswal AS, Chowdhury A, Halder R, Chatterjee S. Aggregation-Induced Modulation of Ground and Excited State Photophysics of 5-( tert-Butyl)-2-Hydroxy-1,3-Isophthalaldehyde (5- tBHI). J Phys Chem B 2024; 128:5437-5453. [PMID: 38662934 DOI: 10.1021/acs.jpcb.4c00258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2024]
Abstract
5-(tert-Butyl)-2-hydroxy-1,3-isophthalaldehyde (5-tBHI) is a photochromic material susceptible to either excited state proton transfer or excited state intramolecular proton transfer, depending upon the solvent. However, it has also been found to aggregate in the presence of sodium dodecyl sulfate. In this current study, based on the steady-state and time-resolved spectroscopy, supported by crystallography, quantum chemical density functional theory calculation, and molecular dynamics (MD) simulation, we report on the aggregation of this potential single benzene-based emitter (SBBE) in neat solvents as well as solid phase to modulate its photophysics. It has been found that 5-tBHI forms mixed aggregates of different orders, owing to the presence of both enolic and tautomeric forms, to yield tunable emission, although the emission intensity is quenched. These findings suggest that the intramolecular hydrogen bonding of 5-tBHI not only limits intermolecular interactions but also promotes nonradiative deactivation pathways. Hence, designing and structural engineering, with a focus to suppressing intramolecular hydrogen bonding as well as increasing through space conjugation by replacing the aldehydic moieties with bulky aliphatic or aromatic ketonic groups, can be a plausible approach to yielding improved probes with tunable emission and higher fluorescence quantum yields.
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Affiliation(s)
- Aparna Shukla
- Department of Chemistry and Chemical Biology, Indian Institute of Technology (Indian School of Mines) Dhanbad, Dhanbad 826004 Jharkhand, India
| | - Abhipsa Sekhar Biswal
- Department of Chemistry and Chemical Biology, Indian Institute of Technology (Indian School of Mines) Dhanbad, Dhanbad 826004 Jharkhand, India
| | - Arkaprava Chowdhury
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra 400076, India
| | - Ritaban Halder
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United States
| | - Soumit Chatterjee
- Department of Chemistry and Chemical Biology, Indian Institute of Technology (Indian School of Mines) Dhanbad, Dhanbad 826004 Jharkhand, India
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Prakash S, Mishra AK. Rapid and sensitive naked eye detection of faecal pigments using their enhanced solid-state green fluorescence on a zinc acetate substrate. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2022; 14:2907-2912. [PMID: 35861373 DOI: 10.1039/d2ay00878e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The identification of trace faecal pigments in real-time and on-site detection remains a challenge for water quality monitoring. Herein, a simple, low-cost and rapid fluorescence-based analytical method has been developed in a solid matrix for faecal pigments like stercobilin and urobilin detection. This was made possible due to significant enhancement of green solid-state fluorescence (520 nm) by zinc(II) complexation with faecal pigments embedded in the surface of zinc acetate crystals. It enables naked-eye detection of these pigments even at a 10 μM level when excited with 365 nm blue-UV. It was demonstrated that easily available white cellulose paper strips or TLC silica plates coated with zinc acetate can be used as substrates. A photophysical study of solid-state faecal pigments-zinc(II) complexes suggests that green fluorescence enhancement results from the complexation, which can be attributed to the substantial decrease of the non-radiative decay rate (knr) as well as more efficient use of excitation light. The observation of reduced interference of humic acid fluorescence makes faecal pigment detection more efficient by this proposed method.
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Affiliation(s)
- Swayam Prakash
- Department of Chemistry, Indian Institute of Technology Madras, Chennai-600036, India.
| | - Ashok Kumar Mishra
- Department of Chemistry, Indian Institute of Technology Madras, Chennai-600036, India.
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Prakash S, Mishra AK. Photophysics of faecal pigments stercobilin and urobilin in aliphatic alcohols: introduction of a sensitive method for their detection using solvent phase extraction and fluorometry. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 13:5573-5588. [PMID: 34787126 DOI: 10.1039/d1ay01539g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Faecal pigments (FPs) are ubiquitous in the environment and are a primary contaminant in groundwater and surface water. This article presents a new analytical paradigm by a fluorescence coupled extraction-based method involving FP fluorescence enhancement and minimization of background fluorescence for high sensitivity detection. FPs show higher fluorescence intensity in aliphatic alcohols due to the breaking down of higher-order H-aggregates into lower-order H-aggregates (dimers). DFT studies using the B3LYP functional and LANL2DZ basis set show π-π stacking and hydrogen-bonding contributions towards forming H-aggregated dimers of FPs in the implicit and explicit solvent environments of 1-hexanol. This study is the first report on the extractability of FPs using 1-hexanol as an efficient extraction medium in comparison to higher-order aliphatic alcohols (1-butanol, 1-hexanol and 1-octanol). Furthermore, FP-Zn(II) complexes in 1-hexanol medium significantly enhance the fluorescence emission intensity (∼14-17 times), and the emission intensity remains stable over time. This further helps to increase the detection limit of FPs in the picomolar to sub-picomolar concentration range. This study proposes a protocol involving extraction of FPs by 1-hexanol followed by the complexation of FPs with Zn(II) in the alcohol media and subsequent fluorimetric detection of the FP-Zn(II) complex with a high level of sensitivity, enabled by reduced interference from the background fluorescence of humic acid. The complexation behaviour of FPs with various metal salts was also examined, which provided an understanding of the fluorescence behaviour of FPs with various other metal ions commonly present in natural environmental water. The proposed analytical method has been further validated using real water samples.
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Affiliation(s)
- Swayam Prakash
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
| | - Ashok Kumar Mishra
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
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Prakash S, Sahu S, Bhattacharya S, Bisht PB, Mishra AK. Carbon Dot-NaCl Crystals for White-Light Generation and Fabry-Perot Lasing. Chem Asian J 2021; 16:783-792. [PMID: 33561299 DOI: 10.1002/asia.202100074] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Indexed: 11/10/2022]
Abstract
Phosphor materials with broad spectral range and an average emission lifetime (20 μs) have been achieved from carbon dots (CDs)-NaCl crystals. A one-pot synthesis pathway has been developed for CDs-NaCl crystals formation at room temperature. Precursor for CDs materials was screened at room temperature by oxidation methodology from different simple sugar molecules. CDs (size less than 10 nm) prepared from the fructose sugar exhibit most intense emission. Utilizing ripe banana peel (contains ∼27% of fructose) as a precursor for the carbon dot formation, white-light emission with a CIE index of (0.29, 0.34) has been achieved from the single source with CDs-NaCl crystals upon excitation at 430 nm. The crystals also function as Fabry-Perot (F-P) mode resonator for lasing, with a laser threshold value of 0.9 mW and a resonating Q-factor of 207. These results outline a new approach for realizing F-P lasing and white light emission from a non-toxic green source with a quick, facile and low-cost synthesis procedure.
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Affiliation(s)
- Swayam Prakash
- Department of Chemistry, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Saugata Sahu
- Department of Chemistry, Indian Institute of Technology Madras, Chennai, 600036, India
| | | | - Prem B Bisht
- Department of Physics, Indian Institute of Technology, Madras, Chennai, 600036, India
| | - Ashok Kumar Mishra
- Department of Chemistry, Indian Institute of Technology Madras, Chennai, 600036, India
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Prakash S, Panigrahi SK, Dorner RP, Wagner M, Schmidt W, Mishra AK. Understanding the photophysics of stercobilin-Zn(II) and urobilin-Zn(II) complexes towards faecal pigment analysis. CHEMOSPHERE 2021; 265:129189. [PMID: 33307503 DOI: 10.1016/j.chemosphere.2020.129189] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 10/12/2020] [Accepted: 12/01/2020] [Indexed: 06/12/2023]
Abstract
A detailed photophysical study of two faecal pigments (FPs), Urobilin (UB) and Stercobilin (SB), and their zinc complexes [FP-Zn(II)] was carried out. The enhancement of UB and SB fluorescence resulting from the formation of their Zn(II) complexes was attributed to the complexation-induced rigidity of the chromophoric units, and the corresponding decrease of nonradiative decay rate constants of the excited singlet states (knr). The effect of various physicochemical environments was also studied in detail in order to understand the fluorescence behaviour of the Zn(II) complexes. FP-Zn(II) complexes have a lower solubility in water that results in the formation of molecular aggregates. The aggregation-induced loss of fluorescence of FP-Zn(II) complexes could be overcome by using the appropriate mixture of ethanol and water (70:30). Molecular orbital calculations on the FP-Zn(II) complexes provided a good idea of the geometry of the complexes and helped rationalise the enhancement of fluorescence after complexation. This study could pave the way towards developing a convenient non-extraction aqueous phase analytical procedure for detection of FPs using Zn(II) complexation method.
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Affiliation(s)
| | | | | | | | - Wido Schmidt
- Technologiezentrum Wasser (TZW), Dresden, Germany
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