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Chowdhury A, Dasgupta S, Gaur N, Shukla A, Adhyapak P, Kabra D, Datta A. Modulation of fluorescence and phosphorescence of organoboron compounds from ortho-substituted phenolic Schiff bases by structural modification. Photochem Photobiol 2024; 100:1089-1099. [PMID: 38801138 DOI: 10.1111/php.13965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 04/20/2024] [Accepted: 04/30/2024] [Indexed: 05/29/2024]
Abstract
Light emission from organoboron compounds of Schiff bases is found to depend strongly on their chemical structure. Two of these compounds (OB1 and OB2), which contain a benzene ring between the Schiff base moieties, exhibit weak fluorescence in methanol, with marked viscosity dependence. Fluorescence lifetimes of these compounds are in picosecond timescale, as determined by femtosecond optical gating (FOG). A significant enhancement in fluorescence intensity and lifetime is observed at 77 K, indicating the operation of an activated nonradiative process. Using fluorescence lifetime imaging microscopy (FLIM), OB1 and OB2 are shown to be potential membrane probes. The third (OB3), which is devoid of this benzene ring, exhibits relatively stronger fluorescence with nanosecond lifetimes at room temperature. No viscosity dependence is observed in this case. The emission spectrum at 77 K is markedly more intense and exhibits an additional red shifted structured feature, which persists for a few seconds. Hence, OB3 seems to have greater promise not only as fluorescent probe but also for light harvesting. The marked improvement of the light emission properties of OB3 compared with OB1 and OB2 is likely to serve as a pointer for the design of Schiff base-derived organoboron luminophores with diverse potential applications.
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Affiliation(s)
- Arkaprava Chowdhury
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, India
| | - Souradip Dasgupta
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, India
| | - Nrita Gaur
- Department of Physics, Indian Institute of Technology Bombay, Mumbai, India
| | - Aparna Shukla
- Department of Chemistry & Chemical Biology, Indian Institute of Technology (ISM) Dhanbad, Dhanbad, India
| | - Pranav Adhyapak
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, India
| | - Dinesh Kabra
- Department of Physics, Indian Institute of Technology Bombay, Mumbai, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, India
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Park SJ, Patil M, Yeom GS, Bendre R, Kuwar A, Nimse SB. A dual-function fluorescence 'turn-on' probe that allows Zn (II) bioimaging and quantification of water in the organic solvent. Methods 2023; 218:84-93. [PMID: 37536375 DOI: 10.1016/j.ymeth.2023.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 07/11/2023] [Accepted: 07/23/2023] [Indexed: 08/05/2023] Open
Abstract
Herein, a Eugenol-derived fluorescence 'turn-on' probe FLHE was synthesized by condensing 2-((3-(trifluoromethyl)phenyl)amino)benzohydrazide with 5-allyl-2-hydroxy-3-methoxybenzaldehyde. FLHE demonstrated very low fluorescence in the studied organic solvents of varying polarities. However, upon titration with Zn2+ in HEPES buffer (pH = 7.4, 50% ACN, v/v), FLHE showed 40-fold higher fluorescence signals indicating the formation of the FLHE-Zn2+ complex. The fluorescence turn-on phenomenon upon FLHE-Zn2+ complex formation results from a chelation-enhanced fluorescence (CHEF) effect. The FLHE-Zn2+ complexation demonstrated a stokes shift of 156 nm (λex = 350 nm, λem = 506 nm) and an about 33-fold increase in the quantum yield (FLHE, Φ = 0.007; FLHE-Zn2+ complex, Φ = 0.23). The binding constant (Ka) determined by the Benesi-Hildebrand plot for interaction between FLHE and Zn2+ was 5.33 × 103 M-1. FLHE demonstrated a LOD of 31.8 nM for detecting Zn2+ in the environmental samples without interference from other cations and anions. FLHE-based paper strip (FLHE-PS) assay was developed to quantify the Zn2+ ions in water and the water content of organic solvent. FLHE-PS allows the detection of Zn2+ in aqueous solutions with a LOD of 63.2 nM and quantifying water in acetonitrile with a LOD of 0.14%. These results indicate that the FLHE has high applicability for detecting Zn2+ in living cells and environmental samples and detecting the presence of water in the organic solvents.
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Affiliation(s)
- Su Jeong Park
- Institute of Applied Chemistry and Department of Chemistry, Hallym University, Chuncheon 24252, Republic of Korea
| | - Manohar Patil
- School of Chemical Science, North Maharashtra University, Jalgaon 425001, India
| | - Gyu Seong Yeom
- Institute of Applied Chemistry and Department of Chemistry, Hallym University, Chuncheon 24252, Republic of Korea
| | - Ratnamala Bendre
- School of Chemical Science, North Maharashtra University, Jalgaon 425001, India
| | - Anil Kuwar
- School of Chemical Science, North Maharashtra University, Jalgaon 425001, India.
| | - Satish Balasaheb Nimse
- Institute of Applied Chemistry and Department of Chemistry, Hallym University, Chuncheon 24252, Republic of Korea.
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Kistwal T, Dasgupta S, Chowdhury A, Datta A. Disruption of aggregates of a Zn2+-complex of a schiff base in water by surfactants: Insights from fluorescence spectroscopy in ensemble and single molecule levels. J INDIAN CHEM SOC 2023. [DOI: 10.1016/j.jics.2023.100986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
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Sahoo DK, Dasgupta S, Kistwal T, Datta A. Fluorescence monitoring of binding of a Zn (II) complex of a Schiff base with human serum albumin. Int J Biol Macromol 2023; 226:1515-1522. [PMID: 36442551 DOI: 10.1016/j.ijbiomac.2022.11.263] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/19/2022] [Accepted: 11/24/2022] [Indexed: 11/27/2022]
Abstract
Zn (II) complexes of Schiff bases have potential applications in biomedical sciences as imaging agents, cancer therapeutics and diagnostics. Thus, it is important to understand their interaction with carrier proteins, like serum albumins. The present paper focuses on the binding interactions between Human serum albumin (HSA) and Znsalampy, making use of fluorescence spectroscopic techniques at ensemble as well as at single molecular level. An idea about the binding constant is obtained from the quenching of the single Trp (Tryptophan) residue of HSA by Znsalampy. Fluorescence correlation spectroscopy (FCS) has also been used to monitor the protein-ligand binding. The location of Znsalampy in its complex with HSA is determined by competitive binding experiments and molecular docking calculations. The binding constant obtained from the Znsalampy-HSA interaction falls in the ideal range for biological applications and the location is found to be in the proximity of Sudlow's site I. The esterase activity of HSA is retained in the presence of the Znsalampy. Hence, it is concluded that this Znsalampy may be a potential probe and biomarker in biomedical applications.
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Affiliation(s)
- Dipak Kumar Sahoo
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
| | - Souradip Dasgupta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
| | - Tanuja Kistwal
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
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Dasgupta S, Chowdhury A, Sahoo DK, Datta A. Interplay of conformational relaxation and hydrogen bond dynamics in the excited states of fluorescent Schiff base anions. Phys Chem Chem Phys 2022; 25:304-313. [PMID: 36477682 DOI: 10.1039/d2cp05007b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Time resolved fluorescence spectroscopic investigation of four Schiff base anions has established that their excited state dynamics is governed by several solvent properties: polarity, viscosity and hydrogen bond donating ability. With viscous protic solvents like glycerol, fluorescence lifetimes of anions have been found to be markedly longer than those in ethanol, implying that conformational relaxation of molecules plays a key role in their nonradiative relaxation. Surprisingly, the lifetimes in less viscous aprotic solvents, like acetonitrile, are found to be even longer. The only plausible rationalization of this observation is in the light of hydrogen bond-assisted nonradiative phenomena that are operative in protic solvents. This contention draws support from a time evolution of the emission in the red end of the spectrum in low to moderately hydrogen bond donating protic solvents, with regard to an absence of such a rise time in aprotic solvents and strongly hydrogen bond donating solvents, viz., 2,2,2-trifluoroethanol. Rudimentary quantum chemical calculations provide a preliminary idea about the nature of excited state hydrogen bond redistribution involved in the process.
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Affiliation(s)
- Souradip Dasgupta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
| | - Arkaprava Chowdhury
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
| | - Dipak Kumar Sahoo
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
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Zhuang H, Shi W, Zhao G, Yang Y, Li Y. Unveiling the sensing mechanism and luminescence property of a new ESIPT-based fluorescent sensor for detecting Zn 2. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 282:121650. [PMID: 35926285 DOI: 10.1016/j.saa.2022.121650] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/14/2022] [Accepted: 07/16/2022] [Indexed: 06/15/2023]
Abstract
Recently, based on the mechanism of excited-state intramolecular proton transfer (ESIPT), a new fluorescent probe named 3-(benzo[d]thiazol-2-yl)-5-bromosalicylaldehyde-4N-phenyl thiosemicarbazone (BTT) was successfully synthesized [Analyst 146 (2021) 4348-4356.]. However, the importance of ESIPT processes of BTT probe and the mechanism of detecting Zn2+ ions have not been studied in detail. In this study, the photochemical behavior of ESIPT-chromophore and the photophysical changes of detecting Zn2+ ions were explained at the molecular level for the first time. The calculated spectral values were in agreement with the experiment. We not only confirmed the excited state hydrogen-bond strengthening by interaction region indicator (IRI), but also scanned the potential energy curves of BTT molecule in different electronic states, which confirmed that the hydrogen proton is easier to transfer in the first excited state. In addition, we had given the reasonable structure of the BTT-Zn2+ complex (L1) by comparing the binding free energies. The hole-electron distribution and interfragment charge transfer (IFCT) methods proved the excitation type of intraligand charge transfer (ILCT). Finally, the photophysical phenomenon of BTT for detecting Zn2+ ions is explained by calculating the electronic spectra and the energy gap (Egap) between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO).
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Affiliation(s)
- Hongbin Zhuang
- School of Physics, Liaoning University, Shenyang 110036, P. R. China
| | - Wei Shi
- School of Physics, Liaoning University, Shenyang 110036, P. R. China
| | - Guijie Zhao
- School of Physics, Liaoning University, Shenyang 110036, P. R. China
| | - Yunfan Yang
- Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, P. R. China
| | - Yongqing Li
- School of Physics, Liaoning University, Shenyang 110036, P. R. China.
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Nandy A, Mukherjee S. A Bioinspired Light Harvesting System in Aqueous Medium: Highly Efficient Energy Transfer through the Self Assembly of β-Sheet Nanostructures of Poly-d-Lysine. J Phys Chem Lett 2022; 13:6701-6710. [PMID: 35848986 DOI: 10.1021/acs.jpclett.2c01309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Nature has beautifully assembled its light harvesting pigments within protein scaffolds, which ensures a very high energy transfer. Designing a highly efficient artificial bioinspired light harvesting system (LHS) thus requires the nanoscale spatial orientation and electronic control of the associated chromophores. Although DNA has been used as a scaffold to organize chromophores, proteins or polypeptides, however, are very rarely explored. Here, we have developed a highly efficient, artificial, bioinspired LHS using polypeptide (poly-d-lysine, PDL) nanostructures making use of their β-sheet structure in an aqueous alkaline medium. The chromophores used herein are compatible for an energy transfer process and are nonfluorescent in an aqueous medium but exhibit high fluorescence intensity when bound to the nanostructure of PDL. The close proximity of the chromophores results in an energy transfer efficiency of ∼92% besides generating white light emission at a particular molar ratio between the chromophores.
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Affiliation(s)
- Atanu Nandy
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462 066, Madhya Pradesh, India
| | - Saptarshi Mukherjee
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462 066, Madhya Pradesh, India
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Das S, Singha PK, Singh AK, Datta A. The Role of Hydrogen Bonding in the Preferential Solvation of 5-Aminoquinoline in Binary Solvent Mixtures. J Phys Chem B 2021; 125:12763-12773. [PMID: 34709811 DOI: 10.1021/acs.jpcb.1c06208] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
5-Aminoquinoline (5AQ) has been used as a fluorescent probe of preferential solvation (PS) in binary solvent mixtures in which the nonpolar component is diethyl ether and the polar component is protic (methanol) or aprotic (acetonitrile). Hence, the roles of solvent polarity and solute-solvent hydrogen bonding have been delineated. Positive deviations of spectral shifts from a linear dependence on the concentration of the polar component, signifying PS, are markedly more pronounced in case of the protic solvent. Solvation dynamics on a nanosecond time scale mark the formation of the solvation shell around the fluorescent probe. Time-resolved area-normalized emission spectra indicate the occurrence of the continuous solvation of the excited state when the polar component is acetonitrile. In contrast, two distinct states were observed when the polar component was methanol, the second state being the hydrogen bonded one. Translational diffusion is the rate-determining step for formation of the solvation shell. The time constant associated with it has been estimated from rise times observed in fluorescence transients monitored at the red end of the fluorescence spectra and also from the time evolution of the spectral width of time-resolved emission spectra.
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Affiliation(s)
- Sharmistha Das
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Prajit Kumar Singha
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Avinash Kumar Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
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