Abhishek Baheti - Academia.edu (original) (raw)
Papers by Abhishek Baheti
The Journal of Organic Chemistry
Journal of Organic Chemistry, May 17, 2011
b S Supporting Information ' INTRODUCTION Organic dyes capable of absorbing a visible light have ... more b S Supporting Information ' INTRODUCTION Organic dyes capable of absorbing a visible light have received immense attention since the first report in 1991 by Gr€ atzel and co-workers 1 on nanocrystalline anatase TiO 2-based dye-sensitized solar cells (DSSCs) as potential alternatives to traditional silicon-based inorganic photovoltaic devices. These cells are usually constructed using wide band gap semiconductor oxides such as TiO 2 , a molecular sensitizer, and a redox electrolyte. Recent research has been focused on the methods to optimize the light-harvesting ability of the sensitizers and to realize a more robust electrolyte system. 2À6 Also, interest for organic dyes as an alternative to noble metal complexes has increased because of their many advantages, such as diversity of molecular structures, high molar extinction coefficient, simple synthesis, as well as low cost and environmental friendliness. Metal-free organic dyes based on triphenylamine, fluorene, thiophene, indoline, merocyanine, coumarin, etc. have been developed and found to exhibit promising device characteristics. 7 Despite the intensive efforts by materials chemists to achieve an efficient organic dye, the DSSCs based on Ru complexes dx.
Journal of Power Sources, Feb 1, 2014
Dye-sensitized solar cells (DSSCs) were co-sensitized with organic SQ2 and JD1 dyes. Co-sensitize... more Dye-sensitized solar cells (DSSCs) were co-sensitized with organic SQ2 and JD1 dyes. Co-sensitizer adsorption kinetics was investigated by UVevisible absorption spectra. The adsorption rate and surface coverage on TiO 2 films of different sensitizers were studied. The DSSC with two organic cosensitizers exhibits a high efficiency of 6.36%.
Materials Technology, Mar 1, 2013
Dye sensitised solar cells (DSSCs) have received immense attention in recent years as they offer ... more Dye sensitised solar cells (DSSCs) have received immense attention in recent years as they offer the possibility of low cost conversion technology of light energy to electrical energy. Organic dyes have been demonstrated as sensitisers in DSSCs with promising photoelectrical conversion efficiencies. Though several polyaromatic hydrocarbon based organic dyes have been developed for use in DSSC, dipolar compounds featuring a fluorene unit have shown promising potential as light harvesting component. In this review, we present a comprehensive survey of the organic dyes containing fluorene either in the donor part or as a p linker in the conjugation pathway in a conventional donor-p-acceptor molecular configuration. Structural features of the molecular materials were correlated with the functional properties, such as optical absorption and oxidation potential.
Journal of materials chemistry. A, Materials for energy and sustainability, 2014
ABSTRACT Novel organic sensitizers comprising one or two fluorenylidene moieties in the donor par... more ABSTRACT Novel organic sensitizers comprising one or two fluorenylidene moieties in the donor part of triarylamine, cyanoacrylic acid as the acceptor/anchoring group and a fluorene and oligothiophene spacer in a D–π–A architecture have been synthesized and characterized as sensitizers for nanocrystalline TiO2-based dye-sensitized solar cells. Their optical, electrochemical and photovoltaic properties are compared with the electron accepting dicyanovinyl unit containing the organic sensitizer. Incorporation of the fluorenylidene moiety dominates the optical properties of the dyes in terms of relatively broad and high molar extinction coefficient absorption when compared to the dicyanovinyl derivatives. Theoretical investigations using TDDFT simulations indicate that the trends in the excitation energies are consistent with the solution spectral data for higher wavelength absorption and the lower wavelength absorptions attributed to the amine to auxiliary acceptor charge transfer. The electrochemical properties are influenced by the number of fluorenylidene chromophores and the electron richness of the linking segment. The dye-sensitized solar cells fabricated using fluorenylidene-based sensitizers showed higher power conversion efficiency than the dicyanovinyl derivatives attributed to their higher photocurrent density. A fluorenylidene-based dye exhibited a high power conversion efficiency of 6.13% under full sunlight (AM 1.5G, 100 mW cm−2).
Chemistry-an Asian Journal, Sep 28, 2012
Organic dyes that contain a 2,7-diaminofluorene-based donor, a cyanoacrylic-acid acceptor, and va... more Organic dyes that contain a 2,7-diaminofluorene-based donor, a cyanoacrylic-acid acceptor, and various aromatic conjugation segments, which are composed of benzene, fluorene, carbazole, and thiophene units, as a p-bridge have been synthesized and characterized by optical, electrochemical, and theoretical investigations. The trends in the absorption and electrochemical properties of these dyes are in accordance with the electron-donating ability of the conjugating segment. Consequently, the dyes that contained a 2,7-carbazole unit in the p-spacer exhibited red-shifted absorption and lower oxidation potentials than their corresponding fluorene-and phenylene-bridged dyes. However, the enhanced power-conversion efficiency that was exhibited by the fluorenebridged dyes in the DSSCs was attributed to their broader and intense absorption. Despite the longer-wavelength absorption and reasonable optical density, carbazole-bridged dyes exhibited lower power-conversion efficiencies, which were ascribed to the poor alignment of the LUMO level in these dyes, thereby leading to the inhibition of electron injection into the TiO 2 conduction band.
Asian Journal of Organic Chemistry, Jun 2, 2014
ABSTRACT Organic dyes containing carbazole as an auxiliary donor, oligothiophene linkers, and cya... more ABSTRACT Organic dyes containing carbazole as an auxiliary donor, oligothiophene linkers, and cyanoacrylic acid acceptors with two different architectures (D-D-π-A and D-D-(π-A)2) were synthesized and characterized by optical and electrochemical measurements. The charge-transfer transitions of the monoanchoring dyes with a D-D-π-A configuration are intense whereas the π–π* transitions of the dianchoring dyes with D-D-(π-A)2 architecture are promising. Incorporation of bithiophene into the conjugation slightly lowers the LUMO level of the dyes. The optical and electrochemical properties of these dyes are better than diphenylamine-based dyes. The TDDFT calculations were performed to rationalize the trends in the optical and electrochemical properties of the dyes. The efficiency of dye-sensitized solar cells based on the monoanchoring dyes is two to fivefold larger than the corresponding cells based on dianchoring congeners. Also, the use of chenodeoxycholic acid as an additive increases the efficiency of the devices reasonably.
Dyes and Pigments, Feb 1, 2011
Novel dipolar compounds containing diarylamine donors, dicyanovinyl acceptors and either a fluore... more Novel dipolar compounds containing diarylamine donors, dicyanovinyl acceptors and either a fluorene or biphenyl linker were prepared in an attempt to unravel the similarities and differences between the biphenyl and fluorene segments in donoreacceptor architectures. The linker segments significantly modify l max and the redox potential of the dyes is influenced by the nature of both the amine and linker. Density functional theory calculations performed at the 6-31G(d,p) level revealed that the higher wavelength absorption contains a major contribution from the chargeetransfer transition between the amine donor to the dicyanovinyl acceptor. The HOMO is mainly located on the triarylamine segment while the LUMO is spread over the dicyanovinyl. The fluorene based dyes exhibit lower thermal stability than their biphenyl analogues.
Organic Electronics, Dec 1, 2013
New metal free dianchoring organic dyes featuring A-p-D-p-D-p-A (acceptor-p bridge-donor-p bridge... more New metal free dianchoring organic dyes featuring A-p-D-p-D-p-A (acceptor-p bridge-donor-p bridge-donor-p bridge-acceptor) configuration have been designed incorporating fluorene and oligothiophene units and successfully synthesized. Elongating the conjugation pathway between the donor and acceptor units altered the distance between the anchoring sites besides the absorption and redox properties. These dyes exhibited broad and intense absorption when compared to the corresponding monoanchoring donor-p-acceptor congeners. Though the dye containing bithiophene unit exhibited comparatively low V oc due to low electron life time and facile back electron transfer, showed high power conversion efficiency arising from the good light-harvesting capability attributable to the intense absorption peak in the visible region and enhanced interfacial electron transfer rate. This work demonstrates that the smaller distance of separation between the anchoring units increases the insulating capacity of the molecular layer which retards the back electron transfer.
Physical Chemistry Chemical Physics, 2011
ACS Applied Materials & Interfaces, Jan 20, 2015
Two types of fluorene-based organic dyes featuring T-shape/rod-shape molecular configuration with... more Two types of fluorene-based organic dyes featuring T-shape/rod-shape molecular configuration with phenothiazine donor and cyanoacrylic acid acceptor have been synthesized and characterized as sensitizers for dyesensitized solar cells. Phenothiazine is functionalized at either nitrogen (N10) or carbon (C3) to obtain T-shape and rod-like organic dyes, respectively. The effect of structural alternation on the optical, electrochemical, and the photovoltaic properties is investigated. The crystal structure determination of the dye containing phenyl linker revealed cofacial slip-stack columnar packing of the molecules. The trends in the optical properties of the dyes are interpreted using time-dependent density functional theory (TDDFT) computations. The rod-shaped dyes exhibited longer wavelength absorption and low oxidation potentials when compared to the corresponding T-shaped dyes attributable to the favorable electronic overlap between the phenothiazine unit and the rest of the molecule in the former dyes. However, the T-shaped dyes showed better photovoltaic properties due to the lowest unoccupied molecular orbital (LUMO) energy level favorable for electron injection into the conduction band of TiO 2 and appropriate orientation of the phenothiazine unit rendering effective surface blocking to suppress the recombination of electrons between the electrolyte I 3 − and TiO 2. The electrochemical impedance spectroscopy investigations provide further support for the variations in the electron injection and transfer kinetics due to the structural modifications.
Acta Crystallographica Section E-structure Reports Online, Feb 29, 2012
Baheti et al. C 51 H 46 BrN 3 o861 supporting information sup-1
![Research paper thumbnail of <i>N</i>-(4,4′-Dibromo-[1,1′-biphenyl]-2-yl)benzamide](https://attachments.academia-assets.com/115953494/thumbnails/1.jpg)
](Acta Crystallographica Section E-structure Reports Online, Jan 12, 2013
Biphenyl aniline, a subclass of biaryl compounds, has been recognized as a privileged structure i... more Biphenyl aniline, a subclass of biaryl compounds, has been recognized as a privileged structure in drug discovery. Its derivatives have been pursued as anti-phlogistic, analgesic, anti-obesity, and anti-tumor agents (Zhu et al., 2008). Amide substituted biphenyl derivatives are commonly used to develop antiparasitic agents for the treatment of African sleeping
Chemical Communications, 2020
A novel SWIFT-based strategy for selective fluorimetric detection of practical amounts of V and G... more A novel SWIFT-based strategy for selective fluorimetric detection of practical amounts of V and G chemical warfare agents is reported.
Journal of Power Sources, Oct 1, 2012
Chemical Communications
Novel calixarene scaffolds incorporating fused carbazole moieties demonstrated aggregation-induce... more Novel calixarene scaffolds incorporating fused carbazole moieties demonstrated aggregation-induced emission-based luminogen (AIEgen) properties in aqueous media, and were applied for the host–guest detection of nitric oxide.
Chemical Communications, 2020
A novel SWIFT-based strategy for selective fluorimetric detection of practical amounts of V and G... more A novel SWIFT-based strategy for selective fluorimetric detection of practical amounts of V and G chemical warfare agents is reported.
Organic Letters, 2020
Conjugated 5,5′-Bicalixarene scaffolds having fluorophores at the chain termini have been prepare... more Conjugated 5,5′-Bicalixarene scaffolds having fluorophores at the chain termini have been prepared and tested in the supramolecular detection of nitric oxide. Scaffolds bearing electron-rich fluorophores demonstrated a stronger turn-off response to the presence of NO than the fluorophore-free analogue in both organic and aqueous media, while no fluorescence quenching happened when the electron-deficient fluorophores were employed. Unprecedented ratiometric supramolecular sensing was observed when fluorophores of the opposite electronic demands were placed at the scaffold's termini.
Journal of the American Chemical Society, 2019
Here, we present a conceptually novel and experimentally straightforward technique for selective ... more Here, we present a conceptually novel and experimentally straightforward technique for selective analyte detection that uses a combination of commercial fluorophores and simple chemicals. The technique utilizes the well-known inner filter effect (IFE), however, the fluorophore's excitation is performed at wavelengths significantly shorter than its absorption maximum. In the presence of the analyte, the "filter" appears or disappears at the excitation wavelength resulting in the fluorescence turning OFF or ON, respectively. Unlike common probes, our technique allows real-time monitoring of fluorophore's stability as well as its recycling. We further demonstrate the applicability of this technique in continuing analyte detection as well as vapor analysis.
The Journal of Organic Chemistry
Journal of Organic Chemistry, May 17, 2011
b S Supporting Information ' INTRODUCTION Organic dyes capable of absorbing a visible light have ... more b S Supporting Information ' INTRODUCTION Organic dyes capable of absorbing a visible light have received immense attention since the first report in 1991 by Gr€ atzel and co-workers 1 on nanocrystalline anatase TiO 2-based dye-sensitized solar cells (DSSCs) as potential alternatives to traditional silicon-based inorganic photovoltaic devices. These cells are usually constructed using wide band gap semiconductor oxides such as TiO 2 , a molecular sensitizer, and a redox electrolyte. Recent research has been focused on the methods to optimize the light-harvesting ability of the sensitizers and to realize a more robust electrolyte system. 2À6 Also, interest for organic dyes as an alternative to noble metal complexes has increased because of their many advantages, such as diversity of molecular structures, high molar extinction coefficient, simple synthesis, as well as low cost and environmental friendliness. Metal-free organic dyes based on triphenylamine, fluorene, thiophene, indoline, merocyanine, coumarin, etc. have been developed and found to exhibit promising device characteristics. 7 Despite the intensive efforts by materials chemists to achieve an efficient organic dye, the DSSCs based on Ru complexes dx.
Journal of Power Sources, Feb 1, 2014
Dye-sensitized solar cells (DSSCs) were co-sensitized with organic SQ2 and JD1 dyes. Co-sensitize... more Dye-sensitized solar cells (DSSCs) were co-sensitized with organic SQ2 and JD1 dyes. Co-sensitizer adsorption kinetics was investigated by UVevisible absorption spectra. The adsorption rate and surface coverage on TiO 2 films of different sensitizers were studied. The DSSC with two organic cosensitizers exhibits a high efficiency of 6.36%.
Materials Technology, Mar 1, 2013
Dye sensitised solar cells (DSSCs) have received immense attention in recent years as they offer ... more Dye sensitised solar cells (DSSCs) have received immense attention in recent years as they offer the possibility of low cost conversion technology of light energy to electrical energy. Organic dyes have been demonstrated as sensitisers in DSSCs with promising photoelectrical conversion efficiencies. Though several polyaromatic hydrocarbon based organic dyes have been developed for use in DSSC, dipolar compounds featuring a fluorene unit have shown promising potential as light harvesting component. In this review, we present a comprehensive survey of the organic dyes containing fluorene either in the donor part or as a p linker in the conjugation pathway in a conventional donor-p-acceptor molecular configuration. Structural features of the molecular materials were correlated with the functional properties, such as optical absorption and oxidation potential.
Journal of materials chemistry. A, Materials for energy and sustainability, 2014
ABSTRACT Novel organic sensitizers comprising one or two fluorenylidene moieties in the donor par... more ABSTRACT Novel organic sensitizers comprising one or two fluorenylidene moieties in the donor part of triarylamine, cyanoacrylic acid as the acceptor/anchoring group and a fluorene and oligothiophene spacer in a D–π–A architecture have been synthesized and characterized as sensitizers for nanocrystalline TiO2-based dye-sensitized solar cells. Their optical, electrochemical and photovoltaic properties are compared with the electron accepting dicyanovinyl unit containing the organic sensitizer. Incorporation of the fluorenylidene moiety dominates the optical properties of the dyes in terms of relatively broad and high molar extinction coefficient absorption when compared to the dicyanovinyl derivatives. Theoretical investigations using TDDFT simulations indicate that the trends in the excitation energies are consistent with the solution spectral data for higher wavelength absorption and the lower wavelength absorptions attributed to the amine to auxiliary acceptor charge transfer. The electrochemical properties are influenced by the number of fluorenylidene chromophores and the electron richness of the linking segment. The dye-sensitized solar cells fabricated using fluorenylidene-based sensitizers showed higher power conversion efficiency than the dicyanovinyl derivatives attributed to their higher photocurrent density. A fluorenylidene-based dye exhibited a high power conversion efficiency of 6.13% under full sunlight (AM 1.5G, 100 mW cm−2).
Chemistry-an Asian Journal, Sep 28, 2012
Organic dyes that contain a 2,7-diaminofluorene-based donor, a cyanoacrylic-acid acceptor, and va... more Organic dyes that contain a 2,7-diaminofluorene-based donor, a cyanoacrylic-acid acceptor, and various aromatic conjugation segments, which are composed of benzene, fluorene, carbazole, and thiophene units, as a p-bridge have been synthesized and characterized by optical, electrochemical, and theoretical investigations. The trends in the absorption and electrochemical properties of these dyes are in accordance with the electron-donating ability of the conjugating segment. Consequently, the dyes that contained a 2,7-carbazole unit in the p-spacer exhibited red-shifted absorption and lower oxidation potentials than their corresponding fluorene-and phenylene-bridged dyes. However, the enhanced power-conversion efficiency that was exhibited by the fluorenebridged dyes in the DSSCs was attributed to their broader and intense absorption. Despite the longer-wavelength absorption and reasonable optical density, carbazole-bridged dyes exhibited lower power-conversion efficiencies, which were ascribed to the poor alignment of the LUMO level in these dyes, thereby leading to the inhibition of electron injection into the TiO 2 conduction band.
Asian Journal of Organic Chemistry, Jun 2, 2014
ABSTRACT Organic dyes containing carbazole as an auxiliary donor, oligothiophene linkers, and cya... more ABSTRACT Organic dyes containing carbazole as an auxiliary donor, oligothiophene linkers, and cyanoacrylic acid acceptors with two different architectures (D-D-π-A and D-D-(π-A)2) were synthesized and characterized by optical and electrochemical measurements. The charge-transfer transitions of the monoanchoring dyes with a D-D-π-A configuration are intense whereas the π–π* transitions of the dianchoring dyes with D-D-(π-A)2 architecture are promising. Incorporation of bithiophene into the conjugation slightly lowers the LUMO level of the dyes. The optical and electrochemical properties of these dyes are better than diphenylamine-based dyes. The TDDFT calculations were performed to rationalize the trends in the optical and electrochemical properties of the dyes. The efficiency of dye-sensitized solar cells based on the monoanchoring dyes is two to fivefold larger than the corresponding cells based on dianchoring congeners. Also, the use of chenodeoxycholic acid as an additive increases the efficiency of the devices reasonably.
Dyes and Pigments, Feb 1, 2011
Novel dipolar compounds containing diarylamine donors, dicyanovinyl acceptors and either a fluore... more Novel dipolar compounds containing diarylamine donors, dicyanovinyl acceptors and either a fluorene or biphenyl linker were prepared in an attempt to unravel the similarities and differences between the biphenyl and fluorene segments in donoreacceptor architectures. The linker segments significantly modify l max and the redox potential of the dyes is influenced by the nature of both the amine and linker. Density functional theory calculations performed at the 6-31G(d,p) level revealed that the higher wavelength absorption contains a major contribution from the chargeetransfer transition between the amine donor to the dicyanovinyl acceptor. The HOMO is mainly located on the triarylamine segment while the LUMO is spread over the dicyanovinyl. The fluorene based dyes exhibit lower thermal stability than their biphenyl analogues.
Organic Electronics, Dec 1, 2013
New metal free dianchoring organic dyes featuring A-p-D-p-D-p-A (acceptor-p bridge-donor-p bridge... more New metal free dianchoring organic dyes featuring A-p-D-p-D-p-A (acceptor-p bridge-donor-p bridge-donor-p bridge-acceptor) configuration have been designed incorporating fluorene and oligothiophene units and successfully synthesized. Elongating the conjugation pathway between the donor and acceptor units altered the distance between the anchoring sites besides the absorption and redox properties. These dyes exhibited broad and intense absorption when compared to the corresponding monoanchoring donor-p-acceptor congeners. Though the dye containing bithiophene unit exhibited comparatively low V oc due to low electron life time and facile back electron transfer, showed high power conversion efficiency arising from the good light-harvesting capability attributable to the intense absorption peak in the visible region and enhanced interfacial electron transfer rate. This work demonstrates that the smaller distance of separation between the anchoring units increases the insulating capacity of the molecular layer which retards the back electron transfer.
Physical Chemistry Chemical Physics, 2011
ACS Applied Materials & Interfaces, Jan 20, 2015
Two types of fluorene-based organic dyes featuring T-shape/rod-shape molecular configuration with... more Two types of fluorene-based organic dyes featuring T-shape/rod-shape molecular configuration with phenothiazine donor and cyanoacrylic acid acceptor have been synthesized and characterized as sensitizers for dyesensitized solar cells. Phenothiazine is functionalized at either nitrogen (N10) or carbon (C3) to obtain T-shape and rod-like organic dyes, respectively. The effect of structural alternation on the optical, electrochemical, and the photovoltaic properties is investigated. The crystal structure determination of the dye containing phenyl linker revealed cofacial slip-stack columnar packing of the molecules. The trends in the optical properties of the dyes are interpreted using time-dependent density functional theory (TDDFT) computations. The rod-shaped dyes exhibited longer wavelength absorption and low oxidation potentials when compared to the corresponding T-shaped dyes attributable to the favorable electronic overlap between the phenothiazine unit and the rest of the molecule in the former dyes. However, the T-shaped dyes showed better photovoltaic properties due to the lowest unoccupied molecular orbital (LUMO) energy level favorable for electron injection into the conduction band of TiO 2 and appropriate orientation of the phenothiazine unit rendering effective surface blocking to suppress the recombination of electrons between the electrolyte I 3 − and TiO 2. The electrochemical impedance spectroscopy investigations provide further support for the variations in the electron injection and transfer kinetics due to the structural modifications.
Acta Crystallographica Section E-structure Reports Online, Feb 29, 2012
Baheti et al. C 51 H 46 BrN 3 o861 supporting information sup-1
Acta Crystallographica Section E-structure Reports Online, Jan 12, 2013
Biphenyl aniline, a subclass of biaryl compounds, has been recognized as a privileged structure i... more Biphenyl aniline, a subclass of biaryl compounds, has been recognized as a privileged structure in drug discovery. Its derivatives have been pursued as anti-phlogistic, analgesic, anti-obesity, and anti-tumor agents (Zhu et al., 2008). Amide substituted biphenyl derivatives are commonly used to develop antiparasitic agents for the treatment of African sleeping
Chemical Communications, 2020
A novel SWIFT-based strategy for selective fluorimetric detection of practical amounts of V and G... more A novel SWIFT-based strategy for selective fluorimetric detection of practical amounts of V and G chemical warfare agents is reported.
Journal of Power Sources, Oct 1, 2012
Chemical Communications
Novel calixarene scaffolds incorporating fused carbazole moieties demonstrated aggregation-induce... more Novel calixarene scaffolds incorporating fused carbazole moieties demonstrated aggregation-induced emission-based luminogen (AIEgen) properties in aqueous media, and were applied for the host–guest detection of nitric oxide.
Chemical Communications, 2020
A novel SWIFT-based strategy for selective fluorimetric detection of practical amounts of V and G... more A novel SWIFT-based strategy for selective fluorimetric detection of practical amounts of V and G chemical warfare agents is reported.
Organic Letters, 2020
Conjugated 5,5′-Bicalixarene scaffolds having fluorophores at the chain termini have been prepare... more Conjugated 5,5′-Bicalixarene scaffolds having fluorophores at the chain termini have been prepared and tested in the supramolecular detection of nitric oxide. Scaffolds bearing electron-rich fluorophores demonstrated a stronger turn-off response to the presence of NO than the fluorophore-free analogue in both organic and aqueous media, while no fluorescence quenching happened when the electron-deficient fluorophores were employed. Unprecedented ratiometric supramolecular sensing was observed when fluorophores of the opposite electronic demands were placed at the scaffold's termini.
Journal of the American Chemical Society, 2019
Here, we present a conceptually novel and experimentally straightforward technique for selective ... more Here, we present a conceptually novel and experimentally straightforward technique for selective analyte detection that uses a combination of commercial fluorophores and simple chemicals. The technique utilizes the well-known inner filter effect (IFE), however, the fluorophore's excitation is performed at wavelengths significantly shorter than its absorption maximum. In the presence of the analyte, the "filter" appears or disappears at the excitation wavelength resulting in the fluorescence turning OFF or ON, respectively. Unlike common probes, our technique allows real-time monitoring of fluorophore's stability as well as its recycling. We further demonstrate the applicability of this technique in continuing analyte detection as well as vapor analysis.