Mahalingavelar Paramasivam - Academia.edu (original) (raw)
Papers by Mahalingavelar Paramasivam
by Mahalingavelar Paramasivam, Anuji K. Vasu and Sriram Kanvah
by Mahalingavelar Paramasivam and Sriram Kanva
Physical Chemistry Chemical Physics
α-Cyanostilbene motif helps tuning the emission intensity and wavelength through intermolecular n... more α-Cyanostilbene motif helps tuning the emission intensity and wavelength through intermolecular non-covalent interactions.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
New Journal of Chemistry, 2021
Acceptor strength regulates the ICT mechanism via AIE or ACQ processes.
Journal of Molecular Liquids, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
New Journal of Chemistry, 2020
Aggregation propensity of pyridyl functionalized α-cyanostilbenes has been investigated with resp... more Aggregation propensity of pyridyl functionalized α-cyanostilbenes has been investigated with respect to various amino donors.
ChemistrySelect, 2017
A simple and efficient construction of a water-soluble glycoconjugate bearing a cyanostilbene wit... more A simple and efficient construction of a water-soluble glycoconjugate bearing a cyanostilbene with glucose pendant and its interaction with proteins is reported. The absorption and fluorescence behavior of this glycoconjugate was investigated in organic solvents, binary-solvent mixtures, water and in the presence of proteins, concanavalin A, bovine serum albumin (BSA) and human serum albumin (HSA). With increase in the solvent polarity, the synthesized derivative exhibited emission quenching but in dioxane-pentane binary mixture, a significant red-shifted emission with substantial Stokes' shift was observed. This emission response is attributed to the formation of aggregates and the results were substantiated by scanning electron microscopy (SEM) and dynamic light scattering (DLS) analysis. In the presence of proteins, the fluorophore exhibits moderate binding efficiency and shows synergistic interactions with a combination of hydrophobic and hydrophilic interactions. Circular Dichroism (CD) studies with protein and the fluorophore reveals changes in ellipticity confirming the binding of the fluorophore within the protein domains.
Physical Chemistry Chemical Physics, 2018
The heteroatom substitution on cross conjugation takes a reverse trend to the linear π-conjugated... more The heteroatom substitution on cross conjugation takes a reverse trend to the linear π-conjugated systems by means of energy levels and photophysical properties. The resultant changes directly affecting the photovoltaic performance of DSSCs.
ACS Applied Materials & Interfaces, 2019
Three phenothiazine based A-π-D-π-D-π-A type small molecules containing various terminal acceptor... more Three phenothiazine based A-π-D-π-D-π-A type small molecules containing various terminal acceptor units, which act as Lewis base blocks, have been synthesized via an efficient and step-economical, direct C-H arylation strategy in the aim towards the development of holetransporting materials (HTMs) with multifunctional features (such as efficient hole extraction layer, trap passivation layer and hydrophobic protective layer) for perovskite solar cells (PrSCs). Optical-electrochemical Correlation and DFT studies reveal that dicyanovinylene (DCV) acceptor in SGT-421 downshifted the HOMO level (-5.41 eV) which is more proximal to the VB (-5.43 eV) of the perovskite, whereas N-methyl rhodanine (NMR) in SGT-420 and indanedione (IND) in SGT-422 destabilized the HOMO, leading to an increased interfacial energy level offset. SGT-421 exhibits superior properties in terms of a sufficiently low-lying HOMO level and favorable energy level alignment, intrinsic hole mobility, interfacial hole transfer, hydrophobicity and trap passivation ability over spiro-OMeTAD as a benchmark small molecule HTM. As envisaged the design concept, SGT-421-based PrSC not only yields a comparable efficiency of 17.3% to the state-of-art of spiro-OMeTAD (18%), but also demonstrates the enhanced long-term stability compared over the spiro-OMeTAD due to its multifunctional features. More importantly, synthetic cost of SGT-421 is estimated to be 2.15 times lower than that of spiro-OMeTAD. The proposed design strategy and the study of acceptor-property relationship of HTMs would provide valuable insights and guidelines to the development of new low-cost and efficient multifunctional HTMs for the realization of efficient and long-term stable PrSCs.
![Research paper thumbnail of Energy level tuning of ‘Z’-shaped small molecular non-fullerene electron acceptors based on a dipyrrolo[2,3-b:2′,3′-e]pyrazine-2,6(1H,5H)-dione acceptor unit for organic photovoltaic applications: a joint experimental and DFT investigation on the effect of fluorination](https://attachments.academia-assets.com/100584903/thumbnails/1.jpg)
](New Journal of Chemistry, 2019
Three dipyrrolo[2,3-b:2′,3′-e]pyrazine-2,6(1H,5H)-dione based small molecule non-fullerene accept... more Three dipyrrolo[2,3-b:2′,3′-e]pyrazine-2,6(1H,5H)-dione based small molecule non-fullerene acceptors with various end-capped fluorine units have been investigated.
Journal of fluorescence, Jan 27, 2018
Various electron donor and acceptor substituted (NO, CN, Cl, H, OCH, NH) p-phenyl ethenyl-E- thio... more Various electron donor and acceptor substituted (NO, CN, Cl, H, OCH, NH) p-phenyl ethenyl-E- thiophenes (1-6) were synthesized and substituent dependent optical properties (dipole moment, transition dipole moment, oscillator strength, optical band gap, hyperpolarizability) were studied using Solvatochromism and Density functional theory. It is shown that thiophene acts as a weak electron donor in presence of an electron withdrawing p-phenyl substituent (NO, CN, Cl), whereas thiophene acts as a weak electron acceptor in presence of an electron donating p-phenyl substituent (OCH, NH). In comparison to ethenyl thiophene 4, the HOMO-LUMO energy band gap is decreased upon increasing the electron donating or electron withdrawing capacity of p-phenyl substituent. From the excited state dipole moment calculation, it is shown that the excited state is highly dipolar for nitro and amino compounds 1 and 6, whereas compounds 2-5 show a non-polar excited state. As compared to the ethenyl thiophe...
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 20, 2018
p‑Phenyl ethenyl‑E‑furans (1-6) with varied electron donor and acceptor substituent (NO, CN, Cl, ... more p‑Phenyl ethenyl‑E‑furans (1-6) with varied electron donor and acceptor substituent (NO, CN, Cl, H, OCH, NH) were synthesized and studied the substituent induced optical properties (dipole moment, transition dipole moment, oscillator strength, optical band gap, hyperpolarizability) using Solvatochromism and Density functional theory. It is shown that furan acts as a weak electron donor in presence of an electron withdrawing p‑phenyl substituent (NO, CN, Cl), whereas furan acts as a weak electron acceptor in presence of an electron donating p‑phenyl substituent (OCH, NH). In comparison to ethenylfuran 4, the HOMO-LUMO energy band gap is decreased upon increasing the electron donating or electron withdrawing nature of the phenyl ring. Calculation of excited state dipole moment and polarizability of 1-6 in solvent of varying polarity suggest that the nitro and amino compounds (1, 6) exhibit charge transfer excited state, whereas excited state of compounds 3-5 is non-polar in nature. As...
The Journal of Physical Chemistry C, 2015
Tuning the parameters to enhance the efficiencies of a novel set of metal free sensitizers for dy... more Tuning the parameters to enhance the efficiencies of a novel set of metal free sensitizers for dye sensitized solar cells (DSSC) is carried out by varying the πconjugated spacers which link the donor benzocarbazole to the acceptor cyanoacrylic acid. The molecules are synthesized by different combinations of spacers, namely fluorene-thiophene (BFT), fluorene-furan (BFF), fluorenephenyl (BFB) and thiophene-phenyl (BTB). The molar extinction coefficients of all the dyes are high which is attributed to benzocarbazole, but it is higher in the dyes in which fluorene is one of the spacers. But interestingly in the photovoltaic device when the non fluorene dye, BTB is the sensitizer, red shifted and broader incident photon-to-current efficiency (IPCE) curves are obtained leading to larger short circuit current density, J sc-almost double when compared to BFB based cell. The efficiency of the device with this dye as the sensitizer is also the highest in this series. The reasons behind these observations are investigated using computational techniques.
Physical Chemistry Chemical Physics, 2017
Fast reverse intersystem crossing in a donor–acceptor system used in OLED and OPV materials.
Lactoferrin was purified from human seminal fluid obtained from the semen bank. The purified samp... more Lactoferrin was purified from human seminal fluid obtained from the semen bank. The purified samples were saturated with Fe 3+ and crystallized by microdialysis method. The crystals belong to orthorhombic space group P2 1 2 1 2 1 with a = 55.9 Å, b = 97.2 Å, c = 156.1 Å and Z = 4. The structure was determined with molecular replacement method and refined to an R factor of 18.7% for all the data to 3.4 Å resolution. The overall structure of seminal lactoferrin is similar to human colostrum lactoferrin. The amino acid sequence of seminal lactoferrin shows that it has one amino acid less than human colostrum lactoferrin and the structure of its N-terminal region is far more ordered than other lactoferrins. The structure of the ironbinding site and its immediate surroundings indicate well defined features.
The Journal of Physical Chemistry C, 2016
A series of cyanostilbene based D−π–A derivatives, comprising 6-(diethylamino)coumarin as a donor... more A series of cyanostilbene based D−π–A derivatives, comprising 6-(diethylamino)coumarin as a donor and benzene and benzothiazole as acceptors bridged by different π-spacers (benzene, thiophene), have been synthesized and characterized. The influence of π-spacer and acceptor units on the photophysical, electrochemical, and thermal properties of the dyes was investigated in detail. The incorporation of coumarin donor results in a significant increase of the fluorescence quantum yield. In the solution phase, the absorption and emission of the dye TB show a bathochromic shift (TB > BBT) indicating dominant dynamic intramolecular rotations (IMR) behavior of cyano group over the acceptor functionality. On the other hand, the emission is reversed (BBT > TB) in the case of aggregates. The synergistic combination of intramolecular planarization and torsional alleviation around cyanostilbenes induced by strong electron withdrawing benzothiazole unit in BBT enabled pronounced bathochromic shift upon aggregation. Upon...
![Research paper thumbnail of Funnel shaped molecules containing benzo/pyrido[1,2,5]thiadiazole functionalities as peripheral acceptors for organic photovoltaic applications](https://attachments.academia-assets.com/100584897/thumbnails/1.jpg)
](RSC Advances, 2016
Energy levels of a funnel shaped molecule was effected by varying donor and acceptor combinations... more Energy levels of a funnel shaped molecule was effected by varying donor and acceptor combinations and a power efficiency of 2.21% achieved for DCTP molecule.
Photochemistry and Photobiology, 2015
A series of ortho-, metaand para-substituted trans-nitro aryl (phenyl and pyridyl) butadienes hav... more A series of ortho-, metaand para-substituted trans-nitro aryl (phenyl and pyridyl) butadienes have been synthesized and characterized. The effect of substitution and positional selectivity on their fluorescence and photoisomerization were systematically investigated. Among all dienes, metaand para-nitro phenyl-substituted derivatives exhibit remarkable solvatochromic emission shifts due to intramolecular charge transfer. On the other hand, ortho derivatives undergo regioselective isomerization upon photoexcitation in contrast to inefficient isomerization of para and meta nitro-substituted dienes. Single crystal X-ray analysis revealed existence of intramolecular hydrogen bonding between the nitro group and the hydrogen of the proximal double bond. This restricts the rotation of the proximal double bond thereby allowing regioselective isomerization. The observations were also supported by NMR spectroscopic studies.
by Mahalingavelar Paramasivam, Anuji K. Vasu and Sriram Kanvah
by Mahalingavelar Paramasivam and Sriram Kanva
Physical Chemistry Chemical Physics
α-Cyanostilbene motif helps tuning the emission intensity and wavelength through intermolecular n... more α-Cyanostilbene motif helps tuning the emission intensity and wavelength through intermolecular non-covalent interactions.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
New Journal of Chemistry, 2021
Acceptor strength regulates the ICT mechanism via AIE or ACQ processes.
Journal of Molecular Liquids, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
New Journal of Chemistry, 2020
Aggregation propensity of pyridyl functionalized α-cyanostilbenes has been investigated with resp... more Aggregation propensity of pyridyl functionalized α-cyanostilbenes has been investigated with respect to various amino donors.
ChemistrySelect, 2017
A simple and efficient construction of a water-soluble glycoconjugate bearing a cyanostilbene wit... more A simple and efficient construction of a water-soluble glycoconjugate bearing a cyanostilbene with glucose pendant and its interaction with proteins is reported. The absorption and fluorescence behavior of this glycoconjugate was investigated in organic solvents, binary-solvent mixtures, water and in the presence of proteins, concanavalin A, bovine serum albumin (BSA) and human serum albumin (HSA). With increase in the solvent polarity, the synthesized derivative exhibited emission quenching but in dioxane-pentane binary mixture, a significant red-shifted emission with substantial Stokes' shift was observed. This emission response is attributed to the formation of aggregates and the results were substantiated by scanning electron microscopy (SEM) and dynamic light scattering (DLS) analysis. In the presence of proteins, the fluorophore exhibits moderate binding efficiency and shows synergistic interactions with a combination of hydrophobic and hydrophilic interactions. Circular Dichroism (CD) studies with protein and the fluorophore reveals changes in ellipticity confirming the binding of the fluorophore within the protein domains.
Physical Chemistry Chemical Physics, 2018
The heteroatom substitution on cross conjugation takes a reverse trend to the linear π-conjugated... more The heteroatom substitution on cross conjugation takes a reverse trend to the linear π-conjugated systems by means of energy levels and photophysical properties. The resultant changes directly affecting the photovoltaic performance of DSSCs.
ACS Applied Materials & Interfaces, 2019
Three phenothiazine based A-π-D-π-D-π-A type small molecules containing various terminal acceptor... more Three phenothiazine based A-π-D-π-D-π-A type small molecules containing various terminal acceptor units, which act as Lewis base blocks, have been synthesized via an efficient and step-economical, direct C-H arylation strategy in the aim towards the development of holetransporting materials (HTMs) with multifunctional features (such as efficient hole extraction layer, trap passivation layer and hydrophobic protective layer) for perovskite solar cells (PrSCs). Optical-electrochemical Correlation and DFT studies reveal that dicyanovinylene (DCV) acceptor in SGT-421 downshifted the HOMO level (-5.41 eV) which is more proximal to the VB (-5.43 eV) of the perovskite, whereas N-methyl rhodanine (NMR) in SGT-420 and indanedione (IND) in SGT-422 destabilized the HOMO, leading to an increased interfacial energy level offset. SGT-421 exhibits superior properties in terms of a sufficiently low-lying HOMO level and favorable energy level alignment, intrinsic hole mobility, interfacial hole transfer, hydrophobicity and trap passivation ability over spiro-OMeTAD as a benchmark small molecule HTM. As envisaged the design concept, SGT-421-based PrSC not only yields a comparable efficiency of 17.3% to the state-of-art of spiro-OMeTAD (18%), but also demonstrates the enhanced long-term stability compared over the spiro-OMeTAD due to its multifunctional features. More importantly, synthetic cost of SGT-421 is estimated to be 2.15 times lower than that of spiro-OMeTAD. The proposed design strategy and the study of acceptor-property relationship of HTMs would provide valuable insights and guidelines to the development of new low-cost and efficient multifunctional HTMs for the realization of efficient and long-term stable PrSCs.
New Journal of Chemistry, 2019
Three dipyrrolo[2,3-b:2′,3′-e]pyrazine-2,6(1H,5H)-dione based small molecule non-fullerene accept... more Three dipyrrolo[2,3-b:2′,3′-e]pyrazine-2,6(1H,5H)-dione based small molecule non-fullerene acceptors with various end-capped fluorine units have been investigated.
Journal of fluorescence, Jan 27, 2018
Various electron donor and acceptor substituted (NO, CN, Cl, H, OCH, NH) p-phenyl ethenyl-E- thio... more Various electron donor and acceptor substituted (NO, CN, Cl, H, OCH, NH) p-phenyl ethenyl-E- thiophenes (1-6) were synthesized and substituent dependent optical properties (dipole moment, transition dipole moment, oscillator strength, optical band gap, hyperpolarizability) were studied using Solvatochromism and Density functional theory. It is shown that thiophene acts as a weak electron donor in presence of an electron withdrawing p-phenyl substituent (NO, CN, Cl), whereas thiophene acts as a weak electron acceptor in presence of an electron donating p-phenyl substituent (OCH, NH). In comparison to ethenyl thiophene 4, the HOMO-LUMO energy band gap is decreased upon increasing the electron donating or electron withdrawing capacity of p-phenyl substituent. From the excited state dipole moment calculation, it is shown that the excited state is highly dipolar for nitro and amino compounds 1 and 6, whereas compounds 2-5 show a non-polar excited state. As compared to the ethenyl thiophe...
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 20, 2018
p‑Phenyl ethenyl‑E‑furans (1-6) with varied electron donor and acceptor substituent (NO, CN, Cl, ... more p‑Phenyl ethenyl‑E‑furans (1-6) with varied electron donor and acceptor substituent (NO, CN, Cl, H, OCH, NH) were synthesized and studied the substituent induced optical properties (dipole moment, transition dipole moment, oscillator strength, optical band gap, hyperpolarizability) using Solvatochromism and Density functional theory. It is shown that furan acts as a weak electron donor in presence of an electron withdrawing p‑phenyl substituent (NO, CN, Cl), whereas furan acts as a weak electron acceptor in presence of an electron donating p‑phenyl substituent (OCH, NH). In comparison to ethenylfuran 4, the HOMO-LUMO energy band gap is decreased upon increasing the electron donating or electron withdrawing nature of the phenyl ring. Calculation of excited state dipole moment and polarizability of 1-6 in solvent of varying polarity suggest that the nitro and amino compounds (1, 6) exhibit charge transfer excited state, whereas excited state of compounds 3-5 is non-polar in nature. As...
The Journal of Physical Chemistry C, 2015
Tuning the parameters to enhance the efficiencies of a novel set of metal free sensitizers for dy... more Tuning the parameters to enhance the efficiencies of a novel set of metal free sensitizers for dye sensitized solar cells (DSSC) is carried out by varying the πconjugated spacers which link the donor benzocarbazole to the acceptor cyanoacrylic acid. The molecules are synthesized by different combinations of spacers, namely fluorene-thiophene (BFT), fluorene-furan (BFF), fluorenephenyl (BFB) and thiophene-phenyl (BTB). The molar extinction coefficients of all the dyes are high which is attributed to benzocarbazole, but it is higher in the dyes in which fluorene is one of the spacers. But interestingly in the photovoltaic device when the non fluorene dye, BTB is the sensitizer, red shifted and broader incident photon-to-current efficiency (IPCE) curves are obtained leading to larger short circuit current density, J sc-almost double when compared to BFB based cell. The efficiency of the device with this dye as the sensitizer is also the highest in this series. The reasons behind these observations are investigated using computational techniques.
Physical Chemistry Chemical Physics, 2017
Fast reverse intersystem crossing in a donor–acceptor system used in OLED and OPV materials.
Lactoferrin was purified from human seminal fluid obtained from the semen bank. The purified samp... more Lactoferrin was purified from human seminal fluid obtained from the semen bank. The purified samples were saturated with Fe 3+ and crystallized by microdialysis method. The crystals belong to orthorhombic space group P2 1 2 1 2 1 with a = 55.9 Å, b = 97.2 Å, c = 156.1 Å and Z = 4. The structure was determined with molecular replacement method and refined to an R factor of 18.7% for all the data to 3.4 Å resolution. The overall structure of seminal lactoferrin is similar to human colostrum lactoferrin. The amino acid sequence of seminal lactoferrin shows that it has one amino acid less than human colostrum lactoferrin and the structure of its N-terminal region is far more ordered than other lactoferrins. The structure of the ironbinding site and its immediate surroundings indicate well defined features.
The Journal of Physical Chemistry C, 2016
A series of cyanostilbene based D−π–A derivatives, comprising 6-(diethylamino)coumarin as a donor... more A series of cyanostilbene based D−π–A derivatives, comprising 6-(diethylamino)coumarin as a donor and benzene and benzothiazole as acceptors bridged by different π-spacers (benzene, thiophene), have been synthesized and characterized. The influence of π-spacer and acceptor units on the photophysical, electrochemical, and thermal properties of the dyes was investigated in detail. The incorporation of coumarin donor results in a significant increase of the fluorescence quantum yield. In the solution phase, the absorption and emission of the dye TB show a bathochromic shift (TB > BBT) indicating dominant dynamic intramolecular rotations (IMR) behavior of cyano group over the acceptor functionality. On the other hand, the emission is reversed (BBT > TB) in the case of aggregates. The synergistic combination of intramolecular planarization and torsional alleviation around cyanostilbenes induced by strong electron withdrawing benzothiazole unit in BBT enabled pronounced bathochromic shift upon aggregation. Upon...
RSC Advances, 2016
Energy levels of a funnel shaped molecule was effected by varying donor and acceptor combinations... more Energy levels of a funnel shaped molecule was effected by varying donor and acceptor combinations and a power efficiency of 2.21% achieved for DCTP molecule.
Photochemistry and Photobiology, 2015
A series of ortho-, metaand para-substituted trans-nitro aryl (phenyl and pyridyl) butadienes hav... more A series of ortho-, metaand para-substituted trans-nitro aryl (phenyl and pyridyl) butadienes have been synthesized and characterized. The effect of substitution and positional selectivity on their fluorescence and photoisomerization were systematically investigated. Among all dienes, metaand para-nitro phenyl-substituted derivatives exhibit remarkable solvatochromic emission shifts due to intramolecular charge transfer. On the other hand, ortho derivatives undergo regioselective isomerization upon photoexcitation in contrast to inefficient isomerization of para and meta nitro-substituted dienes. Single crystal X-ray analysis revealed existence of intramolecular hydrogen bonding between the nitro group and the hydrogen of the proximal double bond. This restricts the rotation of the proximal double bond thereby allowing regioselective isomerization. The observations were also supported by NMR spectroscopic studies.