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Papers by Sathyaraj G
The Journal of …, Jan 1, 2012
Hydrated phenylalanine ionic liquid (Phe-IL) has been used to solubilize myoglobin (Mb). Structur... more Hydrated phenylalanine ionic liquid (Phe-IL) has been used to solubilize myoglobin (Mb). Structural stability of Mb in Phe-IL analyzed using fluorescence and circular dichroism spectroscopy shows that for low levels of hydration of Phe-IL there is a large red shift in the fluorescence emission wavelength and the protein transforms to complete β sheet from its native helical conformation. Rehydration or dilution reverses the β sheet to an α helix which on aging organizes to micrometer-sized fibrils. At concentrations higher than 200 μM, the protein changes from β to a more random coiled structure. Organization of the protein in Phe-IL in a Langmuir film at the air/water interface has been investigated using the surface pressure−molecular area isotherm and shows nearly the same surface tension for both pure Mb and Mb in Phe-IL. Scanning electron microscopy of the films of Mb in Phe-IL transferred using the Langmuir−Blodgett film technique show layered morphology. This study shows that the conformation of Mb is completely reversible going from β → helix → β sheet up to 200 μM of Phe-IL. Similar surface tension values for Mb in water and in Phe-IL suggests that direct ion binding interactions with the protein coupled with the change in local viscosity from the IL seems to not only alter the secondary structure of individual proteins but also drives the self-assembly of the protein molecules leading finally to fibril formation.
Journal of …, Jan 1, 2012
Two chemosensor molecules with the capability of sensing cations and anions have been synthesized... more Two chemosensor molecules with the capability of sensing cations and anions have been synthesized by coupling an electroactive unit based on ferrocene and a sensor unit based on imidazolyl and phenol moieties through a linker. The two receptor molecules have been characterized crystallographically. The sensing of the cations or anions is achieved by monitoring the electrochemical wave or optical signal of the ferrocenyl moiety present in the molecule. Results of electrochemical and spectral titration of the chemosensors with cations and anions show that the response of the chemosensors to cations and anions can be tuned by changing the substituents in the phenolic ring.
![Research paper thumbnail of Ruthenium (ii)[3+ 2+ 1] mixed ligand complexes: substituent effect on photolability, photooxidation of bases, photocytotoxicity and photonuclease activity](https://attachments.academia-assets.com/50822005/thumbnails/1.jpg)
](Dalton Trans., Jan 1, 2012
Mixed ligand complexes of ruthenium(II), [Ru(itpy)(bpy)Cl]ClO 4 1, [Ru(itpy)( phen)Cl]ClO 4 2, [R... more Mixed ligand complexes of ruthenium(II), [Ru(itpy)(bpy)Cl]ClO 4 1, [Ru(itpy)( phen)Cl]ClO 4 2, [Ru(bitpy)(bpy)Cl]ClO 4 3 and [Ru(bitpy)( phen)Cl]ClO 4 4 have been synthesized and characterized. Complex 3 has also been characterized crystallographically. These complexes exhibit photolability of the Ru-Cl bond. Upon irradiation at 440 nm in the presence of nucleosides and nucleotides the complexes exchange chloride for the nucleoside or nucleotide. The photolability of the Ru-Cl bond depends on the nature of the substituent in the tridentate tpy ligand. Photolysis of the complexes in the presence of a nucleoside or nucleotide also produces 8-oxoguanine due to the oxidation of guanine by the excited states of the complexes. These four complexes exhibit photonuclease properties and bring about the cleavage of plasmid DNA when irradiated at 440 nm. These complexes have been found to be toxic towards NIH 3T3 cells under photolytic conditions. † Electronic supplementary information (ESI) available: Additional figures and Cartesian coordinates for optimization of complexes 1-4. CCDC reference number 819095. For ESI and crystallographic data in CIF or other electronic format see
European journal of medicinal …, Jan 1, 2010
La(III) and Ce(III) complexes containing ligand of N-phenyl-2-pyridinecarboxamide (HL) were synth... more La(III) and Ce(III) complexes containing ligand of N-phenyl-2-pyridinecarboxamide (HL) were synthesized and characterized by elemental analyses, conductivity measurement, IR spectra and thermal analysis. The general formulas of the complexes were [Ln(HL)(3)(H(2)O)(2)](NO(3))(3).2H(2)O [Ln=La(III), Ce(III)]. The results indicated that the oxygen of carbonyl and the nitrogen of pyridyl coordinated to Ln(III), and there were also two water molecules taking part in coordination. Ln(III) and HL formed 1:3 chelate complexes and the coordination number was eight. The interaction between the complexes and DNA was studied by means of UV-vis spectra, fluorescence spectra, SERS spectra and agarose gel electrophoresis. The results showed that complexes can bind to DNA. The binding ability decreased in following order: La(III) complex, Ce(III) complex, and HL. The interaction modes between DNA and the three compounds were found to be mainly intercalative.
Journal of Chemical Crystallography
The Journal of …, Jan 1, 2012
Hydrated phenylalanine ionic liquid (Phe-IL) has been used to solubilize myoglobin (Mb). Structur... more Hydrated phenylalanine ionic liquid (Phe-IL) has been used to solubilize myoglobin (Mb). Structural stability of Mb in Phe-IL analyzed using fluorescence and circular dichroism spectroscopy shows that for low levels of hydration of Phe-IL there is a large red shift in the fluorescence emission wavelength and the protein transforms to complete β sheet from its native helical conformation. Rehydration or dilution reverses the β sheet to an α helix which on aging organizes to micrometer-sized fibrils. At concentrations higher than 200 μM, the protein changes from β to a more random coiled structure. Organization of the protein in Phe-IL in a Langmuir film at the air/water interface has been investigated using the surface pressure−molecular area isotherm and shows nearly the same surface tension for both pure Mb and Mb in Phe-IL. Scanning electron microscopy of the films of Mb in Phe-IL transferred using the Langmuir−Blodgett film technique show layered morphology. This study shows that the conformation of Mb is completely reversible going from β → helix → β sheet up to 200 μM of Phe-IL. Similar surface tension values for Mb in water and in Phe-IL suggests that direct ion binding interactions with the protein coupled with the change in local viscosity from the IL seems to not only alter the secondary structure of individual proteins but also drives the self-assembly of the protein molecules leading finally to fibril formation.
Journal of …, Jan 1, 2012
Two chemosensor molecules with the capability of sensing cations and anions have been synthesized... more Two chemosensor molecules with the capability of sensing cations and anions have been synthesized by coupling an electroactive unit based on ferrocene and a sensor unit based on imidazolyl and phenol moieties through a linker. The two receptor molecules have been characterized crystallographically. The sensing of the cations or anions is achieved by monitoring the electrochemical wave or optical signal of the ferrocenyl moiety present in the molecule. Results of electrochemical and spectral titration of the chemosensors with cations and anions show that the response of the chemosensors to cations and anions can be tuned by changing the substituents in the phenolic ring.
Dalton Trans., Jan 1, 2012
Mixed ligand complexes of ruthenium(II), [Ru(itpy)(bpy)Cl]ClO 4 1, [Ru(itpy)( phen)Cl]ClO 4 2, [R... more Mixed ligand complexes of ruthenium(II), [Ru(itpy)(bpy)Cl]ClO 4 1, [Ru(itpy)( phen)Cl]ClO 4 2, [Ru(bitpy)(bpy)Cl]ClO 4 3 and [Ru(bitpy)( phen)Cl]ClO 4 4 have been synthesized and characterized. Complex 3 has also been characterized crystallographically. These complexes exhibit photolability of the Ru-Cl bond. Upon irradiation at 440 nm in the presence of nucleosides and nucleotides the complexes exchange chloride for the nucleoside or nucleotide. The photolability of the Ru-Cl bond depends on the nature of the substituent in the tridentate tpy ligand. Photolysis of the complexes in the presence of a nucleoside or nucleotide also produces 8-oxoguanine due to the oxidation of guanine by the excited states of the complexes. These four complexes exhibit photonuclease properties and bring about the cleavage of plasmid DNA when irradiated at 440 nm. These complexes have been found to be toxic towards NIH 3T3 cells under photolytic conditions. † Electronic supplementary information (ESI) available: Additional figures and Cartesian coordinates for optimization of complexes 1-4. CCDC reference number 819095. For ESI and crystallographic data in CIF or other electronic format see
European journal of medicinal …, Jan 1, 2010
La(III) and Ce(III) complexes containing ligand of N-phenyl-2-pyridinecarboxamide (HL) were synth... more La(III) and Ce(III) complexes containing ligand of N-phenyl-2-pyridinecarboxamide (HL) were synthesized and characterized by elemental analyses, conductivity measurement, IR spectra and thermal analysis. The general formulas of the complexes were [Ln(HL)(3)(H(2)O)(2)](NO(3))(3).2H(2)O [Ln=La(III), Ce(III)]. The results indicated that the oxygen of carbonyl and the nitrogen of pyridyl coordinated to Ln(III), and there were also two water molecules taking part in coordination. Ln(III) and HL formed 1:3 chelate complexes and the coordination number was eight. The interaction between the complexes and DNA was studied by means of UV-vis spectra, fluorescence spectra, SERS spectra and agarose gel electrophoresis. The results showed that complexes can bind to DNA. The binding ability decreased in following order: La(III) complex, Ce(III) complex, and HL. The interaction modes between DNA and the three compounds were found to be mainly intercalative.
Journal of Chemical Crystallography