Lawrence, MA 01843, USA [Boston Area]
Senior Chemist: 2015-Present
Research Professor: 2008-2012.
Research Associate: 1993-2006.
Ph.D. (chemistry); Indian Institute of Science; June 1993.
Thesis title:Coordination Chemistry of Cyclotriphosphazenes.
Research Supervisor: Prof. S.S. Krishnamurthy.
M.Sc. (Chemistry); Madurai Kamarajar University; 1986.
B.Sc. (Chemistry); Madurai Kamarajar University; 1984.
Nucleotides & Nucleosides: Current
Charge Transport Studies: 4 years (see details below)
Chemistry & Spectroscopy: 30 years (see details below)
X-ray Crystallography: 22 years (see details below)
Computers & Programs: 25 years (Details in this Link)
- Published over 67 journal articles in organophosphorus chemistry, organosilicon chemistry, metal complexes and crystallography.
- Reviewed over 45 journal articles.
- Collected single crystal X-ray data & solved structures of ~880 crystals such as zeolites, metal complexes, organic and bio-organic compounds.
- Written various programs to analyze the X-ray data and even a simplest database to handle the hundreds of structures I have solved.
- Recently focusing on the charge transport in organic materials for ion conductivity and electron conductivity for organic solar cells and transistors.
- Set up a new instrument lab for testing materials for ion/electron conductivity.
- Written two major automated programs to analyze FET-mobility and solar cell efficiencies.
- Edited a Free Access Online book (Dec-2011): "Current Trends in X-ray Crystallography"
RESEARCH EXPERIENCE (Details)
2015- Working as Senior Chemist on the synthesis of Nucleotides & Nucleosides.
Present Synthesis, process analysis, column & HPLC purification of nucleotides and related products.
Process improvements in second major line of products: 50% cost and 50% time savings.
Semi-preparative HPLC method development; increased the productivity by 4 fold.
Synthesized several nucleosides and nucleotides, using up to 6 steps (50 mg – 1 kg).
Used several orthogonal protection-deprotection strategies.
Developed expertise in TFA, DMT and succinate functionalizations.
Developed Dowex based trityl deprotection for special products & better quenching stategy.
Standardized synthesis & purification of four cyclic dinucleotide STING anti-sense ligands.
Developed innovative pre-treated TLC plates to monitor column chromatography, used by many colleagues.
2008- Worked on the charge transport in organic materials. Set up a new instrument lab for
2012 testing organic materials for ion/electron transport. The focus is on proton transport
for fuel cell applications, and electron transport for solar cell applications and
organic semiconductors. Full in-charge of this new instrument lab with maintenance,
operation and teaching the students about the instruments.
1994- worked with Professor ROBERT R. HOLMES on the HYPERVALENT COMPOUNDS OF SILICON AND
2006 PHOSPHORUS as a Postdoctoral Research Associate. The work involved:
* The conformational/orientational study of penta coordinated phosphorus compounds
* Syntheses and structural study of phosphoranes based on biologically relevant
Carbohydrates and Nucleosides
* The hexa coordination on phosphorus (nature, strength and conditions)
* The penta/hexa coordination in silicon
1992- worked in the field of PHOSPHAZENE POLYMERS which is an important area in
1994 fire-retardant polymers. Two new kinds of soluble and easily modifiable but low
molecular weight chlorocyclophosphazene polymers and several derivatives of them
were synthesized and characterized. They were found to be highly
fire-retardant and thermally stable.
1986- worked on the coordination chemistry of cyclotriphosphazenes Group VI metal carbonyl
1992 complexes and palladium chloride complexes of various cyclotriphosphazene derivatives
were synthesized and characterized using spectroscopic (IR and 1H, 31P & 13C NMR)
techniques and single crystal X-ray crystallography. In this study, the modifiabl
nature of the phosphazene ring nitrogen-metal bond and a novel palladium assisted
hydrolysis of diazaphospholane ring have been demonstrated with structural evidences.
AREAS OF INTEREST
- Charge Transport: OFET and Organic Solar Cells
- Crystal packing and its effect on charge transport
- Main Group Chemistry
- Coordination Chemistry
- Organometallic Chemistry
- Instruments and Computers
INSTRUMENTS AND TECHNIQUES
- Synthetic Chemistry & Inert Atmosphere Techniques
- Interpretation of IR and 1H, 31P, 13C & 29Si NMR Spectra
- Operation of the following Instruments:
- Agilent Parameter Analyzer (FET Mobility)
- Keithley Instruments and Newport Solar Simulator (Solar Cell Efficiency)
- Newport Quantum Efficiency Measurement System (Solar Cells)
- Hitachi U-3400 UV Spectrometer
- Bio-Rad (FT) and Perkin-Elmer 597 IR Spectrometers
- Heraeus CHN-O-Rapid Elemental Analyzer
- Bruker DPX-300, ACF-200, AF-200 and MSL-300 NMR Instruments.
- Waters HPLC Instrument
- Single crystal X-ray Crystallography: Operation of Enraf-Nonius CAD4 Diffractometer;
Structure Solution and Refinement using MULTAN-82, SHELX-76, SHELXS-86 & SHELXL-93 Programs;
Experienced from ~220 crystal structures during 1989-1999; Written a FORTRAN program for the data processing.
- From January-2000 to December-2011, operated a Nonius KappaCCD diffractometer with latest technology. Using this we can solve several structures in one day!!! (worked on 660 crystals during 2000-2011).
- Use of Personnel Computers (Windows/DOS), some UNIX/Linux/Mac and VAX, PDP, IBM RISC-6000.
- Writing programs in FORTRAN. (Little C, Basic and recently some Python).
- XTALDB.FOR ** To handle the recent KappaCCD's high output of datasets, this small database program has
been written. It stores some sample, cell and data information in ascii database and currently searches on cell, formula, crystal code.
Also it generates summary for: Space Groups, User/Group and Annual data.
- XRAYACS.FOR ** CAD4 Single crystal X-ray data processing (Intensity calculation, LP correction & absortion corrections; either F or F2). More than 1500 lines.
- SELECT.FOR ** To select strong reflections in desired angle range for refining the cell.
- CHIACS.FOR ** For selecting reflections for PSI data collection (upto orthorhombic, additional octants can be searched).
- DATAFALL.FOR ** To study the fall of intensity as a function of Theta.
- FOFC.FOR ** To convert the CIF format Fo-Fc output of SHELXL-93 to three reflections per line for WINWORD.
- CHNACS.FOR ** Calculation of elemental % from Empirical Formula
- NMRTC.FOR ** Calculation of activation energy from NMR Tc (Coalescense Temperature) and frequency difference; it can back calculate where the Tc will be
for peaks for which Tc was not observed but activation energy has been calculated from other peaks.
- Molecular Mechanics calculations using HyperChem program
- Ab Initio Calculations using GAUSSIAN-94 (using the SuperComputer at SanDiego)