Annual Report 2006-2007

Chemical Sciences

Support to frontier areas of research continued during this year. It covers many contemporary areas such as chiral catalysis, rational design and synthesis of biologically active molecules, molecular materials, green chemistry etc. Special initiative was launched in the area of bioinorganic chemistry. Eighteen researchers were awarded Raja Rammana Fellowship for outstanding performance in their respective ongoing projects.

Organic Chemistry

The following are some of the projects funded in this year.

• design and develop diversity oriented green synthesis of industrially and pharmaceutically important heterocyclic scaffolds using carbohydrates as biorenewable feedstocks.
  
• development of new methodology for the synthesis of cyclic ethers. The methodology developed will be applied to synthesize molecules of biological interest.
  
• synthesis of novel dendrimers and explore their catalytic activities.
  
• synthesis of modified oligonucleotides to mimic biological DNA recognition.
  
• synthesis of d-glucose based nonionic Gemini surfactants as micellar and reverse micellar mimics and explore their use in chiral recognition.
  
• develop methodology for the construction of enantiopure bi-, tri and spirocyclic building blocks from a-pinene and use of some of these building blocks in total synthesis of biologically important natural products.
  
• synthesize new chiral liquid crystalline materials containing at least one cholesteryl moiety and study their mesogenic property towards practical application.
  
• study the utility of olefin metathesis reaction for the synthesis of furanomycin, a-amino acids of nonnatural origin and several heterocyclic systems.
  
• synthesize and characterize various oligomers based on thiophene for possible application as NLO or LED devices.
  
• undertake diversity oriented synthesis of bicyclic enediyenes by using intramolecular Kinugasa and [3+2] cycloaddition reactions and study structure-activity relationship. This study may lead to new molecular entities with biological activities.
  

Few interaction meetings with potential project investigators from less endowed institutions were organized. The investigators were requested to make a presentation of the proposed work and suggestions were made with a view to help them prepare a "fundable" project.

Some of the salient achievements in the ongoing projects are:

• A series of bifunctional acridine conjugates were synthesized with potential application as DNA binding and cleaving agents.
• A patent has been filed both in India and abroad for developing a supramolecular fluorescent marker for the detection and quantification for GTP and ATP in buffer and biological fluids.
• Dendrimer type systems capable of sequential electron transfer has been synthesized, which may have applications in photovoltaic system, sensors, xerography etc.
• Significant knowledge has been generated in synthesizing polyoxazole based natural products and in particular towards the structures related to the important natural product, telomestatin. Two macrocyclic structures related to this important anti-cancer natural product have been synthesized which may find application as telomerase inhibitor.
• A new approach has been adopted for synthesis of pyridine ring of camptothecins and related alkaloids by using RCM methodology. This study has opened up new vistas for the synthesis of alkaloids and other natural and non-natural products of industrial importance.
• In a project on crystal engineering, strategies have been developed towards the synthesis of organic/ inorganic hybrid framework materials with the required properties. Specifically, the compounds racemic 2,2'-binol and 4,4'- bipyridine were shown to form two types of host frameworks via O-H…N hydrogen bonds which have affinity to include variety of aromatic guest molecules such as biphenyl, toluene and xylene. Both the architectures does not contain inversion centre and maintains the chirality, but the packing architectures generates the inversion centre. The author was able to replicate the above observed 1D-host framework with chiral 2,2'- binol and bipyridine with guest molecules such as toluene and xylene.
• In a project on polymer chemistry, it has been shown that the incorporation of 3,4-ethylenedioxythoiphene (EDOT) moieties in the main chain high performance polyesters and polyureas improves the processability without compromising thermal properties. Furthermore, the exocyclic bond angle of EDOT unit is found to be compatible with the formation of liquid crystalline phases as the main chain polyesters based on EDOT were found to exhibit mesophasic behaviour. This opens up various avenues wherein new high performance materials can be designed by replacing benzene units with EDOT units wherein the processability can be improved without compromising thermal stability of resulting polymers.
  

Inorganic Chemistry

Launching of new initiative in bioinorganic chemistry was highlight of the year. Ten research proposals in different aspects of bioinorganic chemistry were funded. A major program on "Metal based drugs" is being evolved. Seven research fellowships (6 pre-doctoral and 1 post-doctoral) were also awarded to undertake research in this area. In addition, support to research in other frontier areas of inorganic chemistry also continued.

The following projects were funded as part of the bioinorganic chemistry initative:

• study of functional analogues of molybdenum and tungsten containing oxido-reductase enzymes, generate hybrid enzymes, isolate and purify native proteins of this class. This is an internationally competitive research which aims at understanding the molecular role of molybdenum and tungsten enzymes which have prominent roles in the carbon, nitrogen and sulphur cycles of nature.
• prepare and investigate a series of novel iron, manganese and ruthenium complexes being able to act as structural and functional models for non-heme monooxygenase iron enzymes. This study helps to understand structure-function relationship in monooxygenase systems.
• preparation of new polymer based ligands (nucleobase polymers, organic-inorganic hybrid polymers) and their metal complexes, test their efficacy as catalysts for phosphate ester hydrolysis and peptide bond modifications. The phospho-diester bonds of DNA are resistant to hydrolysis, and with the introduction of metal ions as cofactors, nucleases are able to accelerate the rate enormously. The challenge is in the design of metallopolymers with specific catalytic activities.
• development of gadolinium complexes as contract enhancing agents for magnetic resonance imaging.
• synthesis of novel metal complexes and study their interaction with DNA and cleavage activities.
• synthesis of glycol-conjugates and their metal complexes and study their interaction with biomolecules like lectin and plasmid DNA.

Some of the salient achievements in the ongoing projects are:

• In a projct on exploring the catalytic activity of platinum metal complexes containing a variety of phosphorus based functionalized or hemilabile ligands, the author has developed novel ligand systems, prepared their transition metal complexes and studied their catalytic applications with excellent results. Several phosphorus and nitrogen based ligands have been identified for C-C coupling reactions with remarkable efficiency and turnover numbers. Bis (2-diphenylphosphinoxynaphthalen-1-yl) methane and other related ligands were found to show excellent catalytic activity in homogeneous catalysis (hydrogenation, Suzuki Cross-coupling reactions, Heck reactions, cycloproponation reactions, arylation of ketones, halogen exchange and halogenation reactions). Cyclodiphosphazanes containing hemilabile ponytails were synthesized which exhibit versatile coordination properties. The exclusive formation of either cis or trans Pd(II) complexes was achieved using appropriate metal reagents. The cyclodiphosphazane having ether functionality was found to preferably form the tetranuclear rhodium(I) metallacycle, whereas cyclodiphosphazanes containing thioether and amine functionality gives the bichelated dinuclear rhodium(I) complexes. The latter complexes are the first examples of cyclodiphosphazanes performing as eight-electron donor tetradentate ligands.
• In a project on synthesis and study of magnetic properties of 3d-4f and 4f-nitroxide systems, two compartmental Schiff base ligands have been synthesized and characterized. These ligands have been used to derive two new discrete dinuclear CuIIGdIII compounds, [CuII(H2O)LIGdIII(NO3)3] and [CuIIL2GdIII(NO3)3]. The structures of both the compounds have been determined. Variable temperature magnetic susceptibility as well as variable-field magnetization studies reveal that the metal centers in these two compounds are coupled by strong ferromagnetic interaction. The compound [CuII (H2O)L1GdIII(NO3)3] exhibits strongest ferromagnetic interaction among the related compounds reported so far.
• A number of glycol-conjugates based on galactose and ribose have been synthesized and characterized. The PI has been able to introduce naphthyl moiety at C1-position of carbohydrate and keep all other position free so that the molecules are suitable not only for fluorescence measurements but also for studying their interactions with lectins and glycosidases. A number of transition metal ion complexes were synthesized using the derivatives based on galactosyl and ribosyl moieties. Absorption and fluorescence study of the selective recognition of Cu(II) ions by 1-(â-D-galactopyranosyl-1'-deoxy-1'- iminomethyl)-2-hydroxynaphthalene in HEPES buffer has been made.
  

Physical Chemistry

Some of the projects funded are as follows:

• synthesis of a new class of materials based on delafossite structure using a new synthetic strategy. These materials are potentially important as p-type transparent conductors.
• development of new photocatalytic materials with absorption in visible light for removing organic pollutants. The photocatalytic materials proposed are BiVO4, CeVO4 and AgNbO3.
• further exploration of the recently developed "Fer" expansion in NMR. This expansion has novel features such as better convergence under certain conditions and may lead to design of novel pulse sequences for solid-state NMR leading to improved line-width and ultimately improve applications of NMR for the study of bio-molecules.
• synthesis of aluminophosphates and investigating their photo catalytic properties towards degradation of organic dyes.
• study photolesion of microhydrated DNA building block in vacuum. This research has a promise of solving important fundamental issues regardless of its potential application.
• studies relating to heteropolyacids supported on titania and mesoporous materials as catalysts for acid and redox organic transformations. This work attempts to discover eco-friendly solid acid catalysts for preparation of fine chemicals.
• synthesis of nano-composites and their characterization in order to study their usability as barrier membranes for separating volatile organic compounds from water.

Some interesting results obtained from ongoing projects are given below:

• Studies on ionic liquids were carried out with a view to understand their role as green solvents. Several combinations of ionic liquids were synthesized. Properties such as density, speed of sound, compressibility and viscosity for a variety of ionic liquids were measured at four different temperatures. Investigations were done to find out how these properties play an important role in carrying out organic reactions. For this purpose, some Diels-Alder reactions in ionic liquids and in water were carried out. The author demonstrated that room temperature ionic liquids are not as effective as water in promoting Diels-Alder reactions.
• Solid state metathesis route has been developed for synthesizing perovskite oxides of current interest, such as LaCoO3, LaMnO3, AMnO3 and ATiO3 (A = Ca, Sr, Ba) from rock salt metal oxides. This route has been used for the synthesis of double perovskite oxides, Sr2MWO6 (M = Mg, Mn, Fe, Ni) that enabled to obtain cation-ordered phases at a considerably lower temperature (~750oC) than what was employed in conventional synthesis of these materials. Investigation of the interaction of hydrogen with alkaline earth manganites (IV) AMnO3 (A = Ca, Sr, Ba), dispersed with 1 at % Pt. revealed an unprecedented uptake of hydrogen by BaMnO3/Pt to the extent of ~1.25 mass% at moderate temperatures (190-260oC) and ambient pressure. The work suggests the possibility of developing new hydrogen storage materials based on electropositive metal-transition metal-oxide systems.
• Detailed molecular dynamics and Monte Carlo calculations have been made to obtain a more fundamental understanding of diffusion of real molecular systems within porous solids such as zeolites. A method has been proposed that can yield separation with separation factors that are orders of magnitude higher than existing methods. The usual separation factors obtainable with the existing methods of separation are 103. In contrast, the proposed method can provide a separation factor of the order of 109 with columns of nanometer dimensions (as compared to several metres in normal separations). Another important result is a new and general explanation of the conductivity maximum for ions in polar solvents. Although many theories are available in literature, none of them have been able to explain all the observed conductivity data. For example, they have not been able to explain the conductivity variation with pressure. The author has proposed that Levitation Effect (LE) is the right theory and provides the underlying reason for the observed maximum. The predictions of the Levitation Effect such as the lower activation energy for the ion with maximum conductivity, etc. have received support and the existing experimental data seem to support LE as the underlying cause.
• In a project on investigating biodegradable polymeric hydrogels and exploring them for drug delivery, a simple and new method has been developed to crosslink chitosan using polyethylene glycol (PEG) with different molecular weights. PEG-crosslinked chitosan (PEG-Ch) showed a pH-independent swelling behavior: swelled in both the stimulated stomach (pH 1.1) and intestinal (pH 7.4) solutions. Thus, the prepared PEG-Ch could be a better biomaterial than chitosan in the development of orally sustained drug-delivery devices.

Green Chemistry

A workshop was organized at MS University of Baroda, Vadodara. An interaction meeting was held at Ankleswar with industry representatives to create awareness about the practice of Green Chemistry principles in industrial processes. Several problems have been identified which could be solved using green chemistry approach. Further discussion is in progress.

The following projects were funded:

• How to make ionic liquids more effective for promoting organic reactions. The proposal attempts to investigate the limitations of using ionic liquids for various organic reactions and come up with solution for tailoring the properties of ionic liquids for facile synthesis.
• Non-hazardous bromination with bromide/bromate couple obtained as intermediate of bromine recovery plants. In this project, the use of alkaline bromine intermediate as an inexpensive and eco-friendly brominating agent would be explored in place of liquid bromine.