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Seminar Notice

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Seminar

Department of Chemistry
Indian Institute of Technology Delhi

Programmed Assembly of π-Systems and Macromolecules by Directional Non-covalent Interaction(s)

Dr. Anindita Das

Institute for Complex Molecular Systems and Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, Netherlands

 
   Date   : May 18th 2017 (Thursday)   
                                                    Time   : 11:30 AM     
                                        Venue : Committee Room, Chemistry Department, 6th Floor
 

Supramolecular polymerization of π-systems with an internal order is highly desirable in miniaturized organic electronics. H-bonding, owing to its directional nature and structural diversity, has been established as a powerful tool in programming such molecular assembly. During my doctoral research, we have studied supramolecular polymerization of aromatic donor (D) and acceptor (A) π-systems with an aim to control their mesoscopic structure and topology by interplay of π-stacking, charge-transfer interaction (inter/ intra-) or dipole-dipole interaction and H-bonding, operating synergistically or in orthogonal fashion. Systems those have been investigated include physical mixture of D + A,1a-d D-π-A1e and D-σ-A1f-g type chromophores. We have established that by an appropriate molecular engineering it is possible to gain precise control over their inter-chromophoric interaction (J- or H-aggregation), photophysical properties, mode of co-assembly (alternating or segregated assembly, parallel or anti-parallel stacking), sequence of mixed D-A stacking and morphology (fibrillar gel, vesicle, reverse-vesicle and micelle) both in organic and aqueous medium. We further explored such directional molecular interactions to drive aqueous self-assembly of macromolecules, engineered with a single supramolecular structure-directing unit at the chain terminal.1h

In my first postdoctoral study, we explored the scope of dipole-dipole interaction as a tool for conformational control of macromolecules by probing self-assembly of merocyanine dye (MD)-functionalized flexible polymers synthesized by a new post-polymerization functionalization method developed by us.2a A coil-like polymer, when functionalized with even only 10-30 % pendant MD, spontaneously forms highly stable fluorescent nanogels2b in toluene due to very strong dimerization propensity among the MD.

During my second postdoctoral stint, we have studied the structural impact of two supramolecular building blocks comprised of benzene-1,3,5-tricarboxamide (BTAs) (alkyl-BTA and Siloxane-BTA) on their individual reactivities, mechanisms of homopolymerization and mutual compatibilities on the helical supramolecular copolymerization by “Sergeant and Soldiers” circular dichroism (CD) experiments. The analysis of the experimental data with a newly developed theoretical model quantifies the thermodynamic parameters, the distributions, compositions and stack lengths of the copolymers existing at various feed ratios of the two monomers.3 In an ongoing project, we are investigating the impact of structural precision on hydrophobic block crystallinity in monodisperse (Š = 1.00000) polyLLA-b-PEG block copolymers which are attractive bioplastics.  Highlights of these results will be presented with specific emphasis on molecular design for self-assembly.

 

All are cordially invited to attend

Convener (Seminars)

 

 

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Department of Chemistry, Indian Institute of Technology Delhi