RESEARCH | Hema

POSTDOCTORAL RESEARCH

Supervisor

Prof. Rafal Klajn, Weizmann Institute of Science, Israel

https://nano.weizmann.ac.il/

Research

Studying molecular behaviour in coordination cages

PhD WORK

PhD Supervisor

Prof. Kana M. Sureshan, Indian Institute of Science Education and Research Thiruvananthapuram

https://kms514.wixsite.com/kmsgroup

Thesis title

Synthesis of various biopolymer mimics via topochemical azide-alkyne cycloaddition

Summary

The thesis entitled “Synthesis of various biopolymer mimics via topochemical azide-alkyne cycloaddition” deals with the design of molecules for topochemical azide-alkyne cycloaddition (TAAC). Topochemical reactions are solid-state reactions that transpire in crystals, controlled by molecular packing in the crystal lattice. The reactivity in crystals is determined by two important factors – proximity and orientation of the reactive groups. Since they occur in crystal-state, topochemical reactions are solvent- and catalyst-free environmentally benign reactions. In the thesis, design and execution of azide-alkyne cycloaddition in crystals of various kinds of bio-monomers is presented. Azide-alkyne cycloaddition reaction can happen under topochemical conditions, provided the complementary reactive azide and alkyne are placed in proximity and in a ready-to-react transition-state like orientation in crystals. The role of various non-covalent interactions in placing molecules in the favourable reactive orientation is discussed in the thesis. When the crystals of these suitably packed molecules are stimulated by heat, the azide and alkyne groups undergo [3+2] cycloaddition to form triazole-linked products. The unique nature of products obtained under topochemical conditions and how different they are from products of solution-state cycloaddition reaction is explained.

PUBLICATIONS

1. Polymers with advanced structural and supramolecular features synthesized through topochemical polymerization

Hema, K.;ǂ Ravi, A.;ǂ Raju, C.;ǂ Sureshan, K. M.ǂ Chem. Sci. 2021, 12, 5361-5380. (ǂ These authors contributed equally)
https://doi.org/10.1039/D0SC07066A

2. Topochemical polymerizations for the solid-state synthesis of organic polymers

Hema, K.;ǂ Ravi, A.;ǂ Raju, C.;ǂ Pathan, J. R.; Rai, R.; Sureshan, K. M. Chem. Soc. Rev. 2021, 50, 4062-4099. (ǂ These authors contributed equally)
https://doi.org/10.1039/D0CS00840K

3. Scalable Topochemical Synthesis of a Pseudoprotein in Aerogel for Water-Capturing Applications

Mohanrao, R.;ǂ Hema, K.;ǂ Sureshan, K. M. ACS Appl. Polym. Mater. 2020, 2, 4985-4992. (ǂ These authors contributed equally)
https://pubs.acs.org/doi/10.1021/acsapm.0c00849

4. β-Sheet to helical-sheet evolution induced by topochemical polymerization: Cross-α-amyloid-like packing in a pseudoprotein with Gly-Phe-Gly repeats

Hema, K.; Sureshan, K. M. Angew. Chem. Int. Ed. 2020, 59, 8854-8859.
https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201914975

5. Topochemical synthesis of different polymorphs of polymers as a paradigm for tuning properties of polymers

Mohanrao, R.;ǂ Hema, K.;ǂ Sureshan, K. M. Nat. Commun. 2020, 11, 865. (ǂ These authors contributed equally)
https://www.nature.com/articles/s41467-020-14733-y

6. Crystal-to-crystal synthesis of helically ordered polymers of trehalose via topochemical polymerization

Hema, K.; Gonnade, R. G.; Sureshan, K. M. Angew. Chem. Int. Ed. 2020, 59, 2897-2903.
https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201914164

7. Topochemical azide-alkyne cycloaddition reaction

Hema, K.; Sureshan, K. M. Acc. Chem. Res. 2019, 52, 3149-3163.
https://pubs.acs.org/doi/abs/10.1021/acs.accounts.9b00398

8. Solid-state synthesis of two different polymers in a single crystal: polymer blend via topochemical reaction

Hema, K.; Sureshan, K. M. Angew. Chem. Int. Ed. 2019, 58, 2754-2759.
https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201813198

9. Three-way competition in a topochemical reaction: Permutative azide-alkyne cycloaddition reactions leading to a vast library of products in the crystal

Hema, K.; Sureshan, K. M. CrystEngComm 2018, 20, 1478-1482.
https://pubs.rsc.org/en/content/articlelanding/2018/ce/c8ce00131f#!divAbstract