Crystal Engineering Solutions to Materials Science Problems

Samanta, Ranita (2019) Crystal Engineering Solutions to Materials Science Problems. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Ranita Samanta (12RS035)) 12RS035.pdf - Submitted Version Restricted to Repository staff only Download (9MB)

Abstract

In this Thesis, I have attempted to address some materials science problems by employing crystal engineering approach. At the beginning, I prepared 1,1′-dioxo-1H-2,2′-biindene-3,3′- diyl didodecanoate (BIT-dodeca2), which is a photochromatic molecule. This molecule undergoes single-crystal-to-single crystal polymerization reaction under sun light/visible as well as UV. This study exhibits the possibility of utilization of topochemical polymerization reactions for mechanical actuation. The results presented here demonstrate how a chemical reaction with high yield can be used to prepare a mechanically responsive crystal. It paves the way for development of other bending crystals using other photochemical reactions associated with high yield and crystal integrity. Next, I have developed a single crystal with monomerpolymer heterostructure. There I have demonstrated how the above photochromic compound, BIT-dodeca2 can be converted to single crystal monomer-polymer micro rods. This switching property can be used in digital binary memory devices. Moreover, this can also be used as an inkless printing material and for developing security devices. In the fourth Chapter, I have designed a flexible single crystal, DPP-diMe and two brittle single crystals namely, DPPEt. H2O and DPP-diEt, using derivatives of diketopyrrolopyrrole. Here, I have compared the mobility of single crystals (spread on a flexible substrate) based transistors made of flexible and one brittle derivatives. Durability of both the devices under mechanical stress (i.e; bending) was studied. It was found that the falling of mobility after multiple cycles of bending is minimum in case of the transistor made of flexible crystals compared to the brittle one where the drop in mobility is quite high. Thus, the flexible transistor made of flexible semiconducting single crystals is more advantageous than using brittle semiconducting single crystals. Currently, the device tests are underway for DPP-diEt with collaborators. In the last Chapter, I have explored the utility of cocrystalization process in forming new thermosalient crystals. This approach would open a new path for preparing a series of new thermosalient crystals where one of the coformers is thermally innocent.

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