FleXtal Lab

Research Areas: • Crystal Engineering & Supramolecular Chemistry • Design of Flexible Organic Functional Materials • Solid-State Pharmaceutical Chemistry (Tabletability) • Structure-Mechanical Property Relationship

Research Interests
The focus of our research group is to design the properties of organic materials by establish a reliable structure-property correlationship. Our current major projects include (i) the understanding of structure-mechanical property relationship in flexible organic crystals (ii) design of new solid forms of active pharmaceutical ingredients (APIs) with improved mechanical behaviour and tabletability, (iii) establishing design principles for efficient mechanochromic luminescent solid state fluorophores. The general characterization techniques we use include nanoindentation, hot-stage microscopy, Raman spectroscopy, powder and single crystal x-ray diffraction, TGA, DSC, SEM, TEM etc.

Awards and Honors:

• Prestigious Swarna Jayanti Fellowship Award for the 2014-2015 by Department of science and technology, India.
• "The Distinguished Lectureship Award" by the Chemical Society of Japan, March 2017.
• Co-editor for Acta Crystallographica Section B. (link)
• Performance Based Incentive Award for 2014-2015 by IISER Kolkata.
• Advisory Board Member for CrystEngComm journal published by Royal Society of Chemistry.
• Associate Editor, RSC Advances (2015-2016).

Some Selected Publications:

1. R Samanta, S Ghosh, R Devarapalli, CM Reddy*; Visible Light Mediated Photopolymerization in Single Crystals: Photomechanical Bending and Thermomechanical Unbending;
   Chem. Mater., 2018, 30 (3), 577–581.
2. Krishna, G. R., Devarapalli, R., Lal, G., Reddy, C. M. Reddy,* Mechanically Flexible Organic Crystals Achieved by Introducing Weak Interactions in Structure: Supramolecular Shape Synthons;
   J. Am. Chem. Soc., 2016, 138, 13561–13567.(Front Cover Illustration)
3. Panda, M. K., Ghosh, S., Yasuda, N., Moriwaki, T., Mukherjee, G. D., Reddy, C. M.,* Naumov, P.,*; Spatially resolved analysis of short-range structure perturbations in a plastically bent molecular crystal;
   Nature Chem. 2015, 7, 65-72.
4. Sahoo, S. C., Sinha, S. B., Kiran, M. S. R. N., Ramamurty, U., Dericioglu, A. F., Reddy, C. M.,* Naumov, P.* Kinematic and Mechanical Profile of the Self-actuation of Thermosalient Crystal Twins of 1,2,4,5-tetrabromobenzene: A Molecular Crystalline Analogue of a Bimetallic Strip;
   J. Am. Chem. Soc. 2013, 135, 13843-13850.
5. GR Krishna, MSRN Kiran, CL Fraser, U Ramamurty, CM Reddy; The Relationship of Solid-State Plasticity to Mechanochromic Luminescence in Difluoroboron Avobenzone Polymorphs;
   Advanced Functional Materials (2013) 23 (11), 1422-1430. (Front Cover Illustration)
6. S Ghosh, CM Reddy; Elastic and Bendable Caffeine Cocrystals: Implications for the Design of Flexible Organic Materials;
   Angewandte Chemie (2012) 124 (41), 10465-10469. for more..

Plastic Crystal

Our Team

Reasearch Projects :

Mechanically Flexible Organic Crystals Achieved by Introducing Weak Interactions in Structure: Supramolecular Shape Synthons c&en chemical & engineering news

CRYSTAL CONTORTIONISTS: MAKING FLEXIBLE ORGANIC CRYSTALS: Organic crystals have a variety of useful characteristics that confer advantages over their inorganic counterparts for applications such as transistors, solar cells, photonics, and bioelectronics. However, the brittle nature of these organic materials significantly limits their use in any device that requires flexibility. C. Malla Reddy and colleagues report a way to engineer organic crystals to make them extremely bendable to the extent that they are able to contort into different letters of the alphabet (DOI: 10.1021/jacs.6b05118).

New method for making flexible single crystals: The crystals can respond to external stimuli such as mechanical stress, light and heat, they could be used to make pressure sensors and mechanical actuators,” says lead scientist Chilla Malla Reddy from the Indian Institute of Science Education and Research, Kolkata. Nature India

Research News :

Elastic caffeine crystals Nature Chemistry

Caffeine crystals with an elastic bent Chemistry World

Molecular motors from bendable organic crystal Nature India

Some highlights of the published work :

Elastic bending in the co-crystal solvate 1. a–f) First bending cycle resulting from applied mechanical stress, using a pair of forceps and a metal pin. g) The subsequent recovery upon withdrawal of the force. h) Second bending cycle. i) The breaking of the crystal when the elastic limit is exceeded. Notice the remarkable shape recovery in the two broken halves in (i).

Chemical structures (i), (ii) and (iii) of the compounds (1), molecular crystals of the three individual compounds illuminated under UV (2), their qualitative deformation behaviour upon mechanical action (3), and mechanochromic luminescence behaviour of the crystals upon smearing (4). In column 4, (a), (d) and (g) show the UV (365 nm) emission colour of initial powder films prepared by gently grinding single crystals of the three samples using a mortar and pestle. Images (b), (e) and (h) correspond to the films after firmly scratching the initial films with a pestle, resulting in a colour change from cyan to yellow for BF2dbm(tBu)2 and green to yellow for BF2dbm(OMe)2 while no colour change was observed for BF2dbmOMe at room temperature (h), respectively. For both BF2dbm(tBu)2 and BF2dbm(OMe)2 compounds, the films recover to the parent colour shown in (c) and (f) after a few minutes of heating with a hot-air gun. In the case of BF2dbmOMe the ML experiments were repeated at 98C by immersing the mortar into frozen methanol by cooling wth liquid N2 (g), but no significant colour change was observed in (h) and (i).