@article { ISI:000303366000001, title = {Polymorphs, salts, and cocrystals: what{\textquoteright}s in a name?}, journal = {Crystal Growth \& Design}, volume = {12}, number = {5}, year = {2012}, month = {MAY}, pages = {2147-2152}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The December 2011 release of a draft United States Food and Drug Administration (FDA) guidance concerning regulatory classification of pharmaceutical cocrystals of active pharmaceutical ingredients (APIs) addressed two matters of topical interest to the crystal engineering and pharmaceutical science communities: (1) a proposed definition of cocrystals; (2) a proposed classification of pharmaceutical cocrystals as dissociable {\textquoteleft}{\textquoteleft}API-excipient{\textquoteright}{\textquoteright} molecular complexes. The Indo U.S. Bilateral Meeting sponsored by the Indo-U.S. Science and Technology Forum titled The Evolving Role of Solid State Chemistry in Pharmaceutical Science was held in Manesar near Delhi, India, from February 2-4, 2012. A session of the meeting was devoted to discussion of the FDA guidance draft. The debate generated strong consensus on the need to define cocrystals more broadly and to classify them like salts. It was also concluded that the diversity of API crystal forms makes it difficult to classify solid forms into three categories that are mutually exclusive. This perspective summarizes the discussion in the Indo-U.S. Bilateral Meeting and includes contributions from researchers who were not participants in the meeting.

}, issn = {1528-7483}, doi = {10.1021/cg3002948}, author = {Aitipamula, Srinivasulu and Banerjee, Rahul and Bansal, Arvind K. and Biradha, Kumar and Cheney, Miranda L. and Choudhury, Angshuman Roy and Desiraju, Gautam R. and Dikundwar, Amol G. and Dubey, Ritesh and Duggirala, Nagakiran and Ghogale, Preetam P. and Ghosh, Soumyajit and Goswami, Pramod Kumar and Goud, N. Rajesh and Jetti, Ram R. K. R. and Karpinski, Piotr and Kaushik, Poonam and Kumar, Dinesh and Kumar, Vineet and Moulton, Brian and Mukherjee, Arijit and Mukherjee, Gargi and Myerson, Allan S. and Puri, Vibha and Ramanan, Arunachalam and Rajamannar, T. and Reddy, C. Malla and Rodriguez-Hornedo, Nair and Rogers, Robin D. and Row, T. N. Guru and Sanphui, Palash and Shan, Ning and Shete, Ganesh and Singh, Amit and Sun, Changquan C. and Swift, Jennifer A. and Thaimattam, Ram and Thakur, Tejender S. and Thaper, Rajesh Kumar and Thomas, Sajesh P. and Tothadi, Srinu and Vangala, Venu R. and Variankaval, Narayan and Vishweshwar, Peddy and Weyna, David R. and Zaworotko, Michael J.} } @article { ISI:000306942300059, title = {Polymorphs, salts and cocrystals: what{\textquoteright}s in a name? (vol 12, pg 2147, 2012)}, journal = {Crystal Growth \& Design}, volume = {12}, number = {8}, year = {2012}, month = {AUG}, pages = {4290-4291}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, issn = {1528-7483}, doi = {10.1021/cg300704b}, author = {Aitipamula, Srinivasulu and Banerjee, Rahul and Bansal, Arvind K. and Biradha, Kumar and Cheney, Miranda L. and Choudhury, Angshuman Roy and Desiraju, Gautam R. and Dikundwar, Amol G. and Dubey, Ritesh and Duggirala, Nagakiran and Ghogale, Preetam P. and Ghosh, Soumyajit and Goswami, Pramod Kumar and Goud, N. Rajesh and Jetti, Ram R. K. R. and Karpinski, Piotr and Kaushik, Poonam and Kumar, Dinesh and Kumar, Vineet and Moulton, Brian and Mukherjee, Arijit and Mukherjee, Gargi and Myerson, Allan S. and Puri, Vibha and Ramanan, Arunachalam and Rajamannar, T. and Reddy, C. Malla and Rodriguez-Hornedo, Nair and Rogers, Robin D. and Row, T. N. Guru and Sanphui, Palash and Shan, Ning and Shete, Ganesh and Singh, Amit and Sun, Changquan C. and Swift, Jennifer A. and Thaimattam, Ram and Thakur, Tejender S. and Thaper, Rajesh Kumar and Thomas, Sajesh P. and Tothadi, Srinu and Vangala, Venu R. and Vishweshwar, Peddy and Weyna, David R. and Zaworotko, Michael J.} } @article {47693, title = {Structure-property correlation of halogen substituted benzothiazole crystals}, journal = {Journal of Molecular Structure}, volume = {1243}, year = {2021}, month = {NOV }, pages = {130765}, type = {Article}, abstract = {We have synthesized 3 benzothiazole crystals (1-3) based on existing knowledge of combining flexibility and optical properties towards achieving applications for flexible optoelectronics. However, one crystal was found to be elastically bendable and was found to comply necessary packing features for elasticity. Other two crystals do not obey packing features for elasticity hence they are brittle in nature. Further, Hirshfeld analysis illustrates that elastic crystal 1 possess more number of weak and dispersive interactions compared to other crystals. These interactions were instrumental in invoking elasticity. Moreover, crystals 1-3 were found to be fluorescent as well at specific excitation wavelengths. Therefore, among these crystals, particularly crystal 1 is considered as more promising candidate for flexible optoelectronics. (C) 2021 Elsevier B.V. All rights reserved.}, keywords = {Benzothiazole crystals, Elasticity, Halogen bond, mechanical properties}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2021.130765}, author = {Thekkeppat, Nipun P. and Singla, Labhini and Tothadi, Srinu and Das, Priyadip and Choudhury, Angshuman Roy and Ghosh, Soumyajit} } @article {47764, title = {Different mechanical responses of dimorphic forms of anthracene schiffbase crystal}, journal = {Journal of Molecular Structure}, volume = {1252}, year = {2022}, month = {MAR}, pages = {132182}, type = {Article}, abstract = {We obtained concomitant dimorphic forms of Anthracene Schiffbase (N-(anthracen-9-yl methylene)-2,5dichloroaniline) from hexane solvent. Two polymorphs can be differentiated by their morphology and mechanical properties. One form is long acicular type and elastically bendable while another form is block shaped and brittle in nature. Mechanical property is attributed to underlying crystal packing. Hirshfeld analysis and energy framework calculations were done to corroborate structure-property correlation of two forms (C) 2021 Elsevier B.V. All rights reserved.}, keywords = {Anthracene schiffbase, Dimorphs, Elasticity, mechanical properties}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2021.132182}, author = {Lakshmipathi, Madhumathi and Tothadi, Srinu and Emmerling, Franziska and Bhattacharya, Biswajit and Ghosh, Soumyajit} } @article {49655, title = {Simultaneously mechanically flexible, photobending, and acidochromic cyanostilbene molecular crystals}, journal = {Crystal Growth \& Design}, volume = {25}, year = {2024}, month = {DEC}, pages = {309-318}, type = {Article}, abstract = {

Molecular crystals that respond to multiple stimuli are gaining significant attention for their potential in smart materials like actuators and sensors. However, imparting multiple stimuli-responsive properties to a single crystal remains a major challenge. Herein, we report two cyanostilbene derivative-based crystals 1 and 2, with various responses to stimuli such as mechanical stress, light, acid vapors, etc. Both crystals 1 and 2 demonstrated mechanical flexibility and reversible acidochromism. Additionally, crystal 1 also exhibited light-induced photobending, which is ascribed to Z to E photoisomerization. Detailed structure-property correlation was established to unravel distinct mechanical responses. The development of these multitasking crystals may find applications in multitasking actuators, anticounterfeiting materials, and more.

}, issn = {1528-7483}, doi = {10.1021/acs.cgd.4c01341}, author = {Parthasarathy, Thiyagaraj and Mishra, Manish Kumar and Bhattacharya, Biswajit and Emmerling, Franziska and Ghosh, Soumyajit} } @article {49922, title = {Integrating thermal actuation and acidochromism in schiff base molecular crystals}, journal = {Crystal Growth \& Design}, volume = {25}, year = {2025}, month = {DEC}, pages = {10527-10540}, type = {Article}, abstract = {

Crystalline materials capable of responding to multiple external stimuli have garnered considerable attention in recent years due to their promising potential for various applications in smart materials, sensing, and actuation. In this paper, we report the synthesis and characterization of two developed linker-based Schiff base molecular crystals, designated as 1 and 2, both of which exhibit two distinct reversible stimuli-responsive behaviors: (i) a thermal expansion-contraction response during repeated heating and cooling cycles and (ii) a reversible acidochromic color change upon sequential exposure to acidic and basic vapors. Importantly, these two reversible responses are governed by entirely distinct underlying processes. The thermal expansion-contraction behavior is driven by a martensitic phase transition, from a low-temperature phase to a high-temperature phase, which involves rapid and reversible lattice displacive rearrangements. In contrast, the acidochromic color change arises from a disruption in the electronic conjugation within the molecular framework, where the system undergoes a transformation from an A-pi-D-pi-A (acceptor-pi-donor-pi-acceptor) configuration to an A-pi-A-pi-A (acceptor-pi-acceptor-pi-acceptor) configuration upon protonation, manifested by a distinct shift in optical absorption properties. The unique combination of these two reversible phenomena-thermal expansion-contraction and acidochromic responses-within a single material system offers significant potential for advanced applications, particularly in the development of acid-sensitive sensors and thermally responsive microactuators.

}, issn = {1528-7483}, doi = {10.1021/acs.cgd.5c01283}, author = {Nag, Sayak and Bhowmik, Aritra and Mishra, Manish Kumar and Ghosh, Soumyajit} } @article {49717, title = {Mechanical flexibility, photosalience, and acidochromism of benzylidene indanone-based molecular crystals}, journal = {Crystal Growth \& Design}, volume = {25}, year = {2025}, month = {JUN}, pages = {4481-4493}, type = {Article}, abstract = {

Molecular crystals that respond to multiple external stimuli are of great interest in smart, responsive materials in various fields. However, the integration of multiple responsive properties within the same crystal still remains a significant challenge for materials scientists due to the complex structural and electronic interactions. Previous studies on benzylidene indanone-based molecular crystals have shown only mechanical plasticity; however, we design crystals to elicit diverse responses to external stimuli, including mechanical stress, light, and acid vapor. Herein, we report two benzylidene indanone derivative-based crystals 1 and 2. Crystal 1 is mechanically brittle and exhibits light-induced photosalient splitting and jumping, attributed to [2 + 2] cycloaddition facilitated by the presence of a vinyl moiety. On the other hand, crystal 2 demonstrates anisotropic mechanical flexibility, exhibiting elasticity on one face and plasticity on alternate faces. Furthermore, crystals 1 and 2 both display reversible acidochromism in response to acid vapor. A detailed structure-property correlation has been established to elucidate the distinct mechanical responses of these molecular crystals. The development of such multistimuli-responsive smart materials holds significant potential for applications in flexible acid sensors, multifunctional responsive smart devices, and actuators, paving the way for advanced smart or intelligent molecular materials with tunable mechanical and optical properties.

}, issn = {1528-7483}, doi = {10.1021/acs.cgd.5c00389}, author = {Ahamed, Riyaaz and Bhowmik, Aritra and Mishra, Manish Kumar and Ghosh, Soumyajit} } @article {49920, title = {Water-driven modulation of multiresponsive properties in acylhydrazone-based crystals}, journal = {Chemical Communications}, volume = {61}, year = {2025}, month = {AUG}, pages = {12139-12142}, type = {Article}, abstract = {

A pyrene-substituted acylhydrazone (PyAc) crystal undergoes a water-driven transition from elasticity to thermoplastic bending. The hydrated crystal remains two-dimensional (2D) elastic until heating, after which it becomes brittle and bent upon dehydration. While the hydrated crystal is non-photoresponsive, the anhydrous form exhibits photomechanical bending due to favorable E-Z photoisomerization. These distinct properties, governed by solvent channels, molecular packing, and non-covalent interactions, demonstrate PyAc{\textquoteright}s potential for smart actuators and photoswitchable devices.

}, issn = {1359-7345}, doi = {10.1039/d5cc01375e}, author = {Manoharan, Deepak and Bhowmik, Aritra and Mishra, Manish Kumar and Ghosh, Soumyajit} } @article {49943, title = {Reversible twisting-induced crystalline-polycrystalline transformation in cyanoacrylate crystals}, journal = {Chemical Communications}, volume = {62}, year = {2026}, month = {JAN }, pages = {264-267}, type = {Article}, abstract = {

We report cyanoacrylate-based organic crystalline materials that exhibit reversible hand-induced helical twisting through the combined action of 1D elasticity and 2D plasticity. These crystals twist and untwist without lattice damage, retaining their elastic integrity through pi slip-stacking and Cl \& ctdot;Cl, C-H \& ctdot;Cl, and Me \& ctdot;Me interactions. Their unique integration of elastic recovery, plastic bending, and reversible twisting highlights their potential as mechanically adaptive materials for flexible and responsive devices.

}, issn = {1359-7345}, doi = {10.1039/d5cc05852j}, author = {Parthasarathy, Thiyagaraj and Bhowmik, Aritra and Bhattacharya, Biswajit and Mishra, Manish Kumar and Ghosh, Soumyajit} }