01578nas a2200193 4500008004100000022001400041245010600055210006900161260000800230300001200238490000700250520086800257100003001125700002601155700002701181700002501208700002101233856013001254 2024 eng d a1528-748300aSimultaneously mechanically flexible, photobending, and acidochromic cyanostilbene molecular crystals0 aSimultaneously mechanically flexible photobending and acidochrom cDEC a309-3180 v253 a

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.

1 aParthasarathy, Thiyagaraj1 aMishra, Manish, Kumar1 aBhattacharya, Biswajit1 aEmmerling, Franziska1 aGhosh, Soumyajit uhttps://library.ncl.res.in/content/simultaneously-mechanically-flexible-photobending-and-acidochromic-cyanostilbene-molecular01264nas a2200157 4500008004100000245010600041210006900147260000800216300001400224490000700238520066800245100002000913700002200933700002600955856012500981 2024 eng d00aStructural basis for a two-dimensional flexible pharmaceutical solvate crystal: indomethacin methanol0 aStructural basis for a twodimensional flexible pharmaceutical so cOCT a5694-56980 v263 a

We report the first two-dimensionally (2D) elastically bendable and twistable pharmaceutical-solvate crystal, indomethacin methanol. Its flexibility is due to interlocked packing and a structural buffer acting like isotropic interactions. For the first time, we utilized Raman spectroscopy on the two elastic faces of a bent crystal region, revealing the inhomogeneous molecular distribution in the crystal structure during bending and validating the mechanistic model of the 2D elastic crystal. We present the first 2D elastic pharmaceutical-solvate crystal and utilized Raman spectroscopy to reveal inhomogeneous lattice distribution during bending.

1 aBhowmik, Aritra1 aBamane, Sanjivani1 aMishra, Manish, Kumar uhttps://library.ncl.res.in/content/structural-basis-two-dimensional-flexible-pharmaceutical-solvate-crystal-indomethacin00849nas a2200217 4500008004100000022001400041245016200055210006900217260000900286300001400295490000700309653002700316653001900343653002800362653001900390100002500409700001900434700002600453700002200479856013000501 2024 eng d a1528-748300aTemplate-asisted visible light-induced [2+2] photodimerization in a pseudopolymorphic binary solid: topotactic transformation vs photoinduced crystal melting0 aTemplateasisted visible lightinduced 22 photodimerization in a p cMAY  a5193-51990 v2410aCATION-PI INTERACTIONS10aSINGLE-CRYSTAL10aSTATE PHOTODIMERIZATION10aSupramolecular1 aAhsan, Mollah, Rohan1 aVarma, Harshit1 aMishra, Manish, Kumar1 aMukherjee, Arijit uhttps://library.ncl.res.in/content/template-asisted-visible-light-induced-22-photodimerization-pseudopolymorphic-binary-solid02314nas a2200181 4500008004100000022001400041245010700055210006900162260000900231300001400240490000700254520165900261100002001920700002201940700002601962700002601988856011802014 2025 eng d a1528-748300aCaffeine vs. theophylline cocrystals: insights into structure-mechanical behavior and piezoelectricity0 aCaffeine vs theophylline cocrystals insights into structuremecha cJUN  a5007-50210 v253 a

Cocrystallization offers a versatile approach to modulate the physicochemical including mechanical properties of active pharmaceutical ingredients (APIs). In this study, we employ crystal engineering principles to design cocrystals of two structurally similar methylxanthine compounds-caffeine (CAF) and theophylline (THP)-with 3,5-dinitrosalicylic acid (DNSA) and 3,5-dinitrobenzoic acid (DNBA) as coformers. The resulting cocrystals and cocrystal polymorphs displayed diverse architectures-2D layers, corrugated sheets, and 3D interlocked structures-showing distinct deformation characteristics. Particular attention was given to the mechanical shearing of the layered structure cocrystals THP-DNBA and CAF-DNBA-I, which are critical for pharmaceutical manufacturing processes such as tablet compaction. The sheared fragmented crystal of THP-DNBA also shows plastic bending deformation. On the other hand, the CAF-DNSA, CAF-DNBA-II, and THP-DNSA cocrystals are brittle due to the absence of a flat layer structure. Our findings reveal that structural features such as flat molecular geometry, pi-stacking, and weak interlayer interactions play crucial roles in promoting plastic deformation via shearing and plastic bending. Nanoindentation studies have been performed on the major faces of all the cocrystals to quantify their mechanical properties. Notably, the CAF-DNBA-I cocrystal also exhibited piezoelectric properties. This work provides valuable insights into the structure-mechanical property relationship in pharmaceutical cocrystals and underscores the potential of cocrystallization in addressing formulation-related challenges.

1 aBhowmik, Aritra1 aBamane, Sanjivani1 aSaxena, Ashish, Kumar1 aMishra, Manish, Kumar uhttps://library.ncl.res.in/content/caffeine-vs-theophylline-cocrystals-insights-structure-mechanical-behavior-and02285nas a2200181 4500008004100000022001400041245008600055210006900141260000800210300001600218490000700234520166200241100001501903700002001918700002601938700002101964856011801985 2025 eng d a1528-748300aIntegrating thermal actuation and acidochromism in schiff base molecular crystals0 aIntegrating thermal actuation and acidochromism in schiff base m cDEC a10527-105400 v253 a

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.

1 aNag, Sayak1 aBhowmik, Aritra1 aMishra, Manish, Kumar1 aGhosh, Soumyajit uhttps://library.ncl.res.in/content/integrating-thermal-actuation-and-acidochromism-schiff-base-molecular-crystals02198nas a2200181 4500008004100000022001400041245011000055210006900165260000800234300001400242490000700256520153600263100001901799700002001818700002601838700002101864856013101885 2025 eng d a1528-748300aMechanical flexibility, photosalience, and acidochromism of benzylidene indanone-based molecular crystals0 aMechanical flexibility photosalience and acidochromism of benzyl cJUN a4481-44930 v253 a

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.

1 aAhamed, Riyaaz1 aBhowmik, Aritra1 aMishra, Manish, Kumar1 aGhosh, Soumyajit uhttps://library.ncl.res.in/content/mechanical-flexibility-photosalience-and-acidochromism-benzylidene-indanone-based-molecular01283nas a2200217 4500008004100000022001400041245009700055210006900152260000800221490000700229520047700236653002300713653002400736653002600760653005200786653002800838100002500866700002600891700002200917856012600939 2025 eng d a1861-472800aPhoto-induced cracking in a Bi-component molecular solid: capturing structural intermediates0 aPhotoinduced cracking in a Bicomponent molecular solid capturing cMAY0 v203 a

A photo-responsive bi-component solid is designed based on robust large synthons. The study not only provides a template-based approach for a system that was difficult to photo-dimerize, but the designed solid also leads to photo-induced cracking upon photodimerization. The delicate structural design helps in capturing the structural intermediates, which reveals a possible reorientation of the photodimer within the crystal to maintain structural integrity.

10abi-component solid10acrystal engineering10aphotoinduced cracking10asingle-crystal-to-single crystal transformation10a[2+2] photodimerization1 aAhsan, Mollah, Rohan1 aMishra, Manish, Kumar1 aMukherjee, Arijit uhttps://library.ncl.res.in/content/photo-induced-cracking-bi-component-molecular-solid-capturing-structural-intermediates01239nas a2200181 4500008004100000022001400041245009000055210006900145260000800214300001600222490000700238520060400245100002200849700002000871700002600891700002100917856011900938 2025 eng d a1359-734500aWater-driven modulation of multiresponsive properties in acylhydrazone-based crystals0 aWaterdriven modulation of multiresponsive properties in acylhydr cAUG a12139-121420 v613 a

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's potential for smart actuators and photoswitchable devices.

1 aManoharan, Deepak1 aBhowmik, Aritra1 aMishra, Manish, Kumar1 aGhosh, Soumyajit uhttps://library.ncl.res.in/content/water-driven-modulation-multiresponsive-properties-acylhydrazone-based-crystals03229nas a2200157 4500008004100000245010400041210006900145260000800214300001400222490000700236520263800243100002302881700002602904700001902930856012202949 2026 eng d00aConcentration-dependent nucleation of pyrazinamide polymorphs monitored by dynamic light scattering0 aConcentrationdependent nucleation of pyrazinamide polymorphs mon cMAY a2965-29780 v283 a

Understanding crystal nucleation in solution remains one of the central challenges in crystallization science, particularly in pharmaceutical systems where polymorphism plays a critical role in determining drug properties. In this study, we present a dynamic light scattering (DLS)-based approach to track nucleation pathways of pyrazinamide (PYZ), a frontline antituberculosis drug known to crystallize in multiple polymorphic forms. Five solvents, ethanol (EtOH), methanol (MeOH), tetrahydrofuran (THF), water (H2O), and acetone, were investigated across three solute concentrations. In contrast to earlier DLS-based studies that primarily emphasize particle size evolution, the present work correlates early-stage DLS signatures with solvent- and concentration-dependent polymorphic outcomes across multiple solvent systems. In EtOH, distinct concentration-dependent nucleation signatures corresponded to the gamma-, alpha-, and delta-forms, whereas MeOH and THF exhibited alpha- and delta-forms with differing degrees of competition between phases. In contrast, H2O and acetone consistently produced a single stable polymorph (alpha- and delta-form, respectively), independent of concentration. DLS measurements provided valuable insight into particle size evolution, capturing nucleation events, growth dynamics, and polymorphic selection across solvent systems. Additionally, this work highlights the capability of DLS to differentiate competitive and non-competitive nucleation environments through size distribution behavior, a feature not extensively reported for pharmaceutical systems. Complementary induction time experiments were also conducted to quantitatively assess solvent-dependent nucleation kinetics. The analysis revealed substantial variations in nucleation rates and interfacial energies across the five solvents, providing independent kinetic validation of the trends observed in the DLS measurements. It also represents a significant advancement by enabling both nucleation pathway tracking and induction time analysis within a unified experimental framework by single instrument, providing direct insight into nucleation kinetics. This combined experimental strategy highlights the potential of DLS as a sensitive and non-invasive method to probe nucleation pathways in solution and demonstrates its utility in correlating concentration, solvent environment, and polymorphic outcomes. Beyond advancing the fundamental understanding of nucleation, this approach offers practical promise for monitoring the design of crystallization processes in pharmaceutical and materials science applications.

1 aDahake, Sakshi, P.1 aMishra, Manish, Kumar1 aMishra, Kamini uhttps://library.ncl.res.in/content/concentration-dependent-nucleation-pyrazinamide-polymorphs-monitored-dynamic-light01406nas a2200205 4500008004100000022001400041245009000055210006900145260000900214300001400223490000700237520071400244100001900958700001700977700003200994700002601026700002101052700002201073856010501095 2026 eng d a1528-748300aExploring the role of large synthons in the design of bicomponent salts of cimetidine0 aExploring the role of large synthons in the design of bicomponen cFEB  a1875-18840 v263 a

Cimetidine, a popular histamine H2-receptor antagonist, represents a complex structural landscape exhibiting multiple forms. Attempts to synthesize a bicomponent salt with fumaric acid suffered from crystallization challenges in the past, especially toward the growth of anhydrous single crystals. In this work, we address these crystallization challenges by adopting an alternative crystallization approach involving ionic liquids and analyzing the structural landscape with a large synthon-based approach. Two novel forms of cimetidine fumarate were isolated. The structural differences in the forms of cimetidine fumarate were further explored by using different coformers as structural probes.

1 aKhatun, Saheba1 aSar, Bandana1 aHosmani, Girish, Siddanagou1 aMishra, Manish, Kumar1 aRavi, Punna, Rao1 aMukherjee, Arijit uhttps://library.ncl.res.in/content/exploring-role-large-synthons-design-bicomponent-salts-cimetidine02444nas a2200265 4500008004100000022001400041245010200055210006900157260000800226300001100234490000700245520157000252653002401822653001501846653002401861653002001885653002401905100002001929700001601949700002601965700001901991700002002010700002602030856012202056 2026 eng d a1861-472800aFrom brittle to elastic: substituent effects on mechanical flexibility in aromatic amide crystals0 aFrom brittle to elastic substituent effects on mechanical flexib cMAY ae707950 v213 a

Mechanical flexibility in molecular crystalline materials represents a compelling paradigm shift from the long-held perception of crystals as inherently brittle solids. Herein, we demonstrate a brittle-to-elastic transition by subtle molecular modification in a pair of structurally analogous aromatic amides; N-[(4-methoxyphenyl)methyl]formamide (N4MFA, Crystal 1) and N-benzylformamide (NBFA, Crystal 2). Despite their close structural similarity, Crystal 1 exhibits brittle fracture under minimal stress, whereas Crystal 2 shows 1D elastic flexibility with reversible bending. Structural, computational, and mechanical analyses reveal that this contrast arises from substituent-controlled supramolecular packing. In Crystal 1, the methoxy (-OCH3) group promotes dense, anisotropic packing, leading to rigidity and fracture under stress. Removing the substituent in Crystal 2 enhances isotropy, pi-pi stacking, and interlocked packing, enabling reversible strain during elastic bending. Nanoindentation, energy framework, and elastic tensor analyses confirm this transition: Crystal 2 shows near-isotropic stiffness (E max/E min = 1.65) and interconnected energy networks, whereas Crystal 1 exhibits pronounced anisotropy (E max/E min = 3.95) and 1D cohesion. Hirshfeld surface analysis supports more balanced contacts in the elastic crystal. This work establishes a direct structure-mechanical correlation, showing that minor chemical modifications can tune flexibility and provide insights to guide the development of adaptive crystalline materials.

10acrystal engineering10aElasticity10aMechanical property10ananoindentation10aresponsive crystals1 aBhowmik, Aritra1 aDas, Nirmal1 aSaxena, Ashish, Kumar1 aMishra, Kamini1 aBarsu, Nagaraju1 aMishra, Manish, Kumar uhttps://library.ncl.res.in/content/brittle-elastic-substituent-effects-mechanical-flexibility-aromatic-amide-crystals01116nas a2200181 4500008004100000022001400041245008800055210006900143260000800212300001400220490000700234520047800241100003000719700002000749700002600769700002100795856011800816 2026 eng d a1359-734500aHelically twistable cyanoacrylate crystal with simultaneous photomechanical bending0 aHelically twistable cyanoacrylate crystal with simultaneous phot cMAY a8661-86640 v623 a

A cyanoacrylate derivative crystal exhibits an unusual combination of one-dimensional elasticity, plasticity, and reversible hand-held twisting. Twisting induces a reversible single crystal to polycrystal transition. It also displays photobending via a cycloaddition reaction under 365 nm irradiation and thermally recovers its original state, retaining functionality in the twisted state, indicating potential applications in soft robotics and smart actuators.

1 aParthasarathy, Thiyagaraj1 aBhowmik, Aritra1 aMishra, Manish, Kumar1 aGhosh, Soumyajit uhttps://library.ncl.res.in/content/helically-twistable-cyanoacrylate-crystal-simultaneous-photomechanical-bending01430nas a2200277 4500008004100000022001400041245013500055210006900190260000800259300001100267490000800278520046900286653002400755653002500779653002000804653002000824653002500844100002100869700002500890700002200915700001800937700001700955700002600972700002300998856013101021 2026 eng d a0167-577X00aLanthanide-activated single-phosphor white light emission via Bi3+ → Eu3+ energy transfer in Ca2Ga2GeO7 for next-generation LEDs0 aLanthanideactivated singlephosphor white light emission via Bi3  cMAY a1402360 v4103 a

{We report the design and fabrication of Bi3+ and Eu3+ co-doped Ca2Ga2GeO7 (CGGO) phosphors for highperformance warm-white light-emitting diodes (LEDs). The phosphor exhibits efficient Bi3+ -> Eu3+ energy transfer, as evidenced by spectral overlap, enhanced Eu3+ emission, and quenching of Bi3+ emission with increasing Eu3+ content. The emission color shifts from blue to red with increasing Eu3+, achieving near-white emission at 3% Eu3+ (x = 0.33

10aBi3+/Eu3+ co-doping10aCa2Ga2GeO7 phosphors10aEnergy Transfer10aUV-excited LEDs10aWhite light emission1 aChethana, K., N.1 aKanojiya, Nitesh, S.1 aT.Parayil, Reshmi1 aSreevalsa, S.1 aDas, Subrata1 aMishra, Manish, Kumar1 aGupta, Santosh, K. uhttps://library.ncl.res.in/content/lanthanide-activated-single-phosphor-white-light-emission-bi3-%E2%86%92-eu3-energy-transfer02122nas a2200181 4500008004100000022001400041245012500055210006900180260000800249300001400257490000700271520144100278100002801719700002001747700002601767700002101793856012601814 2026 eng d a1528-748300aMechanically flexible pentadienenitrile derivative-based molecular crystals exhibiting distinct photoresponsive behavior0 aMechanically flexible pentadienenitrile derivativebased molecula cJUN a4225-42360 v263 a

Photoresponsive molecular crystals constitute an emerging class of functional crystalline smart materials that have garnered considerable attention due to their capacity to convert light energy into mechanical motion. These light-induced responses, known as photomechanical effects, render these crystals promising candidates for advanced photoactuators, photonic devices, and intelligent materials. In this study, we synthesized two novel diphenylpenta-2,4-dienenitrile derivative-based crystals 1 and 2, which demonstrate mechanical flexibility and distinct photomechanical responses to 420 nm LED irradiation. Notably, crystal 1 exhibited sequential bending, initially away from the light source and subsequently toward it upon prolonged exposure, whereas crystal 2 exhibited photosalient breaking. These divergent responses are attributed to [2 + 2] photocycloaddition reactions occurring within the crystal lattice. The variations in kinematic behavior are ascribed to differences in the accumulation and subsequent release of strain energy during photocycloaddition. The synergistic integration of photomechanical activity and mechanical flexibility underscores the multifunctional nature of these materials, offering critical insights for the design of crystals with potential applications in optoelectronics, photonics, and molecular switches, thereby expanding the scope of future photoresponsive organic materials.

1 aThanasekar, Vishnukumar1 aBhowmik, Aritra1 aMishra, Manish, Kumar1 aGhosh, Soumyajit uhttps://library.ncl.res.in/content/mechanically-flexible-pentadienenitrile-derivative-based-molecular-crystals-exhibiting01270nas a2200193 4500008004100000022001400041245010100055210006900156260000900225300001200234490000700246520057500253100003000828700002000858700002700878700002600905700002100931856012400952 2026 eng d a1359-734500aReversible twisting-induced crystalline-polycrystalline transformation in cyanoacrylate crystals0 aReversible twistinginduced crystallinepolycrystalline transforma cJAN  a264-2670 v623 a

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.

1 aParthasarathy, Thiyagaraj1 aBhowmik, Aritra1 aBhattacharya, Biswajit1 aMishra, Manish, Kumar1 aGhosh, Soumyajit uhttps://library.ncl.res.in/content/reversible-twisting-induced-crystalline-polycrystalline-transformation-cyanoacrylate