Elastic Organic Crystals Based on Barbituric Derivative: Multi‐faceted Bending and Flexible Optical Waveguide

Abstract

Elastic organic single crystals with light-emitting and multi-faceted bending properties are extremely rare. They have potential application in optical materials and have attracted the extensive attention of researchers. In this paper, we reported a structurally simple barbituric derivative DBDT, which was easily crystallized and gained long needle-like crystals (centimeter-scale) in DCM/CH 3 OH (v/v = 2/8). Upon applying or removing the mechanical force, both the ( 100) and ( 040) faces of the needle-like crystal showed reversible bending behaviour, showing the nature of multi-faceted bending. The average hardness (H) and elastic modulus (E) were 0.28 � 0.01 GPa and 4.56 � 0.03 GPa for the (040) plane, respectively. Through the analysis of the single crystal data, it could be seen that the van der waals (CÀ H•••π and CÀ H•••C), Hbond (CÀ H•••O) and π•••π interactions between molecules were responsible for the generation of the crystal elasticity.Interestingly, elastic crystals exhibited optical waveguide characteristics in straight or bent state. The optical loss coefficients measured at 627 nm were 0.7 dBmm À 1 (straight state) and 0.9 dBmm À 1 (bent state), while the optical loss coefficient (α) were 1.5 dBmm À 1 (straight state) and 1.8 dBmm À 1 (bent state) at 567 nm. Notably, the elastic organic molecular crystal based on barbituric derivative could be used as the candidate for flexible optical devices.

Diverse Mechanical Properties of 1,3-Bis(4-nitrophenyl) thiourea–DMSO Dimorphic Solvates

“…35 Additionally, the dispersion dominated interactions such as C−H•••O, C−H•••S, and C−H••• π along with π-stacks act as a "structural buffer", allowing dissipation of strain energy without irreversible deformation. 12,17,36 The interactions in the orthogonal direction, i.e., N−H S4). The orthogonal arrangement of these interactions with respect to the collective dispersive interactions in the crystalline arrangement accounts for the preliminary conditions for existence of elasticity in organic crystalline materials.…”

“…The computed interaction energy (energy frameworks, Crystal Explorer 17.5, details in section S5 in the SI) reveals the significance of dispersion dominated molecular stacks involving π–π interactions ( E tot = −37.8 kJ/mol, E disp = −67.15 kJ/mol; E disp value is obtained after multiplying the dispersion contribution mentioned in Table S4 with the k disp scale factor) . Additionally, the dispersion dominated interactions such as C–H···O, C–H···S, and C–H··· π along with π-stacks act as a “structural buffer”, allowing dissipation of strain energy without irreversible deformation. ,, The interactions in the orthogonal direction, i.e., N–H···O and C–H···O hydrogen bonds formed between TU and DMSO, are primarily electrostatically driven interactions ( E tot = −79.7 and −29.6 kJ/mol; E elec = −93.016 and −30.01 kJ/mol obtained after multiplying the electrostatic contribution with the k elec scale factor; Table S4). The orthogonal arrangement of these interactions with respect to the collective dispersive interactions in the crystalline arrangement accounts for the preliminary conditions for existence of elasticity in organic crystalline materials.…”

Organic Single Crystal/Polymer Hybrid Actuator with Waveguide, Low Temperature, and Humidity Actuation Properties

“…Polymers have excellent advantages, including light weight, good processability, and diverse stimuli methods, and have been widely used in actuator research . Organic crystals have the characteristics of easy modification and characterization of molecular structure and excellent luminescence properties, showing tremendous potential for applications in optical waveguides, − photonic technology, , lasers, − OLEDs, and so forth. However, the hard and brittle properties of crystalline materials often limit their application .…”

Deep‐Red‐Emissive Flexible Optical Waveguide with High Elastic Performance Based on an Organic Crystal

“…[15] Jia et al synthesized a barbituric derivative and the crystal of that compound showed reversible and multi-faceted bending behavior. [16] The pursuit of high elastic performance of fluorescent organic single crystals remains a work in progress. When high performance elastic crystals are achieved, organic single crystals will have more significant application potential in photonic devices and circuits.…”

“…Jia et al. synthesized a barbituric derivative and the crystal of that compound showed reversible and multi‐faceted bending behavior [16] . The pursuit of high elastic performance of fluorescent organic single crystals remains a work in progress.…”