Exceptionally Plastic/Elastic Organic Crystals of a Naphthalidenimine‐Boron Complex Show Flexible Optical Waveguide Properties

Abstract

The design of molecular compounds that exhibit flexibility is an emerging area of research. Although a fair amount of success has been achieved in the design of plastic or elastic crystals, realizing multidimensional plastic and elastic bending remains challenging. We report herein a naphthalidenimine–boron complex that showed size‐dependent dual mechanical bending behavior whereas its parent Schiff base was brittle. Detailed crystallographic and spectroscopic analysis revealed the importance of boron in imparting the interesting mechanical properties. Furthermore, the luminescence of the molecule was turned‐on subsequent to boron complexation, thereby allowing it to be explored for multimode optical waveguide applications. Our in‐depth study of the size‐dependent plastic and elastic bending of the crystals thus provides important insights in molecular engineering and could act as a platform for the development of future smart flexible materials for optoelectronic applications.

Optical Waveguides in Organic Crystals of Polycyclic Arenes

“…Recently, Neelakandan et al also presented a flexible crystal from a naphthalidenimine complex (structure 2, Figure 9B). [25] First, the crystals of the precursor molecule 1 (Figure 9A) were brittle. Then, boron complexation endowed 2 with intriguing mechanical, luminescence, and optical waveguides properties.…”

Manifold Mechanical Deformations of Organic Crystals with Optical Waveguiding and Polarization Rotation Functions

“…[38][39][40][41] The emerging flexible organic crystals are promising optical waveguiding media and are considered to be the perfect candidates for next-generation optoelectronic devices. [42][43][44][45] Recent achievements demonstrated that elastically and plastically bendable organic crystals can be used as flexible optical media for active and/or passive light transduction. [46] Furthermore, by using a combination of chemical structure modification and crystal engineering, the waveguiding properties of molecular crystals can be combined with a broad range of other functionalities and bring new multifunctional materials.…”

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

“…developed the fluorescent and elastic crystals of from ( E )‐1‐(4‐(dimethylamino)phenyl)iminomethyl‐2‐hydroxyl‐naphthalene.The optical waveguide properties of flexible crystals were explored for the first time, which endowed the elastic crystals with optical/optoelectronic functions [25] . From then on, elastic crystals exhibited good light transmission performance, laying the foundation for their applications in optical waveguide materials [26–38] . However, the elastic crystals with optical waveguide properties were still rare.…”

“…[25] From then on, elastic crystals exhibited good light transmission performance, laying the foundation for their applications in optical waveguide materials. [26][27][28][29][30][31][32][33][34][35][36][37][38] However, the elastic crystals with optical waveguide properties were still rare.…”