Diversified Photo/Electronic Functions Based on a Simple Chalcone Skeleton: Effects of Substitution Pattern and Molecular Packing

Abstract

Structurally simple chalcone derivatives 1–2 are prepared and their diversified emission behaviors are deeply investigated. Two polymorphs (1G: λem = 536 nm, Φf = 0.08, τ = 1.81 ns; 1O: λem = 573 nm, Φf = 0.19, τ = 10.82 ns) with distinctively different emission behaviors are constructed by finely controlling the crystallization conditions of compound 1. 1G exhibits typical amplified spontaneous emission while 1O shows an interesting blue shift under smashing process (1O‐S: λem = 562 nm, Φf = 0.23, τ = 6.42 ns), which is ascribed to their different molecular packing structures and intermolecular interactions. Notably, simply introducing a fluorine substituent effectively endows the crystal with red emission (crystal 2: λem = 598 nm, Φf = 0.16, τ = 18.77 ns). Thus multicolor emissions including green, yellow, orange, and red emissions are obtained based on this simple chalcone skeleton.

AIEgen based polymorphs with solvent regulated crystal-to-crystal switch properties

“…With the increase of the solvent polarity, the FL emission peak of DCzFO gradually red-shifts from 543 nm to 602 nm. 10 The electronic structure of DCzFO was then determined by density functional theory calculations to better understand its ICT feature (Fig. 1c).…”

“…Therefore, it is speculated that more energy from the excitation of RC is lost during the nonradiative process, resulting in the weaker FL intensity and lower quantum yield. 10 Such vastly different solid-state emission properties of OC and RC may be ascribed to their different stacking modes. 11,14c To confirm the hypothesis, the stacking modes of OC and RC were investigated by powder X-ray diffraction (PXRD).…”

“…The orderly stacked structure of the single crystal in the preferred orientation immensely increases the degree of conjugation. 10 To further discover the emission properties of OC and RC, theoretical calculations were performed through the hybrid quantum mechanics and molecular mechanics (QM/MM) approach (Fig. S11, ESI †).…”

“…9 Tang et al prepared two polymorphs of chalcone derivatives with obvious stacking-dependent emission properties. 10 Yang et al reported polymorphs with tunable emission colors upon external stimuli including grinding, heating, and solvent vapor. 11 However, these polymorphs collapse easily under the external stimuli and thus fail the crystal-to-crystal switch test, which makes the study of the structure-property relationships challenging.…”

Naturally and Elastically Bent Organic Polymorphs for Multifunctional Optical Applications

“…Indeed, there are some typical organic solids exhibit polymorph‐dependent luminescent properties and also optical modes. [ 9–12 ] These studies have been mainly focused on tuning the emission color and efficiency of organic solids. The report of organic polymorphs aimed at modifying the mechanical properties is rare.…”