Through‐Space CBr···π Halogen Interaction: Efficient Modulation of Reaction‐Based Photochromism and Photoluminescence at Crystalline States for Irradiation Time‐Dependent Anti‐Counterfeiting

Abstract

Reaction‐based photo‐responsive molecular systems have been used as a reliable platform for building intelligent materials, but often suffer from high inactivity in terms of conversion efficiency and reversibility when it comes to solid‐state applications. Herein, a class of Spiro‐conjugated diphenylindene (DPI) aggregation‐induced emission materials that exhibit solid‐state photocyclization‐based photochromism and photoluminescence, achieved by manipulating through‐space CBr···π halogen interactions is reported. In the crystalline state, the Spiro bridge enables a pair of perpendicularly configured CBr···π interactions that suppress photoluminescence while activating a highly reversible (>10 000 cycles) and efficient photochromism based on photocyclization. After breaking this intermolecular CBr···π interaction, for example, by grinding, the solid‐state photochromic properties are sensitively de‐activated. In addition, this spontaneously reversible photochromism behavior gives a controllable decolorization time (from a few seconds to a few minutes), depending on the light exposure conditions, while displaying a luminescence change. In a proof‐of‐principle study, these photo‐function features demonstrate an attractive potential for novel anti‐counterfeiting applications. This work reveals the efficient regulation of CBr···π halogen interactions for spatial molecular packing, molecular electronic transitions, and chemical transformations, paving the way for the development of solid‐state intelligent materials with good reversibility.

Photochromic and Room Temperature Phosphorescent Donor–Acceptor Hybrid Crystals Regulated by Core-Substituted Naphthalenediimides

“…20 Accordingly, incorporating the heavy-atom effect to the organic moiety is also an efficient way to gain RTP with a higher QY or longer lifetime. 21 Particularly, bromine groups, a typical heavy atom, have a great effect on their crystal structures and functions in the development of crystalline materials. 22 Herein, we introduced bromine and iodine groups to the core of N,N′-bis ( In addition to the structural information, the photochromic and RTP properties of hybrids were also explored.…”

“…Based on previous research, chemical modification at core positions of NDIs (c-NDI) can notably tune the properties through introducing the substitution of electron withdrawing groups or electron donating groups at core positions, like alkyl, cyano, etc. ,− In 2013, Dincǎ and co-workers successfully obtained three core-substituted pyrazolate-based MOFs with −H, −NHEt, and −SHt, which possess and exhibit exceptional hydrolytic stability and water adsorption characteristics . Accordingly, incorporating the heavy-atom effect to the organic moiety is also an efficient way to gain RTP with a higher QY or longer lifetime . Particularly, bromine groups, a typical heavy atom, have a great effect on their crystal structures and functions in the development of crystalline materials .…”

Photochromic and Room-Temperature Phosphorescent D–A Hybrid Crystals Induced by Anion−π Interactions

“…32 More importanly, such photochromic and RTP D−A hybrid crystals have been reported to exhibit potential applications in the data recording, storage, and security technologies. 33,34 To go deep into the structure−property relationships of the POM-NDI hybrid crystals, herein we have extended inorganic donor components to other POM anions (PW 12…”

Spiro-fused bicyclo[3,2,2] octatriene-cored triptycene: synthesis, molecular packing, and functional aggregates

“…Luminescent materials have attracted considerable attention because of their significant applications in fabricating organic light-emitting devices [1][2][3][4], anti-counterfeiting materials [5,6], chemical sensing [7], and bioimaging [8]. Traditional luminescent dyes with strong emission in dilute solutions suffer from significant aggregation-caused quenching (ACQ), which limits their application in the solid state.…”

“…In this work, we report a new spiro-conjugated bicyclo [3,2,2]octatriene-cored triptycene (SBOT) in which an indene group is fused to the bridgehead carbon and methylene of the bridge ring (Figure 1, right). These new molecules were serendipitously obtained during a project aiming to synthesize spiro-functionalized diphenylindene materials [6,19,50]. Unlike the classical bicyclo[2,2,2]octatriene-cored triptycene, which has a rigid scaffold and usually shows a perfect axial symmetry, homotriptycene and SBOT derivatives are somewhat flexible and show asymmetry in the core scaffold.…”