Multi‐Responsive 0D Organic–Inorganic Hybrid Cuprous Bromides Constructed via Ultra‐Facile Approaches for Multimodal Luminescent Anti‐Counterfeiting

Abstract

Luminescent anti-counterfeiting has the advantages of high secrecy, low cost, flexible design, simple operation, and convenient light-regulation of luminescent materials, which makes it easy to achieve high-level multimodal anti-counterfeiting. Here, zero-dimensional (0D) organic-inorganic hybrid luminescent crystals (TPA)CuBr 2 (TPA + = [N(CH 2 CH 2 CH 3 ) 4 ] + ) with multiple responses to ultraviolet (UV) light, water, and thermal stimulus are synthesized through an ultra-facile approach for multimodal luminescent anti-counterfeiting. Water-sensitive (TPA)CuBr 2 could transform into 0D (TPA) 2 Cu 4 Br 6 upon external water stimulus, accompanied by the change of luminescence color from cyan to orange under UV light irradiation. Both (TPA)CuBr 2 and (TPA) 2 Cu 4 Br 6 exhibit high photoluminescence quantum yields, and long photoluminescence decay lifetimes. In addition, (TPA)CuBr 2 and (TPA) 2 Cu 4 Br 6 show reversible "on-off" luminescence phenomena and excellent cycling stability under thermal stimulus. Exhilaratingly, multimodal anti-counterfeiting luminescent labels with high-security level could be fabricated based on the multiple responsive organic-inorganic hybrid cuprous bromides. Moreover, the test paper based on (TPA)CuBr 2 could be fabricated for the detection of trace water in isopropanol. This work demonstrates the capabilities of (TPA)CuBr 2 and (TPA) 2 Cu 4 Br 6 as high-security anti-counterfeiting materials and luminescent sensors, which provides an important reference for exploring 0D metal halides for high-level luminescent anti-counterfeiting.

Reversible tri-state structural transitions of hybrid copper(i) bromides toward tunable multiple emissions

“…Their lifetimes are comparable to those of (C 16 H 36 N)CuBr 2 (232.05 μs), (C 12 H 28 N)CuBr 2 (261.7 μs), (C 8 H 20 N) 2 Cu 2 Br 4 (56 μs), and (C 12 H 28 N) 2 Cu 4 Br 6 (45.12 μs) copper-bromide hybrids reported in previous studies. 20–22,36 The radiative ( K r ) and nonradiative ( K nr ) decay rates were calculated based on PLQY and τ ave . As listed in Table S8,† the K r / K nr of 246 is the highest (3.273), indicating that the nonradiative pathway was greatly minimized, giving rise to the high PLQY.…”

“…29–34 This reversible transformation between two hybrid copper halides under external stimuli was recently reported, demonstrating the potential of solvent-induced phase transition behavior in anti-counterfeiting. 35–37 During this submission, Lei published a reversible single-crystal to single-crystal transition between (ETPP) 2 Cu 4 Br 6 and (ETPP)CuBr 2 very recently. 37 However, there is still not enough research focus on how to rationally design and synthesize hybrid copper halides with more than three different copper–halogen connectivity modes and their structural interconversions.…”

Synthesis and Characterization of New Hybrid Organic–Inorganic Metal Halides [(CH3)3SO]M2I3 (M = Cu and Ag)

“…7 Therefore, PLE in [(CH 3 ) 3 SO]Cu 2 I 3 is assigned to band gap excitation and PL in [(CH 3 ) 3 SO]Cu 2 I 3 can be attributed to STE emission localized around copper(I), similar to that in CsCu 2 I 3 and other luminescent copper(I) metal halides. 3,7,12,13,15,44,45 Single crystals of [(CH 3 ) 3 SO]Ag 2 I 3 show an emission peak at 393 In the literature, copper(I) and silver(I) halides have been considered for optical, electrical, and radiation detection applications. 2,26,50−53 Although the weak light emission properties of the title compounds preclude their use as scintillator materials, we considered their potential use in semiconductor direct conversion X-ray radiation detector applications with [(CH 3 ) 3 SO]Cu 2 I 3 as the representative of the family.…”

Variable halide perovskites: diversification of anti-counterfeiting applications

“…Two-dimensional (2D) OIMHs possess properties associated with their soft lattices and multiple quantum-well structures, allowing for lattice expansion and the occurrence of thermochromic behaviors. 67,68 Sun et al synthesized two-novel multifunctional 2D OIMHs, (PED)CuCl 4 and (BED) 2 CuCl 6 (PED = N -phenylethylenediamine, BED = N -benzylethylenediamine) via a cooling crystallization method, and the molecular structures are shown in Fig. 6a and b.…”