Energy transfer, anticounterfeiting, white light emission and sensing in fine-regulating series of lanthanide metal-organic frameworks

Three lanthanide ions and a rigid(1,1'-biphenyl)-2,4,6-tricarboxylic acid(H_(3)bptc) ligand led to the isostructural lanthanide metal-organic frameworks(Ln-MOFs) {[Ln(bptc)(H_(2)O)_(3)]·3H_(2)O}_n(Lnbptc, Ln = Eu,Tb, Gd, Eu_(x)Tb_(1—x), Eu_(x)Gd_(1-x), Tb_(x)Gd_(1-x), and Eu_(0.12)Tb_(0.52)Gd_(0.36)). The density functional theory(DFT) and time-dependent DFT calculation were expanded on H_3bptc, which point to the occurrence of “antenna effect”. The minor diameter samples of Eubptc, Tbbptc, and Gdbptc can also be attained via the microwave synthesis and employed for handwriting anticounterfeiting. Interestingly, the typical red emission of Eu^(3+) and green emission of Tb~(3+) could be fine-tuned by Gd^(3+) via chemical mixing to be full-color emissions bimetallic doped Eu_(x)Tb_(1-x)bptc, Eu_(x)Gd_(1-x)bptc, and Tb_(x)Gd_(1-x)bptc. The above synthetic bimetallic MOFs can be fixed in positioning boxes of quick response(QR) codes with diverse emission for anticounterfeiting. The message can be decoded under the irradiation of 365 nm ultraviolet lamp while invisible in the daylight. Notably, the trimetallic doped Eu_(0.12)Tb_(0.52)Gd_(0.36)bptc emits white light with the CIE color coordinate(0.34, 0.34). Furthermore, Tbbptc is demonstrated to be a sensitive probe toward nitrobenzene and acetone with multiple mechanisms.

Spatial effect and resonance energy transfer for the construction of carbon dots composites with long-lived multicolor afterglow for advanced anticounterfeiting

Carbon dots(CDs)with room-temperature phosphorescence(RTP)have attracted dramatically growing interest in optical functional materials.However,the photoluminescence mechanism of CDs is still a vital and challenging topic.In this work,we prepared CD-based RTP materials via melting boric acid with various lengths of alkyl amine compounds as precursors.The spatial effect on the structure and the RTP properties of CDs were systematically investigated.With the increase in carbon chain length,the interplanar spacing of the carbon core expands and crosslink-enhanced emission weakens,resulting in a decrease in the phosphorescence intensity and lifetimes.Meanwhile,based on triplet-to-singlet resonance energy transfer,we employed intense and long-lived phosphorescence CDs as the donor and short-lived fluorescent dyes as the acceptor to achieve long-lived multicolor afterglow.By the triplet-to-singlet resonance energy transfer,the afterglow color can change from green to orange.The afterglow lifetimes are more than 0.9 s.Thanks to the outstanding afterglow properties,the composites were used for timeresolved and multiple-color advanced anticounterfeiting.This work will promote the design of multicolor and long-lived afterglow materials and expand their applications.

A Versatile Tetraphenylethene Derivative Bearing Excitation Wavelength Dependent Emission,Multistate Mechanochromism,Reversible Photochromism,and Circularly Polarized Luminescence and Its Applications in Multimodal Anticounterfeiting

Multimodal anticounterfeiting has become increasingly challenging in modern society to guarantee information security and the safety of property.In this study,a versatile cholesterol-containing tetraphenylethene derivative is shown to have multiple optical properties,including stimuli-responsive fluorescence,reversible photochromism,excitation wavelength dependent luminescence,and circularly polarized luminescence.After the application of diverse processing methods(writing,screen painting,drawing,and pyrography),we found that this molecule can serve as an anticounterfeiting toolbox to provide rich anticounterfeiting effects through the synergistical use of multiple optical properties.This work offers important insight for designing novel small organic molecules for advanced multimodal anticounterfeiting technology.

AIE活性抗冻水凝胶可实现低温环境下多级信息的加密与解密

抗冻水凝胶可在低温环境下调控内部水分子的冻结状态,进而维持其优异特性(如智能响应性、离子运输能力等)以及拓展其在低温环境下的应用。本文开发了一系列具有AIE活性的抗冻水凝胶,其可用于低温环境下的信息加密/解密。根据水凝胶中甜菜碱浓度的不同使其具有可调的冻结温度(T_(f))。当温度高于/低于Tf时,编码于水凝胶内的AIE分子表现出不发光/发光行为,从而实现信息的加密/解密。此外,通过调控水凝胶的冷冻程序,或者在水凝胶中原位引入具有光热效应的硫化铜纳米粒子并结合一定的照射条件,可实现多级信息的读取,从而增强信息的安全性。最后,由于该水凝胶对外界温度波动表现出不可逆性,因此可作为无需外界供能的超低温防伪标签,用于实时可视化监测冷链运输过程中细胞的活性。

Multiresponsive,easy-reversible,and dual-visual Pt(Ⅱ)salt nanostructures for advanced anti-counterfeiting application

Smart materials that integrate multi-stimuli response,full reversibility,and dual-visual read-out channel are highly desired for anticounterfeiting and information encryption applications.Herein,we developed a multiresponsive perchlorate terpyridyl Pt(Ⅱ)nano complex which could undergo fully reversible conversion between three forms stimulated by water or formaldehyde molecule due to the extent of Pt–Pt interaction.Meanwhile,a dual-visual channel,i.e.,the colorimetric channel changed from yellow to orange or red and the corresponding luminescent channel from orange to orange-red or red,has also been found.The weak and equivalent strength of ion-dipole interaction and hydrogen bond that generated between formaldehyde/water and Pt(II)salt result in the easy-control reversibility between the three forms.Furthermore,by introducing different polymer matrices,1Cl·ClO_(4)@PMMA(1Cl·ClO_(4):[Pt(tpy)Cl]·ClO4,tpy:2,2':6',2''-terpyridine),PMMA:poly(methyl methacrylate))and 1Cl·ClO4@PVA(PVA:polyvinyl alcohol)are successfully constructed,which exhibit different reversible behaviors since the PMMA and PVA matrix exert different influences on the strength of hydrogen-bond.Those smart Pt(II)salt nanostructures present great potential for high-security-level anticounterfeiting application.

Writing and Erasing Encryption Information Based on Frustrated Lewis Pair Chemistry

Lewis acid−base adducts resulting from instantaneous interactions provide a cost-effective strategy for color tuning and anticounterfeiting information.Herein,we report the construction of luminescent Lewis acid−base adducts via inkjet printing.Due to the unique weak coordination bond of B→N,it is feasible to construct anticounterfeiting information that is easy to erase.The in situ postsynthesis of the luminescent quick response codes via inkjet printing facilitates precision chemistry control to change the emission ranging from deep-blue(peaking at 407 nm)to orange-red(peaking at 597 nm).The encrypted information can be quickly erased either by modulating the temperature to dissociate the weak coordination or strong Lewis base to promote a neutralization reaction.

Fulgide Derivative-Based Solid-State Reversible Fluorescent Switches for Advanced Optical Memory

Solid-state fluorescent switches with reversible luminescence characteristics have attracted considerable attention because of their broad applications in advanced photonics,such as anticounterfeiting inks,optical writing and erasing,and biological imaging.Herein,we have fabricated a solid-state reversible fluorescent switch under alternating UV(365 nm)and visible light treatments based on a fulgide(FUL)-functionalized tetraphenylethylene(TPE)derivative(TPE-FUL)containing a photochromic group FUL and aggregation-induced emission(AIE)luminogen TPE.TPE-FUL exhibited excellent reversible absorption and luminescence owing to the interconversion between open TPE-FUL(O-TPE-FUL)and closed TPE-FUL(C-TPE-FUL).Photophysical and theoretical investigations revealed that the luminescence of O-TPE-FUL is based on the local excited state of the TPE moiety,whereas the fluorescence quenching of C-TPE-FUL originates from the intramolecular charge transfer from the TPE to the FUL moiety.The excellent reversible photoswitching properties of TPE-FUL in the solid state allows for its potential use in advanced optical memory applications,such as anticounterfeiting,optical writing and erasing,and information encryption.

A Simple Approach to Achieve Organic Radicals with Unusual Solid-State Emission and Persistent Stability

Sable organic radicals are promising materials for information storage,molecular magnetism,electronic devices,and biological probes.Many organic radicals have been prepared,but most are non-or weakly emissive and degrade easily upon photoexcitation.It remains challenging to produce stable and efficient luminescent radicals because of the absence of general guidelines for their synthesis.Herein,we present a photoactivation approach to generate a stable luminescent radical from tris(4-chlorophenyl)phosph ine(TCPP)with red emission in the crystal state.The mechanistic study suggests that the molecular symmetry breaking in the crystal causes changes of molecular conformation,redox properties,andmolecular packing that facilitates radical generation and stabilization.This design strategy demonstrates a straightforward approach to develop stable organic luminescent radicals that will open new doors to photoinduced luminescent radical materials.