Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• -emission (AIE)-active aggregates exhibit emissive behavior in hexane, with an emission peak at 679 nm and a shoulder at 717 nm along with a fluorescence quantum yield of 8.5%. This luminescence phenomenon can be aptly considered to be AIE, considering the pronounced constraints imposed on molecular

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• . explored the modulation of optoelectrochemical properties and thermal characteristics of pyridopyrazino[2,3-b]indole-based Qx46 series with varying substituents, i.e., bromine, chlorine, methyl and nitro group. Their study revealed inbuilt ICT and aggregation-induced emission (AIE) effects, forming

• , including solvatochromism and AIE enhancement. These characteristics enable tunable emission and enhanced luminescence efficiency. The potential application of tripodal derivatives in white OLEDs indicates the versatility of quinoxaline-based materials in achieving diverse emission colors [67]. Figure 7

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

• Suangsiri Arunlimsawat,
• Patteera Funchien,
• Pongsakorn Chasing,
• Atthapon Saenubol,
• Taweesak Sudyoadsuk and
• Vinich Promarak

Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122

• aggregation-induced emission (AIE) luminogen. The experimental (solvatochromic and emission in THF/water mixtures studies) and theoretical investigations prove that TPECNz retains cooperative hybridized local and charge transfer (HLCT) and weak AIE features. Thanks to its D–A–D-type structure with a proper

• , respectively, providing well-balanced ambipolar characteristics. On the other hand, the attached 4-(1,2,2-triphenylvinyl)phenyl (TPE) moiety would induce aggregation-induced emission (AIE) as feature into the molecule. It was suspected that AIE would restrain the aggregation-caused quench (ACQ) and the energy

• loss through the vibronic coupling natures of the DR/NIR fluorophores [53]. As a result, TPECNz effectively possesses a strong deep-red emission with combined HLCT, weak AIE, and ambipolar transporting properties, which enabled its application as non-doped emitter. The TPECNz-based non-doped deep-red

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• -induced emission (AIE) character [20][21]. Chitosan (CS) is a natural cationic polysaccharide, which is considered an ideal material for the construction of drug delivery systems due to its nontoxic, biocompatible, biodegradable, and easily functionalized properties [22]. Herein, we designed and

• 20 mol % was calculated to be 1.6, 3.2 and 6.6 mol %, respectively, increasing as Rf increased. Fluorescent properties of CS-TPE in the solid state. CS-TPE bioconjugates were found to be AIE active, like other TPE-modified derivatives in previous works [25][26]. As shown in Figure 2a, the solid

• successfully designed and synthesized different degrees of TPE-labelled CS polymer compounds that exhibit the AIE fluorescence effect and we constructed pH-responsive fluorescent supramolecular spherical nanoparticles based on CS-TPE alone and the host–guest TBTQ-C6/CS-TPE supra-amphiphile. The critical

Supramolecular approaches to mediate chemical reactivity

• Pablo Ballester,
• Qi-Qiang Wang and
• Carmine Gaeta

Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152

• supramolecular nanostructures, displayed aggregation-induced emission (AIE) due to the restricted phenyl-ring rotation of m-TPEWP5 component. Inspired by natural photosynthesis and following an energy transfer process, the supramolecular nanorod assembly was employed as a nanoreactor for a photocatalytic

Computational model predicts protein binding sites of a luminescent ligand equipped with guanidiniocarbonyl-pyrrole groups

• Neda Rafieiolhosseini,
• Matthias Killa,
• Thorben Neumann,
• Niklas Tötsch,
• Jean-Noël Grad,
• Alexander Höing,
• Thies Dirksmeyer,
• Jochen Niemeyer,
• Christian Ottmann,
• Shirley K. Knauer,
• Michael Giese,
• Jens Voskuhl and
• Daniel Hoffmann

Beilstein J. Org. Chem. 2022, 18, 1322–1331, doi:10.3762/bjoc.18.137

• prediction of two C2 related, dominating binding sites on 14-3-3ζ that may bind to two of the supramolecular ligand molecules. Keywords: AIE luminophores; fluorescence emission; guanidiniocarbonyl-pyrrole; ligand binding; 14-3-3 protein; Introduction The 14-3-3 protein family was one of the first

• novel luminophores tailor-made for different applications. One unique, promising class of compounds, the so-called aggregation-induced emitters (AIE) have been used for a wide range of applications, e.g., in OLEDs, liquid crystals [17], stimuli responses, bioassays, protein and ion detection or imaging

• [15][18]. In contrast to classical luminophores, these compounds typically show emission “on” behavior upon aggregation or binding, which can be explained by a restriction of motion. In this contribution, we designed a hybrid compound featuring AIE luminophores based on aromatic thioethers [19] as a

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• tetraphenylethene (TPE) units which act as an aggregation-induced emissive (AIE) fluorophore [65]. The newly designed TPE-based tetraimidazole donor 19 has been treated with 180°/120° trans-Pt(II) acceptors which led to the coordination-driven self-assembly of 3D discrete molecular cages in aqueous medium (Figure 5

Comparative study of thermally activated delayed fluorescent properties of donor–acceptor and donor–acceptor–donor architectures based on phenoxazine and dibenzo[a,j]phenazine

• Saika Izumi,
• Prasannamani Govindharaj,
• Anna Drewniak,
• Paola Zimmermann Crocomo,
• Satoshi Minakata,
• Leonardo Evaristo de Sousa,
• Piotr de Silva,
• Przemyslaw Data and
• Youhei Takeda

Beilstein J. Org. Chem. 2022, 18, 459–468, doi:10.3762/bjoc.18.48

• ). The PL spectrum is similar to that in a CBP host matrix (vide infra). The compound 1 showed an aggregation-induced emission (AIE) behavior in a THF/water system, showing a more red-shifted emission peak at around λem = 600 nm when compared with the as-prepared solid state (Figure S2 in Supporting

Tetraphenylethylene-embedded pillar[5]arene-based orthogonal self-assembly for efficient photocatalysis in water

• Zhihang Bai,
• Krishnasamy Velmurugan,
• Xueqi Tian,
• Minzan Zuo,
• Kaiya Wang and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2022, 18, 429–437, doi:10.3762/bjoc.18.45

• supramolecular self-assembled nanosystem based on host–guest interactions between water-soluble tetraphenylethylene-embedded pillar[5]arene (m-TPEWP5) and ammonium benzoyl-ʟ-alaninate (G) in an aqueous medium. The obtained assembly of m-TPEWP5 and G showed aggregation-induced emission (AIE) via the blocking of

• dehalogenation reaction with high yields within shorter reaction time is vastly essential and of industrial importance. Herein, we have fabricated a supramolecular AIE-emissive photocatalytic system (m-TPEWP5G–EsY) based on the host–guest interactions between meso-TPE embedded water-soluble pillar[5]arene (m

• phenyl-ring rotations thus enhancing the AIE property. The resulting m-TPEWP5G self-assembled worm-like nanosystem acts as an ideal donor and loading EsY as acceptor on the surface of the worm-like nanostructure, leads to the generation of a nanorod assembly via electrostatic interactions. The final AIE

Synthesis of dibenzosuberenone-based novel polycyclic π-conjugated dihydropyridazines, pyridazines and pyrroles

• Ramazan Koçak and
• Arif Daştan

Beilstein J. Org. Chem. 2021, 17, 719–729, doi:10.3762/bjoc.17.61

• exhibit photophysical properties such as photosensitization [13], fluorescence, and aggregation-induced emission (AIE) [14][15][16]. π-Conjugated polycyclic hydrocarbons (CPHs) containing polycyclic heteroaromatic molecules (PHAs) and aza-polycyclic aromatic hydrocarbons (aza-PAHs) have been attracting

Tuning the solid-state emission of liquid crystalline nitro-cyanostilbene by halogen bonding

• Subrata Nath,
• Alexander Kappelt,
• Matthias Spengler,
• Bibhisan Roy,
• Jens Voskuhl and
• Michael Giese

Beilstein J. Org. Chem. 2021, 17, 124–131, doi:10.3762/bjoc.17.13

• fluoroiodoazobenzenes with varying fluorination degree at the iodobenzene moiety was used to investigate the impact of halogen bonding on the properties of the assemblies. Since cyanostilbene molecules are known to show aggregation-induced emission (AIE) behaviour the photophysical properties of the resulting

• -induced emission properties were combined with alkoxystilbazoles to form hydrogen-bonded mesogens. Since NO2-Cn is known to be fluorescent, we were curious how the formation of the halogen-bonded complexes affects the AIE behaviour of NO2-Cn. Therefore, we studied the photophysical properties of 1:1

• fluorescence of the assemblies based on nitro-cyanostilbenes with an odd number of carbon atoms in the alkoxy chain significantly increased, while for the even-numbered NO2-Cn no significant change in the fluorescence was observed. The AIE behaviour of cyanostilbenes was first described by Park and co-workers

Circularly polarized luminescent systems fabricated by Tröger's base derivatives through two different strategies

• Cheng Qian,
• Yuan Chen,
• Qian Zhao,
• Ming Cheng,
• Chen Lin,
• Juli Jiang and
• Leyong Wang

Beilstein J. Org. Chem. 2021, 17, 52–57, doi:10.3762/bjoc.17.6

• ; inversion of CPL handedness; Tröger's base; Introduction Recently, much effort has been devoted to constructing luminescent materials with efficient high emission in the solid state [1][2][3]. More and more types of fluorophores with aggregation-induced emission (AIE) characteristics have been discovered

• inversion of the configuration, and two stable enantiomers could be formed and separated then. Although the TB shows excellent performance in constructing AIE materials, TB-based materials emitting CPL have rarely been reported so far. In general, the luminescent part and the chiral part are necessary to

• , Scheme S2) [26]. When rac-TBPP was mixed with DGG at molar ratios from 1:100 to 1:16 (rac-TBPP/DGG), transparent yellow co-gels were successfully formed by being heated to dissolve in chloroform, and then cooled to ambient temperature (Supporting Information File 1, Figure S6). Owing to the AIE effect of

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• (AIE) [23][24][25][26][27]. They mentioned a series of silole derivatives with propeller-like conformations that show no emission in dilute solutions, but are highly luminescent when aggregated in the solid state. Their work has attracted major attention and quickly became one of the most sought-after

• strategies to overcome ACQ. Up to date, various AIE materials with efficient luminescence have been synthesized for diverse applications [28][29][30][31][32]. The discovery of AIE and especially aggregation-induced emission enhancement fluorogens (AIEEgens) further incentivized the synthesis and analysis of

• materials equally efficient both in solution and in the solid state, thus bridging a gap between the dichotomous phenomena of ACQ and AIE with a new class of luminescent species, so-called dual-state emitting (DSE) compounds (DSEgens) [33]. While in many papers these compounds are called Dual State Emitting

Synthesis of 1,4-benzothiazinones from acylpyruvic acids or furan-2,3-diones and o-aminothiophenol

• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2020, 16, 2322–2331, doi:10.3762/bjoc.16.193

• potential Cu2+ chemosensors [14], and their BF2 chelates, as multicolor fluorescence complexes, some of which exhibited aggregation-induced emission (AIE) properties [15]. In addition, enaminones I and II proved themselves to be versatile and available building blocks for the synthesis of various

Controlling the stereochemistry in 2-oxo-aldehyde-derived Ugi adducts through the cinchona alkaloid-promoted electrophilic fluorination

• Yuqing Wang,
• Gaigai Wang,
• Anatoly A. Peshkov,
• Ruwei Yao,
• Muhammad Hasan,
• Manzoor Zaman,
• Chao Liu,
• Stepan Kashtanov,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2020, 16, 1963–1973, doi:10.3762/bjoc.16.163

• -triggered complexation with boron trifluoride diethyl etherate. The resulting O,O-chelated boron complexes 11 turned out to be strong solid-state emitters featuring clear aggregation-induced emission (AIE) characteristics [61]. Encouraged by these results, we decided to attempt the reaction of 2-oxo

Synthesis of new fluorescent molecules having an aggregation-induced emission property derived from 4-fluoroisoxazoles

• Kazuyuki Sato,
• Akira Kawasaki,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2020, 16, 1411–1417, doi:10.3762/bjoc.16.117

• -opening reaction of 4-fluoroisoxazoles and exhibited highly fluorescent luminescence and aggregation-induced emission (AIE), showing promise as a new fluorophore. Keywords: aggregation-induced emission; boron ketoiminates; fluorescent probe; α-fluorinated boron ketoiminates; 4-fluoroisoxazoles

• concentrated solutions by aggregation-caused quenching (ACQ) [8]. On the other hand, there are molecules that exhibit strong emission even in poor solvents or in the solid state. This property is referred to as aggregation-induced emission (AIE) and has attracted much attention in the field of fluorescence

• be visualized using fluorescent probes, the use of AIE fluorescent probes is being investigated as a tool for analyzing the causal relationship between prion diseases and prion proteins. The importance of fluorinated heterocyclic derivatives in the pharmaceutical and agrochemical industries continues

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• the solid state. This finding suggests that by restricting intramolecular motion and vibration, which enables radiation-less deactivation of the excited state [61], an AIE (aggregation‐induced emission) or AIEE (aggregation-induced enhanced emission), might become operative [62][63][64]. The AIE or

Aggregation-induced emission effect on turn-off fluorescent switching of a photochromic diarylethene

• Luna Kono,
• Yuma Nakagawa,
• Ayako Fujimoto,
• Ryo Nishimura,
• Yohei Hattori,
• Toshiki Mutai,
• Nobuhiro Yasuda,
• Kenichi Koizumi,
• Satoshi Yokojima,
• Shinichiro Nakamura and
• Kingo Uchida

Beilstein J. Org. Chem. 2019, 15, 2204–2212, doi:10.3762/bjoc.15.217

• is one of the examples which express the mechanisms of aggregation-induced emission (AIE). This compound emits orange fluorescence with a large Stokes shift derived from ESIPT in aprotic solvents such as THF or hexane, while it exhibits only a photochromic reaction in protic solvents such as methanol

• fluorescent turn-off behavior during photochromism in aprotic solvents as well as in crystalline state upon UV light irradiation. Furthermore, it showed AIE in THF/water mixtures with blue-shift of the emission. Keywords: AIE; diarylethene; ESIPT fluorescent switching; turn-off fluorescence; Introduction

• points of view, such as sensors, electroluminescent displays, memory devices [9]. On the other hand, molecular aggregation also affects the intensity of fluorescence [10][11]. Some material shows fluorescence by aggregation (aggregation-induced emission (AIE)), while the others decay the fluorescence by

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• charge-transfer dyes. P-TPE was included in the study as a classical aggregation-induced emission (AIE) dye and TPS as a representative of a two-photon fluorescent probe. Ru(dcbpy)3 was involved as a member of luminescent transition-metal complexes. Of our special interest in the present study is to

• sensing (Scheme 1). Besides, they are an eminent matrix for constructing organic luminescent materials and could be engaged in the manufacturing of high-performance supramolecular dye lasers [24][48]. The complexation of GC5A with AIE dye Opposite to ACQ, AIE is a photophysical phenomenon in such way that

• luminescent fluorophores are non-emissive as isolated molecules but become highly luminescent upon aggregate formation [49]. Once reported by Tang’s group [50], AIE luminogens (AIEgens) have attracted great attention and have been applied in various areas including optoelectronic materials [51][52] and

Structure–property relationships and third-order nonlinearities in diketopyrrolopyrrole based D–π–A–π–D molecules

• Jan Podlesný,
• Lenka Dokládalová,
• Oldřich Pytela,
• Adam Urbanec,
• Milan Klikar,
• Numan Almonasy,
• Tomáš Mikysek,
• Jaroslav Jedryka,
• Iwan V. Kityk and
• Filip Bureš

Beilstein J. Org. Chem. 2017, 13, 2374–2384, doi:10.3762/bjoc.13.235

• ]. Moreover, some DPP derivatives also showed aggregation induced emission (AIE) [13][14] and the ability to selectively sense fluoride ions [26][27][28]. The modern era of DPP chromophores has been opened by Gryko et al. [3][11][12][18][20][21][29] who have demonstrated their large and tunable two-photon

One-pot syntheses of blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones by T3P^® activation of 3-arylpropiolic acids

• Melanie Denißen,
• Alexander Kraus,
• Guido J. Reiss and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2017, 13, 2340–2351, doi:10.3762/bjoc.13.231

• by an integrating sphere. The emission maximum appears at 468.5 nm, i.e., at the same longest wavelength band as in solution. Therefore, 1H-benzo[f]isoindole-1,3(2H)-diones 4 can be considered as AIE (aggregation induced emission) chromophores [56][57][58]. In comparison to the 1-phenyl-[2,3-c