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DOI: 10.1039/D5QO00393H (Research Article) Org. Chem. Front., 2025, Advance Article

Tetraphenylethylene or naphthalimide-functionalized dendritic carbazole AIEgens: self-assembly visualization, three disparate force-triggered fluorescence responses, and advanced anticounterfeiting applications†

Yijie Zoua, Zhao Chen*a, Fei Zhaoa, Ya Yind, Kaixin Hea, Xingru Lianga, Hai-feng He*c, Zhijian Li*a and Sheng Hua Liu*b
aJiangxi Province Key Laboratory of Organic Functional Molecules; Institute of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013, PR China. E-mail: 1020160936@jxstnu.edu.cn; hehf0427@jxstnu.com.cn; lizhijianhdd@163.com
bState Key Laboratory of Green Pesticide, College of Chemistry, Central China Normal University, Wuhan 430079, PR China. E-mail: chshliu@mail.ccnu.edu.cn
cSchool of Chemistry and Chemical Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013, PR China
dState Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China

Received 25th February 2025 , Accepted 28th April 2025

First published on 29th April 2025

Abstract

Three 1,8-naphthalimide-modified donor–π–acceptor-type and three tetraphenylethylene-functionalized fluorogenic dendritic carbazole derivatives are designed and synthesized. These six dendrimer-like carbazole-containing compounds are typical aggregation-induced emission (AIE) luminogens. Specially, the AIE-active 3CzB2Nap possessing trimeric carbazole and two 1,8-naphthalimide groups features aggregation-triggered self-assembly, and the visualization of its intriguing self-assembly process is successfully realized through scanning electron microscopy technology. Notably, three types of contrasting anisotropic mechanical force-induced fluorescence responses from the six prepared dendritic carbazole AIEgens are observed. More specifically, 7CzB2TPE and 3CzB2Nap do not exhibit fluorescence changes after grinding; 1CzB2TPE and 3CzB2TPE display irreversible mechanofluorochromic phenomena; 1CzB2Nap and 7CzB2Nap show reversible mechanofluorochromic characteristics. To deeply elucidate the three distinct types of force-responsive emissive features of the six dendritic AIEgens, powder and single-crystal X-ray diffraction, differential scanning calorimetry experiments, and theoretical simulation calculations of molecular packing structures before and after grinding are carried out. Based on the observed three disparate force-dependent fluorescence phenomena, two advanced information security systems involving multilevel painting anticounterfeiting and multimode information encryption are elaborately constructed.

Introduction

Over the past twenty years, organic luminogenic materials have continuously attracted the research interest of scholars and industrial researchers owing to their extensive applications in optical storage, sensor technology, biological imaging and information anticounterfeiting.1–7 In particular, the development of smart emission materials exhibiting solid-state luminescence color changes in response to external stimuli is a highly attractive research topic.8–13 Mechanofluorochromic materials undergoing alterations in molecular conformation and arrangement upon exposure to force stimulation are a promising class of intelligent emissive materials.14–17 To satisfy high-performance requirements for practical applications of mechano-responsive luminogens, highly efficient solid-state emission is important. However, the vast majority of conventional luminogenic dyes experience partial or even complete emission quenching upon aggregation. This troubling phenomenon is attributed to the notorious aggregation-caused quenching (ACQ) effect, which greatly impedes the advancement of mechanofluorochromic emitters.18–20 Tang's group innovatively proposed the concept of aggregation-induced emission (AIE) and corroborated that the AIE behaviors of luminogens primarily derive from the restriction of intramolecular motions.21–23 The discovery of AIE has revolutionized the comprehension of traditional organic emissive materials, paving a path for the construction of high-brightness solid-state luminescent materials.24–27

AIE and mechanofluorochromic materials share common similarities in their molecular structures, such as the presence of rotatable fluorescence units. To date, many AIE materials concomitantly exhibit mechanical force-triggered fluorescence responses.28–32 Indeed, integrating AIE-type structural fragments into molecular architectures offers the possibility for developing high-efficiency mechano-responsive fluorogenic materials.33–36 Tetraphenylethylene (TPE) is widely acknowledged as an AIE-active functional unit and has been effectively applied in the construction of mechanofluorochromic luminogens. In 2022, Yin et al. synthesized a supramolecular hexagonal fluorescent platinum(II) metallacycle containing three TPE units, and the TPE-functionalized supramolecular coordination complex showcased a reversible mechanofluorochromic response.37 Meanwhile, carbazole derivatives are also regarded as among the most popular candidates for emissive materials, and dendritic molecules often contain multiple freely rotatable units connected by carbon–carbon single bonds or carbon–nitrogen single bonds, whose intramolecular rotations can be restricted in the aggregation state, leading to enhanced light emission.38,39 Indeed, it is possible that the dendritic molecular structure is not only conducive to the formation of the AIE phenomenon of the target luminogen but also can endow the luminogenic molecule with a highly twisted molecular conformation, which establishes a foundation for realizing the interesting mechanofluorochromic phenomenon.40–48 Noticeably, carbazole-modified dendritic luminogens have been demonstrated to be capable of displaying remarkable optoelectronic characteristics.49,50

The photophysical properties of donor–acceptor (D–A)-type luminogens can be effectively manipulated by altering the types of electron donors and acceptors among these molecules.51–53 For example, Afrin and his co-worker synthesized six highly solid-state emissive D–π–A carbazole derivatives containing cyano-substituted diarylethylene units, and their aggregated-state emission and mechanofluorochromic behaviors were closely associated with the electronic effects of the substituents and the types of aromatic rings.54

The solvent-mediated self-assembly provides an effective approach for the preparation of high-performance functional materials,55–57 and the visualizations of the self-assembly processes are beneficial for in-depth understanding of the self-assembly mechanisms, which will provide significant references for employing functionalized materials with diverse properties through self-assembly strategies. Herein, we designed three TPE-functionalized and three D–π–A-structure naphthalimide-modified fluorophores, containing carbazole dendrons up to the third generation (Fig. 1a). D–π–A-type compounds were characterized using dendritic carbazole as the donor, 1,8-naphthalimide units as the acceptor, and a phenyl group as the π-conjugated linker. The target products were synthesized according to the corresponding literature with good yields, as shown in Scheme S1.†[thin space (1/6-em)]58,59 The correct chemical structures were confirmed by 1H and 13C NMR spectroscopy and mass spectrometry (ESI†). The crystals of 3CzB2TPE were obtained by slow evaporation in a dichloromethane/n-hexane solution. The photophysical properties of the six dendritic carbazole derivatives were systematically investigated.


image file: d5qo00393h-f1.tif
Fig. 1 (a) Molecular structures of dendritic carbazole derivatives. PL spectra of the compounds (2.0 × 10−5 mol L−1) in DMF/water mixtures with different fw values. Excitation wavelength = 365 nm. Fluorescence images of the compounds (2.0 × 10−5 mol L−1) in DMF/water mixtures with 0% and 90% water fractions under 365 nm UV light: (b) 3CzB2TPE; (c) 1CzB2Nap. SEM images of aggregates formed by 3CzB2Nap (2.0 × 10−5 mol L−1) in DMF/water mixtures with different fw values: (d) fw = 0%; (e) fw = 50%; (f) fw = 90%.

Results and discussion

To study the AIE features of these novel luminogens, the corresponding photoluminescence (PL) spectra and ultraviolet-visible (UV-Vis) absorption spectra in N,N-dimethylformamide (DMF)/water mixtures with different water fractions (fw) were first investigated. As shown in Fig. 1b, under 365 nm UV light, fluorophore 3CzB2TPE (concentration: 2.0 × 10−5 mol L−1) was almost non-emissive in pure DMF, and green fluorescence was noticed in the mixed solvents of DMF/water with fw ≥ 20%. When the fw in the DMF solution reached 70%, the luminescence presented the strongest emission intensity, with a maximum emission wavelength (λmax) at 528 nm. In the UV-Vis absorption spectrum, level-off tails were visible in the long-wavelength region as the fw increased, which implied the formation of nanoscopic aggregates (Fig. S1b†). Indeed, the observed aggregated particles were characterized using a scanning electron microscope (SEM), and the results confirmed the nanoaggregates as the main constituent (Fig. S3b†). Similarly, the emission intensity of 1CzB2Nap in the DMF/water mixture was significantly enhanced with the increase of the fw value (Fig. 1c), and PL spectra of luminogens 1CzB2TPE, 7CzB2TPE, 3CzB2Nap or 7CzB2Nap, in DMF/water mixtures with different fw values are shown in Fig. S2.† The SEM image of the nanoaggregates formed by 1CzB2Nap is also presented in Fig. S3d.† Interestingly, a self-assembly phenomenon triggered by a poor solvent was observed for 3CzB2Nap. More specifically, microscale rod-shaped aggregates were formed in a DMF/water mixture with 90% water content (Fig. 1f), and the formation process of the intriguing solvent-mediated self-assembly microscale aggregates was successfully visualized using SEM technology (Fig. 1d–f). Plots of the relationships between the maximum emission peak intensity and the fw value of the six reported luminogens are exhibited in Fig. S4.† Obviously, these six fluorogenic compounds all displayed excellent AIE properties, which are beneficial for achieving high-brightness solid-state fluorescence.

Next, the anisotropic mechanical force-induced fluorescence responses of TPE-modified and naphthalimide-containing dendritic carbazole derivatives were explored by PL spectroscopy. The solid-state samples of 1CzB2TPE (green), 3CzB2TPE (cyan), 7CzB2TPE (green), 1CzB2Nap (yellow), 3CzB2Nap (orange) and 7CzB2Nap (orange) exhibited high brightness under 365 nm UV irradiation. Among them, after grinding the solid-state 3CzB2TPE in a mortar with a pestle, there was an obvious red shift from cyan to green, and the altered color persisted even after fumigating with CH2Cl2 vapor for 30 seconds (Fig. 2a and d). As shown in Fig. S5a and S5d,† 1CzB2TPE also possessed the same irreversible mechanofluorochromic feature. Compared to the previous compounds, the fluorescent color of 1CzB2Nap changed to orange upon grinding and could be returned to its initial emissive state after a 30-second treatment with CH2Cl2 vapor, exhibiting reversible mechanofluorochromism (Fig. 2b and e). In the same way, the reversible mechanochromic fluorescence phenomenon of 7CzB2Nap is demonstrated in Fig. S5c and S5f.† In the end, the force responses of 7CzB2TPE (Fig. S5b and S5e†) and 3CzB2Nap (Fig. 2c and f) were also explored, and their original emission colors were maintained under mechanical grinding. These six AIEgens displayed three distinct types of fluorescence responses triggered by an external mechanical force. Integrating these three disparate mechano-responsive fluorescence phenomena held significant advantages for the construction of advanced anticounterfeiting systems. Additionally, the maximum emission wavelength values of the six reported AIEgens in various solid states are summarized in Table S1,† and the absolute fluorescence quantum yield (ΦF) values and average fluorescence lifetimes of the six reported compounds before and after grinding are summarized in Table S2.† The average fluorescence lifetimes of unground and ground solid samples of the six reported luminogens showed no significant differences, which suggested that mechanical grinding had a negligible influence on the excited-state stabilities of the six luminogens in solid forms. In contrast, the solid-state ΦF values of the six luminogens demonstrated significant decreases upon grinding. Therefore, it is understandable that mechanical grinding is unfavorable for radiative transitions of the excited states of the six luminogens in solid forms, which is possibly attributed to the formation of their tighter molecular packings after grinding. Indeed, a tighter molecular arrangement may induce the formation of strong intermolecular π–π interactions, which is unfavorable for radiative transition.


image file: d5qo00393h-f2.tif
Fig. 2 PL spectra of luminogens in different solid states. Excitation wavelength = 365 nm: (a) 3CzB2TPE; (b) 1CzB2Nap; (c) 3CzB2Nap. Photographic images of luminogens in different solid states under 365 nm UV light: (d) 3CzB2TPE; (e) 1CzB2Nap; (f) 3CzB2Nap. Powder XRD patterns of luminogens in different solid states: (g) 3CzB2TPE; (h) 1CzB2Nap; (i) 3CzB2Nap. DSC curves of luminogens before and after grinding: (j) 3CzB2TPE; (k) 1CzB2Nap; (l) 3CzB2Nap. The possible schematic diagrams of individual molecular conformations and dimer packing arrangements of luminogens before and after grinding: (m) 3CzB2TPE; (n) 1CzB2Nap; (o) 3CzB2Nap.

In order to gain insight into these three force-triggered fluorescence responses, powder X-ray diffraction (XRD) techniques were employed to analyse the structural transformations in the solids before and after grinding, and treated with CH2Cl2. As indicated in Fig. 2g, the powder XRD pattern of sample 3CzB2TPE displayed numerous intense diffraction peaks, indicating that it was in a stable crystalline state. However, these sharp diffraction peaks largely disappeared after grinding, which implied the initial crystalline phase was converted into an unstable amorphous phase. After fumigating with CH2Cl2 vapor for 30 seconds, the powder XRD spectrum remained unchanged, confirming its irreversible mechanochromic fluorescent properties. The spectra of 1CzB2TPE, which exhibited a similar mechano-responsive behavior, were also analogous (Fig. S7a†). Subsequently, powder XRD analysis of 1CzB2Nap before and after grinding also showed a transition from the crystalline to amorphous phase. Nevertheless, unlike the previous cases, after treatment with CH2Cl2, the powder XRD pattern of the ground solid returned to its initial state, with sharp diffraction peaks roughly reappearing, verifying its reversibility (Fig. 2h). As illustrated in Fig. S7c,† the powder XRD spectra of 7CzB2Nap presented similar properties. Fluorophore 3CzB2Nap did not display fluorescence changes when subjected to an external mechanical force, as evidenced by the consistent powder XRD spectra observed both before and after grinding, demonstrating that this AIEgen persistently existed in an amorphous state (Fig. 2i). The powder XRD patterns of 7CzB2TPE before and after grinding are presented in Fig. S7b.† The powder XRD tests revealed that the mechanofluorochromism was attributed to mechanical force-induced crystal-to-amorphous morphology transitions.

In addition, 3CzB2TPE, 1CzB2Nap, and 3CzB2Nap were selected as representatives to further investigate phase changes upon grinding through differential scanning calorimetry (DSC) experiments. Both the pristine and ground solids of 3CzB2TPE exhibited a sharp endothermic peak at 343 °C in the DSC curves, corresponding to their melting temperature. However, the intensity of the endothermic peak of solid 3CzB2TPE after grinding significantly decreased, which indicated that pristine solid 3CzB2TPE possessed higher thermostability than ground solid 3CzB2TPE, and this DSC experimental result supported the fact that the transition of solid 3CzB2TPE from a stable crystalline phase to a metastable amorphous phase occurred upon grinding (Fig. 2g). Moreover, the initial cyan fluorescence of solid 3CzB2TPE could not be restored when the ground solid 3CzB2TPE was heated at 220 °C for 1 minute (Fig. S6a†), which was consistent with the absence of an exothermic peak in the DSC curve of the ground solid 3CzB2TPE. The DSC curves of solid 1CzB2Nap before and after grinding presented an intense endothermic peak at approximately 260 °C, corresponding to the melting temperature of the unground and ground solid forms of 1CzB2Nap. Different from 3CzB2TPE, the DSC curve of ground solid 1CzB2Nap featured a cold crystallization exothermic peak at 205 °C before melting, verifying the destruction of its crystalline structure and its morphological transition from crystalline to amorphous states of 1CzB2Nap after mechanical grinding. As can be seen in Fig. S6b,† the orange fluorescence of ground solid 1CzB2Nap could be converted into the initial yellow fluorescence upon heating at 220 °C for 1 minute, which was consistent with the observed exothermic peak in the DSC curve of ground solid 1CzB2Nap, and further confirmed the reversible mechanofluorochromism of 1CzB2Nap that was also verified by the powder XRD experimental results of 1CzB2Nap in various solid states. As depicted in Fig. 2l, the DSC curves of both unground and ground solid forms of 3CzB2Nap exhibited exothermic peaks at 428 °C and 406 °C, respectively, and did not show the endothermic peak, which provided a basis for the amorphous morphological feature of solid 3CzB2Nap before and after grinding (Fig. 2i). Furthermore, we speculated the possible monomer and dimer structures of these three typical AIEgens before and after grinding (Fig. 2m–o). The unground molecular structures were distorted, and the conjugation degrees were low in the dimers. Under an anisotropic mechanical force, the molecular distortions decreased and the degree of overlap in the dimers increased, manifesting the redshifted phenomena. Noticeably, the ground 3CzB2TPE had a higher degree of overlap, corresponding to a larger red shift (Fig. 2m). In contrast, 3CzB2Nap did not respond to force, and its conformation displayed inconspicuous changes before and after grinding (Fig. 2o).

Fortunately, through persistent efforts, we successfully cultivated single crystals of 3CzB2TPE, which allowed us to deeply investigate its mechanofluorochromic mechanism. As can be seen in Fig. S14,† the diffraction peaks in the XRD pattern of the as-synthesized powder sample 3CzB2TPE could be matched with some of the characteristic peaks in the simulated powder XRD pattern of the 3CzB2TPE crystal, and 3CzB2TPE crystals displayed an irreversible mechanical force-induced cyan-to-green fluorescence conversion behavior, which was the same as that of microcrystalline 3CzB2TPE powder (Fig. S15†). As shown in Fig. 3a and b, combining the top view and side view of 3CzB2TPE uncovered its highly twisted conformation due to the existence of TPE and dendrimer-like carbazole units. Although the six types of intermolecular C–H⋯π (ranging from 2.350 Å to 2.878 Å) interactions effectively promoted molecular packing within crystals, the absence of strong intermolecular forces probably brings about a rearrangement of the packing under an external mechanical force (Fig. 3d and e). As a result, the weak intermolecular interactions in 3CzB2TPE disappeared, causing the formation of an unstable state, and the emissive color changed from cyan to green. To deeply understand the frontier molecular orbitals of fluorogen 3CzB2TPE, density functional theory (DFT) calculations were performed on the crystals in both monomer and optimized dimer forms (Fig. 3f and g). The TPE groups possessed the largest highest occupied molecular orbital (HOMO) coefficient, and the phenyl, partial TPE and dendritic carbazole units possessed the largest lowest unoccupied molecular orbital (LUMO) coefficient. For the monomer state of 3CzB2TPE crystals, the calculated energy gap (ΔE) was 3.48 eV. The calculated ΔE of dimer-1 (pre-grinding state) was 3.456 eV, while ΔE of dimer-2 (a simulative post-grinding state) was 3.447 eV, indicating a decrease in the energy gap. This phenomenon could be attributed to the underlying mechanism of the redshifted mechanofluorochromism observed in 3CzB2TPE.


image file: d5qo00393h-f3.tif
Fig. 3 Crystal structure of 3CzB2TPE: (a) top view; (b) side view. (c) Fluorescence photograph of the 3CzB2TPE crystal under 365 nm UV light. (d) Crystal packing diagram of 3CzB2TPE, showing weak intermolecular C–H⋯π interactions. (e) Packing arrangement diagram of 3CzB2TPE. Energy diagrams and the frontier orbital contribution of luminogen 3CzB2TPE in various forms: (f) monomer; (g) diverse dimers.

In the era of knowledge-based economy, information security is of utmost importance. Stimuli-responsive fluorescent materials can provide a novel approach for information encryption and anticounterfeiting. By means of fluorescence responses to specific stimuli, the hiding and verification of information can be achieved, ensuring that only authorized parties can correctly read and identify the information, thus providing a strong guarantee for information security. In this work, three completely different types of force-responsive emissive characteristics were observed from the six reported carbazole luminogens, which provided a firm foundation for the construction of advanced anticounterfeiting systems.

First, by taking advantage of dendritic compounds with diverse force-induced fluorescence responses, a multi-layered painting anti-counterfeiting system was constructed, combining 3CzB2TPE with irreversible mechanofluorochromism, 1CzB2Nap with reversible mechanofluorochromism, and 3CzB2Nap with non-response to mechanical force. Under the irradiation of 365 nm UV light, the powders of 3CzB2TPE and 3CzB2Nap, along with the ground powder of 1CzB2Nap, were adhered to a hard plate to draw an eagle. The two fake eagle paintings, constituted by commercial powders of the corresponding colors, were observed under 365 nm UV light. The authentic painting was obtained through grinding and dichloromethane fumigation treatment. Utilizing the precise sequential treatments of mechanical grinding and subsequent CH2Cl2 vapor fuming on three identical paintings (Fig. 4a–c), the authentic painting (Fig. 4b) was disclosed with exceptional accuracy. The truth of the matter was that in Fig. 4b, the cyan “claw” area was coated with 3CzB2TPE, the orange “wing” section was covered with ground 1CzB2Nap, and the remaining portions of the “eagle's body” were coated with 3CzB2Nap. In Fig. 4a, the depicted “eagle” was entirely coated with commercial pigments matching respective colors, whereas in Fig. 4c, the “claw” segment was coated with 3CzB2TPE, and the rest of the painting employed the corresponding commercial dyes to render a similarly colored pattern. This anti-counterfeiting application could convey the correct information to those who understand the decryption rules, providing a new approach for identifying and filtering out counterfeit images in ambiguous pictures and ensuring the acquisition of the authentic item.


image file: d5qo00393h-f4.tif
Fig. 4 Schematic representation of the painting anti-counterfeiting system based on the contrasting stimuli-responsive fluorescence behaviors of 3CzB2TPE, 1CzB2Nap and 3CzB2Nap.

Additionally, based on the reversible mechanochromic fluorescence of 1CzB2Nap and the similarity between the emissive color of ground 1CzB2Nap and the fluorescence color of 3CzB2Nap, an ingenious encryption application was designed. The ground 1CzB2Nap powder and 3CzB2Nap powder were adhered to a hard paper to create a dual-encryption application that embedded the binary code within a QR code. An orange-colored QR code was created using 3CzB2Nap and ground 1CzB2Nap, with the latter filling the partial blocks in rows nine to twenty-one. Scanning this QR code with a smartphone revealed code 1: MECHANOFLUOROCHROMISM. Subsequently, the entire QR code was exposed to CH2Cl2 vapor for 1 minute, and the squares filled with 1CzB2Nap changed from orange to yellow. As shown in Fig. 5, by extracting the first eight blocks of each row from row nine to twenty-one and setting the orange fluorescent blocks as binary code “0” while the yellow fluorescent blocks as binary code “1”, the message can be decrypted according to the American Standard Code for Information Interchange (ASCII) standard, disclosing code 2: HIGH-CONTRAST. The final password information was the incorporation of code 2 and code 1, namely “HIGH-CONTRAST MECHANOFLUOROCHROMISM”.


image file: d5qo00393h-f5.tif
Fig. 5 Schematic diagram of the encryption application based on the QR code and binary ASCII code, applying different stimuli-responsive fluorescence behaviors of 1CzB2Nap and 3CzB2Nap.

Conclusions

In summary, six dendritic carbazole luminogens were prepared, involving three TPE-functionalized 1CzB2TPE, 3CzB2TPE and 7CzB2TPE and three naphthalimide-modified D–π–A-type 1CzB2Nap, 3CzB2Nap and 7CzB2Nap. All these fluorogenic compounds possessed representative AIE characteristics and emitted high-brightness fluorescence in aggregated states. Notably, the aggregation-triggered self-assembly process of AIE-active 3CzB2Nap into nanorods was vividly visualized via SEM. Additionally, it was worth noting that three completely distinct types of anisotropic force-dependent fluorescence phenomena from the six synthesized carbazole AIEgens were noticed, including irreversible mechanofluorochromic behaviors of 1CzB2TPE and 3CzB2TPE, reversible mechanochromic fluorescence responses of 1CzB2Nap and 7CzB2Nap, and no fluorescence changes of 7CzB2TPE and 3CzB2Nap after grinding. Based on these interesting force-responsive fluorescence properties, a multilevel painting anticounterfeiting system and a multimode information encryption system were skillfully established. Powder XRD and DSC experiments were conducted to elucidate the mechanisms underlying the emergence of three disparate types of force-responsive fluorescence phenomena. Meanwhile, the molecular structure of 3CzB2TPE was characterized by the single-crystal X-ray diffraction technique, and its molecular conformation and intermolecular interactions were systematically analyzed. Furthermore, the molecular simulation of the dimer of 3CzB2TPE after grinding and the theoretical calculations of the energy levels of the dimers of 3CzB2TPE before and after grinding were completed to deeply understand the mechanism of its mechanofluorochromism. This work not only provides a significant reference for the preparation of dendritic carbazole AIEgens with self-assembly and various force-responsive fluorescence characteristics but also offers ingenious inspiration for their anticounterfeiting applications involving mechanofluorochromic luminogens.

Data availability

The data supporting this article have been included as part of the ESI.†

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

We are grateful for financial support from the National Natural Science Foundation of China (22361020 and 22175069), the Natural Science Foundation for Distinguished Young Scholars of Jiangxi Province (20212ACB213003), the Academic and Technical Leader Plan of Jiangxi Provincial Main Disciplines (20212BCJ23004), and the Open Fund Project of Jiangxi Province Key Laboratory of Organic Functional Molecules (2024KFJJ14). This work is also supported by the Jiangxi Province Key Laboratory of Organic Functional Molecules (No. 2024SSY05141).

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Footnote

† Electronic supplementary information (ESI) available. CCDC 2419146. For ESI and crystallographic data in CIF or other electronic format see DOI: https://doi.org/10.1039/d5qo00393h
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