Creation of new fluorophores is important for understanding the structure–property relationship, by which the required optical properties are likely to be attained. Herein, through theory calculation, it is found that furan-modified thiadiazolo quinoxaline acting as an electron acceptor can endow donor–acceptor–donor (D–A–D) type second near-infrared (NIR-II) fluorophores with longer emission wavelength than the other thiadiazolo quinoxaline-based acceptors containing pyridine, pyrrole, thiophene, and phenyl groups, respectively. On the basis of this theoretical prediction, a D–A–D type NIR-II fluorophore with 6,7-di(furan-2-yl)-[1,2,5]thiadiazolo[3,4-g] quinoxaline (DFTQ) as the acceptor and dithieno[3,2-b:2′,3′-d]pyrrole (DTP) as the donor is designed and synthesized, and the aggregation-induced emission (AIE) function is further achieved by introducing the AIE units of tetraphenylethylene (TPE) and triphenylamine (TPA), respectively, totally forming three NIR-II fluorophores DFTQ–DTP, DFTQ–DTPE, and DFTQ–DTPA. For biological applications, the fluorophores are encapsulated by amphiphilic DSPE–PEG₂₀₀₀ to generate water-dispersible nanoparticles (NPs). Almost the whole emission of each of the NPs falls into the NIR-II spectral range, with part emission beyond 1300 nm. By using DFTQ–DTPA NPs as the contrast and photothermal therapy (PTT) agent, high-resolution in vivo fluorescence imaging is achieved in the greater than 1300 nm window, and their good performance in photoacoustic imaging and high tumor PTT efficacy in tumor-bearing mice are also demonstrated. Taken together, this work mainly provides a strong electron acceptor for constructing long-emitting fluorophores, and by using the electron acceptor, a AIE fluorophore with desirable quantum yield (QY) and photothermal conversion efficienciy (PCE) is synthesized and demonstrated to be promising in fluorescence/photoacoustic imaging and PTT.

中文翻译：

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呋喃修饰的噻二唑喹喔啉作为电子受体，用于构建第二个近红外聚集诱导发射荧光团，用于超过 1300 nm 的荧光/光声成像和光热治疗

创造新的荧光团对于理解结构-性质关系很重要，通过这种关系可能获得所需的光学性质。本文通过理论计算发现，呋喃修饰的噻二唑喹喔啉作为电子受体可以赋予供体-受体-供体（D-A-D）型第二近红外（NIR-II）荧光团，其发射波长比其他基于噻二唑并喹喔啉的受体分别含有吡啶、吡咯、噻吩和苯基。基于这一理论预测，具有 6,7-二(呋喃-2-基)-[1,2,5]噻二唑并[3,4-g]喹喔啉的 D-A-D 型 NIR-II 荧光团（设计并合成了DFTQ)作为受体和二噻吩并[3,2-b:2′,3′-d]吡咯(DTP)作为供体,并通过引入四苯乙烯（TPE）和三苯胺（TPA）的AIE单元分别形成三个NIR-II荧光团DFTQ-DTP、DFTQ-DTPE和DFTQ-DTPA。对于生物应用，荧光团被两亲性 DSPE-PEG ₂₀₀₀封装以生成水分散性纳米颗粒 (NP)。几乎每个纳米粒子的全部发射都落在 NIR-II 光谱范围内，部分发射超过 1300 nm。通过使用DFTQ-DTPA NPs作为造影剂和光热治疗（PTT）剂，在大于1300 nm的窗口内实现了高分辨率的体内荧光成像，并且其在荷瘤中具有良好的光声成像性能和高肿瘤PTT功效还对小鼠进行了演示。综上所述，这项工作主要为构建长发射荧光团提供了强电子受体，并通过使用电子受体合成了具有理想量子产率（QY）和光热转换效率（PCE）的AIE荧光团，并被证明在荧光/光声成像和 PTT。