Rational design of photofunctional dyes BODIPYs/aza-BODIPYs and applications for photocatalysis, photoelectric conversion and thermochromic materials

4,4-Difluoro-4-bora-3a,4a-diaza-sindacene (BODIPY) is a sort of photofunctional dye which possesses advantages including strong light-capturing property, high photon-resistance, etc. Meso-N substituted aza-BODIPY is a crucial derivative of BODIPY scaffold that has the favorable optical properties and a significant spectral redshift. The photophysical properties can be tuned by molecular design, and the attenuation path of the excited state energy release of absorbed light energy can be well controlled via structural modifications, enabling tailored application. It has been extensively employed in life medicine fields including fluorescence imaging diagnosis, photodynamic therapy photosensitizer and photothermal therapy reagent and so forth. Extensive research and review have been performed in these areas. However, BODIPYs/aza-BODIPYs have a significant role in energy, catalysis, optoelectronics, photo-responsive materials and other fields. Nevertheless, there are relatively few studies and reviews in these fields on the modification and application based on BODIPY/aza-BODIPY scaffold. Herein, in this review we summarized the application of BODIPY/aza-BODIPY in the aforementioned fields, with the molecular regulation of dye as the foundation and the utilization in the above fields as the objective, in the intention of providing inspiration for the exploration of innovative BODIPY/aza-BODIPY research in the field of light resource conversion and functional materials.

氮杂氟硼荧(Aza-BODIPY)染料的研究进展

Aza-BODIPY荧光染料是一种新型荧光化合物,因其突出的优点而得到广泛地应用。从其应用的三方面(光动力学疗法的光敏剂、可控制的荧光传感器、近红外区域的荧光探针)详细描述了Aza-BODIPY荧光染料的研究进展,展望了该领域的研究发展方向。

Julolidinyl aza-BODIPYs as NIR-Ⅱ fluorophores for the bioimaging of nanocarriers

The aggregation-caused quenching(ACQ)rationale has been employed to improve the fluorescence imaging accuracy of nanocarriers by precluding free probe-derived interferences.However,its usefulness is undermined by limited penetration and low spatiotemporal resolution of NIR-Ⅰ(700-900 nm)bioimaging owing to absorption and diffraction by biological tissues and tissue-derived autofluorescence.This study aimed to develop ACQ-based NIR-Ⅱ(1000-1700 nm)probes to further improve the imaging resolution and accuracy.The strategy employed is to install highly planar and electron-rich julolidine into the 3,5-position of aza-BODIPY based on the larger substituent effects.The newly developed probes displayed remarkable photophysical properties,with intense absorption centered at approximately 850 nm and bright emission in the 950-1300 nm region.Compared with the NIR-Ⅰ counterpart P2,the NIR-Ⅱ probes demonstrated superior water sensitivity and quenching stability.ACQ1 and ACQ6 exhibited more promising ACQ effects with absolute fluorescence quenching at water fractions above 40% and higher quenching stability with less than 2.0% fluorescence reillumination in plasma after 24 h of incubation.Theoretical calculations verified that molecular planarity is more important than hydrophobicity for ACQ properties.Additionally,in vivo and ex vivo reillumination studies revealed less than 2.5% signal interference from prequenched ACQ1,in contrast to 15% for P2.

Heavy-atom-free orthogonal configurative dye 1,7-di-anthra-aza-BODIPY for singlet oxygen generation

Spin-orbit,charge-transfer intersystem crossing(SOCT-ISC)can directly overcome the disadvantages of the traditional heavy-atom effect and improve the generation efficiency of reactive oxygen species(ROS).Since orthogonal molecular orbitals of donor-acceptor(D-A)pairs favor the SOCT-ISC transition,herein aza-borondipyrromethenes(aza-BODIPYs)with 1,7-di-anthracyl groups(An-azaBDP)was successfully prepared,owing to steric hindrance to produce a big dihedral angle between the two molecular orbital(MO)planes.Moreover,according to density functional theory(DFT)and time-dependent density functional theory(TDDFT),the energy difference between the S1-T1orbitals of An-aza BDP is small and more inclined towards ISC.An-aza BDP can effectively generate singlet oxygen under light irradiation.An-aza BDP with light irradiation can induce apoptosis in SW620 cells,and can serve as a potential candidate for the treatment of cancer cells and tumors.

Aza-BODIPY dye with unexpected bromination and high singlet oxygen quantum yield for photoacoustic imaging-guided synergetic photodynamic/photothermal therapy

Introducing heavy halogen atoms into organic small molecules is a practical strategy for efficient singlet oxygen(^(1)O_(2))generation.Generally,bromine or iodine atoms are introduced on the aza-borondipyrromethene(aza-BODIPY)core,rather than on the periphery aryl rings for efficient~1O_(2) generation.Herein,an aza-BODIPY dye NBDPBr with unexpected bromination on the periphery aryl rings was synthesized for photoacoustic(PA)imaging-guided synergistic photothermal therapy(PTT)and photodynamic therapy(PDT)in tumor cells.Owing to unexcepted bromination at the periphery aryl rings,NBDPBr demonstrated an outstanding singlet oxygen quantum yield(Φ_(Δ))of 66% which was superior to similar brominated photosensitizers previously reported.After encapsulation with amphiphilic polymer F-127,hydrophilic NBDPBr nanoparticles(NPs)were fabricated and exhibited an excellent photothermal conversion efficiency(η)of 43.0% under 660 nm photoirradiation.In vivo PA imaging results demonstrated that NBDPBr NPs could specifically accumulate at tumor sites and realized the maximum tumor retention at 7 h post-injection.All the in vitro and in vivo results indicated the significant potence of NBDPBr with unexpected bis-bromination for PA imaging-guided synergetic PDT/PTT.

Aza-BODIPY荧光染料的合成、表征及性能研究

aza-BODIPY荧光染料是近10年发展起来并受到广泛关注的一类新型荧光化合物,它极有可能发展成可应用于光动力学治疗的光敏剂.本工作合成了5个aza-BODIPY 1a～1e,用IR,NMR,MS和元素分析对它们进行了表征.研究了它们的紫外吸收光谱与荧光发射光谱,结果表明1a～1e具有较高的摩尔吸光系数,在aza-BODIPY母环的3,5位或1,7位的苯环4位有供电子取代基时能使化合物的最大紫外吸收波长和荧光发射波长红移.测试了1a～1d的循环伏安曲线,根据各化合物的氧化还原电位讨论了它们的结构稳定性.

Synthesis of aza-BODIPY dyes bearing the naphthyl groups at 1,7-positions and application for singlet oxygen generation

Using 2-vinylnaphthalene,aza-BODIPYs with the naphthyl groups at 1,7-positions were prepared and their photophysical properties were characterized.Due to attachment of the naphthyl groups at1,7-positions,aza-BODIPYs show long-wavelength absorption and emission in the near-infrared region.The singlet oxygen generation of the dibromo substituted aza-BODIPY with the naphthyl groups at1,7-positions as a photosensitizer was more effective than that of the corresponding aza-BODIPY with the phenyl groups at 1,7-positions.No photobleaching of the naphthyl-containing aza-BODIPY was observed and such NIR aza-BODIPY could be used for the singlet oxygen generation.

Aza-BODIPY molecular assembly at the liquid-solid interface driven by Br…F-BF interactions

In this work,two aza-BODIPY derivatives,3,5-diphenyl-1,7-di(p-dodecyloxyphenyl)-aza-BODIPY(CJF)and 3,5-di(p-bromophenyl)-1,7-di(p-dodecyloxyphenyl)-aza-BODIPY(2Br-CJF)acted as model molecules to form the self-assembly monolayers on the solid-liquid interface.With the utilizing of scanning tunnelling microscope(STM),we demonstrated that intermolecular Br…F-BF interactions existed in 2Br-CJF self-assembly structure and played an important role in strengthening the stability of 2Br-CJF self-assembly structure.This result is supported by density functional theory(DFT)calculation.

Near-infrared Aza-BODIPY Dyes Through Molecular Surgery for Enhanced Photothermal and Photodynamic Antibacterial Therapy

The widespread use of high-dose antibiotics will not only lead to the rapid acquisition of antibiotic resistance and increased incidence of drug-resistant bacterial infections, but also produce toxic side effects on normal tissues. Herein, two near-infrared dyes BDP-4PTZ and BDP-4DPA were synthesized, and the electron donors of diphenylamine and phenothiazine with the only difference of sulphur(S)-lock between the two phenyl rings were introduced onto the electron acceptor aza-dipyrromethene boron difluoride(aza-BODIPY) through molecular surgery. Through co-precipitation into nanoparticles(NPs), BDP-4PTZ NPs and BDP-4DPA NPs were fabricated with good biocompatibility. Upon 660 nm photoirradiation, BDP-4PTZ NPs and BDP-4DPA NPs showed excellent photothermal conversion efficiency(43% and 50%, respectively) and reactive oxygen species(ROS) production performance(ca. 3.6 and 6 times higher than that of indocyanine green, respectively). In vitro antibacterial experiments indicated that both NPs could effectively destroy the bacteria’s membrane to eradicate drug-resistant bacteria. Furthermore, the bacterial abscess was effectively eliminated after treatment with BDP-4DPA NPs under 660 nm photoirradiation without adverse effects. Thus, through molecular surgery, BDP-4DPA without the S-lock demonstrates synergistic photothermal and photodynamic antimicrobial activities, which is promising for further molecular design towards effective neo-antimicrobial phototherapy.

Near-infrared absorbing(>700 nm)aza-BODIPYs by freezing the rotation of the aryl groups

The typical aza-BODIPYs in the dye family are known for bright fluorescence,excellent stability,and tunable absorption wavelengths.Hence,these dyes are attracting the increasing attention.Aza-BODIPYs having the maxima absorption in the near-infrared(NIR)region(650-900 nm)are very favorable for bioimaging in vivo due to the less photo-damage,deeper tissue penetration,and less interference from background auto-fluorescence by biomolecules in the living systems.Many strategies have been employed to modify the structures of the aza-BODIPY core to provide the NIR absorbing dyes.Among these,the most effective method is the fusion of the aromatic rings in aza-BODIPY system.This review allsidedly summarizes the recent development of ring-fused aza-BODIPY dyes(λ_(abs)>700 nm)focusing on the design,synthesis,and potential applications in the NIR region since 2002.

Aza-BODIPY based probe for photoacoustic imaging of ONOO;in vivo

The effective detecting ONOO^(-)variations in vivo is of great importance to well understand the complex pathophysiological processes. We reported here a photoacoustic(PA) probe AZB-1 for imaging ONOO;in vivo. AZB-1 showed an originally strong photoacoustic signal at 660 nm. And its PA signal can be turned off by shutting the ICT effect caused by the conjugated electron withdrawing group at 2-position of the aza-BODIPY core. Moreover, the probe was successfully employed to imaging ONOO^(-)variations in inflammatory mice models. Wisely utilized this strategy may serve as powerful platforms for the preparation of novel PA chemosensors.

Synthesis,characterization,and tunable semiconducting properties of aza-BODIPY derived polycyclic aromatic dyes

Azadipyrromethene derived polycyclic aromatic complexes(HBPs)containing thirteen fused rings have been synthesized,which show highly selective intense absorption in the near infrared spectrum(NIR)region with high photo-and thermo-stability.The periphery alkoxy and alkyl substituents greatly affect their molecular packing structures in thin films and their thin film transistor performances.With the simple changes of the alkyl substituents,the packing structures changed from discrete-grain with H-aggregation type absorption to lamellar packing with J-aggregation type absorption,and the semiconducting properties were modulated from p-type to interesting ambipolar-type in solution-processed organic field effect transistors(OFETs)with hole and electron mobilities reaching to 0.42 and 0.17 cm^2 V^-1 s^-1,respectively.

二吡咯亚甲基(DPM)类染料在有机光电器件中的应用研究进展

二吡咯亚甲基(DPM)和氮杂二吡咯亚甲基(ADPM)类功能材料具有良好的光电性质,这些发色基团及其分别通过与BF2螯合得到的BODIPY和Aza-BODIPY是众所周知的良好的荧光剂,其在有机光伏(OPV)器件方面得到了广泛应用。详述了基于DPM和ADPM结构物质的设计、合成方法和光物理性质研究,总结当前研究进展,展望应用于下一代小分子和体异质结太阳能电池的基于DPM和ADPM结构的有机光伏的设计方向。

J-aggregation of photosensitizers leads to an ultrahigh drug-loading system for targeted delivery

Drug loading capacity is very important in the construction of targeted drug delivery systems(TDDSs)for the improvement of drug delivery efficiency.However,the drug-loading capacity of most nanomaterials is non-idealistic,and developing the high drug-loading TDDSs is still a critical challenge.In this work,an ultrahigh loading system(denoted as HMPB_(2))was prepared via J-aggregation of an aza-boron dipyrromethene derivative(Bod)by using hollow MnO_(2)modified with glucosamine pillar[5]arene as a carrier,which was demonstrated to have typical J-aggregate absorption of Bod,specific cancer cells targeting ability,negligible dark cytotoxicity,and potent phototoxicity.This work provides a successful example to construct an ultrahigh drug-loading system via J-aggregation for targeted delivery.

Near-infrared fluorophores with absolute aggregation-caused quenching and negligible fluorescence re-illumination for in vivo bioimaging of nanocarriers

Environment-responsive fluorophores with aggregation-caused quenching(ACQ)properties have been applied to track nanocarriers with reduced artefacts caused by unbound or free fluorophores but suffer from incomplete fluorescence quenching and significant re-illumination,which undermine bioimaging accuracy.Herein,through structural modifications to reinforce the hydrophobicity,planarity and rigidity of fluorophores with an aza-BODIPY framework,probes featuring absolute ACQ(aACQ)and negligible re-illumination are developed and evaluated in various nanocarriers.aACQ probes,FD-B21 and FD-C7,exhibit near-infrared emission,high quantum yield,photostability,water sensitivity,and negligible re-illumination in blood,plasma and 1%Tween-80 in contrast to ACQ probe P2 and conventional probe DiR.All nanocarriers can be labeled efficiently by the tested fluorophores.Polymeric micelles(PMs)labeled by different aACQ probes manifest similar biodistribution patterns,which however differ from that of DiR-labeled PMs and could be ascribed to the appreciable re-illumination of DiR.Significantly lower re-illumination is also found in aACQ probes(2%-3%)than DiR(20%-40%)in Caco-2,Hela,and Raw264.7 cells.Molecular dynamics simulations unravel the molecular mechanisms behind aggregation and re-illumination,supporting the hypothesis of planarity dependency.It is concluded that aACQ fluorophores demonstrate excellent water sensitivity and negligible fluorescence re-illumination,making themselves useful tools for more accurate bioimaging of nanocarriers.