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The disposal of long-wavelength-emitting sources is of paramount relevance in technology and biophotonics due to the low interference with the surroundings that these kinds of far-red and near-infrared radiations hold. As a result of the continued efforts carried out during the last few years by our research group to design new boron-dipyrromethene (BODIPY) dyes with improved photonic performance, two approaches were tested to develop a new generation of organic dyes able to display efficient and long-lasting laser emission in both target spectral regions. On the one hand, the annulation of aromatic benzofuran at the dipyrrin backbone leads to conformationally restricted dyes yielding photostable and bright laser emission beyond 600 nm at the far-red spectral region. On the other hand, a more pronounced shift to longer wavelengths reaching 725 nm at the near-infrared region is feasible, while keeping a reasonably high laser efficiency and tolerance to prolonged and intense pumping, based on aza-BODIPYs bearing peripheral aryl rings. These two complementary strategies yield a library of laser-emitting compounds comprising the 600–725 nm spectral region. Moreover, their laser performance is better than the commercially available dye lasers active in this spectral window.

Small molecular NIR‐II dyes are highly desirable for various biomedical applications. However, NIR‐II probes are still limited due to the complex synthetic processes and inadequate availability of fluorescent core. Herein, the design and synthesis of three small molecular NIR‐II dyes are reported. These dyes can be excited at 850–915 nm and emitted at 1280–1290 nm with a large stokes shift (≈375 nm). Experimental and computational results indicate a 2:1 preferable host–guest assembly between the cucurbit[8]uril (CB) and dye molecules. Interestingly, the dyes when self‐assembled in presence of CB leads to the formation of nanocubes (≈200 nm) and exhibits marked enhancement in fluorescence emission intensity (Switch‐On). However, the addition of red carbon dots (rCDots, ≈10 nm) quenches the fluorescence of these host–guest complexes (Switch‐Off) providing flexibility in the user‐defined tuning of photoluminescence. The turn‐ON complex found to have comparable quantum yield to the commercially available near‐infrared fluorophore, IR‐26. The aqueous dispersibility, cellular and blood compatibility, and NIR‐II bioimaging capability of the inclusion complexes is also explored. Thus, a switchable fluorescence behavior, driven by host–guest complexation and supramolecular self‐assembly, is demonstrated here for three new NIR‐II dyes. Three small molecular NIR‐II dyes are employed those exhibit marked enhancement in emission intensity (Switch‐On) when self‐assembled in presence of cucurbit[8]uril. Further addition of red carbon dots to the nanocubes leads to the queching of fluorescence of these host–guest complexes (Switch‐Off) providing flexibility in the user‐defined tuning of photoluminescence.

The development of photoactivatable theranostic probes represents a major focus in precision tumor therapy. However, those previously reported probes often suffer from limited photoresponsivity, short excitation/emission wavelengths, and inactivity in the absence of light, restricting their ability to precisely diagnose deep‐seated tumors or enable effective phototherapy without auxiliary interventions. To address these challenges, this study designs a second near‐infrared (NIR‐II) aggregation‐induced emission (AIE) theranostic probe based on a dihydroindole skeleton, featuring dual reactive oxygen species (ROS)‐ and NIR light‐cascade activation. Upon ROS activation in the tumor microenvironment, TT‐DHIn undergoes transformation into TT‐In, exhibiting NIR‐II fluorescence emission and photodynamic/photothermal therapy (PDT/PTT) capabilities, thereby serving as a photoactivatable “guiding radar” with an exceptional signal‐to‐background ratio. Following pre‐activation, TT‐In efficiently generates ROS under 660 nm laser irradiation, enabling self‐supplementation of intratumor ROS. Furthermore, the intratumor TT‐DHIn undergoes cyclic conversion into TT‐In, significantly enhancing phototherapeutic efficacy and demonstrating potent in vitro cytotoxicity and in vivo tumor eradication. This dual‐activatable cascade strategy synergistically integrates tumor biomarker (ROS) responsiveness with photoactivation, offering a promising platform for NIR‐II imaging‐guided precision phototheranostics with strong potential for clinical translation. ROS‐ and NIR light‐cascade activatable NIR‐II AIE theranostic probe (TT‐DHIn) is developed by integration of dihydroindole skeleton with oxidative dehydrogenation reaction mechanism and AIE skeleton with a twisted configuration. Upon ROS in the tumor microenvironment and NIR light activation, TT‐DHIn can achieve dual‐model imaging‐guided precise tumor therapy with the philosophy of “pre‐localizing tumor, then self‐amplifying phototherapy”.

Self‐trapped excitons (STEs) are generating significant interest due to their broadband emission and self‐absorption‐free advantages. However, achieving high‐efficiency singlet/triplet STE near‐infrared (NIR) emissive tuning remains challenging issues that originate from energy gap law and large Stokes shift. Herein, novel manganese iodide dimers have been demonstrated in CsI crystalline matrix with high photoluminescence quantum yields of 18% and 25% for singlet and triplet STE emissions up to 1200 nm, respectively, where ultrafast spin‐flip process from triplet to singlet excited states is realized via Pb2+‐doping strategy. Temperature‐dependent steady‐state, electron paramagnetic resonance, femtosecond transient absorption spectroscopic techniques and theoretical calculations verify intersystem crossing, and reverse intersystem crossing (RISC) processes are governed by the interplay between spin‐orbit coupling (SOC) and Jahn–Teller (JT) effect. RISC is accelerated by enhanced SOC due to heavy‐atom effects (Pb and I), suppressed JT distortions, and reduced excited‐state structural reorganization, leading to RISC rate as fast as 6.7 × 1011 s‒1, more than two‐order‐of‐magnitude enhancement before Pb doping. Moreover, a unified framework is developed including Mn2+‐Mn2+ ion pair, molecular orbital, and configurational coordinate diagram to interpret STE‐based NIR emissions in 0D systems. These findings gain deep insights into ultrafast STE dynamics for designing highly emissive NIR materials toward photonic applications. Here, unique 0D manganese iodide dimers are developed where Pb2+‐induced strong spin‐orbit coupling can accelerate reverse intersystem crossing for rapid spin‐flip from triplet to singlet manifold, and suppress Jahn–Teller distortions and excited‐state structural reorganization for regulating self‐trapped exciton near‐infrared‐II emissions with high quantum efficiencies toward multiplexed optical information storage.

C dots (CDs) have shown great potential in bioimaging and phototherapy. However, it is challenging to manipulate their fluorescent properties and therapeutic efficacy to satisfy the requirements for clinic applications. In this study, we prepared S, Se-codoped CDs via a hydrothermal method and demonstrated that the doping resulted in excitation wavelength-independent near-infrared (NIR) emissions of the CDs, with peaks at 731 and 820 nm. Significantly, the CDs exhibited a photothermal conversion efficiency of ~58.2%, which is the highest reported value for C nanostructures and is comparable to that of Au nanostructures. Moreover, the CDs had a large two-photon absorption cross section (~30,045 GM), which allowed NIR emissions and the photothermal conversion of the CDs through the two-photon excitation (TPE) mechanism. In vitro and in vivo tests suggested that CDs can function as new multifunctional phototheranostic agents for the TPE fluorescence imaging and photothermal therapy of cancer cells.

Three‐photon (3P) fluorescence imaging (FLI) utilizing excitation wavelengths within the near‐infrared‐III (NIR‐III, 1600–1870 nm) window has emerged as a transformative modality for intravital imaging, owing to its combined advantages of excellent spatiotemporal resolution and remarkable tissue penetration. High‐performance fluorescent probes are the cornerstone of high‐quality NIR‐III 3P FLI. However, the construction of such probes is often hindered by inherent trade‐offs in molecular design principles, posing significant challenges for their performance optimization and practical application. Here, we propose a straightforward and effective strategy based on π‐bridge manipulation to reconcile those competing molecular design parameters and substantially enhance 3P fluorescence properties. Leveraging this approach, a robust AIE‐active small molecule, named TSSID, was developed, which exhibits bright NIR‐I (700–950 nm) emission under 1665 nm NIR‐III 3P excitation when formulated into nanoparticles (NPs). Remarkably, upon retro‐orbital injection into mice following craniotomy, TSSID NPs achieved the best performance in deep‐brain angiography among all reported organic 3P materials in terms of vascular imaging depth, signal‐to‐background ratio, spatial resolution, and hemodynamic imaging depth. Additionally, TSSID NPs demonstrated outstanding biocompatibility through systematic biosafety evaluations. This study provides an excellent imaging agent and useful molecular design philosophy, facilitating the development of advanced organic 3P FLI probes. A robust NIR‐III 3P excitable AIE probe was developed based on the proposed design strategy of π‐bridge manipulation to reconcile competing molecular parameters and optimize 3P fluorescence properties, which achieved optimal quality in intravital deep‐brain angiography among all reported organic 3P probes in terms of vascular imaging depth, SBR, spatial resolution, and hemodynamic imaging depth after formulated into nanoparticles.

Near-infrared (NIR) fluorescence materials have exhibited formidable power in the field of biomedicine, benefiting from their merits of low autofluorescence background, reduced photon scattering, and deeper penetration depth. Fluorophores possessing planar conformation may confront the shortcomings of aggregation-caused quenching effects at the aggregate level. Fortunately, the concept of aggregation-induced emission (AIE) thoroughly reverses this dilemma. AIE bioconjugates referring to the combination of luminogens showing an AIE nature with biomolecules possessing specific functionalities are generated via the covalent conjugation between AIEgens and functional biological species, covering carbohydrates, peptides, proteins, DNA, and so on. This perfect integration breeds unique superiorities containing high brightness, good water solubility, versatile functionalities, and prominent biosafety. In this review, we summarize the recent progresses of NIR-emissive AIE bioconjugates focusing on their design principles and biomedical applications. Furthermore, a brief prospect of the challenges and opportunities of AIE bioconjugates for a wide range of biomedical applications is presented.

Photoactivatable nitric oxide donors (photoNORMs) are promising agents for controlled NO release and real-time optical tracking in biomedical theranostics. Here, we report a comprehensive density functional theory (DFT) and time-dependent DFT (TDDFT) study on a series of hybrid ruthenium–gold nanocluster systems of the general formula [(L)Ru(NO)(SH)@Au20], where L = salen, bpb, porphyrin, or phthalocyanine. Structural and bonding analyses reveal that the Ru–NO bond maintains a formal RuNO6 configuration with pronounced Ru → π*(NO) backbonding, leading to partial reduction of the NO ligand and an elongated N–O bond. Natural Bond Orbital (NBO), Natural Energy Decomposition Analysis (NEDA), and Extended Transition State–Natural Orbitals for Chemical Valence (ETS–NOCV) analyses confirm that Ru–NO bonding is dominated by charge-transfer and polarization components, while Ru–S and Au–S linkages exhibit a delocalized, donor–acceptor character coupling the molecular chromophore with the metallic cluster. TDDFT results reproduce visible–near-infrared (NIR) absorption features arising from mixed metal-to-ligand and cluster-mediated charge-transfer transitions. The calculated zero–zero transition and reorganization energies predict NIR-II emission (1.8–3.8 μm), a region of high biomedical transparency, making these systems ideal candidates for luminescence-based NO sensing and therapy. This study establishes fundamental design principles for next-generation Ru-based photoNORMs integrated with plasmonic gold nanoclusters, highlighting their potential as multifunctional, optically trackable theranostic platforms.

Selective doping of Ni 2+ in octahedral sites provided by nanocrystals embedded in glass-ceramics (GCs) is crucial to the enhancement of broadband near-infrared (NIR) emission. In this work, a NIR emission with a full-width-at-half-maximum (FWHM) of 288 nm is first reported from ZnGa 2 O 4 : Ni 2+ nano-spinels embedded GCs with excellent transparency. A comparison is made of the NIR luminescence properties of Ni 2+ doped GCs containing ZnGa 2 O 4 , germanium-substituted ZnGa 2 O 4 nano-spinels (Zn 1+ x Ga 2−2 x Ge x O 4 ), and Zn 2 GeO 4 /Li 2 Ge 4 O 9 composite nanocrystals that are free of Ga 3+ . The results show that ZnGa 2 O 4 : Ni 2+ GCs exhibit a significantly enhanced NIR emission. The incorporation of the nucleating agent TiO 2 is favored in terms of the increased luminescence intensity and prolonged lifetime. The possible causes for the enhancement effect are identified from the crystal structure/defects viewpoint. The newly developed GCs incorporate good reproducibility to allow for a tolerance of thermal treatment temperature and hence hold great potential of fiberization via the recently proposed “melt-in-tube” method. They can be considered as promising candidates for broadband fiber amplifiers.

Fluorescent organic dyes that absorb and emit in the near-infrared (NIR, 700–1000 nm) and shortwave infrared (SWIR, 1000–1700 nm) regions have the potential to produce noninvasive high-contrast biological images and videos. BODIPY dyes are well known for their high quantum yields in the visible energy region. To tune these chromophores to the NIR region, fused nitrogen-based heterocyclic indolizine donors were added to a BODIPY scaffold. The indolizine BODIPY dyes were synthesized via microwave-assisted Knoevenagel condensation with indolizine aldehydes. The non-protonated dyes showed NIR absorption and emission at longer wavelengths than an aniline benchmark. Protonation of the dyes produced a dramatic 0.35 eV bathochromic shift (230 nm shift from 797 nm to 1027 nm) to give a SWIR absorption and emission (λmaxemis = 1061 nm). Deprotonation demonstrates that material emission is reversibly switchable between the NIR and SWIR.