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When encountering complex fluorescence decays that deviate from exponentiality, a very appealing approach is to use lifetime or rate constant distributions. These are related by Laplace transform to the sum of exponential functions, stretched exponentials, Becquerel's decay function, and others. However, the limitations of this approach have not been sufficiently discussed in the literature. In particular, the time-independent probability distributions of the rate constants or decay times are occasionally used to describe bimolecular quenching. We show that in such a case, this mathematical formalism has a clear physical interpretation only when the fluorophore and quencher molecules are immobile, as in the solid state. However, such an interpretation is no longer possible once we consider the motion of fluorophores with respect to quenchers. Therefore, for systems in which the relative motion of fluorophores and quenchers cannot be neglected, it is not appropriate to use the time-independent rate or decay time distributions to describe, fit, or rationalize experimental results on fluorescence decay. [ABSTRACT FROM AUTHOR]

Photolysis of aryl azides is a convenient method to approach more functionalized systems in chemical biology. Here, we present a set of photoactivatable aryl azides that undergo controlled reaction pathways within the cucurbit[7]uril (CB7) cavity upon photolysis. The fluorescence turn-on process is utilized for bioimaging. [ABSTRACT FROM AUTHOR]

The second near‐infrared window (NIR‐II) fluorescence imaging has aroused more and more interest in biomedical applications due to negligible autofluorescence and deep penetration ability. However, the fluorescence quantum yield of NIR‐II fluorophores with more than 1100 nm emission wavelength is typically less than 1%, thus limiting the imaging quality of deep tissues. In this study, a novel NIR‐II organic small molecule CTB1125 is designed and synthesized. Due to an efficient intramolecular charge transfer (ICT) facilitated by a high donor‐acceptor‐donor (D‐A‐D) strength structure, CTB1125 exhibits a maximum emission wavelength of 1125 nm. Additionally, branched alkyl chains are modified on the conjugated fused ring backbone to reduce intermolecular stacking. CTB1125 is encapsulated in the amphiphilic copolymer PS2000‐PEG2000 to form CTB1125‐NPs, which exhibit ultrahigh fluorescence quantum yield up to 4.84% in aqueous solution, excellent photostability, and high signal‐to‐noise rate. Due to these outstanding properties, CTB1125‐NPs have been successfully used for clear and long‐duration NIR‐II vessel imaging with small amounts of CTB1125‐NPs, low laser power and short exposure time, and precisely guiding the surgical resection of tumors in mice through fluorescence imaging. This work provides a promising NIR‐II fluorophore with ultrahigh brightness for deep‐tissue imaging and imaging‐guided surgery. [ABSTRACT FROM AUTHOR]

A novel category of asymmetric boron chromophores with the attachment of two BF2 moieties denoted as BOPAM has been successfully synthesized via a one‐pot three‐step reaction starting from N‐phenylbenzothioamide. This synthetic route results in the production of [a] and [b]benzo‐fused BOPAMs along with post‐functionalization of the [a]benzo‐fused BOPAMs. The photophysical properties of these compounds have been systematically investigated through steady‐state absorption and fluorescence emission measurements in solvents at both ambient and cryogenic temperatures, as well as in the solid state. Computational methods have been employed to elucidate the emissive characteristics of the benzo‐fused BOPAMs, revealing distinctive photophysical attributes, including solvent‐dependent fluorescence intensity. Remarkably, certain BOPAM derivatives exhibit noteworthy photophysical phenomena, such as the induction of off‐on fluorescence emission under specific solvent conditions and the manifestation of intermolecular charge transfer states in solid‐state matrices. Through post‐functionalization strategies involving the introduction of electron‐donating groups onto the [a]benzo‐fused BOPAM scaffold, an intramolecular charge transfer (ICT) pathway is activated, leading to substantial fluorescence quenching via non‐radiative decay processes. Notably, one [a]benzo‐fused BOPAM variant exhibits a pronounced fluorescence enhancement upon exposure to acidic conditions, thereby underscoring its potential utility in pH‐sensing applications. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are crystalline materials characterized by their porous structures, formed through coordination bonding between metal ions/clusters and multidentate organic linkers. MOFs have emerged as a significant class of materials with applications in energy storage, CO2 adsorption, and catalysis. This study serves as a brief introduction to the currently available synthesis methods of MOFs, aimed at acquainting beginners in the field of chemical engineering with the ongoing developments in MOF research. The discussed synthesis methods encompass traditional solvothermal/hydrothermal approaches, microwave synthesis of MOFs, one-pot synthesis, MOF nanocomposites, isothermal synthesis, and fluid-fluid synthesis. Notably, the MOF/NH2/Fe3O4 combination exhibited enhanced adsorption capacity of 618 mg/g and retained an efficiency of over 90 %. This study displays a valuable technique for designing functional MOF hybrid composites. By combining MOFs with specific materials, numerous advantages can be achieved in the newly created compounds (MOF composites), including synergistic effects beneficial in catalytic applications, and overcoming the challenges associated with using bare MOFs. [ABSTRACT FROM AUTHOR]

Flow cytometry is a sophisticated technology used widely in both basic research and as a routine tool in clinical diagnosis. The technology has progressed from single parameter detection in the 1970s and 1980s to high end multicolor analysis, with currently 30 parameters detected simultaneously, allowing the identification and purification of rare subpopulations of cells of interest. Flow cytometry continues to evolve and expand to facilitate the investigation of new diagnostic and therapeutic avenues. The present review gives an overview of basic theory and instrumentation, presents and compares the advantages and disadvantages of conventional, spectral and imaging flow cytometry as well as mass cytometry. Current methodologies and applications in both research, pre- and clinical settings are discussed, as well as potential limitations and future evolution. This finding encourages the reader to promote such relationship between basic science, diagnosis and multidisciplinary approach since the standard methods have limitations (e.g., in differentiating the cells after staining). Moreover, such path inspires future cytometry specialists develop new/alternative frontiers between pre- and clinical diagnosis and be more flexible in designing the study for both human as well as veterinary medicine. [ABSTRACT FROM AUTHOR]

Correlative super‐resolution microscopy has the potential to accurately visualize and validate new biological structures past the diffraction limit. However, combining different super‐resolution modalities, such as deterministic stimulated emission depletion (STED) and stochastic single‐molecule localization microscopy (SMLM), is a challenging endeavour. For correlative STED and SMLM, the following poses a significant challenge: (1) the photobleaching of the fluorophores in STED; (2) the subsequent reactivation of the fluorophores for SMLM and (3) finding the right fluorochrome and imaging buffer for both imaging modalities. Here, we highlight how the deep ultraviolet (DBUE) wavelengths of the Mercury (Hg) arc lamp can help recover STED bleaching and allow for the reactivation of single molecules for SMLM imaging. We also show that Alexa Fluor 594 and the commercially available Prolong Diamond to be excellent fluorophores and imaging media for correlative STED and SMLM. [ABSTRACT FROM AUTHOR]

Exploiting photothermal agents with second‐near‐infrared (NIR‐II, 1000−1700 nm) emission and a high photothermal conversion efficiency (PCE) is an appealing and challenging task. Herein, by simultaneously tailoring the D−A interaction and planarity in fluorophores, two donor‐acceptor (D−A) −type semiconducting polymers (SPs), T‐BTP and B‐BTP, are constructed. Compared with T‐BTP, B‐BTP shows increased intramolecular interactions and improved molecular planarity, leading to bathochromic‐shift absorption, NIR‐II emission, and high PCE. Notably, the B‐BTP NPs achieve a remarkable PCE of 84.7%, which is among the highest PCEs of SPs in NIR‐II fluorescence imaging‐guided photothermal therapy (PTT). Because of these promising features, B‐BTP NPs are successfully used in NIR‐II vascular imaging and cancer therapy. This study provides valuable guidelines for the development of high‐performance NIR‐II SPs. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) are ideal fluorophores for optoelectronic devices. However, it is still a great challenge to obtain CDs with high solid‐state photoluminescence quantum yields (PLQYs). In this work, it is first reported that the barium‐doped CDs (Ba‐CDs), which can be simply synthesized on a large scale via a direct one‐step heating approach using an open vessel. The as‐synthesized Ba‐CDs exhibit ultrabright luminescence both in liquid and solid states. The as‐synthesized Ba‐CDs with a scale of 8.6 g per batch show a Stokes shift of ≈0.68 eV and high PLQYs of 80.8% and 66.8% in liquid and solid state, respectively. Interestingly, an efficient fluorescence enhancement phenomenon occurs when Ba‐CDs are mixed with polyvinylpyrrolidone (PVP), which reveals the critical issue of compatibility between CDs and polymer matrix can be well resolved. As a proof‐of‐concept, the Ba‐CDs are employed as fluorophores for high‐efficiency luminescent solar concentrator (LSC) fabrication. The Ba‐CDs@PVP‐based LSC has a PLQY of 88.78%, showing a breakthrough optical conversion efficiency of 7.16% and power conversion efficiency of 6.87% under natural light irradiation (40 mW cm−2). The results demonstrate the potential application of the ultrabright Ba‐CDs in efficient photovoltaic devices. [ABSTRACT FROM AUTHOR]

Tumor heterogeneity and tumor evolution contribute to cancer treatment failure. To understand how selective pressures drive heterogeneous tumor evolution, it would be useful to image multiple important components and tumor subclones in vivo. We propose a supercontinuum-tailoring two-photon microscope (SCT-TPM) and realize simultaneous observation of nine fluorophores with a single light beam, breaking through the 'color barrier' of intravital two-photon fluorescence imaging. It achieves excitation multiplexing only by modulating the phase of fiber supercontinuum (SC), allowing to capture rapid events of multiple targets with maintaining precise spatial alignment. We employ SCT-TPM to visualize the spatiotemporal dynamics of heterogeneous tumor evolution under host immune surveillance, particularly the behaviors and interactions of six tumor subclones, immune cells and vascular network, and thus infer the trajectories of tumor progression and clonal competition. SCT-TPM opens up the possibility of tumor lineage tracking and mechanism exploration in living biological systems. Studying tumour heterogeneity and tumour evolution remains a challenging task. Here, the authors propose a supercontinuum-tailoring two-photon microscope to enable the imaging of multiple fluorophores with a single light beam. They use this tool to monitor the dynamics of heterogeneous tumour evolution. [ABSTRACT FROM AUTHOR]

The fluorophores, the fluorescence of which can be switched between multi bright colors in the solid state, show promising applications not only in the sophisticated multicolor display but also in the advanced encryption and anti‐counterfeiting systems. However, it is very challenging to obtain such fluorophores. Herein, we disclose such an example, g‐BPhANMe2‐Cp, which contains an electron‐donating dimethylamino (NMe2) and an electron‐accepting [(2‐dimesitylboryl)phenyl]acetyl at the pseudo‐gem position of [2.2]paracyclophane skeleton. This molecule can display tricolor mechanochromic luminescence (MCL) due to the different responses of the mechanically ground amorphous state to heating and solvent‐fuming. Owing to the absence of intermolecular π‐π interactions in the solid state, the fluorescence efficiency is very high irrespective of its morphological state (ΦF=0.60–0.87). Moreover, this molecule also displays reversible acidochromic luminescence (ACL) by protonation and deprotonation of NMe2 with trifluoroacetic acid (TFA) and triethylamine (TEA), respectively. The protonated sample fluoresces (ΦF=0.31) at much shorter wavelength due to the interruption of intramolecular charge transfer process. Therefore, with the combination of tricolor MCL and ACL properties, the solid‐state emission of g‐BPhANMe2‐Cp can be switched among four bright fluorescence colors of yellow, green, cyan and blue via treatment with appropriate stimulus. [ABSTRACT FROM AUTHOR]

A new class of oxygen-sensing dual-emitting cyclometalated Ir(III) complexes is described. They function as ratiometric sensors that combine the blue fluorescence from coumarin as a self-referenced internal standard with yellow to red phosphorescence from bis-cyclometalated iridium complexes. The compounds have phosphorescence quantum yields up to 15%, lifetimes ranging from 0.23 to 9.4 μs, and are capable of sensing a wide range of O2 partial pressures. [ABSTRACT FROM AUTHOR]

Temperature is an essential physical characteristic that influences all biological processes. Building on previous research on dialkylamino-functionalized rhodamine-based thermo-sensors, we investigate herein the thermosensitive properties of triamino-phenazinium dyes. Through a simple five-step synthetic route, we synthesized amino-phenazinium chromophores 6 and 7, featuring diethylamine substituents at different positions. A comparative analysis of optical properties and thermosensitivity was conducted on these compounds and an isomer, 5, in which butylamine moiety replaced the diethylamine group. The different emissive behaviors of the three fluorophores emphasize that not only the chemical nature but also the specific position of the alkylamine substituent play fundamental roles in the synthesis of highly emissive thermo-probes. [ABSTRACT FROM AUTHOR]

Near‐infrared region (NIR; 650–1700 nm) dyes offer many advantages over traditional dyes with absorption and emission in the visible region. However, developing new NIR dyes, especially organic dyes with long wavelengths, small molecular weight, and excellent stability and biocompatibility, is still quite challenging. Herein, we present a general method to enhance the absorption and emission wavelengths of traditional fluorophores by simply appending a charge separation structure, dihydropyridopyrazine. These novel NIR dyes not only exhibited greatly redshifted wavelengths compared to their parent dyes, but also displayed a small molecular weight increase together with retained stability and biocompatibility. Specifically, dye NIR‐OX, a dihydropyridopyra‐zine derivative of oxazine with a molecular mass of 386.2 Da, exhibited an absorption at 822 nm and an emission extending to 1200 nm, making it one of the smallest molecular‐weight NIR‐II emitting dyes. Thanks to its rapid metabolism and long wave‐length, NIR‐OX enabled high‐contrast bioimaging and assessment of cholestatic liver injury in vivo and also facilitated the evalua‐tion of the efficacy of liver protection medicines against cholestatic liver injury. [ABSTRACT FROM AUTHOR]

Herein, we present the preparation of a series of electronically and/or sterically distinct borenium‐type species based on a simple 2‐arylpyridine scaffold. Corresponding arylpyridine was firstly subjected to electrophilic borylation (BBr3/i‐Pr2NEt) and formed BBr2 chelate was reduced with LiAlH4 to yield arylpyridine boron dihydride. Elimination of one hydride led to Lewis acidic borenium‐like products. Four methods of hydride elimination were evaluated and influence of counterions on reactivity, Lewis acidic and luminescent properties was assessed both experimentally and computationally. Arylpyridine chelates featuring weakly coordinating counterions exhibit fluorescent properties upon UV irradiation. Several general trends were inferred to modulate emission wavelength and fluorescence quantum yield. Based on our observations, we have devised and prepared borenium‐type fluorophores with yellow‐green fluorescence and quantum yields up to 93 %. [ABSTRACT FROM AUTHOR]

This article reports the synthesis, along with structural and photophysical characterization of 2‐(2'‐hydroxyphenyl)benzazole derivatives functionalized with various azaheterocycles (pyridine, pyrimidine, terpyridine). These compounds show dual‐state emission properties, that is intense fluorescence both in solution and in the solid‐state with a range of fluorescent color going from blue to orange. Moreover, the nature of their excited state can be tuned by the presence of external stimuli such as protons or metal cations. In the absence of stimuli, these dyes show emission stemming from anionic species obtained after deprotonation (D* transition), whereas upon protonation or metal chelation, ESIPT process occurs leading to a stabilized and highly emissive K* transition. With the help of extensive ab initio calculations, we confirm that external stimuli can switch the nature of the transitions, making this series of dyes attractive candidates for the development of stimuli‐responsive fluorescent ratiometric probes. [ABSTRACT FROM AUTHOR]

Carbonized polymer dots (CPDs) exhibiting tunable solid‐state emission (SSE) show great promise as rare‐earth‐free functional phosphors. Nevertheless, progress in this field has been hindered by the structural heterogeneity of CPDs and a lack of fundamental understanding of the underlying emission mechanisms. In this work, a universal approach is presented for the large‐scale, controlled synthesis of CPDs with tailored SSE properties. This strategy leverages intraparticle Förster resonance energy transfer (FRET) by incorporating selected fluorophores into self‐assembled CPDs nanostructures. The resulting CPDs exhibit exceptional SSE characteristics, such as high quantum yields, adjustable band structures, narrow emission linewidths, and excellent photostability in both solution and solid‐state. Moreover, the multifunctional capabilities of these CPDs are demonstrated, including efficient light harvesting, their potential as nanocarriers, and their application in light‐emitting diodes (LEDs). This findings establish self‐assembly‐mediated doping as a robust platform for engineering CPDs with unique SSE properties, underpinned by the principles of intraparticle FRET. [ABSTRACT FROM AUTHOR]

Proteins, which are ubiquitous in cells and critical to almost all cellular functions, are indispensable for life. Fluorescence imaging of proteins is key to understanding their functions within their native milieu, as it provides insights into protein localization, dynamics, and trafficking in living systems. Consequently, the selective labeling of target proteins with fluorophores has emerged as a highly active research area, encompassing bioorganic chemistry, chemical biology, and cell biology. Various methods for selectively labeling proteins with fluorophores in cells and tissues have been established and are continually being developed to visualize and characterize proteins. This review highlights research findings reported since 2018, with a focus on the selective labeling of cellular proteins with small organic fluorophores and their biological applications in studying protein-associated biological events. We also discuss the strengths and weaknesses of each labeling approach for their utility in living systems. [ABSTRACT FROM AUTHOR]

Single‐molecule localization microscopy (SMLM), which has revolutionized nanoscale imaging, faces challenges in densely labelled samples due to fluorophore clustering, leading to compromised localization accuracy. In this paper, we propose a novel convolutional neural network (CNN)‐assisted approach to address the issue of locating the clustered fluorophores. Our CNN is trained on a diverse data set of simulated SMLM images where it learns to predict point spread function (PSF) locations by generating Gaussian blobs as output. Through rigorous evaluation, we demonstrate significant improvements in PSF localization accuracy, especially in densely labelled samples where traditional methods struggle. In addition, we employ blob detection as a post‐processing technique to refine the predicted PSF locations and enhance localization precision. Our study underscores the efficacy of CNN in addressing clustering challenges in SMLM, thereby advancing spatial resolution and enabling deeper insights into complex biological structures. [ABSTRACT FROM AUTHOR]

We describe the synthesis, full photophysical study, and ab initio calculations of 2‐(2'‐hydroxyphenyl)benzazole (HBX) fluorophores substituted, at the meta position of the phenol group, by pyridine derivatives. HBX are commonly used as model dyes to study the stimuli‐induced modulation of the Excited State Intramolecular Proton Transfer (ESIPT) process. The meta‐substituted fluorophores reported herein, display a photophysical profile different from the previously reported ortho‐ and para‐substituted HBO pyridine isomers. Indeed, while all dyes undergo spontaneous deprotonation in neutral conditions, leading to highly emissive anionic species; upon protonation, ortho‐ and para‐pyridine substitution leads to resonance‐stabilized keto isomers, formed after ESIPT. Protonated meta derivatives, unable to stabilize their excited structure by such electronic delocalization process, display sizable intramolecular charge transfer (ICT) processes, translating into significantly redshifted emission. In addition, all dyes present a strong emission intensity, not only in neutral and acidic solutions, but also in the solid‐state. The nature of the emissive transitions was confirmed in each case by theoretical calculations combining Time‐Dependent Density Functional Theory (TD‐DFT) and second‐order Coupled Cluster (CC2) methods. [ABSTRACT FROM AUTHOR]

Single‐benzene fluorophores have attracted increasing interest owing to their simple molecular structure and unique photophysical properties. Developing novel single‐benzene fluorophores with facile synthesis, bright and tunable dual‐state emissions, and diversified functions is highly desirable. Herein, a strategy of controlling electron density on amino of 2,5‐diaminoterephthalates is proposed to modulate their dual‐state emission, acidichromism, Cu2+ detection, and lipid droplets (LDs) staining. A series of efficient dual‐state single‐benzene fluorophores based on 2,5‐diaminoterephthalate skeleton with tunable emissions in blue to red region and large Stokes shifts is facilely developed. The obtained fluorophores with various substituents on amino groups exhibit different acidichromism property. Two of fluorophores (ABB and ABM) with high electron density on amino groups exhibit high sensitivity and selectivity toward Cu2+ detection with a ratiometric and "turn‐off" fluorescence mechanism for ABM and ABB, respectively. The limit of detection for Cu2+ is determined to be 1.40 × 10−7 and 4.35 × 10−9 mol L−1 for ABB and ABM, respectively. Moreover, three of fluorophores (ABT, ABB, and ABM) with green to red emission display superior LDs‐targeting capability with high specificity, and brightness. This molecular design philosophy provides a new way of designing highly bright dual‐state fluorophores for practical applications. [ABSTRACT FROM AUTHOR]

Circularly polarized long afterglow (CPLA) attracts great interests in multi‐disciplinary fields with significant potentials in optical multiplexing applications, but achieving full‐color and white CPLA is still challenging. The present contribution reports the first success in utilizing circularly polarized phosphorescence energy transfer (CPP‐ET) combined with chirality‐selective absorption (CSA) to construct full‐color and white CPLA materials. Blue CPLA with luminescence dissymmetry factor (glum) of 3×10−2 is firstly obtained via the CSA effect of chiral helical polyacetylene and blue ultralong afterglow of inorganic phosphor BP. Significantly, full‐color and white CPLA films are prepared by simply blending different fluorophores into the blue‐CPLA films via CPP‐ET. Benefited from the persistent luminescence of BP, the lifetimes of the fluorophores increase from nanoseconds to minutes, and ultralong full‐color CPLA emissions lasting for more than 20 min are realized with glum of 10−3. Also noticeably, chiral optoelectronic devices, multi‐dimension information encryption and chiral logic gate are developed based on the full‐color tunable CPLA‐active materials. The established strategy provides a universal platform for future development of CPLA‐active materials with great applications. [ABSTRACT FROM AUTHOR]

Excited‐state intramolecular proton transfer (ESIPT) has attracted great attention in fluorescent sensors and luminescent materials due to its unique photobiological and photochemical features. However, the current structures are far from meeting the specific demands for ESIPT molecules in different scenarios; the try‐and‐error development method is labor‐intensive and costly. Therefore, it is imperative to devise novel approaches for the exploration of promising ESIPT fluorophores. This research proposes an artificial intelligence approach aiming at exploring ESIPT molecules efficiently. The first high‐quality ESIPT dataset and a multi‐level prediction system are constructed that realized accurate identification of ESIPT molecules from a large number of compounds under a stepwise distinguishing from conventional molecules to fluorescent molecules and then to ESIPT molecules. Furthermore, key structural features that contributed to ESIPT are revealed by using the SHapley Additive exPlanations (SHAP) method. Then three strategies are proposed to ensure the ESIPT process while keeping good safety, pharmacokinetic properties, and novel structures. With these strategies, >700 previously unreported ESIPT molecules are screened from a large pool of 570 000 compounds. The ESIPT process and biosafety of optimal molecules are successfully validated by quantitative calculation and experiment. This novel approach is expected to bring a new paradigm for exploring ideal ESIPT molecules. [ABSTRACT FROM AUTHOR]

The second near‐infrared window (NIR‐II, 1000–1700 nm) fluorescence imaging has attracted significant attention in research fields because of its unique advantages compared with conventional optical windows (400–900 nm). A variety of NIR‐II fluorophores have been actively studied because they serve as a key component of fluorescence imaging. Among them, organic small molecule NIR‐II fluorophores display outstanding imaging performance and many advantages, but types of small molecule NIR‐II fluorophores with high biocompatibility are still quite limited. Novel molecular scaffolds based NIR‐II dyes are highly desired. Herein, we hypothesized that chlorophyll is a new promising molecular platform for discovery NIR‐II fluorophores. Thus, seven derivatives of derivatives were selected to characterize their optical properties. Interestingly, six chlorophyll derivatives displayed NIR‐II fluorescence imaging capability. This characteristic allowed the successful NIR‐II imaging of green leaves of various plants. Furthermore, most of these fluorophores showed capacity to monitor viscosity change because of their sensitive for viscosity. For demonstration of its biomedical applications, these probes were successfully used for NIR‐II fluorescence‐guided surgical resection of lymph nodes. In summary, chlorophylls are novel valuable tool molecules for NIR‐II fluorescence imaging and have potential to expand their applications in biomedical field and plant science. [ABSTRACT FROM AUTHOR]

Excited-state intramolecular proton transfer (ESIPT) materials have emerged as highly promising candidates for emitters in organic light-emitting diodes (OLEDs), attributed to their distinctive photophysical properties. These materials have garnered considerable attention due to their pronounced Stokes shifts, exceptional color purity, and potential for achieving high efficiency and stability in OLED applications. To develop highly luminescent solids with large Stokes shifts, two imidazole-based ESIPT-AIE emitters, PPy-HPI and PPy-HPIC, have been synthesized following the strategy of combining excited-state intramolecular proton transfer (ESIPT) and aggregation-induced emission (AIE) systems. These emitters integrate the ESIPT cores 2-(2-hydroxy-5-methylphenyl)-1,4,5-triphenylimidazole (HPI) and 2-(2-hydroxy-5-methylphenyl)-1- phenylphenanthroimidazole (HPIC) with the AIE-active luminogen 4-(1-phenylvinyl)pyridine (PPy). The ESIPT and AIE properties were confirmed through both theoretical and experimental studies. The emitters demonstrated ESIPT and AIE characteristics, featuring a large Stokes shift and strong yellow-green to yellow emission in the solid state, which originated from the pure keto form. A non-doped OLED utilizing PPy-HPIC demonstrated yellow emission with CIE coordinates of (0.47, 0.51), a maximum external quantum efficiency (EQEmax) of 3.13% and a maximum current efficiency (CEmax) of 9.48 cd A-1. Notably, the non-doped OLED incorporating PPy-HPI exhibited yellow-green emission with CIE coordinates of (0.15, 0.10), EQEmax of 3.61%, and CEmax of 10.56 cd A-1, with minimal efficiency roll-off. These results signify a major breakthrough in creating ESIPT molecules for use as non-doped emitters in fluorescent OLEDs. [ABSTRACT FROM AUTHOR]

Real-time and accurate guidance for tumor resection has long been anticipated by surgeons. In the past decade, the flourishing material science has made impressive progress in near-infrared fluorophores that may fulfill this purpose. Fluorescence imaging-guided surgery shows great promise for clinical application and has undergone widespread evaluations, though it still requires continuous improvements to transition this technique from bench to bedside. Concurrently, the rapid progress of artificial intelligence (AI) has revolutionized medicine, aiding in the screening, diagnosis, and treatment of human doctors. Incorporating AI helps enhance fluorescence imaging and is poised to bring major innovations to surgical guidance, thereby realizing precision cancer surgery. This review provides an overview of the principles and clinical evaluations of fluorescence-guided surgery. Furthermore, recent endeavors to synergize AI with fluorescence imaging were presented, and the benefits of this interdisciplinary convergence were discussed. Finally, several implementation strategies to overcome technical hurdles were proposed to encourage and inspire future research to expedite the clinical application of these revolutionary technologies. [ABSTRACT FROM AUTHOR]

As a modality of optical imaging, fluorescence imaging of biochemical analytes holds significant potential in the field of disease diagnosis and therapy. However, the non‐responsive fluorophores are not able to selectively and sensitively detect lesions, resulting in a poor signal‐to‐background ratio and compromised accuracy. The utilization of activatable sensors, in contrast, is capable of effectively overcoming these limitations by displaying variations in fluorescence intensity and spectral wavelength in response to physiological parameters. Aggregation‐induced emission luminogens (AIEgens), particularly those emitting fluorescence in the near‐infrared (NIR, 700–1700 nm) window, have practical application prospects in disease theranostics due to their excellent photostability, deeper penetration depth, and enhanced fluorescence intensity in physiological environments. In this review, an overview of the advancements in research on NIR AIEgens for internal stimuli‐activated diagnosis and treatment of diseases is provided. The design principles of responsive NIR AIEgens and their biomedical applications are exemplified with representative examples, categorized based on the type of stimuli. Finally, the review concludes with a brief discussion of the challenges, opportunities, and future prospects of activatable NIR AIEgens in the field of disease photo theranostics. [ABSTRACT FROM AUTHOR]

This review article discusses the emerging amino‐terephthalonitrile (Am‐TN) and amino terephthalate‐based single benzene fluorophores (SBFs) for their highly emissive nature and potential for numerous technical applications. Am‐TN‐SBFs are a new class of SBFs having amine as the electron donating (EDG) and dinitrile as the electron withdrawing group (EWG). The beauty of these Am‐TN‐SBFs lies in excellent intramolecular charge transfer between the EDG and EWG. The placement of two nitrile groups in para‐position on the benzene ring allows better charge transfer from the donating amines to the linear nitrile group leading to the strongly emissive nature. We also outline here the latest developments in the well‐known family of amino terephthalate SBFs reported in the last 2 to 3 years. Amino terephthalate SBFs have esters as the EWG and amine as the EDG. These have intramolecular H‐bonding between the EDG and EWG which is responsible for their emissive behavior. [ABSTRACT FROM AUTHOR]

A range of novel BODIPY derivatives with a tripodal aromatic core was synthesized and characterized spectroscopically. These new fluorophores showed promising features as probes for in vitro assays in live cells and offer strategic routes for further functionalization towards hybrid nanomaterials. Incorporation of biotin tags facilitated proof‐of‐concept access to targeted bioconjugates as molecular probes. Computational explorations using DFT and TD‐DFT calculations identified the most stable tripodal linker conformations and predicted their absorption and emission behavior. The uptake and speciation of these molecules in living prostate cancer cells was imaged by single‐ and two‐photon excitation techniques coupled with two‐photon fluorescence lifetime imaging (2P FLIM). [ABSTRACT FROM AUTHOR]

ABSTRACT Fluorescence spectroscopy has been applied for analysis of complex samples, such as food and beverages. Parallel factor analysis (PARAFAC) is a well‐known decomposition method for fluorescence excitation–emission matrices (EEMs). When the complexity of the system increases, it becomes considerably more difficult to determine the optimal number of PARAFAC components, especially when the fluorophores of the system are unknown. The two commonly applied diagnostics, core consistency and split‐half analysis, appear to underestimate the model complexity due to covarying components and local minima, respectively. As a more robust alternative, we propose a resampling approach with multiple initializations and submodel comparisons for estimating the optimal number of PARAFAC components in complex data. [ABSTRACT FROM AUTHOR]

Luminescent materials require systems that exhibit both dual‐state emission (DSE) and aggregation‐induced emission (AIE) to overcome the limitation of aggregation‐caused quenching (ACQ). Herein, a molecular assembler capable of crafting nanowires that exhibit programmable fluorescence across a broad spectrum of colors in a precisely quantized manner is reported. Because it is a starburst dendritic box made of PAMAM dendrimer (P), controller (C) molecules, and motor (M) molecules, the assembler is called PCM. Here, Nile red is chosen as C and placed into the hollow core of the dendrimer; a double ratchet motor (DRM) is chosen as M and is connected to the N‐terminals of the PAMAM dendrimer. While aqueous dispersed PCM assemblers have broad fluorescence bands beyond 300 nm, their crafted nanowires produce quantized cyan‐green, yellow, and orange‐red light emission in the spectra. These PCM assemblers are shown to hold long‐term memory, rapid switching, and energy harvesting by modulating photonic bandgaps, causing a longer redshift in the solid phase. The DSE of PCM can yield versatile photonics applications like bioimaging and energy harvesting. As PCM nanowires can modulate photonic bandgaps to cause a longer redshift, PCM fluorophores hold promise for drug delivery and cell separation like infrared‐sensitive operations. [ABSTRACT FROM AUTHOR]

Many stimuli‐responsive materials harness the reversible association of supramolecular binding motifs to enable advanced functionalities such as self‐healing, switchable adhesion, or mechanical adaptation. Despite extensive research into the structure–property relationships of these materials, direct correlations between molecular‐level changes in supramolecular binding and macroscopic material behaviors have mostly remained elusive. Here, we show that this challenge can be overcome with supramolecular binding motifs featuring integrated binding indicators. We demonstrate this using a novel motif that combines a hydrogen‐bonding ureido‐4‐pyrimidinone (UPy) with two strategically placed pyrene fluorophores. Dimerization of this motif promotes pyrene excimer formation, facilitating the straightforward optical quantification of supramolecular assembly under various conditions. We exploit the new motif as a supramolecular cross‐linker in poly(methyl acrylate)s to probe the extent of (dis)assembly as a function of cross‐linker content, processing history, and applied stimuli. We demonstrate that the stimuli‐induced dissociation of hydrogen‐bonding linkages strongly depends on the initial cross‐link density, which also dictates whether the force‐induced dissociation in polymer films correlates with the applied stress or strain. Thus, beyond introducing a robust tool for the in situ study of dynamic (dis)assembly mechanisms in supramolecular systems, our findings provide new insights into the mechanoresponsive behavior of such materials. [ABSTRACT FROM AUTHOR]

Imaging with multiple modalities can maximise the information gained from the analysis of a single sample. probes for optical fluorescence and X-ray fluorescence microscopy based on brominated 4-amino-1,8-naphthalimide and BODIPY scaffolds have been successfully designed and synthesised. Herein we show that these prototype probes, based on each of these scaffolds, can be imaged in two different cancer cell lines, and that the respective optical fluorescence and X-ray fluorescence signals are well correlated in these images. [ABSTRACT FROM AUTHOR]

The excited-state tautomer equilibrium of the urea-fused single-benzene fluorophore was synthetically modulated to produce exceptionally large Stokes shifts (>12 400 cm−1). The key N–H⋯N hydrogen bonding motif utilizes an endogenous proton for long-wavelength emission or an exogenous proton for acid–base chemistry, the balance of which is exploited for fluorescence switching in the solid state. [ABSTRACT FROM AUTHOR]

This study aims to identify continuous water quality changes and identify fluorescence properties from urban rivers to marine zones. Various types of natural and anthropogenic sources derived dissolved organic matter (DOM) have been identified in this study. These include soil‐derived DOM, plant remnants, and soluble particles produced when organic material partially decomposes and is released by microorganisms, such as bacteria, algae, and plants. DOM was characterized using a three‐dimensional excitation–emission matrix (3DEEM), parallel factor analysis (PARAFAC), and water quality parameters from the Buriganga River, Dhaka to Patenga Seaport, Chittagong, along with the Shitalakshya River, a small portion of the Padma River, and the Meghna River. To better understand the data analysis, the study area was divided into three central regions: urban industrial rivers, industrial estuarine rivers, and marine zones. In the urban industrial river, 3DEEM and PARAFAC identified five fluorophores (peaks: A, C, M, T, and Tuv) with five components: detergent‐like, fulvic‐like, tryptophan or protein‐like, fulvic‐like (C‐type), and protein‐like, which might originate from the industrial activities and sewage pollution. In the industrial estuarine river zone, three fluorophores have been identified (peaks: A, C, Tuv) with two known components, namely, fulvic acid (A‐type) and fulvic acid (C‐type), with an unknown photoproduct at Ex/Em = 295/368 (peak Tuv). Components in the industrial river zone may originate from terrestrial sources, indicating vegetation along the river. In the marine zone, four fluorophores have been identified (peaks: Tuv, A, T, C) with two components, that is, protein‐ or tryptophan‐like and humic acid‐like from coral origin. The intensities of both fulvic‐like and protein‐like substances were high in urban industrial river water owing to industrial activity and sewage pollution. SUVA254 suggests high aromaticity in all three regions, whereas the optical properties suggest that terrestrial and microbial components are present in the urban industrial and estuarine rivers. This further indicates that urban industrial river water quality is highly polluted. The lowest degradation potential index (DPI) in the marine zone might result from the presence of the highest number of dissolved solids in the water, and the highest DPI of industrial estuarine rivers explains the comparatively high presence of terrestrial‐derived humic (A)‐ and humic (C)‐like components in the ratio to the unknown photoproduct of mid‐wavelength. Practitioner Points: This study's uniqueness is a 220‐km cruise from an urban river to a coastal seaport to analyze fluorescence properties.The study found that most water parameters were within the DoE standards, except for DO, which was consistently low.3DEEM‐PARAFAC identified five fluorophores linked to detergent, fulvic, and protein‐like substances from sewage and industrial sources.Our study concludes that microbial and terrestrial sources dominate dissolved organic matter in urban, estuarine, and marine regions. [ABSTRACT FROM AUTHOR]

Lipid droplets (LDs) dysfunction is closely associated with a multitude of diseases, including nonalcoholic fatty liver disease (NAFLD). Therefore, it is imperative to develop fluorescent probes that specifically target LDs for the early detection and diagnosis of NAFLD. In this study, a series of lipophilic fluorophores CZ1-CZ4 that feature a D-π-A configuration were designed and synthesized based on the carbazole and tricocyanofuran derivatives. The photophysical data revealed that all four probes exhibited large Stokes shifts (~ 120 nm) in high-polarity solvents (e.g., DMSO) and demonstrated enhanced fluorescence in solvents ranging from low-polarity (e.g., 1,4-Dioxane) to high-polarity. Notably, by utilizing probe CZ1, we could specifically visualize LDs and captured high-quality images, even eliminating the need for a time-consuming wash procedure. Moreover, CZ1 enabled monitoring of LDs dynamic changes in-real time within live cells, and importantly, it could be used to effectively distinguish normal and NAFLD tissues at both the organ and in vivo level. This exceptional property of probe CZ1 provides a practical tool for the diagnosis and intervention of NAFLD. [ABSTRACT FROM AUTHOR]

Flow cytometry (FC) was developed in the late 1950s and is nowadays the gold standard for automated quantitative cellular analysis. In the early 1990s, a new generation of cytometry became commercially available—laser scanning cytometry (LSC). While the hardware of LSC was related to FC, LSC provided images of forward scatter and all fluorochromes. This new technique allowed the analysis of solid tissues and reanalysis of samples and provided data similar to those of FC. A number of peer-reviewed, frequently cited studies were published using the features of LSC. Only a minority, however, must have believed that LSC would replace FC by that time. Currently, the LSC is still sold but withheld from any further development. It seems an epoque has come to an end. How did it come? The presented literature review tries to answer some questions. [ABSTRACT FROM AUTHOR]

[Display omitted] As an emerging fluorophore, aggregation-induced emission luminogens (AIEgens) have received widespread attention in recent years, but the inherent drawbacks of AIEgens, such as the poor water-solubility and insufficient fluorescence stability in complex environments, restrict their performance in practical applications. Herein, we report a universal strategy based on hydrophobic dendritic mesoporous silica (HMSN) that can integrate different AIE molecules to construct multi-color fluorescent AIE materials. Specifically, HMSN with central radial pores was used as a powerful carrier for direct loading AIE molecules and restricting their intramolecular motions. Due to the pore-domain restriction effect and hydrophobic interaction, the obtained silica-based AIE materials have bright fluorescence with a maximum quantum yield of 68.38%, high colloidal/fluorescence stability, and excellent biosafety. Further, these silica-based AIE materials can be conjugated with functional antibodies to obtain probes with different targetability. After integration with immunomagnetic beads, the prepared detection probes achieved the quantitative detection of cardiac troponin I with the limit of detection (LOD) of 0.508 ng/mL. Overall, the targeting probes stemming from silica-based AIE materials can not only achieve cell-specific imaging, but quantify the number of Jurkat cells (LOD = 270 cells/mL) to further determine the specific etiology of the disease. [ABSTRACT FROM AUTHOR]

In the current paper, we represent intrinsic fluorescence anisotropies as four-dimensional normalized Stokes vectors defined by the maximum excitation and emission in the fluorescence process with respect to linear, linear-45 and circular polarizations of light. Depending upon the transition moments for absorption/excitation and emission of fluorophores, eight types of these Stokes vectors can be realized from the Mueller fluorescence matrix of the system. These Stokes vectors probe the orientational distribution of fluorophores and predict the nature of optically active biological proteins, whether laevorotatory or dextrorotatory. The orthogonality relation between the Stokes vectors corresponding to the excitation and emission processes of fluorescence connects the molecular ground and excited states of biological and non-biological systems. [ABSTRACT FROM AUTHOR]

The synthesis of organic photosensitizers with effective reactive oxygen species (ROS) generation remains one of the urgent needs for cancer therapy. In this study, a simple strategy is developed to endow the intrinsic non‐photosensitizer fluorophores with profound ROS‐generating ability upon light irradiation. This strategy is featured by introducing donor–acceptor (D‐A) structured fluorophores as auxiliary ligands into the Ir(III) metal complex, which provides the Ir(III) metal center‐based triplet state (T1) as an energy level springboard to efficiently enhance the energy transition to the D‐A ligand‐based triplet state (T1'). The energy level difference between T1 and T1' can be regulated through altering the cyclometalated ligands of Ir(III), facilitating the energy transfer from T1 to T1' for augmented ROS generation. To improve the pharmacological properties of the obtained D‐A coordinated Ir(III) complex, it is incorporated with the exosomes extracted from M1 phenotype macrophages (M1‐Exos). The generated nanocomplexes are able to trigger synergistic photodynamic therapy, facilitating the reprogramming of tumor‐associated macrophages and eradicating the tumors in mice. This study provides a general strategy to transform non‐photosensitizer fluorophores into effective photosensitizers for biomedical applications. [ABSTRACT FROM AUTHOR]

Activation of caged fluorophores in microscopy has mostly relied on the absorption of a single ultraviolet (UV) photon of ≲400 nm wavelength or on the simultaneous absorption of two near-infrared (NIR) photons >700 nm. Here, we show that two green photons (515 nm) can substitute for a single photon (~260 nm) to activate popular silicon-rhodamine (Si-R) dyes. Activation in the green range eliminates the chromatic aberrations that plague activation by UV or NIR light. Thus, in confocal fluorescence microscopy, the activation focal volume can be matched with that of confocal detection. Besides, detrimental losses of UV and NIR light in the optical system are avoided. We apply two-photon activation (2PA) of three Si-R dyes in different superresolution approaches. STED microscopy of thick samples is improved through optical sectioning and photobleaching reduced by confining active fluorophores to a thin layer. 2PA of individualized fluorophores enables MINSTED nanoscopy with nanometer-resolution. Activation of caged fluorophores has mostly relied on the absorption of either a single ultraviolet photon or two NIR photons. Here, the authors show that two green photons (515 nm) can substitute for a single photon (~ 260 nm) to activate rhodamine-based dyes, thus enabling STED imaging in thick samples. [ABSTRACT FROM AUTHOR]

Synthesis and characterization of two curcumin analogues BAA and Br‐AA via a condensation reaction was reported. Both the synthesized organic luminophores exhibited aggregation‐induced emission (AIE) with bright yellow and green emission respectively. Increase in the water% enhanced the emission by both the compounds confirmed the AIE property. A detailed study of latent fingerprints visualization was also carried out for both the analogues. Both the compounds showed good to normal capability to develop latent fingerprints (LFPs). Compound BAA performed better as a fluorescent material to develop LFPs compared to Br‐AA. The LFPs developed were analyzed to obtain 1–3 level of fingerprint patterns under UV 365 nm illumination. The LFPs developed using BAA exhibited excellent efficiency, sensitivity, high contrast with low background interreference. All three levels of fingerprint patterns were identified by BAA. However, Br‐AA showed inability to develop high clarity images of latent fingerprints. The solid‐state emission nature of the analogues was also evaluated from their emission spectra and CIE coordinates were found to be were (0,187, 0.518) and (0.265, 0.484) for BAA and Br‐AA respectively. [ABSTRACT FROM AUTHOR]

Currently, much research effort has been devoted to improving the exciton utilization efficiency and narrowing the emission spectra of ultraviolet (UV) fluorophores for organic light‐emitting diode (OLED) applications, while almost no attention has been paid to optimizing their light out‐coupling efficiency. Here, we developed a linear donor‐acceptor‐donor (D–A–D) triad, namely CDFDB, which possesses high‐lying reverse intersystem crossing (hRISC) property. Thanks to its integrated narrowband UV photoluminescence (PL) (λPL: 397 nm; FWHM: 48 nm), moderate PL quantum yield (ϕPL: 72 %, Tol), good triplet hot exciton (HE) conversion capability, and large horizontal dipole ratio (Θ//: 92 %), the OLEDs based on CDFDB not only can emit UV electroluminescence with relatively good color purity (λEL: 398 nm; CIEx,y: 0.161, 0.040), but also show a record maximum external quantum efficiency (EQEmax) of 12.0 %. This study highlights the important role of horizontal dipole orientation engineering in the molecular design of HE UV‐OLED fluorophores. [ABSTRACT FROM AUTHOR]

Chromophores undergoing excited‐state intramolecular proton transfer (ESIPT) feature a distinct four‐level photocycle and significant Stokes shift, which make them ideal for achieving population inversion upon photoexcitation, a fundamental prerequisite for lasing, by mitigating the concerns of self‐absorption owing to spectral overlap. This study focuses on functionalizing the hydroxyphenyl‐benzothiazole (HBT) ESIPT laser dye through the introduction of fluorene and phenyl‐carbazole moieties at the para‐position to the hydroxyl group, to demonstrate amplified spontaneous emission (ASE) activities. The synthesized HBT derivatives not only exhibit high thermal and photostability, but also high photoluminescence quantum yields, exceeding 40%, which is noteworthy for ESIPT materials emitting in the yellow–orange to red color ranges. Computational analyses show that these new HBT materials possess substantially lower ESIPT energy barriers, compared to their parent HBT, facilitating their efficient ESIPT processes. Moreover, these derivatives demonstrate a high radiative rate of 1.47 × 108 s−1. Thin films of a fluorene‐substituted HBT (HBT‐pFl) show a low solid‐state amplified spontaneous emission threshold value of 3.8 µJ cm−2 at 582 nm, representing the lowest reported solid‐state ASE threshold for laser dyes in the orange emission region (575–600 nm) to date. [ABSTRACT FROM AUTHOR]

Purpose Methods Results Conclusions To characterize fundus autofluorescence (FAF) in complete (cRORA) and incomplete retinal pigment epithelium and outer retinal atrophy (iRORA) by fluorescence lifetime imaging ophthalmology (FLIO).Overall, 98 macular atrophy (MA) lesions in 42 eyes of 37 age‐related macular degeneration (AMD) patients (mean age: 80.9 ± 5.8 years), 25 of them classified as iRORA and 73 as cRORA by OCT, were investigated by FLIO in a short (SSC: 498–560 nm) and a long wavelength channel (LSC: 560–720 nm). Differences of FAF lifetimes and peak emission wavelength (PEW) between atrophic lesions and intact retinal pigment epithelium (RPE) in the outer ring of the ETDRS grid were considered.FAF lifetimes in MA were longer and PEW were significantly (p < 0.001) shorter than in intact RPE by 112 ± 78 ps (SSC), 91 ± 64 ps (LSC), 27 ± 18 nm (PEW) in iRORA and by 227 ± 112 ps (SSC), 167 ± 81 ps (LSC), and 54 ± 17 nm (PEW) in cRORA. 37% of iRORA and 24% of cRORA were hyperautofluorescent in SSC. Persistent sub‐RPE‐BL material in MA was newly found as a hyperautofluorescent entity with lifetimes considerably longer than that of drusen and RPE.Despite RPE and, thus, lipofuscin are greatly absent in MA, considerable FAF, preferably at short wavelengths, was found in those lesions. Drusen, persistent sub‐RPE‐BL material, basal laminar deposits, persistent activated RPE, and sclera were identified as putative sources of this fluorescence. FLIO can help to characterize respective fluorophores. [ABSTRACT FROM AUTHOR]

Accurate fluorescence imaging of nanocarriers in vivo remains a challenge owing to interference derived mainly from biological tissues and free probes. To address both issues, the current study explored fluorophores in the near-infrared (NIR)-II window with aggregation-caused quenching (ACQ) properties to improve imaging accuracy. Candidate fluorophores with NIR-II emission, ACQ984 (λem = 984 nm) and IR-1060 (λem = 1060 nm), from the aza-BODIPY and cyanine families, respectively, were compared with the commercial fluorophore ICG with NIR-II tail emission and the NIR-I fluorophore P2 from the aza-BODIPY family. ACQ984 demonstrates high water sensitivity with complete fluorescence quenching at a water fraction greater than 50%. Physically embedding the fluorophores illuminates various nanocarriers, while free fluorophores cause negligible interference owing to the ACQ effect. Imaging based on ACQ984 revealed fine structures in the vascular system at high resolution. Moreover, good in vivo and ex vivo correlations in the monitoring of blood nanocarriers can be established, enabling real-time noninvasive in situ investigation of blood pharmacokinetics and dynamic distribution in various tissues. IR-1060 also has a good ACQ effect, but the lack of sufficient photostability and steady post-labeling fluorescence undermines its potential for nanocarrier bioimaging. P2 has an excellent ACQ effect, but its NIR-I emission only provides nondiscriminative ambiguous images. The failure of the non-ACQ probe ICG to display the biodistribution details serves as counterevidence for the improved imaging accuracy by NIR-II ACQ probes. Taken together, it is concluded that fluorescence imaging of nanocarriers based on NIR-II ACQ probes enables accurate in vivo bioimaging and real-time in situ pharmacokinetic analysis. [ABSTRACT FROM AUTHOR]

Solvent-extracted fractions of six Indian coal samples of different ranks were investigated using multiple geochemical, petrological and spectroscopic proxies and an attempt was made to indicate possible fingerprint regions for different polycyclic aromatic hydrocarbons (PAH) with the help of excitation-emission matrix (EEM). In this study, for the very first time, the influence of rank and maturation of organic matter in the characterisation of coal solvent-extracts from Indian coals were perceived from the viewpoint of fluorescence EEM. Vitrinite reflectance (VRo) values were used to determine the general ranks of the original coal samples viz. lignite, subbituminous, bituminous and anthracite. Different fluorescence peak regions corresponding to different fused aromatic ring (FAR) systems were delineated using the EEM and their indicative depositional environments could be inferred. Our observations indicate that solvent-extracted fractions of low rank coals comprise of a larger number of shorter carbon chains compared to the other samples. For the low rank coal samples, the solvent-extracts show a strong humic influence and the presence of smaller PAH rings while for the medium rank coals, the extracted fractions tend to show a more bimodal distribution of PAHs, possibly comprising of different sized PAHs. Higher fluorescence sensitivity and quick response of smaller PAHs impart a singular centralised region in the EEM for the low rank coal samples while interference in the fluorescence of differently sized PAHs indicate a multimodal distribution of the fluorophores in the medium rank coals. The high rank coal used in this study shows a bimodal distribution with very low intensity of the peaks, indicating the low abundance of extractable macromolecules, possibly as a result of deformation. [ABSTRACT FROM AUTHOR]

Solid-state near-infrared (NIR) luminescence fluorophores have attracted much attention due to their potential in bio applications and advanced optical devices. Therefore, it is essential to design and synthesize novel NIR AIE fluorophores and investigate their structure–activity relationships for applications. Here, we synthesized two NIR AIE o-carborane fluorophores with donor–acceptor–donor (D–A–D) structures. These fluorophores have emissions extending into the NIR region and are named CPO and CPS with phenoxazine (PXZ) and phenothiazine (PTZ) derivatives as the electron donors, respectively. Despite the very similar chemical structures of PXZ and PTZ, CPO and CPS exhibited rather different photophysical properties. The o-carborane fluorophores CPO and CPS show large Stokes shifts (>14 000 cm−1), near-infrared AIE characteristics, and self-recovering mechanochromic luminescence. The reorganization of the molecular structures in the excited state leads to the planarization of their conjugated backbones and enhances the Stokes shifts. This work not only demonstrates an efficient strategy for constructing organic NIR AIE o-carborane-containing fluorophores, but also indicates their promising potential as advanced optoelectronic materials. [ABSTRACT FROM AUTHOR]

The development of fluorescent molecular imprinting sensors for direct, rapid, and sensitive detection of small organic molecules in aqueous systems has always presented a significant challenge in the field of detection. In this study, we successfully prepared a hydrophilic colloidal molecular imprinted polymer (MIP) with 2,4-dichlorophenoxyacetic acid (2,4-D) using a one-pot approach that incorporated polyglycerol methacrylate (PGMMA-TTC), a hydrophilic macromolecular chain transfer agent, to mediate reversible addition-fragmentation chain transfer precipitation polymerization (RAFTPP). To simplify the polymerization process while achieving ratiometric fluorescence detection, red fluorescent CdTe quantum dots (QDs) and green fluorescent nitrobenzodiazole (NBD) were introduced as fluorophores (with NBD serving as an enhancer to the template and QDs being inert). This strategy effectively eliminated background noise and significantly improved detection accuracy. Uniform-sized MIP microspheres with high surface hydrophilicity and incorporated ratiometric fluorescent labels were successfully synthesized. In aqueous systems, the hydrophilic ratio fluorescent MIP exhibited a linear response range from 0 to 25 μM for the template molecule 2,4-D with a detection limit of 0.13 μM. These results demonstrate that the ratiometric fluorescent MIP possesses excellent recognition characteristics and selectivity towards 2,4-D, thus, making it suitable for selective detection of trace amounts of pesticide 2,4-D in aqueous systems. [ABSTRACT FROM AUTHOR]