This work aims to design BODIPY-(Zn-porphyrin) 2 conjugates that channel all harvested light energy into one conjugate moiety, providing a specific photoresponse with an extended excitation range. Three BODIPY-porphyrin conjugates have been prepared, and their excitation energy deactivation channels have been established. In two of them, the BODIPY π-conjugation was extended at either the 2,6-positions or the 3,5-positions via Sonogashira coupling. Then the click reaction was applied to conjugate it to two Zn-porphyrins. The π-conjugation extension shifts the BODIPY absorption spectra bathochromically, with the 3,5-substituted BODIPY spectra being more shifted compared to those of the 2,6-substituted ones. These BODIPY-(Zn-porphyrin) 2 conjugates exhibit fluorescence spectra that are almost identical to those of the parent BODIPYs, independently of the excitation wavelength. The Zn-porphyrin transfers its own excitation energy to the BODIPY moiety and simultaneously acts as a BODIPY fluorescence quencher by enhancing the BODIPY radiationless transition rate in the conjugate. The third BODIPY-(Zn-porphyrin) 2 conjugate was prepared by attaching two Zn-porphyrins via click reaction to azide groups in the meta-positions of the phenyl ring at the 8-position of BODIPY. Here, the BODIPY moiety harvests the excitation energy, which ultimately goes to the Zn-porphyrins with no traces of BODIPY emission. Notably, the intramolecular transition rates in the Zn-porphyrins remain unperturbed in the conjugate.

Abstract Polymer optical fibers (POFs) are increasingly utilized in optical sensing due to their mechanical flexibility and low fabrication cost. However, the effect of thermal fusion on their photophysical properties remains inadequately understood. This study investigates the correlation between fusion-induced structural modifications and light–electron interactions in step-index POFs fabricated from polymethyl methacrylate (PMMA). Fiber segments were subjected to controlled thermal fusion. Comprehensive optical characterization was performed on fused and non-fused fibers, including UV–VIS absorbance, transmission, and reflection spectroscopy, fluorescence emission analysis, and optical band gap estimation via Tauc plots employing the Kubelka–Munk function. Fused fibers exhibited significantly increased absorbance, decreased transmission, and enhanced reflection relative to controls, indicative of refractive index modulation and defect formation at the fused interface. Fluorescence spectra revealed a pronounced red shift from approximately 632 nm to 651 nm, accompanied by a strong enhancement in emission intensity, indicative of defect-assisted radiative recombination pathways formed during fusion. These fusion-induced optical responses enable the fused region to function as a localized sensing element in multiple configurations. Intensity-modulated sensing can be realized through fusion-induced absorption and scattering changes that respond to external perturbations such as mechanical deformation or refractive index variations. Fluorescence-based sensing modes may exploit defect-assisted emission intensity and wavelength shifts under fixed optical excitation, while enhanced reflectance at the fused junction supports reflectometric sensing schemes sensitive to surface or interfacial changes. These findings establish a direct relationship between thermal processing and photonic behavior in PMMA-based POFs, providing a physically grounded framework for the development of tunable POF sensing platforms.

Multimodal deep learning method based on multiple spectra for lung cancer early diagnosis.

Microplastic (MP) pollutes our terrestrial and aquatic ecosystems due to their uncontrolled discharge into our environment. The analysis of MP contamination is still a challenge, although significant improvements are made for different environmental matrices. Using mass-based particle analysis methods such as thermal extraction and desorption-gas chromatography/mass spectroscopy (GC/MS) or pyrolysis GC/MS, essential parameters such as the MP's morphology, size, and shape cannot be obtained, which are indispensable to assess the hazard of the respective particles. Raman, micro-Fourier transform infrared, and attenuated total reflectance spectroscopy are particle-based analysis methods, which are time-consuming due to the high purification effort. Thus, novel, reliable, and time-efficient methods for MP analysis are required. Previously, studies showed the potential of frequency domain fluorescence lifetime imaging microscopy (FD-FLIM) to identify plastics' type, shape, size, and morphology, and distinguishing these from natural materials. However, only pure plastic granules were investigated, omitting that commodity plastics accumulating in our environment contain various additive, filler, or dye concentrations. To circumvent the dependency of additive, filler, and dye concentrations, we investigated the fluorescence spectra and lifetimes of three plastic types, individually composed with two fillers, three additives, and two dyes in six different concentrations. We heuristically modeled the dependency of the concentration on plastics' fluorescence lifetime using a logarithmic model with a high correlation and showed that identifying the plastic types is hardly possible when fillers, additives, or dyes are added in various concentrations because of their superimposing fluorescence lifetimes. However, further research has to be conducted to investigate different emission states of fluorescence to optimize the FD-FLIM method, as only one excitation wavelength and emission band was used for the investigations.

Non-invasive detection of cold chain disruptions in modified-atmosphere packaged minced pork using a handheld fluorescence device.

The post-synthetic modification of a Cd-MOF and its fluorescence sensing properties.

Evaluation of near-infrared two-photon absorption response and excited state dynamics of asymmetric aza-BODIPY derivatives.

Spectroscopic investigation of the competitive-allosteric-synergistic mechanism in the binding of benazepril/apigenin to bovine serum albumin.

Dual-mode Tb-cyclophosphazene-MOF sensors for on-site discrimination and quantification of structurally similar flunoquinolone antibiotics in aquatic organisms via smartphone platform.

Effect of introducing electron-donating and electron-withdrawing substituents on the ESIPT process and fluorescence properties of 2-hydroxy-3-phenyliminomethyl-10-butyl phenothiazine derivatives: A DFT/TD-DFT study.

The metal-complex formation of 1,4-dihydroxyanthraquinone (quinizarin, QNZ) and 6,11-dihydroxy-5,12-naphthacenedione (DHN) with Al(III) ions is investigated by stationary and time-resolved emission spectroscopy combined with quantum chemical calculations of optical properties. UV-vis and fluorescence spectra revealed small red-shifts of 200 and 60 meV for the QNZ and DHN metal complexes, respectively. The fluorescence quantum yield increases from 0.08 to 0.23 for QNZ, while for DHN it changes from 0.24 to 0.79 upon complexation, suggesting the presence of J-aggregate-like exciton coupling within the coordination structure. The average fluorescence lifetime of QNZ varies from 0.65 ns of the free ligand to 2.77 ns, and in the case of DHN it goes from 1.57 to 2.61 ns after Al(III) complexation. These results are consistent with formation of a more rigid molecular structure which effectively decreases the nonradiative rate constant. Confocal fluorescence microscopy images of Al(III) complexes adsorbed into the μmZeolite L structure gave similar red-shifted J type emission. Density functional theory, at the B3LYP/def2-TZVP level of theory, and the analysis of the electronic transition dipole moment, calculated with TDDFT at the CAM-B3LYP/def2-TZVP level, supports a near head-to-tail chromophore arrangement containing two metal centers coordinated with two chromophores. The Al(III)2DHN2 complex exhibits the stronger transition dipole coupling and a more pronounced J-type character when compared with Al(III)2QNZ2 complex. The radiative rate constant of Al(III)2DHN2 is twice that of the single DHN chromophore.

A novel mixed-ligand copper(II) complex, [Cu(Asp)(bpy)]·nH₂O, incorporating aspartic acid (Asp) and 4,4′-bipyridine (bpy), was synthesized and extensively characterized to elucidate its redox, magnetic, thermal, and spectroscopic properties. Fourier-transform infrared spectra confirmed coordination through the carboxylate oxygen of Asp and the nitrogen atoms of bpy, forming a mixed N,O-donor environment around the Cu(II) center. UV–Visible spectroscopy revealed d–d and metal-to-ligand charge transfer transitions, while fluorescence spectra displayed emission quenching due to the paramagnetic Cu(II) ion, confirming effective metal–ligand interaction. The complex exhibited an effective magnetic moment (μeff) of 2.46 Bohr magnetons, consistent with a single unpaired electron in a distorted octahedral geometry. Thermogravimetric analysis indicated a multi-step decomposition pattern with stability up to 350 °C, suggesting strong metal–ligand coordination and potential thermal robustness. Electrochemical investigations using cyclic voltammetry demonstrated a quasi-reversible Cu(II)/Cu(I) redox couple, with diffusion-controlled kinetics and ligand-induced stabilization of the Cu(I) oxidation state. Molar conductivity measurements indicated the formation of a neutral complex, further confirming complete coordination. Collectively, these findings establish the structural integrity and multifunctional nature of the Cu–Asp–bpy complex. Owing to its redox reversibility, paramagnetic character, and high thermal stability, the complex shows promise for applications in electrocatalysis, redox-active materials, and bioinspired electron-transfer systems. This study provides valuable insight into how synergistic N,O-ligand coordination can modulate copper redox chemistry and enhance functional stability for potential catalytic and electronic applications. These findings collectively demonstrate that the Cu–Asp–bpy complex possesses a stable Cu(II)/Cu(I) redox couple and high thermal durability, making it a promising candidate for electrocatalytic and bioinspired electron-transfer applications. IUBAT Review—A Multidisciplinary Academic Journal, 8(2): 82-104

A biosensing device based on optical waveguide spectrometry was developed using fluorescent solvatochromic beads as a sensor material. This device facilitated the analysis of the avidin-biotin interaction without labeling avidin. The fluorescent solvatochromic beads were synthesized from the 4-iodobenzoic-acid-substituted Wang resin, 2-bromothiophene, and N-tert-butyloxycarbonyl (Boc)-protected phenylpiperazine boronic ester through Suzuki-Miyaura cross-coupling, followed by condensation with NHS-biotin after the deprotection of the Boc-protected piperazine. The fluorescence spectrum of the beads showed a blue shift, and the fluorescence intensity rapidly increased with the addition of the neutravidin-dissolved phosphate-buffered saline (PBS) solution. This phenomenon indicated that the fluorescent solvatochromic dye on the beads was incorporated into neutravidin. Additionally, the kinetic and equilibrium properties of the interaction were analyzed by measuring the fluorescence intensity of the beads and comparing it with that of bovine serum albumin (BSA). The observed binding rate constants were found to be 2.7 × 10-2s-1 at 17mg mL-1 of neutravidin and 4.3 × 10-4s-1 at 18mg mL-1 of BSA. Furthermore, the fluorescence intensity of the beads with the BSA solution decreased upon washing the beads with PBS. In contrast, the beads with the added neutravidin solution showed constant fluorescence intensity even after washing.

Modeling optical spectra of pigment-protein complexes requires accurate treatment of both excitonic and vibronic interactions. While nonperturbative approaches, such as the hierarchical equations of motion, are, in principle, numerically exact, they are computationally demanding, making the use of approximate lineshape theories appealing. However, the biases introduced by these perturbative treatments still need assessment. Here, we systematically compare methods based on cumulant expansion and successive approximations against exact calculations. Using chlorophyll dimers in the water-soluble chlorophyll-binding protein and the CP29 light-harvesting complex as test systems, we analyze absorption spectra under varying coupling strengths. Our results show that vibronic renormalization of excitonic coupling can be captured by the partially Markovian complex Redfield (cR) theory, whereas fully non-Markovian approaches are essential for reproducing the intensities of vibronic sidebands. A model that treats electronic transitions involving high-frequency vibrational modes as localized recovers many of the non-Markov and non-secular effects. We extend our analysis to fluorescence spectra, which pose more difficulties because excitonic and vibrational states are entangled before emission. While non-Markovian methods still perform better for fluorescence, their performance in reproducing vibronic sidebands is less than satisfactory. Our results allow quantifying the errors made by approximate theories and define a reliability range for spectroscopic simulations.

Rapid determination of chloropropanol in edible vegetable oil by the combination of a simple fluorescence sensor and chemometrics.

We present an efficient numerical implementation of the quasi-classical doorway-window approximation, specifically designed for on-the-fly simulations of time-resolved nonlinear spectroscopic signals, in the Julia package WaveMixings.jl. The code takes as input quasi-classical trajectory data (energies of electronic states and transition dipole moments between elecronic states) as a function of discretized time, which may be provided by any nonadiabatic quasi-classical dynamics package. The output of WaveMixings.jl are raw spectroscopic data, that is, spectral intensities as functions one or more frequencies and pump-probe delay time. The package contains modules that facilitate standard tasks such as input/output data handling, data filtering, and postprocessing, among others. WaveMixings.jl includes implementations of various signals, including integral and dispersed transient absorption pump-probe signals, time- and frequency-resolved fluorescence spectra, and two-dimensional electronic spectra. By developing WaveMixings.jl we aim to create a versatile platform to perform simulations and develop new methodologies within the quasi-classical doorway-window framework. WaveMixings.jl differs from other existing codes for the simulation of nonlinear time-resolved spectra by the explicit inclusion of the shapes and durations of the laser pulses.

High-precision and wide-range feature wavelength quantitative analysis (FWQA) method for fluorescent substances based on IFE-induced CDRS.

The sensitivity of laser-induced fluorescence (LIF) to slight biochemical changes has made it an effective tool for non-invasive biomedical diagnostics. Since milk is a biological fluid that is both optically and biochemically complex, we employed it as a model sample to evaluate how effectively LIF senses thermally induced molecular changes. Full-fat and skimmed milk samples were systematically examined under 405 nm excitation both before and after controlled heating. The collected fluorescence spectra were then subjected to chemometric analysis using Principal Component Analysis (PCA) for unsupervised classification and Partial Least Squares Regression (PLSR), Support Vector Classifier (SVC), and Random Forest (RF) for predictive modeling. The statistical significance of the observed spectral changes was validated using paired t-tests. Following thermal processing, the emission band at around 533 nm, which corresponds to riboflavin, was significantly reduced, based on fluorescence spectra. The statistical significance of this decrease was validated by paired t-tests (p <0.0001). The discriminative power of LIF was further confirmed by chemometric evaluation: PCA successfully classified samples based on both fat content and thermal treatment, with the first two principal components predicting almost 85% of the total variance. The robustness of the approach was verified by the high calibration and cross-validated prediction accuracy (R2 >0.95) achieved by PLSR. Excellent classification performance was achieved by the SVM classifier with RBF kernels, correctly classifying 100% of data sets. Good model generalization without overfitting is indicated by the close agreement between the test set and cross-validation accuracies. Furthermore, the robustness and generalizability of the model were confirmed by the low out-of-bag error rate in RF implementations. These results show the potential of LIF as a sensitive, non-destructive method for assessing thermal and metabolic changes in biomedical contexts and validate milk as a practical surrogate system for comparing fluorescence-based methods.

Organic pollution in the lake water bodies poses a serious threat to the stability of aquatic ecosystems and human health. Dissolved organic matter (DOM) is a key component of organic pollution. The analysis of its sources is crucial for pollution control. In order to accurately trace the source of organic pollution in the Changdang Lake basin, this study proposes a traceability method combining three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy technology with a deep learning model. First, water quality samples were collected from the rivers connected to Changdang Lake and surrounding industrial wastewater, agriculture, and domestic pollution sources. Raw data were obtained by 3D-EEM spectroscopy. Parallel factor analysis (PARAFAC) was used to analyze the fluorescence data. Obtain fluorescence spectral images that characterize different pollution sources. Industrial wastewater, agricultural, and domestic pollution sources were used as training data (labeled 0, 1, and 2, respectively) to build and pre-train a deep learning model. Four deep learning models (Transformer, GoogLeNet, VGG, and AlexNet) were selected for comparison. Transformer model performs better in terms of both recognition efficiency and accuracy. The fluorescence spectrum images of the rivers connected to Changdang Lake and Lake body were input into the trained Transformer model to identify the sources of pollution. Tucker Congruence (TC) coefficients are introduced to quantify and verify the recognition results. The results show that for 40 fluorescent components in the Changdang Lake basin, the identification results of 38 components are consistent with the TC coefficients, with an identification accuracy rate of 95%. Compared with the traditional manual tracing method that relies on TC coefficients, this method significantly reduces the workload. The time required has been reduced from hours to minutes. This study provides efficient and reliable technical support for tracing the source of organic pollution in lake basins.

Hydrazones and their metal complexes have acquired a lot of interest because of their various biological and catalytic applications. The reaction of the symmetrical hydrazone (NBHD) with Cu(II) salts, including Cl-, Br-, and SO42-, has been investigated. The structures of Cu-NBHD complexes were explored by using various spectroscopic and analytical tools. Fluorescence spectra for NBHD and Cu(II)-NBHD complexes were recorded in a large number of solvents to probe their solvatochromic manners. Theoretical calculations for NBHD and Cu-NBHD complexes were conducted, and the results were correlated with the experimental data. The anticancer action of Cu-NBHD complexes was investigated towards Hepatocellular carcinoma and the results were supported by molecular docking studies. The Cu-NBHD complexes have distorted octahedral geometrical structures as evidenced from magnetic moment, electronic and ESR spectral data. NBHD acts as a bis(monoanionic bidentate) in case of Cl- and Br- ions and bis(neutral bidentate) in case of SO42- ion. The coordinating sites are phenolic oxygen and azomethine nitrogen atoms. In case of bromo and sulfato complexes, binuclear complexes were obtained. However, a tetranuclear complex was obtained in case of the chloro complex. DFT calculations for NBHD and Cu-NBHD complexes were performed, and the results were correlated with the practical results. All Cu-NBHD complexes exhibited anticancer activity towards Hepatocellular carcinoma. The bromo complex 2 showed an enhanced activity than that of cisPt. Using different copper(II) salts gives different bi- and tetra-nuclear complexes. Al complexes exhibited anticancer activity towards Hepatocellular carcinoma and the bromo complex 2 showed enhanced activity than that of cisPt. The encouraging activity prompts further studies about the complex as an antitumor agent.