Search Results (1,668)

We developed an efficient and modular route to 2- and 6-(1,2,3-triazol-1-yl)azulenes to expand the synthetic accessibility and functional scope of azulene-based π-systems with stimulus-responsive photophysics. Readily accessible 2- and 6-azidoazulenes, prepared in excellent yields via S_NAr reactions of haloazulenes, were subjected to Cu(I)-catalyzed Huisgen [3 + 2] cycloaddition with a broad range of terminal alkynes to afford the corresponding triazolylazulenes in good to high yields, followed by acid-mediated decarboxylation and Staudinger reduction to enable further diversification to 2-azulenyltriazoles and a 6-aminoazulene derivative. Single-crystal X-ray diffraction analysis revealed substitution-position-dependent torsional arrangements and variations in π-conjugation between the azulene and triazole units. Photophysical characterization by UV/Vis absorption and fluorescence spectroscopy showed pronounced halochromism under acidic conditions, and selected derivatives displayed substantially enhanced fluorescence quantum yields. Overall, these results establish the azulene–1,2,3-triazole motif as a versatile building block for designing optoelectronic π-systems with acid-responsive emission properties. Full article

Metalloporphyrin-based covalent organic frameworks (MPor-COFs) are emerging porous crystalline materials that combine the optoelectronic properties of metalloporphyrins with the highly ordered structure of COFs. Such a combination not only extends the light absorption spectrum of COFs by incorporating porphyrins but also improves the separation and transport capabilities of photo-generated electrons and holes by leveraging the structural advantages of organic frameworks. At the same time, the metal ions embedded in the porphyrin ring provide abundant active sites and optimize charge transfer channels, showing particular advantages in photocatalysis. The molecular design, construction, and photocatalytic application of MPor-COFs were reviewed in this paper. The intrinsic relationship among the structure, optoelectronic properties, and specific photocatalytic application received special attention. First, the role of the metal center in regulating the electronic structure and photophysical property of porphyrin monomers was introduced, as well as the impact of bond type on framework stability and charge transport efficiency. Then, the synthesis strategies for MPor-COFs were summarized. Finally, the applications of these materials in photocatalysis were critically reviewed, and their prospects and challenges in energy conversion and environmental remediation were also discussed. Full article

Organic light-emitting diodes (OLEDs) have attracted remarkable interest in display and lighting. To effectively address triplet exciton harvesting and enhance external quantum efficiency (EQE), delayed fluorescence AIEgens have gained significant prominence. The primary luminescence mechanism involves the efficient harvesting of triplet excitons via reverse intersystem crossing (RISC) channels, categorized into three types: thermally activated delayed fluorescence (TADF), hybridized local and charge transfer (HLCT), and triplet–triplet annihilation (TTA). In this review, we summarize the recent development of doped and non-doped delayed fluorescent AIEgens-based OLEDs. This review mainly discusses the molecular design strategies and photophysical properties of delayed fluorescent AIEgens and the electroluminescent properties of OLEDs as emitting layers. Finally, the challenges and prospects of delayed fluorescent AIEgens for the fabrication of OLEDs are also briefly discussed. Full article

Photodynamic therapy (PDT) is an established light-based treatment modality that relies on the activation of photosensitizers to generate reactive oxygen species (ROS) and induce localized cytotoxicity. In recent years, microalgae have emerged as a promising and sustainable source of natural photosensitizers due to their ability to biosynthesize structurally diverse pigments with strong light-harvesting capacity. This review provides a comprehensive, application-oriented analysis of microalgae-derived photosensitizers, focusing on chlorophylls and their derivatives, carotenoids, and phycobiliproteins. Particular attention is given to analytical strategies for pigment extraction, purification, and characterization, as well as to photophysical properties, subcellular localization, and ROS-mediated mechanisms underlying photodynamic activity. Recent advances in the chemical modification of algal pigments, including chlorin-based derivatives and 5-aminolevulinic acid–related systems, are critically discussed in relation to structure–activity relationships and translational performance. The accumulated evidence demonstrates that microalgae-derived pigments and their synthetic analogues can achieve efficient singlet oxygen generation, organelle-specific phototoxicity, and favorable therapeutic selectivity. Taken together, these findings highlight microalgae as a renewable and versatile platform for developing next-generation photosensitizers with broad biomedical potential in oncology, dermatology, and antimicrobial photodynamic therapy. Full article

Photodynamic therapy is a cancer treatment that relies on a photosensitizer (PS) to generate reactive oxygen species upon light activation, thereby destroying cancer cells. The photophysical properties of porphyrins make them effective PSs, while nanoparticles (NPs) enhance their delivery and stability. The bioavailability and targeting efficiency of NPs-PS complexes may be improved through transport via human serum albumin (HSA). This study investigates the HSA binding affinity with 5,10,15,20-(Tetra-4-carboxyphenyl)porphyrin (TCPP) and with TiO₂-TCPP complexes. The interactions were analyzed using UV-Vis absorption, laser-induced fluorescence (LIF), and FTIR spectroscopy. Molecular docking was performed and provided consistent binding constant values for the TCPP–HSA complex with UV-Vis absorption measurements. LIF data revealed a slightly lower affinity when compare free porphyrin with TiO₂-TCPP, possibly due to competitive binding between TiO₂ and HSA. Docking simulations indicated that TCPP favorably interacts with amino acid residues located in subdomains IB and IIIA of HSA, supporting a preferential binding near Sudlow site I. FTIR measurements revealed conformational changes in HSA for both its interactions with TCPP and TiO₂-TCPP, including alterations in α-helical content and reorganization of the hydrogen bonding network within the polypeptide backbone. Full article

A novel series of benzoxazole-derived iminocoumarins was synthesized via a Knoevenagel condensation and fully characterized using NMR, UV–Vis spectroscopy, and computational methods. Their photophysical properties were systematically examined in solvents of varying polarity, revealing pronounced effects of both substituents and solvent environment on absorption maxima and intensity. Derivatives bearing electron-donating substituents on the coumarin core exhibited distinct and reversible pH-responsive spectral shifts, confirming their potential as optical pH probes. Experimental pK_a values derived from absorption titrations showed excellent agreement with DFT-calculated data, validating the proposed protonation-deprotonation equilibria and associated electronic structure changes. Structure–property relationships revealed that electron-donating groups enhance intramolecular charge transfer, while electron-withdrawing substituents modulate spectral response and stability. In parallel, the compounds were evaluated for antiproliferative, antiviral, and antifungal activities in vitro. Strong electron-donating substituents were associated with potent but non-selective cytotoxicity, whereas derivatives bearing electron-withdrawing groups displayed moderate and more selective antiproliferative effects against leukemia cell lines. Antifungal screening revealed moderate inhibition of phytopathogenic fungi, particularly for compounds with electron-withdrawing or methoxy substituents. Overall, these findings demonstrate that benzoxazole iminocoumarins represent a promising class of multifunctional heterocycles with potential applications as optical pH sensors and scaffolds for bioactive compound development. Full article

This review summarizes recent advances (2023–2025) in coumarin-based fluorescent probes, highlighting their structural modularity, tunable VIS–NIR photophysics, and broad applicability in detecting metal ions, biothiols, ROS/RNS, organelle-specific microenvironments, and amyloid-β aggregates. Particular emphasis is placed on multifunctional and organelle-targeted probes, as well as emerging NIR-emissive and theranostic systems enabling deep-tissue imaging and modulation of pathological processes. The perspectives section outlines current limitations and future directions toward clinically relevant coumarin-based imaging tools. A though the review focuses on literature published from 2023 onward, several earlier studies are cited selectively to clarify fluorescence mechanisms, illustrate reaction pathways, or provide essential photophysical benchmarks necessary for contextual understanding. Full article

Background/Objectives: Boron-dipyrromethene (BODIPY) derivatives are a superior class of fluorophores prized for their exceptional photostability and tunable photophysical properties. While ideal for imaging, their translation to photodynamic therapy (PDT) has been hampered by excitation in the visible range, leading to poor tissue penetration. To overcome this, intense research has focused on developing near-infrared (NIR)-absorbing BODIPY photosensitizers (PS). This review aims to systematically summarize the hierarchical design strategies, from molecular engineering to advanced nanoplatform construction, that underpin the recent progress of NIR-BODIPY PS in therapeutic applications. Methods: We conducted a comprehensive literature review using PubMed, Scopus, and Web of Science databases. The search focused on keywords such as “BODIPY”, “aza-BODIPY”, “near-infrared”, “photodynamic therapy”, “photothermal therapy”, “nanocarriers”, “hypoxia”, “immuno-phototherapy”, and “antibacterial.” This review analyzes key studies describing molecular design, chemical modification strategies (e.g., heavy-atom effect, π-extension), nanoplatform formulation, and therapeutic applications in vitro and in vivo. Results: Our analysis reveals a clear progression in design complexity. At the molecular level, we summarize strategies to enhance selectivity, including active targeting, designing “smart” PS responsive to the tumor microenvironment (TME) (e.g., hypoxia or low pH), and precise subcellular localization (e.g., mitochondria, lysosomes). We then detail the core chemical strategies for achieving NIR absorption and high singlet oxygen yield, including π-extension, the internal heavy-atom effect, and heavy-atom-free mechanisms (e.g., dimerization). The main body of the review categorizes the evolution of advanced theranostic nanoplatforms, including targeted systems, stimuli-responsive ‘smart’ systems, photo-immunotherapy (PIT) platforms inducing immunogenic cell death (ICD), hypoxia-overcoming systems, and synergistic chemo-phototherapy carriers. Finally, we highlight emerging applications beyond oncology, focusing on the use of NIR-BODIPY PS for antibacterial therapy and biofilm eradication. Conclusions: NIR-BODIPY photosensitizers are a highly versatile and powerful class of theranostic agents. The field is rapidly moving from simple molecules to sophisticated, multifunctional nanoplatforms designed to overcome key clinical hurdles like hypoxia, poor selectivity, and drug resistance. While challenges in scalability and clinical translation remain, the rational design strategies and expanding applications, including in infectious diseases, confirm that NIR-BODIPY derivatives will be foundational to the next generation of precision photomedicine. Full article

Novel A-D-A (acceptor–donor–acceptor)-type molecules were synthesized and tested in organic photovoltaics (OPV) devices. For a pristine film of compound 1b with a 2,2′-(naphtho[2,3-b]thiophene-4,9-diylidene)dipropanedinitrile A unit and carbazole-based donor D unit, efficient exciton splitting by intermolecular electron transfer was proved. The observation of the out-of-phase electron spin echo in the pristine 1b film unambiguously testifies to a high yield of charge-transfer state formation. Despite this, the yield of free charge generation in pristine 1b is low due to the fast geminate and non-geminate recombination. This process is detrimental for OPV performance when the compound capable of exciton self-splitting is used as an acceptor component of the bulk heterojunction (BHJ) active layer because of the fast charge recombination within this component. Exciton self-splitting can be of general significance for push–pull OPV acceptors or donors in bulk heterojunctions, although it can be masked by other photophysical processes in the BHJ active layer. This is the reason why molecules with a strong intermolecular charge-transfer band are not suitable components of the active layer of efficient OPV devices. Full article

This Perspective sets out to raise awareness about the chemical and photophysical properties of an assortment of blue colorants; it is generally regarded that blue is the most popular color worldwide and is recognized for its serenity and calming effect. In fact, blue colorants have a long and rich history, perhaps starting with Egyptian Blue, and have found colossal usage in the dyeing of uniforms and popular clothing. Other blue colorants have made major contributions to our understanding of the fields of molecular spectroscopy and photophysics and continue to underpin contemporary opto-electronic devices. This is in addition to their socio-cultural, economic, and ecological benefits to society. Originally, blue colorants were extracted from minerals by tedious and ineffectual grinding to give a product carrying an exorbitant price. Later, these materials were supplemented by synthetic analogues, such as copper phthalocyanine, more affordable to the general public. It is stressed that the journal Colorants would welcome submissions that describe the chemistry and/or spectroscopy of other archetypal colorants. Full article

Understanding the influence of solvent environments on the excited-state charge transfer process remains a fundamental question in molecular photophysics and photochemistry. While twisted intramolecular charge transfer (TICT) is crucial in determining fluorescence efficiency and photostability, the combined effects of solvent polarity and hydrogen bonding interactions are still elusive. Here, we employ steady-state and femtosecond transient absorption (fs-TA) spectroscopy with density functional theory (DFT) calculations to investigate the excited-state dynamics of 7-(diethylamino)coumarin-3-carboxylic acid (7-DCCA) in different solvents. Our findings reveal that in highly polar solvents with strong hydrogen-donating and hydrogen-accepting capabilities, 7-DCCA undergoes significant TICT formation, resulting in fluorescence quenching. Conversely, in environments with low polarity or weak hydrogen-bonding interactions, this transformation is largely suppressed. Quantitative correlation analysis utilizing the Kamlet–Taft and Catalán four-parameter models further elucidates the synergistic role of solvent polarity and specific hydrogen-bonding parameters in modulating the steady-state spectral behavior of 7-DCCA. This study provides microscopic insights into solvent–charge transfer interactions and establishes a general framework for enhancing the luminescence efficiency and structural robustness of organic optoelectronic materials through strategic solvent engineering. Full article

Background/Objectives: Introducing a demanding home-based program (HBP) of Vojta therapy (VT) into their daily activities is a life-altering event for parents of children with global developmental delay (GDD). This study aims to document the experiences of parents of children with GDD administering a HBP of VT. Methods: A multicentre study with a qualitative case design based on an interpretative approach is presented. Interviews were conducted with 10 parents using photo-elicitation (PE). Inductive and thematic analyses were used. Results: Four common experiential themes were identified. Firstly, crying was identified as the most significant barrier to administering therapy (despite parents accepting that crying was not pain-related). Secondly, parents described the intense and variable emotional impact of being responsible for the therapy and its effects on their child. Thirdly, parents unanimously felt that their involvement was worthwhile, with the developmental results they perceived outweighing the emotional, physical and time demands of administering the VT. Finally, parents developed a narrative of hope stemming from the therapy and its observed effects. Conclusions: The physical, emotional and time demands on parents when administering a HBP of VT are very significant. The main barriers to adherence to the program are identified as the child’s crying during therapy and time management. Intense emotional experiences, both positive and negative, arise while administering a HBP of VT. Parents are not only able to overcome all emotional and logistical challenges when they recognize improvements in their child, but they also begin to hope for further improvement. Implications for the professional design of HBPs of VT include the following: advanced warning that crying is normal, part of the therapy and not pain-related; training and ongoing support from a qualified therapist; training in recognising developmental improvement; and psychological support to deal with the emotional journey. Full article

The photochemistry of transition metal complexes has been crucial for the development of many fundamental topics, as well as to pave the way for several important applications. However, in most cases, photoactive transition metal complexes involved precious metals, with luminescent ruthenium polypyridine complexes playing the dominant role. Developing photoactive species based on earth-abundant metals is highly important for fundamental and applicative reasons. Iron is one of the most abundant metals on Earth’s crust, so luminescent iron complexes are highly desired. The recent search for iron complexes with long-lived and luminescent excited states is here presented, including Fe(II) species with metal-to-ligand charge transfer (MLCT) excited states and Fe(III) species with luminescent ligand-to-metal charge transfer (LMCT) states. The excited-state equilibration approach to prolong the luminescence lifetimes of Fe(III) compounds in multichromophoric species is also discussed. This latter approach can increase the possibility of luminescent iron complexes being involved in bimolecular processes as well as in photoinduced electron and energy transfer at interfaces, which is relevant for many applications. Full article

Divalent europium complexes have attracted significant attention in various fields due to the unique electronic configuration of the Eu(II) ion. Given the high sensitivity of the 5d → 4f emission of Eu(II) ions to the ligand field, it is crucial to explore the relationship between ligands and this emission in Eu(II) complexes. However, the heavy-atom effects on the 5d → 4f emission of Eu(II) complexes coordinated with non-metal elements in the same group remain unclear. In this study, five mononuclear Eu(II)-chalcogenide complexes, Eu[H₃B·EPh-κE,H,H]₂(DME)₂ (E = S for 1 and Se for 2; DME = 1,2-Dimethoxyethane) and Eu[EPh]₂(18-C-6) (E = S for 3, Se for 4, and Te for 5; 18-C-6 = 1,4,7,10,13,16-Hexaoxacyclooctadecane), were synthesized via reduction of diphenyl disulfide chalcogenide analogs with Eu(BH₄)₂(THF)₂ or NaH. The structures of these complexes were investigated by single-crystal X-ray diffraction, and their properties were characterized by thermogravimetric analysis and photophysical property tests. Complexes 1 and 2 are isomorphous and show similar yellowish-green luminescence, while complexes 3–5 have similar structures but crystallize in different space groups with bluish-green luminescence. This research reveals the influence of chalcogenide ligands on the 5d → 4f emission of Eu(II) complexes, providing a theoretical basis and new research ideas for the application of Eu(II) complexes in various fields, including luminescent materials, cryogenic refrigerants, and magnetic materials. Full article

Photoluminescent liquid crystals with photoluminescence (PL) and liquid-crystalline (LC) properties have attracted attention as PL-switching materials owing to their thermally induced phase transitions, such as crystal → smectic A/nematic → isotropic phase transitions. Our group previously developed tetrafluorinated tolane mesogenic dimers linked by flexible alkylene-1,n-dioxy spacers, demonstrating that the position of the tetrafluorinated aromatic ring critically influences the LC behavior. However, these compounds exhibited very weak fluorescence owing to an insufficient D–π–A character of the π-conjugated mesogens, which facilitated internal conversion from emissive ππ* to non-emissive πσ* states. We designed and synthesized derivatives in which the mesogen–spacer linkage was modified from ether to ester, thereby enhancing the D–π–A character. Thermal and structural analyses revealed spacer-length parity effects: even-numbered spacers induced nematic phases, whereas odd-numbered spacers stabilized smectic A phases. Photophysical studies revealed multi-state PL across solution, crystal, and LC phases. Strong blue PL (Φ_PL = 0.39–0.48) was observed in solution, while crystals exhibited aggregation-induced emission enhancement (Φ_PL = 0.48–0.77) with spectral diversity. In LC states, Φ_PL values up to 0.36 were maintained, showing reversible intensity and spectral shifts with phase transitions. These findings establish design principles that correlate spacer parity, phase behavior, and PL properties, enabling potential applications in PL thermosensors and responsive optoelectronic devices. Full article