The charge and electron spin density distribution in the lowest excited triplet state of a cofacial Al(III) porphyrin‐P(V) porphyrin heterodimer (AlPor‐O‐PPor·PF 6 ) has been studied at low temperature in different glass‐forming solvents using electron nuclear double resonance (ENDOR) spectroscopy and density functional theory (DFT) calculations. The 1 H hyperfine couplings (hfcs) at specific positions of the porphyrin rings have been used to differentiate spin delocalization and charge transfer (CT) character in the heterodimer. While both effects contribute similarly to the zero‐field splitting tensor, they can be distinguished by ENDOR spectroscopy through comparing the heterodimer triplet state hfcs with those of the corresponding monomers in their triplet state, oxidized, and reduced radical forms. From ENDOR data and DFT calculations, the triplet state of AlPor‐O‐PPor·PF 6 is estimated to have ~24% and ~35% CT character respectively, in agreement with the Mulliken partial charges. These results indicate that the CT character is modulated by solvent interactions, depending both on its polarity and coordination of the Al(III) center. The estimate of the CT character in the triplet state and its dependence on the molecular structure and the solvent is crucial to achieve efficient long‐lived triplet born charge separation in model photosynthetic systems.
Spatiotemporal photomodulation of ion (proton) transport is a key issue in creating functional ion‐based applications, ranging from energy systems to emerging neuromorphic devices. In this paper, we demonstrate reversible and stable photomodulation of proton transport. Proton‐conducting side‐chain liquid crystalline (SCLC) copolymers with varying sulfonic acid contents are synthesized via free‐radical copolymerization. The LC nature of the copolymers is investigated by polarized optical microscopy, differential scanning calorimetry, and X‐ray scattering (XRS) measurements. Ultraviolet (UV)–visible absorption spectroscopy and grazing‐incidence XRS measurements reveal that the SCLC copolymers form hetero‐lamellar structures formed by nanosegregation of hydrophobic liquid crystalline azobenzene (Az) side chains and hydrophilic sulfonic acid side chains along the polymer main chain. Moreover, we reveal that the sulfonic acid nanochannels serve as proton‐conducting pathways. Proton conductivity of the copolymer thin films is evaluated by impedance spectroscopy under controlled temperature and relative humidity conditions. These results demonstrate stable and reversible photoswitching of proton conductivity by approximately two orders of magnitude, attributed to the trans – cis photoisomerization of Az side chains under UV light irradiation. These findings open up opportunities for applications in ion (proton)‐based photofunctional neuromorphic devices.
We have revealed that a 1:1 complex can be selectively formed with a saddle‐distorted Sn IV ‐dodecaphenylporphyrin, Sn IV (DPP), and sterically hindered p ‐ferrocenylbenzoate derivatives through axial coordination of the carboxy group to the Sn IV center of Sn IV (DPP). In the 1:1 complex, we observed photoinduced electron transfer (PET) from the ferrocene moiety as an electron donor to the singlet excited state of the Sn IV (DPP) moiety as an electron acceptor and analyzed the PET by femtosecond transient absorption spectroscopy. The rate constant of the PET was determined to be k ET = (1.35 ± 0.03) × 10 10 s –1 , for p ‐ferrocenylbenzoate as an electron donor. We observed the reduced species of Sn IV (DPP) in the charge‐separated state with a nanosecond‐order lifetime and also revealed that, considering the Marcus theory of electron transfer, the PET proceeded with relatively small reorganization energy of 0.75 eV. The function of Sn IV (DPP) as an electron acceptor is unprecedented. Consequently, we have revealed that Sn IV (DPP) works as a good electron acceptor in the PET system, based on the axial coordination of an electron donor to the metal center.
The MLCT excited state of the Creutz–Taube analog [(NH 3 ) 5 Ru II ( μ −4,4′‐bpy)Ru II (NH 3 ) 5 ] 4+ was studied using femtosecond transient‐absorption spectroscopy in combination with DFT/TD‐DFT calculations. The computations show that strongly mixed d xz (Ru) orbitals, whose symmetry favors metal–metal interactions, are involved in the lowest‐energy 3 MLCT state. Detection of photoinduced IVCT transitions allowed to calculate, using comparative actinometry and the Mulliken–Hush formalism, an excited‐state electronic coupling of H DA > 1510 cm –1 . The influence of bridging‐ligand conformation was analyzed in the context of ground‐state versus excited‐state mixed‐valence interactions. Despite the long geometric donor–acceptor separation, hole delocalization promoted a two‐order‐of‐magnitude extension of MLCT lifetimes relative to monometallic analogs.
This study presents a comprehensive investigation of nitrogen‐doped carbon dots ( N‐ CDs) synthesized using perylene‐3,4,9,10‐tetracarboxylic dianhydride (PTCDA) as the carbon source and urea as the nitrogen dopant. Notably, the N ‐CDs exhibit remarkable preservation of PTCDA‐like characteristics, as evidenced by a distinctive photoluminescence (PL) profile with multiple well‐defined emission bands. The PL is dominated by strong core emission from core electronic states that serve as the primary radiative pathway. Dual excitation‐independent and excitation‐dependent PL behavior was also observed, unveiling a complex emission mechanism involving hierarchical electronic transitions from core states, interface regions, and surface‐localized states. The observed luminescence originates from synergistic interactions between the carbon dot core and its nitrogen‐functionalized surface, rather than from discrete localized electronic transitions. Investigations revealed exceptional stability characteristics, including sustained photoluminescence under continuous UV irradiation, storage stability, and remarkable pH resilience across a wide range (pH 3–14). The preservation of PTCDA‐like domains, coupled with nitrogen‐induced electronic modifications, results in a unique class of high‐quantum‐yield (QY = 49.7%), bright‐green, fluorescent carbon dots that combine the advantages of molecular fluorophores with the versatility of carbon nanomaterials. This work provides fundamental insights into the structure–property relationships of surface‐functionalized nitrogen‐doped carbon dots and establishes their potential for a range of applications.
A continuous flow photochemical hydroacylation protocol of azodicarboxylates was developed, offering broad substrate compatibility and delivering products in good to excellent yields in short reaction times. The developed protocol has also been applied to a telescoped continuous flow multistep synthesis of the antidepressant drug Moclobemide, which was isolated in 55% total yield.
C–N axial chirality remains largely unexplored in luminescent molecules due to its inherently low configurational stability, despite its potential for chiroptical applications. Herein, we report the design and synthesis of donor–acceptor (D–A)‐type molecules incorporating benzo[ b ]phenoxazine (BPO) as an asymmetric electron donor and dicyanobenzene as an electron acceptor. These molecules were efficiently synthesized via nucleophilic aromatic substitution, enabling straightforward access to C–N axially chiral architectures. It was demonstrated that steric substitution at both ortho ‐positions of the BPO unit effectively increases the rotational barrier around the C─N bond, allowing optical resolution. These compounds exhibited dual emission arising from locally excited (LE) states of the BPO unit and charge‐transfer (CT) states, along with long‐lived emission in the solid matrix attributable to triplet‐state‐mediated processes. Notably, these compounds exhibit enhanced circularly polarized luminescence (CPL) at low temperature, attributable to suppression of conformational fluctuations around the C–N axis. These results demonstrate an effective molecular design strategy for CPL emitters based on C–N axial chirality.
We report an artificial monooxygenase system that drives enantioselective oxidation directly utilizing molecular oxygen under visible‐light irradiation. This biohybrid catalyst consists of noncatalytic protein and metal complexes, i.e., copper 4,4‐tetraaza‐29H,31H phthalocyanine (CuTPC) bound to bovine serum albumin (BSA) and then assembled onto a synthetic photocatalyst, graphitic carbon nitride (g‐C 3 N 4 ). The resulting hybrid system facilitates a photocatalytic reaction cascade to enable enantioselective oxidation using molecular oxygen as an oxidant: g‐C 3 N 4 reduces oxygen photocatalytically and produces H 2 O 2 , which subsequently activates CuTPC‐BSA to drive enantioselective oxidation reactions. Using styrene and propionic acid as model substrates, the photocatalytic system selectively produces R‐styrene oxide and L‐lactic acid, respectively, achieving enantiomeric excesses exceeding 99% under visible‐light irradiation. In contrast, g‐C 3 N 4 alone did not provide enantioselectivity. Thus, CuTPC‐BSA/g‐C 3 N 4 represents a promising and cost‐effective alternative to natural enzymes to produce chiral oxidation products in a much sustainable way.
In this work, mesoporous silica nanoparticles with centrally radial open pore channels were synthesized, followed by the uniform deposition of small‐sized (5–10 nm) anatase–brookite biphasic TiO 2 semiconductor nanoparticles with varying loadings. The mesoporous silica framework effectively promotes homogeneous dispersion of the TiO 2 nanoparticles and suppresses their aggregation. Comprehensive structural and optical characterizations were performed using UV–vis spectroscopy, powder X‐ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and high‐resolution transmission electron microscopy (HRTEM). The results confirm the coexistence of anatase and brookite phases uniformly distributed over the mesoporous silica support. The optimized mesoporous silica‐supported anatase–brookite biphasic TiO 2 photocatalyst exhibited superior photocatalytic CO 2 reduction performance in pure water, yielding 23.8 µmol g −1 of CO and 1.54 µmol g −1 of CH 4 without the use of any sacrificial agent or cocatalyst. The synergistic coexistence of anatase and brookite phases within a single particle enhances charge separation through faster electron trapping across the S‐scheme heterojunction interface and lower electron/hole pair recombination, which is believed to be responsible for the significantly improved CO 2 reduction activity.
When a fluorescent molecule bearing a planar polycyclic aromatic hydrocarbon chromophore is placed in a chiral environment, it is expected to exhibit chiroptical properties such as circular dichroism and circularly polarised luminescence (CPL). Previously, we comparatively studied the fluorescence properties of the chiral bis‐1,8‐naphthalimide derivatives D ‐LyMebNI and L ‐LyMebNI in various solvents and successfully observed CPL originating from intramolecular excimer formation. This study aimed to develop compounds that form intramolecular excimers and exhibit higher CPL brightness ( B CPL ). To this end, we synthesised new chiral bis(1,8:4,5‐naphthalene tetracarboxy)imide derivatives, D ‐LyMebNDI and L‐ LyMebNDI, and investigated their photophysical properties. These molecules exhibited intramolecular excimer fluorescence in polar organic solvents. Mirror‐image circular dichroism and CPL spectra were obtained. In acetonitrile, D ‐ and L ‐LyMebNDI exhibited relatively large luminescence dissymmetry factors (| g lum |) of 2.2 × 10 −3 and 2.8 × 10 −3 , respectively. The B CPL of LyMebNDI was 12 M −1 cm −1 , representing a five‐fold increase relative to LyMebNI (2.5 M −1 cm −1 ). These findings provide insights into the development of practical CPL emitters and the modulation of CPL performance.
Two new transition‐metal complexes based on a dipyrazinylpyridine (dppy) ligand, 4‐( tert ‐butoxyphenyl)‐2,6‐di(pyrazin‐2‐yl)pyridine ( L ), namely {[Co L 2 ](ClO 4 ) 2 ( 1 ) and [Ni L 2 ](ClO 4 ) 2 ( 2 )}, were synthesized and characterized using various spectroscopic techniques. Single‐crystal X‐ray diffraction analysis revealed that complexation occurs in a 1:2 metal‐to‐ligand stoichiometry and both complexes exhibit distorted octahedral geometries. Furthermore, the binding studies with serum albumins (human serum albumin [HSA] and bovine serum albumin [BSA]) revealed that the complex 2 shows greater affinity than complex 1. Emission spectra showed binding constants of 3.83 × 10 4 M −1 and 2.63 × 10 7 M −1 for complex 1 and 2 , respectively, with BSA, whereas the corresponding values for HSA were 2.57 × 10 3 M −1 and 1.41 × 10 7 M −1 , respectively. Fluorescence quenching tests revealed a static quenching mechanism. The anticancer activity of the complexes was evaluated against Dalton’s lymphoma (DL) cells by MTT assay after 24–96 h of treatment at half IC 50 concentrations. Complexes 1 and 2 showed IC 50 values of 45 and 157 µM, respectively, indicating enhanced cytotoxic potency of complex 1 against DL cells.
Solid molecular catalysts (SMCs) represent a promising class of photocatalysts. Here, we report the influence of distinct donor and acceptor moieties of terpyridine‐based SMCs on the photocatalytic hydrogen peroxide (H 2 O 2 ) production. An aromatic and linear donor proved to be advantageous due to its favorable optoelectrical properties, achieving an activity of 8.55 mmol g −1 h −1 under white light irradiation without any sacrificial agents. The variation of backbone functionalities (toluene (C), pyrrole (N), furan (O), and thiophene (S)) revealed the important role of charge stabilization in the acceptor units through inductive and mesomeric effects. Scaling up the reaction with the best performing SMC C2‐SP1 yielded a photocatalytic activity of 12.8 mmol g −1 h −1 (405 nm). To facilitate the transition from laboratory studies to practical applications, H 2 O 2 production has been successfully demonstrated under natural sunlight. Under optimized reaction conditions, concentrations of up to 108.3 mg L −1 were achieved, demonstrating the potential of SMCs for sustainable hydrogen peroxide generation.
CuBi 2 O 4 (CBO) is a visible‐light‐absorbing p‐type semiconductor material, but its photoelectrochemical (PEC) reduction performance is often limited by poor charge transport and recombination. Herein, we establish practical guidelines for precursor concentration and Cu:Bi ratio in organic‐additive‐free, aqueous spray pyrolysis of CBO‐based thin films on fluorine‐doped tin oxide (FTO), followed by air annealing (600 °C, 1 h). By systematically varying the total cation concentration and Cu:Bi ratio in dilute HNO 3 solutions containing Cu(NO 3 ) 2 and Bi(NO 3 ) 3 , we correlate film morphology and phase constitution with PEC activity evaluated in neutral phosphate buffer under simulated sunlight, using H 2 O 2 electron acceptor as benchmarking conditions. For the stoichiometric precursor ratio (Cu:Bi = 1:2), an optimal total cation concentration of 300 mM maximizes the cathodic photocurrent. Tuning the Cu:Bi ratio enables phase‐selective film formation from CBO‐dominant films to CuO–CBO composites under identical processing conditions. Under H 2 O 2 ‐assisted evaluation, the cathodic photocurrent increases with increasing Cu fraction, while a CuO‐only reference shows the highest activity across the series, indicating that CuO‐rich surface sites dominate the reduction kinetics in this assay. These results provide a simple and scalable route to control phase constitution and microstructure of spray‐pyrolyzed p‐type oxide photocathodes via precursor engineering.
A water‐soluble and water‐stable 2,5‐bis(arylethynyl)rhodacyclopentadiene ( 4a ) containing terminal 4‐Me 3 N–C 6 H 4 groups has been synthesized for bioimaging and sensing of biomolecules, and its linear and nonlinear optical properties investigated. Complex 4a exhibits fluorescence from the S 1 excited state in both organic and aqueous solutions, with no observable phosphorescence from T 1 at RT. However, competitive intersystem crossing (ISC) to T 1 leads to potent 1 O 2 sensitization. DFT calculations show that the HOMO and LUMO are essentially ligand‐localized with very modest contributions from Rh, leading to slow S 1 → T 1 ISC and competitive fluorescence and triplet state formation, typical of such 2,5‐bis(arylethynyl)rhodacyclopentadienes. Complex 4a shows a two‐photon absorption cross‐section of 290 GM at 680 nm. It binds strongly to DNA, RNA, and protein (BSA) with similar affinities, but gives opposite fluorimetric response, the emission being strongly enhanced for BSA but efficiently quenched by DNA/RNA. Compound 4a efficiently enters living human cells and accumulates preferentially in mitochondrial membranes, being nontoxic even at high (10 µM) concentrations. Although 4a is a potent 1 O 2 sensitizer in a cuvette, exposure of the complex to intense visible light inside human cell results in fast bleaching of 4a with no effect on cell viability, suggesting local consumption of 1 O 2 by the complex.
Direct oxidative C─H trifluoromethylation utilizing inexpensive trifluoroacetic acid (TFA) is a highly desirable but thermodynamically challenging transformation, primarily due to the exceptionally high oxidation potential of the trifluoroacetate anion (CF 3 COO − ). In this work, we report a photoelectrocatalytic (PEC) strategy that leverages rational crystal facet engineering of tungsten trioxide (WO 3 ) photoanodes to overcome this kinetic bottleneck. By systematically modulating the growth conditions, we demonstrate that increasing the proportion of the (200) facet in the WO 3 photoanode enhances photoactivity, facilitating the conversion of electron‐rich arene into its mono‐trifluoromethylated derivative, with a maximum yield of 80%. To better understand this observation, we analyzed the reaction progression by examining the active surface on the photoanode, as well as the reactant, intermediate, and product. Our studies reveal that the activation and oxidation of trifluoroacetate anion (CF 3 COO – ) represent key barriers in this transformation. The (200) facets of WO 3 appear to favor CF 3 COO – adsorption, thereby facilitating its conversion. This study demonstrates the application of a PEC system for C─H trifluoromethylation and provides valuable insights into the relationship between crystal facets and the performance of organic transformations. It offers a new PEC platform for controlled trifluoromethylation reactions, which could inspire further advancements in related organosynthesis fields.
Circularly polarized luminescence (CPL) was enhanced by biasing the coordination geometry of chiral Zn(II) complexes. In solution, an equilibrium between the Λ and Δ coordination geometries was observed, and the diastereomer excess ( de ) increased with decreasing temperature. Notably, bromine substitution significantly enhanced this bias, leading to a pronounced preference for a single‐coordination geometry and reaching 63% de at −60 °C. The Zn(II) complexes exhibited blue fluorescence under UV excitation with moderate emission efficiencies. Interestingly, a gradual enhancement of CPL intensity was observed upon lowering the temperature, and the luminescence dissymmetry factor ( g lum ) reached a maximum value of 1.8 × 10 −3 for bromine‐substituted complexes. Importantly, biasing the coordination geometry resulted in effective tuning of the CPL while preserving the blue‐emissive character of the Zn(II) complexes. These findings present coordination geometry biasing as a powerful design tool for controlling CPL in chiral metal‐based luminophores.
Understanding how interfacial electronic structure governs photogenerated charge flow is central to advancing heterogeneous photocatalysis. Herein, a three‐dimensional ZnO/CsPbBr 3 nanoheterostructure (NHS) system is constructed to elucidate the relationship between band alignment, carrier dynamics, and photocatalytic CO 2 reduction under solid–gas conditions using CO 2 and H 2 O as reactants. Ultraviolet photoelectron spectroscopy reveals staggered band alignment that enables formation of an S‐scheme heterojunction with an internal electric field at the ZnO/CsPbBr 3 interface. This configuration preserves the strong reduction potential of CsPbBr 3 and the oxidation capability of ZnO while promoting directional recombination of low‐energy carriers and spatial separation of highly reactive electrons and holes. The investigation of charge carrier dynamics demonstrates accelerated interfacial electron migration and enhanced carrier separation in the optimized heterostructure. The apparent quantum efficiency follows the optical absorption profile, confirming efficient photon‐to‐chemical energy conversion. 13 C isotope labeling verifies that CO originates from CO 2 reduction accompanied by H 2 O oxidation. A clear correlation between band alignment, carrier lifetime modulation, interfacial charge‐transfer rate, and catalytic activity is established, providing mechanistic insight into interfacial photochemistry in perovskite–metal oxide heterostructures for solar fuel generation.
Antibiotics and heavy metals are increasingly polluting water systems, and photocatalysis is a promising method to remove these pollutants. This article prepared carbon‐doped BiOCl nanosheets with high {001} facet exposure via hydrothermal method using glucose as carbon source, which can remove ciprofloxacin (CIP) and Cr(VI) individually or simultaneously. When precursor glucose content increases, nanosheet thickness decreases while {001} facet exposure still stays at a high level of 78%. The synergy of carbon doping, reduced thickness, and high {001} exposure improves the visible light absorption efficiency, narrows the bandgap, and enhances the separation and migration efficiency of carriers. As a result, the material has much higher photocatalytic activity than pure BiOCl in both photooxidation and photoreduction of pollutants. The optimized C‐7‐BiOCl sample with Bi 3+ /glucose molar ratio 5:7 has 173% higher CIP oxidation efficiency and 230% higher Cr(VI) reduction efficiency than pure BiOCl. It also has excellent simultaneous removal efficiency for CIP and Cr(VI) in mixed pollutants, and its photocatalytic activity is 3.80 times and 4.64 times higher than that in single‐pollutant system, respectively. This study provides a simple preparation method for C‐doped BiOCl with improved photooxidation and photoreduction activity, and it is expected to be used in actual wastewater treatment.
Plasmon‐induced charge separation (PICS), which is based on electron injection from plasmonically excited nanoparticles (NPs) into an electron collector, has predominantly employed wide‐bandgap semiconductors such as TiO 2 as the electron collector. If polyoxometalates (POMs), which can serve as capping agents to assist the dispersion of plasmonic metal NPs in water, could also function as electron collectors, metal–POM nanocomposites would be promising as photocatalysts. In the present study, commercially available α‐H 4 SiW 12 O 40 (SiW 12 ) was used as a POM and assembled as thin films on electrodes by a layer‐by‐layer method. PICS via electron injection from Au NPs and that from Ag NPs into SiW 12 was demonstrated by photoelectrochemical measurements and visible absorption spectroscopy, respectively.
Aggregation‐induced emission (AIE) has revolutionized the design of photoluminescent materials by enabling strong solid‐state emission from molecularly nonemissive compounds. However, rational prediction of AIE properties remains challenging because photophysical behavior depends not only on molecular structure but also on aggregate‐state packing and measurement conditions. This study develops a quantitative and interpretable machine learning (ML) framework for predicting experimentally reported emission energies of AIE‐active molecules using continuous physicochemical descriptors derived from molecular structures. A dataset of 590 AIE luminogens—including conjugated organics, donor–acceptor (D–A) systems, silicon‐containing luminogens, and transition‐metal complexes—was analyzed using Gaussian process regression (GPR) combined with SHapley Additive exPlanations (SHAP). The optimized descriptor‐based model achieved moderate predictive performance (test R 2 = 0.58) and provided chemically interpretable structure–property trends. Feature attribution indicated that nitrogen‐ and sulfur‐containing motifs, electrotopological‐state descriptors, Burden–CAS–University of Texas (BCUT) descriptors, and stereodefined vinylene units are statistically associated with lower emission energies within the present dataset. Morgan fingerprint baseline models showed higher random‐split accuracy, whereas leave‐one‐cluster‐out validation revealed cluster‐dependent degradation for structurally separated regions. This work therefore provides an interpretable initial screening strategy for AIE luminogens while clarifying the need for future models incorporating measurement conditions, solid‐state structural descriptors, and electronic‐structure‐informed features.
