Photochem, Volume 5, Issue 1 (March 2025) – 9 articles

In this work, we report the fabrication of CuI@g-C₃N₄/MoS₂ thin films by the thermal evaporation of Cu films and their conversion into hybrid films by a simple wet chemical method. Compared to pure CuI, CuI@g-C₃N₄/MoS₂ shows enhanced absorption near the UV region, which improves its DC photoconductivity. The conductivity of the films is enhanced by the addition of g-C₃N₄/MoS₂, which is distributed on the surface of the CuI film. The band gap of the films red-shifts upon adding g-C₃N₄/MoS₂. We evaluate this material’s potential application as a photodetector and in photocatalysis by evaluating its photoelectrochemical properties using impedance spectroscopy measurements, cyclic voltammetry, and DC photoresponse measurements. We find that upon the addition of g-C₃N₄/MoS₂, the conductivity of the films is increased, as evidenced by the time-dependent photo amperometry measurements. Also, a higher DC photoresponse is observed upon increasing the concentration of MoS₂. This work marks the first time a hybrid CuI@g-C₃N₄/MoS₂ film and its photoelectrochemical characteristics have ever been reported. Full article

Chemically identical chlorophyll (Chl) molecules undergo conformational changes when they are embedded in a protein matrix. The conformational changes will modulate their absorption spectra to meet the need for programmed excitation energy transfer or electron transfer. To interpret spectroscopic data using the knowledge of pigment–protein interactions requires a single pigment embedded in one polypeptide matrix. Unfortunately, most of the known photosynthetic systems contain a set of multiple pigments in each protein subunit. This makes it complicated to interpret spectroscopic data using structural data due to the potential overlapping spectra of two or more pigments. Chl–protein interactions have not been systematically studied to answer three fundamental questions: (i) What are the structural characteristics and commonly shared substructures of different types of Chl molecules (e.g., Chl a, b, c, d, and f)? (ii) How many structural groups can Chl molecules be divided into and how are different structural groups influenced by their surrounding environments? (iii) What are the structural characteristics of pigment surrounding environments? Having no clear answers to the unresolved questions is probably due to a lack of computational methods for quantifying conformational changes in individual Chls and individual surrounding amino acids. The first version of the Triangular Spatial Relationship (TSR)-based method was developed for comparing protein 3D structures. The input data for the TSR-based method are experimentally determined 3D structures from the Protein Data Bank (PDB). In this study, we take advantage of the 3D structures of Chl-binding proteins deposited in the PDB and the TSR-based method to systematically investigate the 3D structures of various types of Chls and their protein environments. The key contributions of this study can be summarized as follows: (i) Specific structural characteristics of Chl d and f were identified and are defined using the TSR keys. (ii) Two and three clusters were found for various types of Chls and Chls a, respectively. The signature structures for distinguishing their corresponding two and three clusters were identified. (iii) Histidine residues were used as an example for revealing structural characteristics of Chl-binding sites. This study provides evidence for the three unresolved questions and builds a structural foundation through quantifying Chl conformations as well as structures of their embedded protein environments for future mechanistic understanding of relationships between Chl–protein interactions and their corresponding spectroscopic data. Full article

We report on the phosphorescence of singlet oxygen photogenerated through a stimulated Raman process. Nanosecond radiation in the green spectral region focused on hexane and carbon tetrachloride induces a Raman transition of the dissolved solvent oxygen molecules towards the singlet oxygen state, producing a Stokes signal in the near-infrared. The excited oxygen relaxes to the ground, emitting an infrared photon at 1272 nm. While the Stokes signal’s wavelength changes with the light’s wavelength, the wavelength of the phosphorescent photon remains unaltered. The result confirms previous reports on the stimulated Raman excitation of singlet oxygen. Full article

Visible-light-responsive silver-phosphate-sensitized fly-ash particles loaded on polyurethane nanofiber (Ag₃PO₄–FA/PU NFs) membrane photocatalysts were prepared by electrospinning followed by an ion-exchange method and characterized with state-of-art techniques. With the assistance of Ag₃PO₄–FA/PU NFs, 98 % of methylene blue (MB) was degraded within 60 min. The combination of FA and Ag₃PO₄ particles provided simultaneous adsorption and degradation of MB in an aqueous solution, resulting in the fast removal of the dye. Also, the Ag₃PO₄–FA/PU NFs exhibited excellent antibacterial performance toward Escherichia coli and Staphylococcus aureus bacteria. Thus, the prepared photocatalyst may provide a potential outcome for environmental remediation, especially wastewater treatment applications. Full article

Astrophysical ices play a crucial role in the chemistry of cold interstellar environments. However, their diverse compositions, temperatures, and grain morphologies pose significant challenges for molecular identification and quantification through infrared observations. We investigate the ability of implicit solvation approaches to capture temperature-dependent infrared spectral features of CO₂ molecules embedded in astrophysical ice analogues, comparing their performance to that of explicit ice models and experimental data. Using DFT calculations and vibrational frequency scaling, we model CO₂ trapped in both amorphous (cold) and crystalline (warm) H₂O ice clusters. The implicit model qualitatively identifies certain trends but fails to reliably capture the magnitude of frequency shifts and band strengths. Explicit models correctly reproduce the gas-to-solid redshifts for both the asymmetric stretch and bending modes; however, neither approach successfully replicates the experimentally observed temperature-dependent trend in the bending mode. While continuum-like methods may be useful as first-order approximations, explicit modelling of the molecular environment is essential for accurately simulating the infrared spectral behaviour of CO₂ in astrophysical ices and for interpreting observational data on ice composition and evolution. Full article

This communication aims to comprehensively elucidate the intricate mechanism governing the interaction between the excited triplet state of 4-Carboxybenzophenone (CB*) and the anionic form of 2-Naphthalene Sulfonate (NpSO₃⁻), employing the 337 nm Nanosecond Laser Flash Photolysis technique for this investigation. When the CB is selectively excited by a 337 nm laser, two primary processes become possible: (i) energy transfer from ³CB* to NpSO₃⁻ and (ii) electron transfer from NpSO₃⁻ to ³CB*. The dynamics of these interactions are explored through experimental observations of transient absorption spectra and the analysis of respective kinetic traces. The primary process dominating in the ³(CB...NpSO₃⁻)* system is identified as triplet energy transfer from excited ³CB* to ³(NpSO₃⁻), as demonstrated by characteristic spectral features observed at 410–420 nm. Comparisons are made with a similar system studied by Yamaji and co-workers, ³(BP^•−...NpO^•)*, revealing differences in the priority of primary process occurrences. These findings contribute to a deeper understanding of the intricate interactions between excited molecules and ground-state donors, aiding in the comprehension of mechanisms governing these reactions. Full article

Atomically precise noble metal nanoclusters protected by ligands are broadly discussed in the literature as a promising new class of materials with many interesting properties. Of those, the most prominent is the characteristic luminescence in the visible and near-infrared light. Within the plethora of conjugates of metal nanoclusters to various protective ligands, protein-enveloped systems present several unique features arising from an interplay of the nanocluster photophysics and the protein chemistry along its macromolecular dynamics. The specific properties of protein–metal nanocluster conjugates underlie various applications of these systems, especially in bioimaging. This review, in contrast to many already published, focuses on protein-protected gold nanoclusters (AuNCs) from the standpoint of the proteinaceous shell which plays a crucial role in the biocompatibility, solubility, and excellent in-solution stability of such nanohybrid complexes. Factors such as the protein’s size, structural rigidity, amino acid composition, electric charge, and the electron donor properties of composite amino acids are discussed. Full article

Biomarker detection is imperative in the realms of modern medicine, biology, and environmental science, owing to the numerous avenues for its application. The recent scientific upsurge in the development of molecules, materials, and mechanisms for such scientific development has garnered considerable attention among scientists. In this connection, excited-state intramolecular proton transfer (ESIPT) properties of photoluminescent compounds provide considerable insights into the designing, development, and detection of biomarkers. ESIPT molecules significantly show a Stokes-shifted emission due to their sensitive nature and unique photophysical properties. Leveraging this photophysical property and tunable nature, several fluorescent probes of this genre can be designed and synthesized for a plethora of application spheres. Schiff bases encompass one such category of functional molecules displaying ESIPT properties, which can be mitigated by adding several other functionalities and desired optical characteristics. The current review article spans the basics of ESIPT properties of certain photoluminescent molecules and also envisages biosensing applications of recently developed imine–functionalized Schiff base molecules with such properties as the prima-foci, along with other applications. Full article

The textile industry is a major contributor to environmental pollution, primarily through the discharge of wastewater loaded with dyes and contaminants that disrupt natural ecosystems. This study aims to develop a hybrid material by functionalizing carbon nanodots (CNDs) with the donor-π-acceptor organic dye L1 via amide coupling. By chemically modifying the surface of CNDs, we can enhance their multifunctionality and tailor their molecular composition. This innovative approach seeks to replace expensive dyes with cost-effective CNDs synthesized from citric acid and ethylenediamine using a domestic microwave oven, potentially improving the stability of the resulting hybrid. Additionally, TiO₂ anatase particles were synthesized as a metal oxide platform and sensitized with both pristine materials and the CND-L1 hybrid. A range of physicochemical methods was employed to analyze the elemental, structural, and optical properties of these materials. In photocatalytic degradation tests of methyl orange, the sensitized catalysts demonstrated significantly improved efficiency compared to TiO₂ alone. While CNDs exhibited good stability and enhanced L1’s stability, scavenger experiments revealed that holes and hydroxyl radicals play crucial roles in the degradation mechanism. This research underscores the promise of CND hybrids in advancing pollutant degradation technologies while reducing reliance on costly photocatalysts. Full article