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Photo-physical properties of substituted 2,3-distyryl indoles: Spectroscopic, computational and biological insights
摘要： The structural dependence of the photo-physical properties of substituted 2,3-distyryl (23DSI) indoles were studied using several spectroscopic techniques including steady-state UV-VIS spectroscopy, steady-state fluorescence spectroscopy, steady-state excitation spectroscopy, time correlated single photon counting (TCSPC) spectroscopy, and time-resolved fluorescence upconversion spectroscopy (TRFLS). Each of 23DSI derivatives investigated showed distinct fluorescence emission and UV-VIS spectra, indicating strong structural dependence of the emission and the excitation. The UV-VIS spectra of the 23DSI derivatives showed three main identical absorption bands with minor deviations in the absorbance caused by substituent groups on the distyryl rings. The time-resolved fluorescence up-conversion studies indicated that the fluorescence undergoes a mono-exponential decay whereas the calculated fluorescence lifetime showed relatively short fluorescence lifetimes of approximately 1 ns. All of the 23DSI derivatives showed two-photon absorption upon direct excitation of 1.6 W laser pulses at 800 nm. These studies suggest that the substituents, attached to distyryl core, are capable of boosting or hindering fluorescence intensities by distorting the π-conjugation of the 23DSI molecule. Our studies showed that 23DSI (p-F) has the highest fluorescence emission quantum yield. Theoretical calculations for the ground state of 23DSI derivatives confirmed differences in electron densities in 23DSI derivatives in the presence of different substituent attachments. The excellent fluorescence emission, high fluorescence quantum yield and two-photon absorption properties of these 23DSI molecules make them attractive candidates for potential applications in the fields of biological imaging, biomedicine, fluorescent probes, and photodynamic inactivation (PDI). B. subtilis samples, treated with micro molar solutions of 23DSI (p-OCH3) and 23DSI (p-CH3), showed very effective photodynamic inactivation (PDI) upon irradiation with white light.
关键词： Two photon absorption,Time-resolved fluorescence upconversion laser spectroscopy,Photodynamic inactivation,Gaussian calculations,Photo-physical properties,Light-activation
更新于2025-11-14 15:26:12
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Carbons dots: The next generation platform for biomedical applications
摘要： Among the wide range of carbon family nanomaterials, carbon dots (CDs) one of the promising candidate which have attracted tremendous attention due to its unique advantages such as facile synthesis procedure, easy surface functionalization, outstanding water solubility, low toxicity and excellent photo-physical properties. Due to these unique advantages, CDs are extensively used in catalysis, electronics, sensing, power as well as in biological sectors. In this review we will discuss recent progress in synthesis, structure and fluorescence properties of CDs with special highlight on its biomedical applications, more precisely we will highlight on CDs, for drug/gene delivery, bioimaging and photothermal and photodynamic therapy applications. Furthermore, we discuss the current challenges and future perspective of CDs in the field of biomedical sector.
关键词： Photo-physical properties,Bioimaging,Photothermal and photodynamic therapy,Drug/gene delivery
更新于2025-09-23 15:21:01
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Impact of K+ Doping on Modulating Majority Charge Carrier Type and Quality of Perovskite Thin Films by Two-step Solution Method for Solar Cells
摘要： Traditional hetero-junction perovskite solar cells are composed of light-absorbing layers, charge carrier-transporting layers, and electrodes. Recently, a few papers on homo-junction perovskite solar cells have been studied. Here, we studied the effect of K+ doping on TiO2/PbI2 interface quality, perovskite film morphology, photo-physical properties, and majority carrier type. In particular, the K+ extrinsic doping can modulate the majority carrier type of the perovskite thin film. The study indicated that the interface between the perovskite layer and the TiO2 layer deteriorates with the K+ doping concentration, affecting the electron transport ability from the perovskite film to the TiO2 layer and the photo-physical properties of the perovskite layer by K+ doping. In addition, the majority charge carrier type of perovskite thin films can be changed from n-type to p-type after K+ extrinsic doping, and the corresponding hole concentration increased to 1012 cm?3. This approach of modulating the majority charge carrier type of perovskite thin film will pave the way for the investigation of perovskite homo-junction by extrinsic doping for solar cells.
关键词： p-n junction,perovskite solar cells,K+ doping,photo-physical properties
更新于2025-09-16 10:30:52
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Synthesis, optical characterization, and TD-DFT studies of novel mero/bis-mero cyanine dyes based on N-Bridgehead heterocycles
摘要： Novel mero/bis-mero cyanine dyes based on N-Bridgehead imidazo[1,2-g]quinolino[2,1-a][2,6]naphthyridine have been synthesized and characterized to evaluate intramolecular charge transfer (ICT) effect on the energy gap (E0-0). The UV–Vis/emission spectral studies revealed that, dyes are absorbed in the region of λmax (485-577) nm and emitted at (567-673) nm. Their solvatochromic behavior in solvents of various polarities, viz. (CCl4, C6H6, H2O, CHCl3, acetone, and DMF) was studied to emphasize the effect of solvent polarity on the absorption maxima, molar extinction coefficients of the dyes, and excitation energy of the dyes. Their electron cloud delocalization in HOMO/LUMO levels were studied by DFT using Gaussian 09 software. Time-dependent density functional theory (TD-DFT) was applied to theoretically explore the first excitation energy (E0-0) of these dyes which in well agreement with experimental results.
关键词： TD-DFT calculations,Photo-physical properties,Solvatochromic behavior,Mero cyanine
更新于2025-09-09 09:28:46