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Investigation of ultrafast energy transfer mechanism in BODIPY–Porphyrin dyad system
摘要： Novel β-fused BODIPY-Porphyrin compounds that contain free base porphyrin (TPP2BDP) and its Ni(II) complex (NiTPP2BDP) were synthesized to investigate intramolecular energy transfer mechanisms of β-fused BODIPY-porphyrin dyads and effect of the unfilled d shell metal ion on energy transfer mechanism. Fluorescence spectra of compounds exhibited that BODIPY emission was diminished upon excitation of the BODIPY unit because of the energy transfer from BODIPY to porphyrin unit. Femtosecond pump-probe spectroscopy measurements revealed that energy transfer of investigated compounds are faster than previous studies in literature. Rapid energy transfer (about 500 fs) from BODIPY to porphyrin was observed for both compounds when BODIPY unit is excited due to direct linkage of BODIPY to porphyrin unit. Intersystem crossing mechanism was also observed for the compound that contains free base porphyrin (TPP2BDP), whereas d-d transition was observed for the compound that contains metalloporphyrin (NiTPP2BDP) due to unfilled d orbital of Ni(II) ion.
关键词： Fast energy transfer,Borondipyrromethene,Porphyrin,Ultrafast pump-probe spectroscopy
更新于2025-09-23 15:23:52
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405 nm and 450 nm photoinactivation of <i>Saccharomyces cerevisiae</i>
摘要： Photoinactivation of bacteria with visible light has been reported in numerous studies. Radiation around 405 nm is absorbed by endogenous porphyrins and generates reactive oxygen species that destroy bacteria from within. Blue light in the spectral range of 450–470 nm also exhibits an antibacterial effect, but it is weaker than 405 nm radiation, and the photosensitizers involved have not been clarified yet, even though flavins and porphyrins are possible candidates. There are significantly fewer photoinactivation studies on fungi. To test if visible light can inactivate fungi and to elucidate the mechanisms involved, the model organism Saccharomyces cerevisiae (DSM no. 70449) was irradiated with violet (405 nm) and blue (450 nm) light. The mean irradiation doses required for a one log reduction of colony forming units for this strain were 182 J/cm2 and 526 J/cm2 for 405 nm and 450 nm irradiation, respectively. To investigate the cell damaging mechanisms, trypan blue staining was performed. However, even strongly irradiated cultures hardly showed any stained S. cerevisiae cells, indicating an intact cell membrane and thus arguing against the previously suspected mechanism of cell membrane damage during photoinactivation with visible light at least for the investigated strain. The results are compatible with photoinactivated Saccharomyces cerevisiae cells being in a viable but nonculturable state. To identify potential fungal photosensitizers, the absorption and fluorescence of Saccharomyces cerevisiae cell lysates were determined. The spectral absorption and fluorescence results are in favor of protoporphyrin IX as the most important photosensitizer at 405 nm radiation. For 450 nm irradiation, riboflavin and other flavins may be the main photosensitizer candidates, since porphyrins do not play a prominent role at this wavelength. No evidence of the involvement of other photosensitizers was found in the spectral data of this strain.
关键词： photoinactivation,porphyrin,450 nm irradiation,flavin,Saccharomyces cerevisiae,disinfection,405 nm irradiation
更新于2025-09-23 15:23:52
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Design and Implementation of Digital Phase Locked Loop for Single-Phase Grid-Tied PV Inverters
摘要： The rational design of porphyrin sensitizers is always crucial for dye-sensitized solar cells (DSSCs), since the change of only a single atom can have a significant influence on the photovoltaic performance. We incorporated the pyridothiadiazole group, as a stronger electron-withdrawing group, into the commonly well-established skeleton of D-porphyrin-triple bond-acceptor sensitizers by a single atom change for a well-known strong electron-withdrawing benzothiadiazole (BTD) unit as an auxiliary acceptor. The impact of the pyridothiadiazole group on the optical; electrochemical; and photovoltaic properties of D–π–A porphyrin sensitizers was investigated with comparison for a benzothiadiazole-substituted SGT-020 porphyrin. The pyridothiadiazole-substituted SGT-024 porphyrin dye was red-shifted so that the absorption range might be expected to achieve higher light harvest efficiency (LHE) than the SGT-020 porphyrin. However, all the devices were fabricated by utilizing SGT-020 and SGT-024, evaluated and found to achieve a cell efficiency of 10.3% for SGT-020-based DSSC but 4.2% for SGT-024-based DSSC under standard global AM 1.5G solar light conditions. The main reason is the lower charge collection efficiency of SGT-024-based DSSC than SGT-020-based DSSC, which can be attributed to the tilted dye adsorption mode on the TiO2 photoanode. This may allow for faster charge recombination, which eventually leads to lower Jsc, Voc and power conversion efficiency (PCE).
关键词： D–π–A structural porphyrin,charge collection efficiency,acceptor units,charge recombination,dye-sensitized solar cells
更新于2025-09-23 15:23:52
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Preparation of a star-shaped copolymer with porphyrin core and four PNIPAM-b-POEGMA arms for photodynamic therapy
摘要： A series of thermosensitive star-shaped copolymers THPP-(PNIPAM-b-POEGMA)4 with 5, 10, 15,20-tetrakis-(4-hydroxyphenyl)-21H,23H-porphyrin (THPP) core and four poly(N-isopropylacrylamide)-b-poly(oligo(ethylene glycol) mono methyl ether methacrylate) (PNIPAM-b-POEGMA) arms were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The low critical solution temperatures (LCSTs) of THPP-(PNIPAM-b-POEGMA)4 with different molecular weights were 37.5 °C, 39.9 °C and 41.9 °C respectively, which depending on the hydrophilic POEGMA contents of copolymers. The micellar structures of copolymers could be formed above the LCSTs. The MTT study indicated that THPP-(PNIPAM-b-POEGMA)4 and THPP showed no significant cytotoxicity toward HeLa cells and L929 cells. And THPP-(PNIPAM-b-POEGMA)4 under light irradiation showed photodynamic activity which photo-toxicity toward HeLa cells was stronger than THPP.
关键词： Porphyrin,Thermosensitivity,Reversible addition-fragmentation chain transfer (RAFT),THPP-(PNIPAM-b-POEGMA)4,Photodynamic therapy
更新于2025-09-23 15:22:29
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Structural and Functional Consequences of the Weak Binding of Chlorin e6 to Bovine Rhodopsin
摘要： The chlorophyll-derivative chlorin e6 (Ce6) identified in the retinas of deep-sea ocean fish is proposed to play a functional role in red bioluminescence detection. Fluorescence and 1H NMR spectroscopy studies with the bovine dim-light photoreceptor, rhodopsin, indicate that Ce6 weakly binds to it with μM affinity. Absorbance spectra prove that red light sensitivity enhancement is not brought about by a shift in the absorbance maximum of rhodopsin. 19F NMR experiments with samples where 19F labels are either placed at the cytoplasmic binding site or incorporated as fluorinated retinal, indicate that the cytoplasmic domain is highly perturbed by binding, while little to no changes are detected near the retinal. Binding of Ce6 also inhibits G protein activation. Chemical shift changes in 1H,15N NMR spectroscopy of 15N-Trp labeled bovine rhodopsin reveal that Ce6 binding perturbs the entire structure. These results provide experimental evidence that Ce6 is an allosteric modulator of rhodopsin.
关键词： G protein coupled receptor,chlorophyll-derivative,porphyrin,night vision,light activation,photosensitization,bovine rhodopsin,Allosteric modulator
更新于2025-09-23 15:22:29
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Chiral Recognition of L- and D- Amino Acid by Porphyrin Supramolecular Aggregates
摘要： We report of the interactions between four amino acids lysine (Lys), arginine (Arg), histidine (His), and phenylalanine (Phe) with the J-aggregates of the protonated 5,10,15,20-tetrakis(4-sulfonatophenyl)-porphyrin H4TPPS. Several aspects of these self-assembled systems have been analyzed: (i) the chiral transfer process; (ii) the hierarchical effects leading to the aggregates formation; and, (iii) the influence of the amino acid concentrations on both transferring and storing chiral information. We have demonstrated that the efficient control on the J-aggregates chirality is obtained when all amino acids are tested and that the chirality transfer process is under hierarchical control. Finally, the chiral porphyrin aggregates obtained exhibit strong chiral inertia.
关键词： porphyrin,self-assembly,amino acid,circular dichroism,supramolecular chirality
更新于2025-09-23 15:22:29
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Fabrication and characterization of VOC sensor array based on SnO2 and ZnO nanoparticles functionalized by metalloporphyrins
摘要： A volatile organic compound (VOC) sensor array based on metal oxide nanoparticles (MOX NPs) functionalized by metalloporphyrins (MPPs) was demonstrated. The VOC sensor array was composed of four single sensors based on SnO2 NPs/cobalt-porphyrin, SnO2 NPs/zinc-porphyrin, SnO2 NPs/nickel-porphyrin and ZnO NPs/cobalt-porphyrin. The MOX NP/MPP-based sensors were fabricated by drop-casting the MOX NPs dispersion and MPPs solution onto a MEMS platform. The fabricated sensor successfully detected toluene at a concentration as low as 20 ppb, which is below the limit detection concentration of previously reported porphyrin-based VOC sensor arrays. We also confirmed the selectivity between benzene, toluene, ethylbenzene, and xylene (BTEX) by using principal component analysis in contrast to previous studies on MOX/MPP-based sensor. BTEX was classified from 1 to 9 ppm at a resolution of 2 ppm, and the sensor array showed stable performance even after considerable impact.
关键词： Gas sensor array,Porphyrin,Principle component analysis,Metal oxide,Volatile organic compound
更新于2025-09-23 15:22:29
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Synthesis, Photophysical and Electrochemical Studies on Peripherally Ruthenated Tetraphenylporphyrin
摘要： Ruthenium(II) complexes of 5-(4-hydroxyphenyl)-10,15,20-tris-(4-methylphenyl)porphyrin and 5,10,15,20-tetrakis(4-hydroxyphenyl)-porphyrin have been synthesized in basic medium and spectroscopically characterized. The complexes show broad bands in the visible region due to overlap of porphyrin transitions with the metal-to-ligand charge transfer (MLCT) transitions arising from cis-Ru(bipy)2Cl2. 1H NMR indicates π-electron interactions between the porphyrin ring and bipyridyl rings. The complexes are emissive both at room temperature and at 77 K with two independent emissions at 77 K, one from the excited state of the porphyrin moiety at 650 and 720 nm and the other from the excited state of the ruthenium moiety at 700 nm. No excited state intramolecular energy transfer reactions have been detected. However the quantum yield of the complexes is reduced due to heavy atom effect. Time resolved fluorescence decay analyses show dual life time at 1.5 and 7.7 ns in dichloromethane. The shorter life time is assigned to singlet-excited state of ruthenium and longer life time to porphyrin singlet excited state. Electrochemical analysis of these species in dichloromethane exhibits three anodic peaks at around 0.68, 0.98 and 1.42 V versus SCE, analogous to the Ru3+/2+ couple and two successive one-electron oxidation processes on the porphyrin ring, respectively. On the other hand, cathodic potentials at around -0.8, -1.4 and -1.54 V versus SCE, with first two peaks corresponding to two successive reduction taking place at the porphyrin ring and the third peak corresponding to reduction of bipyridyl unit. All spectroscopic studies reveal perturbation on the electronic levels of both porphyrin ring and ruthenium chromophore.
关键词： Porphyrin,Ruthenated,Life time,Perturbation,Emission,Electrochemistry
更新于2025-09-23 15:22:29
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Enhanced nonlinear optical properties of porphyrin with an extended π-conjugated bridge
摘要： In this work, a series of molecules with an extended π-conjugated bridge have been theoretically designed based on porphyrin, where -(CH=CH)n- (n = 1–4, 8, 12) chain is served as an extended π-conjugated bridge. It is found that all molecules exhibit large energy gaps in the range of 3.484–4.151 eV for porphyrin-(CH=CH)n-NH2, and 3.624–4.250 for porphyrin-(CH=CH)n-NO2. The maximum absorption wavelengths of all molecules show a red shift trend with increasing -(CH=CH)n- length, which leads to small transition energy. It is observed that long chain brings these molecules the large first hyperpolarizability, which are 1.04 × 105 au for porphyrin-(CH=CH)12-NH2, 1.26×105 au for porphyrin-(CH=CH)12-NO2. Moreover, compared with -(CH=CH)n-NH2 with the same chain length, -(CH=CH)n-NO2 chain can achieve larger nonlinear optical response. It is hoped that the research in this paper can provide a new strategy for the experimental design of nonlinear optical materials.
关键词： First hyperpolarizability,Porphyrin,An extended π-conjugated bridge
更新于2025-09-23 15:22:29
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Study on Five Porphyrin-Based Photosensitizers for Singlet Oxygen Generation
摘要： Five porphyrin derivatives were synthesized and characterized in order to be utilized as photosensitizers for singlet oxygen generation. UV-Vis absorption properties of porphyrins were experimentally and theoretically discussed. The results indicated that the increase in π-conjugation of porphyrin core can lower the S1-T1 energy gap and is favorable for efficient energy transfer. The singlet oxygen generation ability of porphyrins was measured and compared under both simulated sunlight and yellow light. As for the results using simulated sunlight, EBHPP and CEBHPP exhibited best and similar performance because they bear strong near-IR absorption and S1-T1 interactions. However, under yellow light conditions CEBHPP has better ability for singlet oxygen generation because of strong absorbance from 650–750 nm. The DNA photocleavage measurements were performed to evaluate the biological activity of the porphyrin derivatives. The photocleavage activities were in the order of TPP < TPP-NO2 < BHPP < EBHPP < CEBHPP, and the possible reasons were discussed. This work is useful for the design of more efficient photosensitizers.
关键词： Photosensitizer,Porphyrin,Singlet oxygen,UV-Vis absorption,Photodynamic therapy
更新于2025-09-23 15:22:29