| 1. |
- Zhu, Haibo, et al.
(författare)
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Insight into Benzothiadiazole Acceptor in D-A-pi-A Configuration on Photovoltaic Performances of Dye-Sensitized Solar Cells
- 2014
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 2:4, s. 1026-1034
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Tidskriftsartikel (refereegranskat)abstract
- The option of conjugated pi-linkers is critical for molecular engineering toward the energy-level strategy of donor-pi-acceptor (D-pi-A) sensitizers. There is always a balance in the optimization of a it-linker. The pi-conjugation should be enlarged to expand the light-harvesting capability of sensitizers for an increase in photocurrent; however, the oversized it-linker also would affect seriously the photovoltage and photostability. Two sensitizers, WS-22 and WS-23, are constructed without or with benzothiadiazole (BTD) in a molecular skeleton, aiming to gain insight into the effect of an auxiliary acceptor in D-A-pi-A sensitizers on the photophysical and photovoltaic performances, especially focusing on the exploitation of the short circuit current density (J(sc)) and open circuit voltage (V-oc). Compared with the typical D-pi-A sensitizer WS-22, the incorporation of an auxiliary acceptor of BTD in WS-23 can improve the light-harvesting ability both in red-shifting the absorption peaks and the increment of absorption coefficient. The predominant increase by 15.6% in light-harvesting efficiency (LHE) of WS-23 results in a relatively higher J(sc) from 13.77 (WS-22) to 16.91 mA cm(-2) (WS-23). Moreover, the improvement of the V-oc in WS-23 is originated by a synergy contribution of the uplifting of E-CB and inhibition of charge recombination. The stepped light-induced transient (SLIT) measurements indicate that the introduction of BTD can negatively shift the conduction band of the TiO2 film. For WS-23, the higher molecular dipole moment can bring forth a more effective charge separation between donor and acceptor units, also resulting in an increase in V-oc. The incorporated BTD unit can increase V-oc by 57 mV, arising from the CB edge shift of TiO2 (accounting for 40%, 23 mV) and the retarding charge recombination (accounting for 60%, 34 mV). As a consequence, WS-23 realizes an optimizing photovoltaic efficiency (eta = 8.15%), with an improvement of 36.5% with respect to WS-22.
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| 2. |
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| 3. |
- Ding, Yubin, et al.
(författare)
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Acid/Base Switching of the Tautomerism and Conformation of a Dioxoporphyrin for Integrated Binary Subtraction
- 2014
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 20:40, s. 12910-12916
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Tidskriftsartikel (refereegranskat)abstract
- Compared with most of the reported logic devices based on the supramolecular approach, systems based on individual molecules can avoid challenging construction requirements. Herein, a novel dioxoporphyrin DPH22 was synthesized and two of its tautomers were characterized by single-crystal X-ray diffraction studies. Compound DPH22 exhibits multichannel controllable stepwise tautomerization, protonation, and deprotonation processes through interactions with H and F- ions. By using the addition of H+ and F- ions as inputs and UVNis absorption values at.1=412, 510, 562, and 603 nm as outputs, the controlled tautomerism of DPH22 has been successfully used for the construction of an integrated molecular level half-subtractor and comparator. In addition, this acid/base-switched tautomerism is reversible, thus endowing the system with ease of reset and recycling; consequently, there is no need to modulate complicated intermolecular interactions and electron-/chargetransfer processes.
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| 4. |
- Ding, Yubin, et al.
(författare)
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alpha-Monoacylated and alpha,alpha '- and alpha,beta '-Diacylated Dipyrrins as Highly Sensitive Fluorescence "Turn-on" Zn2+ Probes
- 2013
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 78:11, s. 5328-5338
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Tidskriftsartikel (refereegranskat)abstract
- With the purpose of developing readily synthesized CHEF (chelation-enhanced fluorescence) type Zn2+ probes with relatively simple molecular structures and excellent sensing behavior, p-anisoyl chloride was used for the acylation of 5-(pentafluorophenyl)dipyrromethane. Interestingly, the alpha,beta'-diacylated product PS2 with a unique substitution mode was obtained in high yield in addition to the normal a-substituted mono- and diacylated products PSI and PS3. Further oxidation of PS1-PS3 afforded dipyrrins S1-S3. Crystal structure and H-1 NMR measurements of S2 demonstrate the existence of a pure tautomer, which is consistent with DFT calculations. S1-S3 show highly Zn2+ selective "turn-on" fluorescence based on a CHEF mechanism by the formation of 2:1 (probe:metal) Zn2+ complexes. The emission colors can be easily tuned from green to red by changing the dipyrrin substitution modes. Furthermore, these probes demonstrate fast responses and wide applicable pH ranges. Among them, S2 shows the highest Zn2+ sensitivity, with a detection limit of 4.4 x 10(-8) M.
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| 5. |
- Ding, Yubin, et al.
(författare)
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From nonconjugation to conjugation : novel meso-OH substituted dipyrromethanes as fluorescence turn-on Zn2+ probes
- 2013
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Ingår i: Organic and biomolecular chemistry. - : Royal Society of Chemistry (RSC). - 1477-0520 .- 1477-0539. ; 11:16, s. 2685-2692
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Tidskriftsartikel (refereegranskat)abstract
- Most reported Zn2+ probes suffer from the interference of background fluorescence originated from the conjugated structures of commonly utilized fluorophores. In this work, three novel meso-hydroxyl group substituted dipyrromethanes DPMOH1-DPMOH3 were synthesized and found to be colourless and nonfluorescent due to the interruption of the conjugated p system by an sp(3) carbon between the two pyrrolic units. Interestingly, only the addition of Zn2+ to the solutions of DPMOH1-DPMOH3 promoted their oxidation to dipyrrin forms, and bright fluorescence "turn on" was observed due to the formation of corresponding dipyrrin complexes with the dipyrrin : zinc stoichiometry of 2 :1. Zn2+ detection mechanism was investigated by UV-Vis, fluorescence, H-1 NMR and HRMS analyses, which can be ascribed to the CHEF type fluorescence enhancement, resulting from good rigidity of the dipyrrin complexes. Hence, DPMOH1-DPMOH3 can be used as fluorescence turn-on Zn2+ probes with the advantage of no background fluorescence.
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| 6. |
- Song, Liwen, et al.
(författare)
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Synthesis and Photochromism of Naphthopyrans Bearing Naphthalimide Chromophore : Predominant Thermal Reversibility in Color-Fading and Fluorescence Switch
- 2011
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 115:49, s. 14648-14658
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Tidskriftsartikel (refereegranskat)abstract
- Two novel photochromic naphthopyrans containing naphthalimide moieties (Nip1 and Nip2) were studied in solution under flash photolysis conditions, exhibiting highly photochromic response, rapid thermal bleaching rate and good fatigue-resistance. Owing to the different N-substituted imide groups at the naphthalimide units, the thermal bleaching rate of Nip2 bearing phenyl on the naphthalimide unit is found to be approximately 2 times that of Nip1 bearing n-butyl, indicating that the photochromic properties can be modulated with introduction of different functional groups on the naphthalimide unit. In Nip1 and Nip2, the strong electron-withdrawing effect of the imide group incorporated at the naphthalimide moiety maintains several merits: (i) shifting absorption bands to longer wavelength, (ii) beneficial to an enhancement in the ratio of transoid-cis (TC) isomer and an increase in the transformation rate from transoid-trans (TT) to TC with respect to reference compound NP, and (iii) resulting in a preferable color bleaching rate and fading absolutely to their colorless state with thermal reversibility. As demonstrated in the system of NP, the slow transformation process from TT to TC might be the predominant dynamic step in thermal back process, leading to the residual color of NP being only faded to its original colorless state by visible light irradiation. The optical densities of colored forms for Nip1 and Nip2 are dependent upon the intensity of incident light, ensuring a possible application in the manufacture of ophthalmic lenses and smart windows. Moreover, the fluorescence of Nip1 and Nip2 can be switched on and off by photoinduced conversion between the closed and open forms.
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| 7. |
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| 8. |
- Wang, Yueqiang, et al.
(författare)
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Porphyrins bearing long alkoxyl chains and carbazole for dye-sensitized solar cells : tuning cell performance through an ethynylene bridge
- 2013
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 3:34, s. 14780-14790
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Tidskriftsartikel (refereegranskat)abstract
- Two novel porphyrin dyes (Q1 and Q2) bearing alkoxyl chains with a carbazole moiety as the electron donor have been synthesized and utilized as sensitizers for dye-sensitized solar cells (DSSCs). Compared with Q2, the molecule of Q1 has an additional ethynylene bridge between the carbazole moiety and the porphyrin framework. Photophysical and electrochemical properties of the two dyes were investigated by UV-vis, fluorescence spectroscopy and cyclic voltammetry. DFT calculations indicated that Q2 has a more twisted non-planar conformation associated with a smaller p conjugation size because of the absence of ethynylene bridge, which resulted in its better solubility and larger amount of adsorption on TiO2. Compared with Q1, Q2 showed better photovoltaic performance, with a short-circuit photocurrent density (J(sc)) of 11.3 mA cm(-2), an open-circuit photovoltage (V-oc) of 0.68 V, and a fill factor (ff) of 0.71, corresponding to an overall conversion efficiency of 5.51% under standard global AM 1.5 solar light conditions. The additional ethynylene bridge in Q1 extends the absorption bands to a longer wavelength region with the absorption threshold of 743 nm on the TiO2 film compared with that of 681 nm for Q2, but the cell efficiency is decreased to 2.22%, which may be ascribed to the worse solubility and stronger aggregation tendency resulting from the better molecule planarity. These results indicate that the extension of the absorption bands to a longer wavelength region by the introduction of an additional ethynylene bridge may result in worse solubility and more severe aggregation, and thus decrease the cell efficiency. For the design of efficient DSSC sensitizers, these contradictory effects must be fully considered and well balanced.
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| 9. |
- Yuan, Haifeng, et al.
(författare)
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Mustard seeds (Sinapis Alba Linn) attenuate azoxymethane-induced colon carcinogenesis
- 2011
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Ingår i: REDOX REPORT. - : MANEY PUBLISHING, STE 1C, JOSEPHS WELL, HANOVER WALK, LEEDS LS3 1AB, W YORKS, ENGLAND. - 1351-0002. ; 16:1, s. 38-44
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Tidskriftsartikel (refereegranskat)abstract
- Mustard seeds (MS), which are consumed in considerable amounts by the Japanese people that, interestingly, have the longest life expectancy in the world, are known to contain a number of yet not fully defined but quite powerful anti-oxidants. A suspension of extracted MS was found to suppress oxidized-LDL-induced macrophage respiratory burst in vitro, to prevent growth, and to induce apoptotic death of SW480 cells (a human colon cancer cell line), while no such effects were found for normal 3T3 cells. A diet enriched with MS decreased plasma levels of the lipid peroxidation product malonaldehyde in mice exposed to the colon cancer-inducer azoxymethane (AOM). Such a diet also dose-dependently enhanced the activity of several anti-oxidant enzymes, such as superoxide dismutase (SOD), catalase, and GSH-peroxidase and, moreover, reduced AOM-mediated formation of colon adenomas by about 50%. Further studies are required to detail and explore the beneficial effects of MS and their rich content of powerful anti-oxidants.
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