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61.
Nagappanpillai Adarsh Madhesh Shanmugasundaram Dr. Rekha R. Avirah Dr. Danaboyina Ramaiah 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(40):12655-12662
A new series of aza‐BODIPY derivatives ( 4 a – 4 c , 5 a , c , and 6 b , c ) were synthesized and their excited‐state properties, such as their triplet excited state and the yield of singlet‐oxygen generation, were tuned by substituting with heavy atoms, such as bromine and iodine. The effect of substitution has been studied in detail by varying the position of halogenation. The core‐substituted dyes showed high yields of the triplet excited state and high efficiencies of singlet‐oxygen generation when compared to the peripheral‐substituted systems. The dye 6 c , which was substituted with six iodine atoms on the core and peripheral phenyl ring, showed the highest quantum yields of the triplet excited state (ΦT=0.86) and of the efficiency of singlet‐oxygen generation (ΦΔ=0.80). Interestingly, these dyes were highly efficient as photooxygenation catalysts under artificial light, as well as under normal sunlight conditions. The uniqueness of these aza‐BODIPY systems is that they are stable under irradiation conditions, possess strong red‐light absorption (620–680 nm), exhibit high yields of singlet‐oxygen generation, and act as efficient and sustainable catalysts for photooxygenation reactions. 相似文献
62.
Jun‐Ling Jin Hai‐Bin Li Dr. Yun Geng Yong Wu Yu‐Ai Duan Prof. Dr. Zhong‐Min Su 《Chemphyschem》2012,13(16):3714-3722
The geometric and electronic structures and photophysical properties of anilido‐pyridine boron difluoride dyes 1 – 4 , a series of scarce 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) derivatives with large Stokes shift, are investigated by employing density functional theory (DFT) and time‐dependent DFT (TD‐DFT) calculations to shed light on the origin of their large Stokes shifts. To this end, a suitable functional is first determined based on functional tests and a recently proposed index—the charge‐transfer distance. It is found that PBE0 provides satisfactory overall results. An in‐depth insight into Huang–Rhys (HR) factors, Wiberg bond indices, and transition density matrices is provided to scrutinize the geometric distortions and the character of excited states pertaining to absorption and emission. The results show that the pronounced geometric distortion due to the rotation of unlocked phenyl groups and intramolecular charge transfer are responsible for the large Stokes shift of 1 and 2 , while 3 shows a relatively blue‐shifted emission wavelength due to its mild geometric distortion upon photoemission, although it has a comparable energy gap to 1 . Finally, compound 4 , which is designed to realize the rare red emission in BODIPY derivatives, shows desirable and expected properties, such as high Stokes shift (4847 cm?1), red emission at 660 nm, and reasonable fluorescence efficiency. These properties give it great potential as an ideal emitter in organic light‐emitting diodes. The theoretical results could complement and assist in the development of BODIPY‐based dyes with both large Stokes shift and high quantum efficiency. 相似文献
63.
Liliana N. Trevani Jenene C. Roberts Peter R. Tremaine 《Journal of solution chemistry》2001,30(7):585-622
The spectra of copper(II)–ammonia solutions in 2 mol-kg–1 NH4NO3(aq) were recorded as a function of pH with a new UV–visible flow cell, capable of operating at conditions up to 325°C and 300 bars. Equilibrium constants for the formation of copper(II)–ammonia complexes Cu(NH3)n
2+, 1 n 4, from 30 to 150°C were determined by evolving factor analysis and nonlinear least-squares regression. Measurements at higher temperatures were limited by thermal decomposition of NH4NO3(aq). The formation constants of Cu(NH3)n
2+ decrease with temperature, consistent with extrapolations of literature data from measurements below 100°C. Measurements above 150°C were carried out in 0.5 mol-kg–1 CF3SO3H (aq), at the very high ammonia concentrations required to avoid the precipitation of CuO(s). The spectra are consistent with Cu(NH3)4
2+ as the predominant species, based on extrapolations of peak maxima and molar absorptivities from lower temperatures. Shifts in the spectra of Cu2+ and the Cu(NH3)n
2+ species to higher wavelength and increases in molar absorbance with increasing temperature are discussed in terms of the structure of the complexes. 相似文献
64.
Sanjoy Mukherjee Prof. Dr. Pakkirisamy Thilagar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(29):9052-9062
Three new NPI–BODIPY dyads 1 – 3 (NPI=1,8‐naphthalimide, BODIPY=boron‐dipyrromethene) were synthesized, characterized, and studied. The NPI and BODIPY moieties in these dyads are electronically separated by oxoaryl bridges, and the compounds only differ structurally with respect to methyl substituents on the BODIPY fluorophore. The NPI and BODIPY moieties retain their optical features in molecular dyads 1 – 3 . Dyads 1–3 show dual emission in solution originating from the two separate fluorescent units. The variations of the dual emission in these compounds are controlled by the structural flexibilities of the systems. Dyads 1 – 3 , depending on their molecular flexibilities, show considerably different spectral shapes and dissimilar intensity ratios of the two emission bands. The dyads also show significant aggregation‐induced emission switching (AIES) on formation of nano‐aggregates in THF/H2O with changes in emission color from green to red. Whereas the flexible and aggregation‐prone compound 1 shows AIES, rigid systems with less favorable intermolecular interactions (i.e., 2 and 3 ) show aggregation‐induced quenching of emission. Correlations of the emission intensity and structural flexibility were found to be reversed in solution and aggregated states. Photophysical and structural investigations suggested that intermolecular interactions (e.g., π–π stacking) play a major role in controlling the emission of these compounds in the aggregated state. 相似文献
65.
Marc Dittmann Franziska F. Graupner Benjamin Maerz Sven Oesterling Prof. Dr. Regina de Vivie‐Riedle Prof. Dr. Wolfgang Zinth Prof. Dr. Martin Engelhard Prof. Dr. Wolfgang Lüttke 《Angewandte Chemie (International ed. in English)》2014,53(2):591-594
The photochemical properties of indigo, a widely used industrial dye, has attracted both experimentalists and theoreticians from the beginning. Especially the high photostability of indigo has been the subject of intensive research. Recently, it was proposed that after photoexcitation an intramolecular proton transfer followed by a nonradiative relaxation to the ground state promote photostability. In indigo the hydrogen bond and the proton transfer occur between the opposing hemiindigo parts. Here, we provide experimental and theoretical evidence that a hydrogen transfer within one hemiindigo or hemithioindigo part is sufficient to attain photostability. This concept can serve as an interesting strategy towards new photostable dyes for the visible part of the spectrum. 相似文献
66.
Lysosomal pH Rise during Heat Shock Monitored by a Lysosome‐Targeting Near‐Infrared Ratiometric Fluorescent Probe 下载免费PDF全文
Dr. Qiongqiong Wan Prof. Dr. Suming Chen Prof. Dr. Wen Shi Lihong Li Prof. Dr. Huimin Ma 《Angewandte Chemie (International ed. in English)》2014,53(41):10916-10920
Heat stroke is a life‐threatening condition, featuring a high body temperature and malfunction of many organ systems. The relationship between heat shock and lysosomes is poorly understood, mainly because of the lack of a suitable research approach. Herein, by incorporating morpholine into a stable hemicyanine skeleton, we develop a new lysosome‐targeting near‐infrared ratiometric pH probe. In combination with fluorescence imaging, we show for the first time that the lysosomal pH value increases but never decreases during heat shock, which might result from lysosomal membrane permeabilization. We also demonstrate that this lysosomal pH rise is irreversible in living cells. Moreover, the probe is easy to synthesize, and shows superior overall analytical performance as compared to the existing commercial ones. This enhanced performance may enable it to be widely used in more lysosomal models of living cells and in further revealing the mechanisms underlying heat‐related pathology. 相似文献
67.
Promotion of Förster Resonance Energy Transfer in a Saponite Clay Containing Luminescent Polyhedral Oligomeric Silsesquioxane and Rhodamine Dye 下载免费PDF全文
Francesco Olivero Dr. Fabio Carniato Dr. Chiara Bisio Prof. Leonardo Marchese 《化学:亚洲杂志》2014,9(1):158-165
A new hybrid photostable saponite clay with embedded donor–acceptor dyes was prepared and characterized in this work. The saponite is intercalated with a luminescent polyhedral oligomeric silsesquioxane, which transfers the photoexcitation energy directly to an acceptor dye (rhodamine B). The obtained composite material was characterized by means of XRD, TEM microscopy, and UV/Vis and photoluminescence spectroscopy. A physicochemical study showed that the system behaved as an efficient Förster resonance energy transfer pair, owing to the very good spectral overlap of donor emission (λem=510–540 nm) and acceptor absorption in the λ=530–570 nm range. The hybrid material represents the first example of a photonic antenna based on a synthetic saponite clay and can be considered a step forward in the search for new, efficient, and stable materials suitable for light‐harvesting applications. 相似文献
68.
Photo‐ and pH‐Tunable Multicolor Fluorescent Nanoparticle‐Based Spiropyran‐ and BODIPY‐Conjugated Polymer with Graphene Oxide 下载免费PDF全文
Shazid Md. Sharker Chan Jin Jeong Sung Min Kim Jung‐Eun Lee Prof. Ji Hoon Jeong Prof. Insik In Prof. Haeshin Lee Prof. Sung Young Park 《化学:亚洲杂志》2014,9(10):2921-2927
We report a stimuli‐responsive fluorescent nanomaterial, based on graphene oxide coupled with a polymer conjugated with photochromic spiropyran (SP) dye and hydrophobic boron dipyrromethane (BODIPY) dye, for application in triggered target multicolor bioimaging. Graphene oxide (GO) was reduced by catechol‐conjugated polymers under mildly alkaline conditions, which enabled to formation of functionalized multicolor graphene nanoparticles that can be induced by irradiation with UV light and by changing the pH from acidic to neutral. Investigation of these nanoparticles by using AFM, fluorescence emission, and in vitro cell and in vivo imaging revealed that they show different tunable colors in bioimaging applications and, more specifically, in cancer‐cell detection. The stability, biocompatibility, and quenching efficacy of this nanocomposite open a different perspective for cell imaging in different independent colors, sequentially and simultaneously. 相似文献
69.
o‐Fluorination of Aromatic Azides Yields Improved Azido‐Based Fluorescent Probes for Hydrogen Sulfide: Synthesis,Spectra, and Bioimaging 下载免费PDF全文
Chao Wei Runyu Wang Dr. Lv Wei Longhuai Cheng Zhifei Li Prof. Dr. Zhen Xi Prof. Dr. Long Yi 《化学:亚洲杂志》2014,9(12):3586-3592
Hydrogen sulfide (H2S) is an endogenously produced gaseous signaling molecule with multiple biological functions. To visualize the endogenous in situ production of H2S in real time, new coumarin‐ and boron‐dipyrromethene‐based fluorescent turn‐on probes were developed for fast sensing of H2S in aqueous buffer and in living cells. Introduction of a fluoro group in the ortho position of the aromatic azide can lead to a greater than twofold increase in the rate of reaction with H2S. On the basis of o‐fluorinated aromatic azides, fluorescent probes with high sensitivity and selectivity toward H2S over other biologically relevant species were designed and synthesized. The probes can be used to in situ to visualize exogenous H2S and D ‐cysteine‐dependent endogenously produced H2S in living cells, which makes them promising tools for potential applications in H2S biology. 相似文献
70.
Ángela Martínez‐Peragón Dr. Delia Miguel Rocío Jurado Dr. José Justicia Prof. José M. Álvarez‐Pez Dr. Juan M. Cuerva Dr. Luis Crovetto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(2):447-455
9‐Alkyl xanthenones with different aliphatic pendant groups have been easily prepared by means of nucleophilic addition of the corresponding Grignard derivative to a tert‐butyldimethylsilyl ether (TBDMS)‐protected 3,6‐dihydroxy‐xanthenone. The photophysical behavior of the new dyes has been explored by using absorption, steady‐state‐, and time‐resolved fluorescence measurements. We determined the equilibrium constants, visible spectral characteristics, fluorescence quantum yield, and decay times. Remarkably, they retain similar fluorescent properties of fluorescein including the characteristic phosphate‐mediated excited‐state proton‐transfer (ESPT) reaction. 6‐Hydroxy‐9‐isopropyl‐3H‐xanthen‐3‐one ( 5 ) was investigated in living cells; it presented a good permeability and efficient accumulation inside the cytosol. For the first time, we reported that the requirement of an aryl group at C‐9 is no longer needed and new fluorescent sensors can be therefore easily developed. 相似文献