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https://www.readbyqxmd.com/read/29336548/judicious-design-of-cationic-cyclometalated-ir-iii-complexes-for-photochemical-energy-conversion-and-optoelectronics
#1
Isaac N Mills, Jonathan A Porras, Stefan Bernhard
The exponential growth in published studies on phosphorescent metal complexes has been triggered by their utilization in optoelectronics, solar energy conversion, and biological labeling applications. Very recent breakthroughs in organic photoredox transformations have further increased the research efforts dedicated to discerning the inner workings and structure-property relationships of these chromophores. Initially, the principal focus was on the Ru(II)-tris-diimine complex family. However, the limited photostability and lack of luminescence tunability discovered in these complexes prompted a broadening of the research to include 5d transition metal ions...
January 16, 2018: Accounts of Chemical Research
https://www.readbyqxmd.com/read/29320869/challenges-and-opportunities-for-small-molecule-fluorescent-probes-in-redox-biology-applications
#2
Xiqian Jiang, Lingfei Wang, Shaina Laufer Carroll, Jianwei Chen, Meng C Wang, Jin Wang
SIGNIFICANCE: The concentrations of reactive oxygen/nitrogen species (ROS/RNS) are critical to various biochemical processes. Small molecule fluorescent probes have been widely used to detect and/or quantify ROS/RNS in many redox biology studies and serve as an important complementary to protein-based sensors with unique applications. Recent Advances: New sensing reactions have emerged in probe development allowing more selective and quantitative detection of ROS/RNS, especially in live cells...
January 10, 2018: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/29303585/effect-of-mixing-ammonia-and-alkylamines-on-sulfate-aerosol-formation
#3
Berhane Temelso, Elizabeth F Morrison, David L Speer, Bobby C Cao, Nana A Appiah-Padi, Grace Kim, George C Shields
Sulfate aerosols' cooling effect on the global climate has spurred research to understand their mechanisms of formation. Both theoretical and laboratory studies have shown that the formation of sulfate aerosols is enhanced by the presence of a base like ammonia. Stronger alkylamine bases such as monomethylamine (MMA), dimethylamine (DMA) and trimethylamine (TMA) further increase aerosol formation rates by many orders of magnitude relative to that of ammonia. However, recent lab measurements have found that presence of ammonia and alkylamines together increases nucleation rates by another 1-2 orders of magnitude relative to the stronger alkylamines alone...
January 5, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29231908/conjugated-polymer-nanoparticles-for-bioimaging
#4
REVIEW
Yasmine Braeken, Srujan Cheruku, Anitha Ethirajan, Wouter Maes
During the last decade, conjugated polymers have emerged as an interesting class of fluorescence imaging probes since they generally show high fluorescence brightness, high photostability, fast emission rates, non-blinking behavior and low cytotoxicity. The main concern related to most conjugated polymers is their lack of hydrophilicity and thereby poor bio-availability. This can, however, be overcome by the formulation of conjugated polymer nanoparticles in aqueous medium. This review provides an overview of the different techniques employed for the preparation of conjugated polymer nanoparticles, together with methods to improve their photoluminescence quantum yields...
December 12, 2017: Materials
https://www.readbyqxmd.com/read/29189716/recent-advances-in-nucleic-acid-targeting-probes-and-supramolecular-constructs-based-on-pyrene-modified-oligonucleotides
#5
REVIEW
Olga A Krasheninina, Darya S Novopashina, Evgeny K Apartsin, Alya G Venyaminova
In this review, we summarize the recent advances in the use of pyrene-modified oligonucleotides as a platform for functional nucleic acid-based constructs. Pyrene is of special interest for the development of nucleic acid-based tools due to its unique fluorescent properties (sensitivity of fluorescence to the microenvironment, ability to form excimers and exciplexes, long fluorescence lifetime, high quantum yield), ability to intercalate into the nucleic acid duplex, to act as a π-π-stacking (including anchoring) moiety, and others...
November 30, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29171858/advances-in-single-quantum-dot-based-nanosensors
#6
Juan Hu, Zi-Yue Wang, Chen-Chen Li, Chun-Yang Zhang
Single-molecule detection provides a simple and ultrasensitive platform to quantify target molecules by simply counting the individual fluorescence signals. Quantum dots (QDs) are novel semiconductor nanocrystals with distinct characteristics of high brightness, large Stokes shift and broad absorption spectra, high molar extinction coefficients, high quantum yield, good photostability and long fluorescence lifetime. The combination of single-molecule detection with QDs enables the development of single QD-based nanosensors with extremely high sensitivity...
November 24, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29132640/fluorescence-enhancement-for-noble-metal-nanoclusters
#7
REVIEW
Dan Li, Zhenhua Chen, Xifan Mei
Noble metal nanoclusters have attracted great attentions in the area of fluorescence related applications due to their special properties such as low toxicity, excellent photostability and bio-compatibility. However, they still describe disadvantages for low quantum yield compared to quantum dots and organic dyes though the brightness of the fluorescence play an important role for the efficiency of the applications. Attentions have been attracted for exploring strategies to enhance the fluorescence based on the optical fundamentals through various protocols...
November 7, 2017: Advances in Colloid and Interface Science
https://www.readbyqxmd.com/read/29125159/development-of-luminescent-sensors-based-on-transition-metal-complexes-for-the-detection-of-nitroexplosives
#8
Veerasamy Sathish, Arumugam Ramdass, Murugesan Velayudham, Kuang-Lieh Lu, Pounraj Thanasekaran, Seenivasan Rajagopal
The detection of chemical explosives is a major area of research interest and is essential for the military as well as homeland security to counter the catastrophic effects of global terrorism. In recent years, tremendous effort has been devoted to the development of luminescent materials for the detection of explosives in the vapor, solution, and solid states with a high degree of selectivity and sensitivity and a rapid response time. Apart from the wide range of organic fluorescent chemosensors, transition metal complexes play a prominent role in the sensing of nitroaromatic explosives owing to their rich photophysical characteristics...
November 10, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29118667/twistor-theory-at-fifty-from-contour-integrals-to-twistor-strings
#9
REVIEW
Michael Atiyah, Maciej Dunajski, Lionel J Mason
We review aspects of twistor theory, its aims and achievements spanning the last five decades. In the twistor approach, space-time is secondary with events being derived objects that correspond to compact holomorphic curves in a complex threefold-the twistor space. After giving an elementary construction of this space, we demonstrate how solutions to linear and nonlinear equations of mathematical physics-anti-self-duality equations on Yang-Mills or conformal curvature-can be encoded into twistor cohomology...
October 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28961367/high-performance-metal-halide-perovskite-light-emitting-diode-from-material-design-to-device-optimization
#10
REVIEW
Qingsong Shan, Jizhong Song, Yousheng Zou, Jianhai Li, Leimeng Xu, Jie Xue, Yuhui Dong, Boning Han, Jiawei Chen, Haibo Zeng
Metal halide perovskites have drawn significant interest in the past decade. Superior optoelectronic properties, such as a narrow bandwidth, precise and facile tunable luminance over the entire visible spectrum, and high photoluminescence quantum yield of up to ≈100%, render metal halide perovskites suitable for next-generation high-definition displays and healthy lighting systems. The external quantum efficiency of perovskite light-emitting diodes (LEDs) increases from 0.1 to 11.7% in three years; however, the energy conversion efficiency and the long-term stability of perovskite LEDs are inadequate for practical application...
September 29, 2017: Small
https://www.readbyqxmd.com/read/28956876/long-lived-luminescence-of-silicon-nanocrystals-from-principles-to-applications
#11
Raffaello Mazzaro, Francesco Romano, Paola Ceroni
Silicon nanocrystals (SiNCs) synthesized by plasma-induced or high temperature processes (e.g., thermal disproportionation of hydrogen silsesquioxane at T > 1100 °C) display bright (photoluminescence quantum yield up to 70%) and long-lived luminescence (hundreds of μs), which can be tuned from green to red and near-infra-red spectral regions according to nanocrystal dimensions. The present review focuses on the parameters affecting the optical properties of these SiNCs, namely size, shape, surface, degree of crystallinity, and on a method to increase their brightness by functionalising SiNCs with dyes to build up a light-harvesting antenna...
October 11, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28902157/triarylborane-based-materials-for-oled-applications
#12
REVIEW
Gulsen Turkoglu, M Emin Cinar, Turan Ozturk
Multidisciplinary research on organic fluorescent molecules has been attracting great interest owing to their potential applications in biomedical and material sciences. In recent years, electron deficient systems have been increasingly incorporated into fluorescent materials. Triarylboranes with the empty p orbital of their boron centres are electron deficient and can be used as strong electron acceptors in conjugated organic fluorescent materials. Moreover, their applications in optoelectronic devices, energy harvesting materials and anion sensing, due to their natural Lewis acidity and remarkable solid-state fluorescence properties, have also been investigated...
September 13, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28895105/1-3-diphenylisobenzofuran-a-model-chromophore-for-singlet-fission
#13
REVIEW
Justin C Johnson, Josef Michl
In this review we first provide an introductory description of the singlet fission phenomenon and then describe the ground and electronically excited states of the parent 1,3-diphenylisobenzofuran chromophore (1) and about a dozen of its derivatives. A discussion of singlet fission in thin polycrystalline layers of these materials follows. The highest quantum yield of triplet formation by singlet fission, 200% at 80 K, is found in one of the two known crystal modification of the parent. In the other modification and in many derivatives, excimer formation competes successfully and triplet yields are low...
September 11, 2017: Topics in Current Chemistry (Journal)
https://www.readbyqxmd.com/read/28829477/upconversion-processes-versatile-biological-applications-and-biosafety
#14
REVIEW
Arif Gulzar, Jiating Xu, Piaoping Yang, Fei He, Liangge Xu
Lanthanide-doped photon upconverting nanomaterials are evolving as a new class of imaging contrast agents, offering highly promising prospects in the area of biomedical applications. Owing to their ability to convert long-wavelength near-infrared excitation radiation into shorter-wavelength emissions, these nanomaterials are well suited to yield properties of low imaging background, large anti-Stokes shift, along with high optical penetration depth of NIR light for deep tissue optical imaging or light-activated drug release and therapy...
August 31, 2017: Nanoscale
https://www.readbyqxmd.com/read/28814860/quantum-dots-in-imaging-drug-delivery-and-sensor-applications
#15
REVIEW
Cristian T Matea, Teodora Mocan, Flaviu Tabaran, Teodora Pop, Ofelia Mosteanu, Cosmin Puia, Cornel Iancu, Lucian Mocan
Quantum dots (QDs), also known as nanoscale semiconductor crystals, are nanoparticles with unique optical and electronic properties such as bright and intensive fluorescence. Since most conventional organic label dyes do not offer the near-infrared (>650 nm) emission possibility, QDs, with their tunable optical properties, have gained a lot of interest. They possess characteristics such as good chemical and photo-stability, high quantum yield and size-tunable light emission. Different types of QDs can be excited with the same light wavelength, and their narrow emission bands can be detected simultaneously for multiple assays...
2017: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/28802828/photolyase-dynamics-and-electron-transfer-mechanisms-of-dna-repair
#16
REVIEW
Meng Zhang, Lijuan Wang, Dongping Zhong
Photolyase, a flavoenzyme containing flavin adenine dinucleotide (FAD) molecule as a catalytic cofactor, repairs UV-induced DNA damage of cyclobutane pyrimidine dimer (CPD) and pyrimidine-pyrimidone (6-4) photoproduct using blue light. The FAD cofactor, conserved in the whole protein superfamily of photolyase/cryptochromes, adopts a unique folded configuration at the active site that plays a critical functional role in DNA repair. Here, we review our comprehensive characterization of the dynamics of flavin cofactor and its repair photocycles by different classes of photolyases on the most fundamental level...
October 15, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28762723/single-molecule-plasmon-sensing-current-status-and-future-prospects
#17
Adam B Taylor, Peter Zijlstra
Single-molecule detection has long relied on fluorescent labeling with high quantum-yield fluorophores. Plasmon-enhanced detection circumvents the need for labeling by allowing direct optical detection of weakly emitting and completely nonfluorescent species. This review focuses on recent advances in single molecule detection using plasmonic metal nanostructures as a sensing platform, particularly using a single particle-single molecule approach. In the past decade two mechanisms for plasmon-enhanced single-molecule detection have been demonstrated: (1) by plasmonically enhancing the emission of weakly fluorescent biomolecules, or (2) by monitoring shifts of the plasmon resonance induced by single-molecule interactions...
August 25, 2017: ACS Sensors
https://www.readbyqxmd.com/read/28745302/advanced-carbon-nanotubes-functionalization
#18
A Setaro
Similar to graphene, carbon nanotubes are materials made of pure carbon in its sp(2) form. Their extended conjugated π-network provides them with remarkable quantum optoelectronic properties. Frustratingly, it also brings drawbacks. The π-π stacking interaction makes as-produced tubes bundle together, blurring all their quantum properties. Functionalization aims at modifying and protecting the tubes while hindering π-π stacking. Several functionalization strategies have been developed to circumvent this limitation in order for nanotubes applications to thrive...
July 26, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28492303/a-unique-integration-strategy-for-the-rational-design-of-optically-tunable-near-infrared-fluorophores
#19
Hua Chen, Baoli Dong, Yonghe Tang, Weiying Lin
Fluorescence imaging is a rapidly growing technique for noninvasive imaging of biological molecules and processes with high spatial and temporal resolution. For effective biological imaging, it is essential and important to develop robust fluorescent dyes, in particular, near-infrared (NIR) fluorescent dyes with favorable optical properties. Compared with the visible light emitting dyes, NIR dyes have relatively longer emission wavelengths (650-900 nm) with lower energy and are advantageous as imaging agents owing to the minimum photodamage of NIR light to biological samples, deep penetration into tissues, and low interference from autofluorescence of biomolecules...
May 11, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28433535/bioimaging-and-biodetection-assisted-with-tta-uc-materials
#20
REVIEW
Qingqing Dou, Lu Jiang, Dan Kai, Cally Owh, Xian Jun Loh
Upconversion of light has attracted intensive studies for biomedical research, because it enables deeper tissue analysis owing to the longer wavelength of incident light, compared with conventional downconversion fluorescent materials. Triplet-triplet annihilation (TTA), as a typical mechanism of upconversion, does not necessitate high power excitation and exhibits a higher quantum yield than rare earth upconversion owing to more sensitizer options with higher absorption coefficients. A desirable wavelength range of excitation and emission can be realized by careful selection of the combination of sensitizer and activator...
September 2017: Drug Discovery Today
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