Signaling Recognition Events with Fluorescent Sensors and Switches.

Lanthanide ions possess fascinating optical properties and their discovery, first industrial uses and present high technological applications are largely governed by their interaction with light. Lighting devices (economical luminescent lamps, light emitting diodes), television and computer displays, optical fibres, optical amplifiers, lasers, as well as responsive luminescent stains for biomedical analysis, medical diagnosis, and cell imaging rely heavily on lanthanide ions. This critical review has been tailored for a broad audience of chemists, biochemists and materials scientists; the basics of lanthanide photophysics are highlighted together with the synthetic strategies used to insert these ions into mono- and polymetallic molecular edifices. Recent advances in NIR-emitting materials, including liquid crystals, and in the control of luminescent properties in polymetallic assemblies are also presented. (210 references.)

Taking advantage of luminescent lanthanide ions

About Supramolecular Assemblies of π-Conjugated Systems

Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

3.7. Palladium Nanoparticles as Catalysts 888 3.8. Other Transition-Metal Complexes 888 3.9. Transition-Metal-Free Reactions 889 4. Applications 889 4.1. Alkynylation of Arenes 889 4.2. Alkynylation of Heterocycles 891 4.3. Synthesis of Enynes and Enediynes 894 4.4. Synthesis of Ynones 896 4.5. Synthesis of Carbocyclic Systems 897 4.6. Synthesis of Heterocyclic Systems 898 4.7. Synthesis of Natural Products 903 4.8. Synthesis of Electronic and Electrooptical Molecules 906

https://www.chem.ccu.edu.tw/~joyce/referance/ericyang/Chem.%20Rev/Chem.%20Rev.%202007,%20107,%20874-922.pdf

The Sonogashira Reaction: A Booming Methodology in Synthetic Organic Chemistry†

Each generation is confronted with new challenges and new opportunities. In a restricted system like the Earth, however, opportunities discovered and exploited by a generation can cause challenges to the subsequent ones. Fossil fuels have offered astounding opportunities during the 20th century in the rich countries of the western world, but now mankind has to face the challenges arising from fossil-fuel exploitation. The proven reserves of fossil fuels are progressively decreasing, and their continued use produces harmful effects, such as pollution that threatens human health and greenhouse gases associated with global warming. Currently the world&s growing thirst for oil amounts to almost 1000 barrels a second, which means about 2 liters a day per each person living on the Earth (Figure 1). The current global energy consumption is equivalent to 13 terawatts (TW), that is, a steady 13 trillion watts of power demand. How long can we keep running this road?

The Future of Energy Supply: Challenges and Opportunities

Higher efficiency in the end-use of energy requires substantial progress in lighting concepts. All the technologies under development are based on solid-state electroluminescent materials and belong to the general area of solid-state lighting (SSL). The two main technologies being developed in SSL are light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs), but in recent years, light-emitting electrochemical cells (LECs) have emerged as an alternative option. The luminescent materials in LECs are either luminescent polymers together with ionic salts or ionic species, such as ionic transition-metal complexes (iTMCs). Cyclometalated complexes of IrIII are by far the most utilized class of iTMCs in LECs. Herein, we show how these complexes can be prepared and discuss their unique electronic, photophysical, and photochemical properties. Finally, the progress in the performance of iTMCs based LECs, in terms of turn-on time, stability, efficiency, and color is presented.

Luminescent ionic transition-metal complexes for light-emitting electrochemical cells.

Hydrogen is often proposed as the fuel of the future, but the transformation from the present fossil fuel economy to a hydrogen economy will need the solution of numerous complex scientific and technological issues, which will require several decades to be accomplished. Hydrogen is not an alternative fuel, but an energy carrier that has to be produced by using energy, starting from hydrogen-rich compounds. Production from gasoline or natural gas does not offer any advantage over the direct use of such fuels. Production from coal by gasification techniques with capture and sequestration of CO₂ could be an interim solution. Water splitting by artificial photosynthesis, photobiological methods based on algae, and high temperatures obtained by nuclear or concentrated solar power plants are promising approaches, but still far from practical applications. In the next decades, the development of the hydrogen economy will most likely rely on water electrolysis by using enormous amounts of electric power, which in its turn has to be generated. Producing electricity by burning fossil fuels, of course, cannot be a rational solution. Hydroelectric power can give but a very modest contribution. Therefore, it will be necessary to generate large amounts of electric power by nuclear energy of by renewable energies. A hydrogen economy based on nuclear electricity would imply the construction of thousands of fission reactors, thereby magnifying all the problems related to the use of nuclear energy (e.g., safe disposal of radioactive waste, nuclear proliferation, plant decommissioning, uranium shortage). In principle, wind, photovoltaic, and concentrated solar power have the potential to produce enormous amounts of electric power, but, except for wind, such technologies are too underdeveloped and expensive to tackle such a big task in a short period of time. A full development of a hydrogen economy needs also improvement in hydrogen storage, transportation and distribution. Hydrogen and electricity can be easily interconverted by electrolysis and fuel cells, and which of these two energy carriers will prevail, particularly in the crucial field of road vehicle powering, will depend on the solutions found for their peculiar drawbacks, namely storage for electricity and transportation and distribution for hydrogen. There is little doubt that power production by renewable energies, energy storage by hydrogen, and electric power transportation and distribution by smart electric grids will play an essential role in phasing out fossil fuels.

The hydrogen issue

Over the past two decades the photochemical and photophysical 
properties of Cu(I)–phenanthrolines 
([Cu(NN)2]+) have been investigated in detail. A high 
degree of control of the metal-to-ligand charge-transfer (MLCT) absorption 
and luminescence properties of [Cu(NN)2]+ is now 
possible, by means of a thorough choice and positioning of the 
phenanthroline ligand substituents. Exchange of Cu(I) with a 
variety of metal ions (Mn+) allows tuning of the 
electrochemical and photophysical properties of the 
[M(NN)2]n+ motif. This has prompted the 
design of fascinating multicomponent molecular architectures (catenates, 
knots, rotaxanes, dendrimers) in which photoinduced intercomponent 
processes like energy- and electron-transfer occur. The possibility of a 
fine tuning of the absorption and emission properties, long excited state 
lifetimes, and a characteristic structural flexibility, suggest 
Cu(I)–phenathrolines as interesting alternatives to 
Ru(II)–polypyridines, still the most popular family of 
complexes among inorganic photochemists.

Nicola Armaroli

Papers

The Future of Energy Supply: Challenges and Opportunities

Luminescent ionic transition-metal complexes for light-emitting electrochemical cells.

The hydrogen issue

Photoactive mono- and polynuclear Cu(I)–phenanthrolines. A viable alternative to Ru(II)–polypyridines?

Luminescent complexes beyond the platinum group: the d10 avenue