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Five cationic iridium(III) complexes (1-5) were synthesized exploiting two triazole-based cyclometalating ligands, namely, 1-methyl-4-phenyl-1H-1,2,3-triazole (A) and the corresponding mesoionic carbene 1,3-dimethyl-4-phenyl-1H-1,2,3-triazol-5-yliclene (B). From the combination of these two ligands and the ancillary one, i.e., 4,4'-di-tert-butyl-2,2'-bipyridine (for 1-3) or tert-butyl isocyanide (for 4 and 5), not only the typical bis-heteroleptic complexes but also the much less explored tris-heteroleptic analogues (2 and 5) could be synthesized. The redox and emission properties of all of the complexes are effectively fine-tuned by the different ligands: (i) cyclometalating ligand A induces a stronger highest occupied molecular orbital (HOMO) stabilization compared to B and leads to complexes with progressively narrower HOMO-lowest unoccupied molecular orbital (LUMO) and redox gaps, and lower emission energy; (ii) complexes 1-3, equipped with the bipyridine ancillary ligand, display fully reversible redox processes and emit from predominantly metal-to-ligand charge transfer (MLCT) states with high emission quantum yields, up to 60% in polymeric matrix; (iii) complexes 4 and 5, equipped with high-field isocyanide ligands, display irreversible redox processes and high-energy emission from strongly ligand-centered triplets with long emission lifetimes but relatively low quantum yields (below 6%, both in room-temperature solution and in solid state). This work demonstrates the versatility of phenyl-triazole derivatives as cyclometalating ligands with different chelation modes (i.e., CN and CC:) for the synthesis of photoactive iridium(III) complexes with highly tunable properties.

Iridium(III) complexes have assumed a prominent role in the areas of photochemistry and photophysics due to the peculiar properties of both the metal itself and the ligand environment that can be assembled around it. Ir(III) is larger, heavier, and bears a higher ionic charge than its analogue and widely used d6 ions such as Fe(II) and Ru(II). Accordingly, its complexes exhibit wider ligand-field d-d orbital splitting with electronic levels centered on the metal, typically nonemissive and photodissociative, not playing a relevant role in excited-state deactivations. In other words, iridium complexes are typically more stable and/or more emissive than Fe(II) and Ru(II) systems. Additionally, the particularly strong heavy-atom effect of iridium promotes singlet-triplet transitions, with characteristic absorption features in the UV-vis and relatively short excited-state lifetimes of emissive triplet levels. Ir(III) is also a platform for anchoring ligands of rather different sorts. Its versatile chemistry includes not only coordination with classic N∧N neutral ligands but also the binding of negatively charged chelators, typically having a cyclometalating C∧N anchor. The carbon-metal bond in these systems has some degree of covalent character, but this does not preclude a localized description of the excited states of the related complexes, which can be designated as metal-centered (MC), ligand-centered (LC), or charge transfer (CT), allowing a simplified description of electronic and photophysical properties. The possibility of binding different types of ligands and making heteroleptic complexes is a formidable tool for finely tuning the nature and energy of the lowest electronic excited state of cationic Ir(III) complexes by ligand design. Herein we give an account of our work on several families of iridium complexes typically equipped with two cyclometalating bidentate ligands (C∧N), in combination with mono or bidentate "ancillary"ligands with N∧N, C∧N, and C∧C motifs. We have explored new synthesis routes for both cyclometalating and ancillary ligands, obtaining primarily cationic complexes but also some neutral or even negatively charged systems. In the domain of the ancillary ligands, we have explored isocyanides, carbenes, mesoionic triazolylidenes, and bis-tetrazolic ligands. For the cyclometalating moiety, we have investigated carbene, mesoionic triazolylidene, and tetrazolic systems. Key results of our work include new strategies to modify both cyclometalating and ancillary ligands by relocating ionic charges, the determination of new factors affecting the stability of complexes, a demonstration of subtle structural effects that strongly modify the photophysical properties, new options to get blue-greenish emitters for optoelectronic devices, and a set of ligand modifications allowing the optimization of electrochemical and excited-state properties to obtain new promising Ir(III) complexes for photoredox catalysis. These results constitute a step forward in the preparation of custom iridium-based materials crafted by excited-state engineering, which is achieved through the concerted effort of computational and synthetic chemistry along with electrochemistry and photochemistry

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Three new heteroleptic Cu(I) complexes containing one phenanthroline and one diphosphine type ligand ([Cu(N-N)(P-P)]+) have been prepared. In particular, one ligand is constituted by 1,10-phenanthroline (1), 2,9-dimethyl-1,10-phenanthroline (2) and 2,9-diphenethyl-1,10-phenanthroline (3) and the other ligand is in all cases 1,12-bis(diphenylphosphino)ferrocene (dppf). Therefore, copper and iron metal centres are quite close one another, as evidenced by X-ray crystal diffraction. The structure together with the electrochemical and photophysical properties of these complexes have been compared to that of the corresponding complexes where dppf has been replaced by bis[2-(diphenylphosphino)-phenyl]ether (POP). Cyclic voltammetric experiments evidenced that the first oxidation process is located on the ferrocene moiety and that oxidation of Cu(I) is moved to more positive potential values and a chemical reaction is coupled to the electron transfer process. The absorption spectra show a metal-to-ligand charge transfer (MLCT) band, typical of Cu(I) phenanthroline complexes, at a higher energy compared to the homoleptic [Cu(N-N)2]+ species. No emission at either room temperature or 77 K has been observed for compounds 2 and 3, contrary to the high luminescence observed for the corresponding POP complexes. This result is consistent with a photoinduced energy transfer from the Cu(I) complex to the ferrocene moiety.

Cu(I) complexes and clusters are the largest class of compounds of relevant photochemical and photophysical interest based on a relatively abundant metal element. Interestingly, Nature has given an essential role to copper compounds in some biological systems, relying on their kinetic lability and versatile coordination environment. Some basic properties of Cu(I) and Cu(II) such as their coordination geometries and electronic levels are compared, pointing out the limited significance of Cu(II) compounds (d 9 configuration) in terms of photophysical properties. Well-established synthetic protocols are available to build up a variety of molecular and supramolecular architectures (e.g. catenanes, rotaxanes, knots, helices, dendrimers, cages, grids, racks, etc.) containing Cu(I)-based centers and exhibiting photo- and electroluminescence as well as light-induced intercomponent processes. By far the largest class of copper complexes investigated to date is that of Cu(I)-bisphenanthrolines ([Cu(NN)2]+) and recent progress in the rationalization of their metal-to-ligand charge-transfer (MLCT) absorption and luminescence properties are critically reviewed, pointing out the criteria by which it is now possible to successfully design highly emissive [Cu(NN)2]+ compounds, a rather elusive goal for a long time. To this end the development of spectroscopic techniques such as light-initiated time-resolved X-ray absorption spectroscopy (LITR-XAS) and femtosecond transient absorption have been rather fruitful since they have allowed us to firmly ground the indirect proofs of the molecular rearrangements following light absorption that had accumulated in the past 20 years. A substantial breakthrough towards highly emissive Cu(I) coordination compounds is constituted by heteroleptic Cu(I) complexes containing both N- and P-coordinating ligands ([Cu(NN)(PP)]+) which may exhibit luminescence quantum yields close to 30% in deaerated CH2Cl2 solution and have been successfully employed as active materials in OLED and LEC optoelectronic devices. Also copper clusters may exhibit luminescence bands of halide-to-metal charge transfer (XMCT) and/or cluster centered (CC) character and they are briefly reviewed along with miscellaneous Cu(I) compounds that recently appeared in the literature, which show luminescence bands ranging from the blue to the red spectral region.

A Eu-III complex, tris-dibenzoylmethane mono-1,10-phenanthroline-europium(III) [Eu(DBM)(3)(Phen)], can be easily adsorbed If in situ via hydrophobic interactions to single-walled carbon nanotube (SWNT) surfaces from a methanol solution. The Eu-III containing material has been comprehensively characterized via thermogravimetric analysis (TGA), UV-vis-NIR absorption and luminescence spectroscopy, Raman spectroscopy, atomic force microscopy (AFM), high-resolution transmission electron microscopy (HR-TEM)), Z-contrast scanning transmission electron microscopy (STEM) imaging, and energy dispersive X-ray spectroscopy (EDS). The photophysical investigations revealed that the presence of a SWNT framework does not affect the lanthanide-centered luminescence stemming from the characteristic electronic transitions within the 4f shell of the Eu-III, ions. Such straightforward synthetic route leads to the preparation of luminescent SWNTs without significantly affecting the electronic and structural properties of the carbon framework, opening new possibilities of designing new classes of CNTs for biomedical applications.

Da un punto di vista ambientale la tecnologia a ciclo combinato a gas naturale è una valida scelta per la riconversione di vecchie centrali ad olio combustibile o a carbone. Le emissioni di gas serra ed inquinanti sono comunque tutt'altro che trascurabili, e includono rilevanti quantità di polveri fini. Nel caso di nuovi impianti di grandi dimensioni, l'autorizzazione andrebbe concessa con cautela ed in presenza di adeguate misure compensative sulla qualità dell'aria, seguendo l'esempio della legislazione statunitense.

A two-component ligand system (1) containing 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A)as the hosting unit for the lanthanide cations and an appended asymmetrically functionalized 1,10-phenanthroline (phen) as the chromophore was synthesized. The 1:1 complexes with Eu3 +,Gd3+,Tb3+, and Yb3+ have been prepared and studied in aqueous solution. For Gd‚1, a relaxivity value of 2.4 mM-1 s-1 has been measured at 20 MHz and 25 °C, which indicates that there are no water molecules in the first coordination sphere of the metal ion. The analysis of high resolution 1H NMR spectra of Yb‚1 supports this view and suggests the direct involvement of the phen moiety in the coordination of the metal ion. For Eu‚1 and Tb‚1, the absorption and luminescence spectra, the overall luminescence efficiencies, and the metal-centered (MC) lifetimes were obtained; coordination features were also determined by comparing luminescence properties in water and deuterated water. For Eu‚1 and Tb‚1, the overall emission sensitization (se) process in air-equilibrated water was found to be notably effective with ?se= 0.21 and 0.11, respectively. A detailed study of the steps originating from light absorption at the phen unit and leading to MC sensitized emission was performed.

New oligophenylenevinylene-terminated phenylenevinylene dendrons have been prepared and attached to C-60 by a 1,3-dipolar cycloaddition of the azomethine ylides generated in situ from the dendritic aldehydes and N-methylglycine. Preliminary photophysical investigations of the resulting fullerodendrimers have revealed interesting light-harvesting properties.

Fullerene derivatives A-3PV and B-3PV in which an oligophenylenevinylene trimeric subunit (3PV) is attached to C60 through, respectively, a pyrrolidine or a pyrazoline ring have been prepared. The electrochemical and excited-state properties Of the multicomponent arrays A-3PV and B-3PV have been investigated in Solution using the related oligophenylenevinylene derivative 3PV, fullerenopyrrolidine A and fullerenopyrazoline B as reference Compounds. In A-3PV quantitative OPV --> C60 photoinduced singlet-singlet energy transfer has been observed. Population of the lowest fullerene singlet excited state is followed by nearly quantitative intersystem crossing to the lowest fullerene triplet excited state in CH2Cl2 and toluene. whereas OPV --> C60 electron transfer is able to compete significantly in the more polar solvent benzonitrile. In the case of B-3PV, the excited-state properties are more complex due to the electron donating ability of the pyrazoline ring. As observed for A-3PV, quantitative OPV --> C-60 photoinduced singlet-singlet energy transfer Occurs in B-3PV. However, in this case, the population of the lowest fullerene singlet excited state is followed by an efficient electron transfer from the pyrazoline ring in CH2Cl2 and benzonitrile. In B-3PV. studies of the dependence of photoinduced processes on solvent polarity. addition of acid. and temperature also reveal that this Compound can be considered as a fullerene-based molecular switch, the switchable parameters being the photoinduced processes. Finally, A-3PV and B-3PV have been tested as active materials in photovoltaic devices and the differences of light to energy conversion efficiencies found for the two compounds have been rationalised on the basis of their photophysical properties.

Poly(aryl ether) dendritic branches terminated with peripheral triethyleneglycol chains have been attached to C60. The resulting fullerodendrimers have been characterised by electrospray mass spectrometry (ESMS), which appears to be a particularly interesting analytical tool for the unambiguous structural assignment of such high molecular weight fullerene derivatives. Their photophysical properties have been systematically investigated in three solvents, namely toluene, dichloromethane, and acetonitrile. The changes observed in the photophysical properties along the series suggest an increasing interaction between the poly(aryl ether) dendritic wedges and the fullerene core, which brings about an increasing isolation of the central chromophore from the exterior. Finally, thanks to their high solubility, fullerodendrimers 1-4 have been easily incorporated in mesoporous silica glasses and preliminary measurements on the resulting doped samples have revealed efficient optical limiting properties.

The rhenium(I) and ruthemum(II) complexes of a fullerene-substituted bipyridine ligand have been prepared. Electrochemical studies indicate that so..,ne ground state electronic interaction between the fullerene subunit and the metal-complexed moiety are present in the Re(I) but not the Ru(II) complex. The photophysical properties have been investigated by steady-state and time-resolved UV/Vis-NIR luminescence spectroscopy and nanosecond laser flash photolysis in CH2Cl2 solution, and compared to those of the corresponding model compounds. Excitation of the methanofullerene moiety in the dyads does not lead to excited state intercomponent interactions. Instead, excitation of the metal-complexed unit shows that the lowest triplet metal-to-ligand-charge-transfer excited state (3MLCT) centered on the Re(I) or Ru(II)-type unit is quenched with a rate constant of about 2.5 x 10(8) s(-1). The quenching, is attributed to an electron-transfer (EIT) process leading to the reduction of the carbon sphere, as determined by luminescence spectroscopy for the Ru(II) dyad. Experimental detection of electron transfer in the Re(II) dyad is prevented clue to the unfavorable absorption of the metal-complexed moiety relative to the fullerene unit. However. it can tic postulated on the basis of energetic/ kinetic arguments and by comparison with the Ru(II)-type array. The primary EIT process is followed by charge-recombination to give [fie lowest-lying fullerene triplet excited state (3C60) with quantitative yield, as determined by sensitized singlet oxygen luminescence experiments. Direct 1MLCT --> 3C60 triplet-triplet energy-transfer (EnT) does not successfully compete with EIT since it is highly exoergonic and located in the Marcus inverted region. The quantum yield of singlet oxygen sensitization (1O2) of the Re(I)-based dyad is found to be lower (0.80) than for the cot-responding Ru(II) derivative (1.0). This is likely to be the consequence of different conformational structures for the two dyads, rather than a different yield of 3C60 formation.

Two novel cone calix[4]arene ligands 11a and 11b bearing two iminodiacetic chelating units and two C-6 or C substituted 2,2'-bipyridine chromophores in diametral position at the lower rim were synthesized. These ligands form complexes with lanthanide ions in methanol solution whose stability (4.5 < log K-ass < 6.2) depends on the substitution pattern (C-6 or C-5) of the 2,2'-bipyridine units. Contrary to that observed with other neutral calixarene ligands, the luminescence properties of the Eu3+ and Tb3+ complexes are not very much affected by the type of the 2,2'-bipyridine chromophore. Luminescence lifetimes (0.31 ms < tau < 1.1 ms) and quantum yields (0.017 < phi < 0.130) are higher for Terbium compared with the corresponding Europium complexes.

A two-component ligand system (1) containing 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A) as the hosting unit for the lanthanide cations and an appended asymmetrically functionalized 1,10-phenanthroline (phen) as the chromophore was synthesized, The 1:1 complexes with Eu3+, Gd3+, Tb3+, and Yb3+ have been prepared and studied in aqueous solution. For Gd.1, a relaxivity value of 2.4 mM(-1) s(-1) has been measured at 20 MHz and 25degreesC, which indicates that there are no water molecules in the first coordination sphere of the metal ion. The analysis of high resolution H-1 NMR spectra of Yb.1 supports this view and suggests the direct involvement of the phen moiety in the coordination of the metal ion. For Eu.1 and Tb.1, the absorption and luminescence spectra, the overall luminescence efficiencies, and the metal-centered (MC) lifetimes were obtained; coordination features were also determined by comparing luminescence properties in water and deuterated water. For Eu.1 and Tb.1, the overall emission sensitization (se) process in air-equilibrated water was found to be notably effective with phi(se) = 0.21 and 0.11, respectively. A detailed study of the steps originating from light absorption at the phen unit and leading to MC sensitized emission was performed.

Novel 5,15-bis(9-anthracenyl)porphyrin derivatives (1a, 1b) were synthesized by stepwise Suzuki-type coupling reactions using anthracenyl-boronates bearing various electronically active moieties. Absorption spectra of these porphyrin conjugates reveal some degree of delocalisation with the directly linked chromophores, particularly in the case of anthracenyl-porphyrin bearing dimethylanilino moieties at the two extremities. Fluorescence and 77 K phosphorescence properties indicate that the excitation energy is invariably funnelled to the lowest singlet and triplet states of the porphyrin chromophore. The latter levels have been probed also by transient absorption spectroscopy, showing the typical triplet features detected in meso-substituted porphyrins. Extensive electrochemical studies have been performed to unravel the electronic properties of the newly synthesized porphyrins. Low-temperature cyclic voltammetry investigations showed that the anthracenyl-porphyrins are capable of undergoing as many as four electron transfer processes. In particular, by means of UV-Vis-NIR spectroelectrochemical measurements, a NIR-centred intramolecular photoinduced intervalence charge transfer (IV-CT) from a neutral N,N-dimethylanilino moiety to the N,N-dimethylanilino radical cation has been observed for the doubly-oxidised porphyrin 1b2+. The molecules also showed unexpected electrogenerated chemiluminescence properties, which revealed to be largely controlled by the electronic characteristics of the peripheral anthracenyl substituents. The structural and the electronic properties of these complexes have been also characterised by DFT calculations, as well as by X-ray crystallographic analyses. © The Royal Society of Chemistry 2009.

Five cationic iridium(III) complexes with fluorinated cyclometalating tetrazole ligands [Ir(dfptrz)2L]+, where Hdfptrz = 5-(2,4-difluorophenyl)-2-methyl-2H-tetrazole and L = 2,2′-bypiridine (1F), 4,4′-ditert-butyl-2,2′-bipyridine (2F), 1,10-phenantroline (3F), 4,4′-bis(dimethylamino)-2,2′-bipyridine (4F), and tert-butyl isocyanide (5F), were prepared following a one-pot synthetic strategy based on a bis-cyclometalated solvato complex obtained via silver(I)-assisted cyclometalation, which was then reacted with the proper ancillary ligand to get the targeted complexes. The X-ray crystal structures of 2F and 4F were determined, showing that the tetrazole ligands are in a trans arrangement with respect to the iridium center. Electrochemical and photophysical properties, along with density functional theory calculations, allowed a full rationalization of the electronic properties of 1F-5F. In acetonitrile solution at 298 K, complexes 1F-3F, equipped with bipyridine and phenanthroline ligands, exhibit strong vibronically structured luminescence bands in the blue region with photoluminescence quantum yields (PLQYs) in the range 56-76%. This behavior is radically different from the nonfluorinated analogues reported previously, which emits in the green region from 3MLCT excited states. 4F shows relatively strong emission (PLQY = 40%) of charge transfer character centered on the amino-bipyridine ancillary ligand, whereas the emission of 5F is very weak (PLQY = 0.6%), further blue-shifted and attributed to the lowest ligand-centered (3LC) triplet state of the tetrazolyl cyclometalated moiety. A similar photophysical behavior is observed in PMMA at 298 K, whereas in a 77 K matrix, all of the compounds are strong emitters. This novel fluorinated phenyl-tetrazole cyclometalating ligand provides the corresponding iridium(III) complexes with a combination of excited-state energy and redox potentials that make them very promising as photoredox catalysts.

Tetraphenylmethane appended with four pyridylpyridinium units works as a scaffold to self-assemble four ruthenium porphyrins in a tetrahedral shape-persistent giant architecture. The resulting supramolecular structure has been characterised in the solid state by X-ray single crystal analysis and in solution by various techniques. Multinuclear NMR spectroscopy confirms the 1 : 4 stoichiometry with the formation of a highly symmetric structure. The self-assembly process can be monitored by changes of the redox potentials, as well as by modifications in the visible absorption spectrum of the ruthenium porphyrin and by a complete quenching of both the bright fluorescence of the tetracationic scaffold and the weak phosphorescence of the ruthenium porphyrin. An ultrafast photoinduced electron transfer is responsible for this quenching process. The lifetime of the resulting charge separated state (800 ps) is about four times longer in the giant supramolecular structure compared to the model 1 : 1 complex formed by the ruthenium porphyrin and a single pyridylpyridinium unit. Electron delocalization over the tetrameric pyridinium structure is likely to be responsible for this effect.

A series of molecules in which 9H-carbazole (electron donor, D) and 2,2':6',2''-terpyridine (electron acceptor, A) are connected through rigid π-conjugated bridges (D-π-A systems) have been synthesized and their photophysical properties examined in detail, with the support of DFT calculations. The bridges are made of different sequences of ethynylene, phenylene, and anthracene groups. The synthetic strategies involve condensation of 2-acetylpyridine with the aromatic aldehyde moiety on different functionalized π-conjugated bridges and couplings with carbazole derivatives. The system incorporating anthracene in the bridge shows the typical absorption and emission fingerprints of this polycyclic hydrocarbon. The other systems have HOMOs and LUMOs centred, respectively, over the carbazole and the bridge and exhibit solvatochromic charge-transfer (CT) luminescence with high photoluminescence yield up to 70 %, except when an ethynylene unit is directly attached to the carbazole ring, due to a trans-bent non-emissive π-σ* excited state.

Dinuclear copper(I) complexes have been prepared starting from bis(diphenylphosphanyl)acetylene (dppa), [Cu(CH3CN)(4)](BF4) and various 1,10-phenanthroline ligands (NN), namely 1,10-phenanthroline (phen), neocuproine (dmp), bathophenanthroline (Bphen), bathocuproine (Bdmp) and 2-phenyl-1,10-phenanthroline (mpp). The resulting [Cu-2(mu-dppa)(2)(NN)(2)](BF4)(2) complexes have been thus obtained in excellent yields (88 to 94 %). X-ray crystal structure analysis of four complexes revealed that the 10-membered dimetallacycle adopts a chair-like conformation in the solid state. Detailed variable temperature NMR investigations have evidenced dynamic coordination/decoordination of the NN ligands as well as ligand exchange reactions. At high temperature (100 degrees C), entropic effects tend to destabilize the dinuclear heteroleptic complexes. As a result, homoleptic mononuclear complexes, i.e. [Cu(NN)(2)](+) and undefined dppa copper(I) complexes, start to appear in solution. In contrast, the heteroleptic coordination scenario is almost exclusively favored at lower temperatures. For most of the dinuclear complexes, the 10-membered dimetallacycle remains flexible and chair-to-chair interconversion occurs faster than the NMR timescale even at -70 degrees C. In the particular case of the mpp derivative, the bulky phenyl substituent prevents the isomerization of the metallacycle and thus contributes to rigidify the structure. This rigidification has a dramatic effect on the emission properties of this particular compound. The emission quantum yield of [Cu-2(mu-dppa)(2)(mpp)(2)](BF4)(2) is effectively one order of magnitude higher when compared to all the other complexes in this series (20 % vs. 0.3-1.7 % in the solid state).

The electronic and structural properties of ten heteroleptic [Cu(NN)(PP)]+ complexes have been investigated. NN indicates 1,10-phenanthroline (phen) or 4,7-diphenyl-1,10-phenanthroline (Bphen); each of these ligands is combined with five PP bis-phosphine chelators, i.e., bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)benzene (dppb), and bis[(2-diphenylphosphino)phenyl] ether (POP). All complexes are mononuclear, apart from those based on dppm, which are dinuclear. Experimental data - also taken from the literature and including electrochemical properties, X-ray crystal structures, UV-vis absorption spectra in CH2Cl2, luminescence spectra and lifetimes in solution, in PMMA, and as powders - have been rationalized with the support of density functional theory calculations. Temperature dependent studies (78-358 K) have been performed for selected complexes to assess thermally activated delayed fluorescence. The main findings are (i) dependence of the ground-state geometry on the crystallization conditions, with the same complex often yielding different crystal structures; (ii) simple model compounds with imposed C2v symmetry ([Cu(phen)(PX3)2]+ X = H or CH3) are capable of modeling structural parameters as a function of the P-Cu-P bite angle, which plays a key role in dictating the overall structure of [Cu(NN)(PP)]+ complexes; (iii) as the P-Cu-P angle increases, the energy of the metal-to-ligand charge transfer absorption bands linearly increases; (iv) the former correlation does not hold for emission spectra, which are red-shifted for the weaker luminophores; (v) the larger the number of intramolecular π-interactions within the complex in the ground state, the higher the luminescence quantum yield, underpinning a geometry locking effect that limits the structural flattening of the excited state. This work provides a general framework to rationalize the structure-property relationships of [Cu(NN)(PP)]+, a class of compounds of increasing relevance for electroluminescent devices, photoredox catalysis, and solar-to-fuels conversion, which so far have been investigated in an unsystematic fashion, eluding a comprehensive understanding. © Copyright 2018 American Chemical Society.

International audience; A series of copper(I) pseudorotaxanes has been prepared from bis[2-(diphenylphosphino)phenyl] ether (POP) and macrocyclic phenanthroline ligands with different ring sizes (m30, m37, and m42). Variable-temperature studies carried out on the resulting [Cu(mXX)(POP)]+ (mXX = m30, m37, and m42) derivatives have revealed a dynamic conformational equilibrium due to the folding of the macrocyclic ligand. The absorption and luminescence properties of the pseudorotaxanes have been investigated in CH2Cl2. They exhibit metal-to-ligand charge-transfer emission with photoluminescence quantum yields (PLQYs) in the range 20–30%. The smallest system [Cu(m30)(POP)]+ shows minimal differences in spectral shape and position compared to its analogues, suggesting a slightly distorted coordination environment. PLQY is substantially enhanced in poly(methyl methacrylate) films (∼40−45%). The study of emission spectra and excited-state lifetimes in powder samples as a function of temperature (78–338 K) reveals thermally activated delayed fluorescence, with sizable differences in the singlet–triplet energy gap compared to the reference compound [Cu(dmp)(POP)]+ (dmp = 2,9-dimethyl-1,10-phenanthroline) and within the pseudorotaxane series. The system with the largest ring ([Cu(m42)(POP)]+) has been tested as emissive material in OLEDs and affords bright green devices with higher luminance and greater stability compared to [Cu(dmp)(POP)]+, which lacks the macrocyclic ring. This highlights the importance of structural factors in the stability of electroluminescent devices based on Cu(I) materials.

The covalent functionalization of (7, 6)-enriched single-walled carbon nanotubes (SWCNTs) with oligophenylenevinylene (OPV) moieties terminating with a dimethylamino group is proposed as an efficient way to enhance the affinity of CNTs with Spiro-MeOTAD in perovskite-based solar cells. The evidence of SWCNTs functionalization and the degree of OPV substitution on SWCNTs are established from TGA, XPS, TEM and Raman techniques. Our tailored doping materials display photovoltaic performances in line with conventional Li-doped spiro-MeOTAD system, showing at the same time a significantly improved chemical stability of the perovskite component over time. Furthermore, the comparison of the photovoltaic performances with those obtained with non-functionalized SWCNTs clearly suggest that the presence of the organic appends ensures highly reproducible PV performances. Our results demonstrate the suitability of this material as a valid doping agent for spiro-MeOTAD, representing a viable alternative to the conventional Li-salt.

A EuIII complex, tris-dibenzoylmethane mono-1,10-phenanthroline- europium(III) [Eu(DBM)3(Phen)], can be easily adsorbed in situ via hydrophobic interactions to single-walled carbon nanotube (SWNT) surfaces from a methanol solution. The EuIII containing material has been comprehensively characterized via thermogravimetric analysis (TGA), UV-vis-NIR absorption and luminescence spectroscopy, Raman spectroscopy, atomic force microscopy (AFM), high-resolution transmission electron microscopy (HR-TEM)), Z-contrast scanning transmission electron microscopy (STEM) imaging, and energy dispersive X-ray spectroscopy (EDS). The photophysical investigations revealed that the presence of a SWNT framework does not affect the lanthanide-centered luminescence stemming from the characteristic electronic transitions within the 4f shell of the EuIII ions. Such straightforward synthetic route leads to the preparation of luminescent SWNTs without significantly affecting the electronic and structural properties of the carbon framework, opening new possibilities of designing new classes of CNTs for biomedical applications.

The solar energy alternative could provide us with all the energy we need as it exist in vast quantities all around us. We only should be innovative enough in order to improve the efficiency of our systems in capturing and converting solar energy in usable forms of power. By making a case for the solar energy alternative, we identify areas where efficiency can be improved and thereby Solar Energy can become a competitive energy source. This paper suggests an innovative approach to solar energy power production, which is manifested in a prototype given the name HelioTrope. The Heliotrope Solar Energy Production prototype is tested on its' capabilities to efficiently covert solar energy to generation of electricity and other forms of energy for storage or direct use. HelioTrope involves an innovative Stirling engine design and a parabolic concentrating dish with a sun tracking system implementing a control algorithm to maximize the capturing of solar energy. Further, it utilizes a patent developed by the authors where a mechanism is designed for the transmission of reciprocating motion of variable amplitude into unidirectional circular motion. This is employed in our prototype for converting linear reciprocating motion into circular for electricity production, which gives a significant increase in efficiency and reduces maintenance costs. Preliminary calculations indicate that the Heliotrope approach constitutes a competitive solution to solar power production. © Owned by the authors, published by EDP Sciences, 2014. 79 Sponsors: Conference code: 109596

In liberalized electricity markets, suppliers are offering several kinds of voluntary green electricity products marketed as environmentally friendly. This paper focuses on the development of these voluntary markets at household level in the UK, Germany and Finland. Since there are already existing renewable energy policies regulating and encouraging the use of renewable energy, it is important to consider whether voluntary products offer real additional benefits above these policies. Problems such as double counting or re-marketing hydropower produced in existing plants are identified. According to our study, the demand varies between countries: in Germany the number of green electricity customers has increased and is also higher than in the UK or Finland. Typically the average additional cost to consumer from buying green electricity product instead of standard electricity product is in the range of 0–5% in all studied countries, although the level of price premium depends on several factors like electricity consumption. Case study of Finland and literature show that the impacts of green energy are not solely environmental. Renewable energy can benefit local public policy peerReviewed

Shining treasure: Like treasure safeguarded in a chest, a tris-hexafluoro acetylacetonate Eu complex was encapsulated inside MWCNTs to preserve its luminescent output (see figure). These structures could open the way to novel luminescent hybrid materials with potential applications in biological and materials sciences.

Luminescent carbon-based materials have been prepared by electrostatic self-assembly of negatively-charged luminescent Eu(iii)-complex with imidazolium-functionalized MWCNTs.

The photophysical properties of molecules containing anthracene, pyrene, or phenyleneethynylene chromophores bearing complementary triple H-bonding terminal units, namely, 2,6-di(acetylamino)pyridine (donor–acceptor–donor, DAD) and uracyl (acceptor–donor–acceptor, ADA) have been investigated as a function of solvent polarity. For asymmetric systems, presenting only one H-bonding unit, a solvatochromic effect is found, suggesting a charge-transfer character of the lowest electronic excited state. Systematic absorption and emission studies carried out as a function of temperature show that phenylene-ethynylenes having linear geometry and H-bonding functionalities at both ends undergo reversible self-aggregation in cyclohexane (CHX), leading to the formation of spherical nanoparticles, as evidenced by wide-field fluorescence microscopy (WFM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). A combination of an anthracene derivative bearing only one ADA terminal functionality and a linear phenylene-ethynylene derivative possessing two DAD terminal groups in CHX (2:1 molecular ratio) leads to the formation of vesicular nanostructures. The interaction of linear phenylene-ethynylenes possessing two terminal 2,6-di(acetylamino)pyridine functionalities with that bearing bis uracylic units gives origin to nanofibers, while the assembly of the former with bisuracylic units exhibiting bent geometry leads to the formation of helical nanofibers. The length of these fibers can be controlled by addition of the anthracene derivative having only one uracyl group which effectively blocks the extent of H-bonding, prompting the formation of shorter nanorods.

The ability of two complementary molecular modules bearing H-bonding uracilic and 2,6-(diacetylamino)pyridyl moieties to self-assemble and self-organize into submicrometer morphologies has been investigated by means of spectroscopic, thermogravimetric, and microscopic methods. Using uracilic N-3-BOC-protected modules, it has been possible to thermally trigger the self-assembly/self-organization process of the two molecular modules, inducing the formation of objects on a mica surface that exhibit crater-like morphology and a very homogeneous size distribution. Confirmation of the presence of the hydrogen-bonding-driven self-assembly/self-organization process in solution was obtained by variable-temperature (VT) steady-state UV-vis absorption and emission measurements. The variation of the geometric and spatial features of the morphologies was monitored at different T by means of atomic force microscopy (AFM) and was interpreted by a nonequilibrium diffusion model for two chemical species in solution. The formation of nanostructures turned out to be affected by the solid substrate (molecular interactions at a solid-liquid interface), by the matter-momentum transport in solution (solute diffusivity D-0 and solvent kinematic viscosity nu), and the thermally dependent cleavage reaction of the BOC functions (T-dependent differential weight loss, theta = theta(T)) in a T interval extrapolated to similar to 60 K. A scaling function, f = T(nu D-0, nu/D-0, theta), relying on the onset condition of a concentration-driven thermosolutal instability has been established to simulate the T-dependent behavior of the structural dimension (i.e., height and radius) of the self-organized nanostructures as < h > approximate to f(T) and < r > approximate to 1/f (T).