An organic based microcavity showing fully reversible color tunability has been achieved for the first time. The emission output changes according to the modulation from pure photonic to polaritonic resonant modes through UV irradiation of the light-switchable matrix.

COMMUNICATION on A Luminescent Host-Guest Hybrid between a EuIII Complex and MWCNTs

A new series of D-?-A (TKB1-TKB3) structural chromophores with various electron donor units were designed, synthesized, and fully characterized. Their photophysical properties and cytotoxicity were investigated, and practical applications evaluated by fluorescence imaging in living cells. A direct dependence of the optical properties on the electron donor groups has been revealed for all the samples. To this purpose, time-dependent density functional theory calculations were conducted. Finally, dyes showed high biocompatibility, long-term retention and low cytotoxicity in different cell-lines including neuroblastoma cell (SH-SY5).

Treatment of 2-diphenylphosphino-6-methylpyridine (dpPyMe) with Cu(CH3CN)(4)BF4 afforded the stable dinuclear Cu(I) complex [Cu-2(mu-dpPyMe)(3)(CH3CN)](BF4)(2). This compound is a weak emitter in solution, however a remarkably high emission quantum yield (46%) has been found in a rigid matrix at room temperature.

A ferrocene (Fc) functionalized bis-porphyrin molecule has been synthesized as a host for fullerenes. The porphyrin used in these studies was prepared using a mixed boronic acid Suzuki reaction, which gives A(2)BC type porphyrins in high yield. The bis-porphyrin was characterized through (1)H NMR spectroscopy, high-resolution mass spectroscopy and analyzed via molecular modeling studies. Complexation experiments with fullerenes utilizing both UV-visible and fluorescence spectroscopy demonstrated formation of strong complexes for the bis-porphyrin. A short-lived charge transfer luminescent state is detected for the fullerene adducts. Owing to the tight coupling of the fullerene and porphyrin partners, the host-appended Fc moiety does not show a direct role in the pattern of photoinduced processes upon excitation of either chromophores, but causes blue-shift of the NIR CT luminescence compared to previously investigated systems without appended fragments. Instead, the active role of Fc in photoinduced processes is observed for the guest molecules alone, where photoinduced energy transfer from the porphyrin to the ferrocene occurs.

Dinuclear N-heterocyclic dicarbene gold(I) complexes of general formula [Au-2(RIm-Y-ImR)(2)](PF6)(2) (R = Me, Cy; Y = (CH2)(1-4), o-xylylene, m-xylylene) have been synthesized and screened for their luminescence properties. All the complexes are weakly emissive in solution whereas in the solid state some of them show significant luminescence intensities. In particular, crystals or powders of the complex with R = Me

We report new bis-cyclometalated cationic indium(III) complexes [((CN)-N-boolean AND)(2)Ir(CN-tert-Bu)(2)](CF3SO3) that have tert-butyl isocyanides as neutral auxiliary ligands and 2-phenylpyridine or 2-(4'-fluoropheny1)-R-pyridines (where R is 4-methoxy, 4-tert-butyl, or 5-trifluoromethyl) as (CN)-N-boolean AND ligands. The complexes are white or pale yellow solids that show irreversible reduction and oxidation processes and have a large electrochemical gap of 3.58-3.83 V. They emit blue or bluegreen phosphorescence in liquid/solid solutions from a cyclometalating-ligand-centered excited state. Their emission spectra show vibronic structure with the highest-energy luminescence peak at 440-459 nm. The corresponding quantum yields and observed excited-state lifetimes are up to 76% and 46 mu s, respectively, and the calculated radiative lifetimes are in the range of 46-82 mu s. In solution, the photophysical properties of the complexes are solvent-independent, and their emission color is tuned by variation of the substituents in the cyclometalating ligand. For most of the complexes, an emission color red shift occurs in going from solution to neat solids. However, the shift is minimal for the complexes with bulky tert-butyl or trifluoromethyl groups on the cyclometalating ligands that prevent aggregation. We report the first example of an iridium(III) isocyanide complex that emits blue phosphorescence not only in solution but also as a neat solid.

Charged cyclometalated (C?N) iridium(III) complexes with carbene-based ancillary ligands are a promising family of deep-blue phosphorescent compounds. Their emission properties are controlled primarily by the main C?N ligands, in contrast to the classical design of charged complexes where N?N ancillary ligands with low-energy ?* orbitals, such as 2,2'-bipyridine, are generally used for this purpose. Herein we report two series of charged iridium complexes with various carbene-based ancillary ligands. In the first series the C?N ligand is 2-phenylpyridine, whereas in the second one it is 2-(2,4-difluorophenyl)-pyridine. One bis-carbene (:C?C:) and four different pyridine-carbene (N?C:) chelators are used as bidentate ancillary ligands in each series. Synthesis, X-ray crystal structures, and photophysical and electrochemical properties of the two series of complexes are described. At room temperature, the :C?C: complexes show much larger photoluminescence quantum yields (?PL) of ca. 30%, compared to the N?C: analogues (around 1%). On the contrary, all of the investigated complexes are bright emitters in the solid state both at room temperature (1% poly(methyl methacrylate) matrix, ?PL 30-60%) and at 77 K. Density functional theory calculations are used to rationalize the differences in the photophysical behavior observed upon change of the ancillary ligands. The N?C:-type complexes possess a low-lying triplet metal-centered (3MC) state mainly deactivating the excited state through nonradiative processes; in contrast, no such state is present for the :C?C: analogues. This finding is supported by temperature-dependent excited-state lifetime measurements made on representative N?C: and :C?C: complexes.

The incorporation of luminescent lanthanide complexes in solid matrices with controlled structural organization is of widespread interest in materials science and has witnessed important improvements with the development of low-temperature soft chemistry solution processes. such as sol-gel. In this review, after an introductory part concerning some relevant aspects of the electronic and coordination properties of lanthamides, the prominent issues related to the design and synthesis of efficient luminescent antenna complexes, and their photophysical properties are presented. We describe the basic principles of ligands design to yield systems featuring a coordination site for the metal cation with appended suitable chromophores as sensitizers (two-component approach). When properly designed, these ligands are capable of forming highly luminescent complexes (overall sensitization yield, phi(se) > 0.05 in aqueous medium). The photophysical properties of these complexes together with the description of some emitting materials prepared are discussed in detail. In particular we focus the attention toward those complexes emitting in the visible region that can be used in the lighting industry (e.g. for the preparation of photo- and electro-luminescent materials) and for biological immunoassays. Subsequently, some selected results of our recent work concerning the synthesis of highly luminescent colour tunable films for applications in lighting and light conversion technologies are reported. Such materials have been obtained by combining the peculiar luminescence properties of Eu3+. and Tb3+ antenna complexes with optically transparent inorganic matrices. The notion is to create materials with innovative properties by integrating inorganic and organic components at nanoscale or molecular level. Due to the number of scientific publications in this field, this work is far from providing an exhaustive review on the previously performed research activities. Fora more detailed discussion on these methodologies, the reader can refer to specific pertinent literature.

A series of reactions have been performed by mixing 2-diphenylphosphino-6-methyl-pyridine (dpPyMe) and [Cu(CH3CN)4]BF4 in different molar ratios. Starting from equimolar quantities of dpPyMe and Cu+, a dinuclear Cu(I) complex with two P,N binucleating bridging ligands has been obtained. This compound is stable in the solid state, however ligand exchange reactions leading to a mixture of species have been evidenced in solution. By increasing the amount of dpPyMe, the reaction of dpPyMe and [Cu(CH3CN)4]BF4 afforded the dinuclear Cu(I) complex [Cu2(?-dpPyMe)3(CH3CN)](BF4)2 in which the three bridging dpPyMe ligands are in a head-to-head arrangement. This compound is remarkably stable in solution. It has been also shown that the axial CH3CN ligand of [Cu2(?-dpPyMe)3(CH3CN)](BF4)2 can be suitably exchanged with other nitrile ligands [benzonitrile, 4-(dimethylamino)-benzonitrile, 4-nitrobenzonitrile and bromoacetonitrile] but also with triphenylphosphine oxide. The electrochemical and photophysical properties of the resulting complexes have been systematically investigated. The [Cu2(?-dpPyMe)3(L)](BF4)2 derivatives are weak emitters in solution but remarkable emission quantum yields (6 to 46%) have been found in rigid matrices at room temperature. One complex was utilized as active material for preliminary tests in LEC devices.

Four novel dinuclear N-heterocyclic dicarbene gold(i) complexes with a propylene linker between the carbene moieties have been synthesized and their luminescence and electrochemical properties, together with their reactivity towards bromine oxidative addition, have been screened. All the complexes emit in the solid state in the blue-green spectral range (400-500 nm) with appreciable intensities (<inf>em</inf> up to ?10%). In cyclic voltammetry, the Au(i)/Au(0) peak splits at low temperature into two separate peaks relative to the couples Au(i)-Au(i)/Au(i)-Au(0) and Au(i)-Au(0)/Au(0)-Au(0), thus indicating the presence of an Au?Au interaction in the dinuclear complex. Oxidative addition of bromine affords as a major or unique product Au(ii)-Au(ii) complexes most likely as a consequence of the interaction between the two gold centres favoured by the propylene linker. © The Royal Society of Chemistry 2013.

We report the synthesis of 7 new para-phenylene-bridged zinc porphyrin dimers, five of which were characterized by single-crystal X-ray analysis. A variety of links were tested for holding the paraphenylene bridges in p-conjugation with the porphyrins, and the natures of these restraining links strongly influence the properties of the porphyrin dimers. The keto-linked dimer exhibits a long-lived singlet excited state and strong fluorescence at 960 nm (1.7% quantum yield) in contrast to most previously reported conjugated porphyrin tapes, which are essentially non-emissive. Replacement of the cross-conjugated keto links by directly conjugated C-C bonds eradicates the fluorescence and shifts the absorption maximum to 1077 nm. On the other hand, replacement of the keto links with nonconjugated CPh2 links confers fluorescence at 736 nm (10% quantum yield) and results in remarkably similar one- and two-photon absorption behavior to that of meso-meso ethynylene-bridged porphyrin dimers (peak two-photon cross section: 7,300 GM at 878 nm). Cross-conjugated keto links do more than just hold the para-phenylene bridge coplanar with the porphyrins; they reduce the HOMO- LUMO gap, although to a lesser extent than direct p-conjugated links. Planarized para-phenylenebridged porphyrin dimers provide insights into the relationship between previously investigated classes of conjugated porphyrin oligomers, and they open up possibilities for the synthesis of new types of near-IR two-photon absorbing dyes.

In this work, we investigate the optical and structural properties of the well-known triplet emitter bis(4?,6?-difluorophenylpyridinato)-iridium(III) picolinate (FIrpic), showing that its ability to pack in two different ordered crystal structures promotes attractive photophysical properties that are useful for solid-state lighting applications. This approach allows the detrimental effects of the nonradiative pathways on the luminescence performance in highly concentrated organic active materials to be weakened. The remarkable electro-optical behavior of sky-blue phosphorescent organic light-emitting diodes incorporating crystal domains of FIrpic, dispersed into an appropriate matrix as an active layer, has also been reported as well as the X-ray diffraction, nuclear magnetic resonance, electro-ionization mass spectrometry, and scanning electron microscopy analyses of the crystalline samples. We consider this result as a crucial starting point for further research aimed at the use of a crystal triplet emitter in optoelectronic devices to overcome the long-standing issue of luminescence self-quenching.

A series of homoleptic copper(I), silver(I), and gold(I) complexes of two bisphosphine ligands {1,2-bis(diphenylphosphino)benzene, dppb; bis[2-(diphenylphosphino)phenyl]ether, POP} have been prepared. Whilst all three [M(dppb)(2)]BF4 complexes are tetracoordinate, this geometry is found only for the silver(I) complex with POP. Instead, [Cu(POP)(2)](+) and [Au(POP)(2)](+) adopt a trigonal coordination geometry with an uncoordinated phosphorus atom. A close inspection of the P-M bond lengths reveals an interesting trend. From the copper to silver and gold complexes, a substantial elongation is found. On the other hand, from the silver to gold compounds, a decrease in the M-P bond length is found. Indeed, gold(I) has a smaller van der Waals radius than silver(I) as a result of its peculiar relativistic effects. Electrochemical investigations revealed two oxidation processes for all of the [M(dppb)(2)]BF4 and [M(POP)(2)]BF4 complexes. The first oxidation is likely metal-centered, whereas the second one corresponds to ligand-centered processes in all cases. The emission properties of these compounds in solution, in frozen rigid matrices at 77 K, and in the solid state at room temperature have been systematically investigated. Although all of them are weak emitters in solution, remarkably high emission quantum yields were found in the solid state, in particular for [Cu(dppb)(2)]BF4 and [Ag(dppb)(2)]BF4. Finally, these two compounds were used for the fabrication of light-emitting devices. Interestingly, both the copper(I) and the silver(I) complex afford quite broad electroluminescence spectra with white light emission.

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

The European Union set the ambitious target of reducing energy consumption by 20% within 2020. This goal demands a tremendous change in how we generate andconsume energy and urgently calls for an aggressive policy on energy efficiency. Since 19% of the European electrical energy is used for lighting, considerable savings can be achieved with the development of novel and more efficient lighting concepts [1].In this talk, some selected objectives accomplished in the frame of the EU project CELLO will be briefly presented [2a]. The main target of this project was to develophighly efficient, flat, low cost and flexible electroluminescent devices termed Light-Emitting Electrochemical Cells (LECs), based on cationic cyclometalated iridium(III)complexes [2].After a short introduction about LECs and solid-state lighting, the research carried out on cyclometalated iridium(III) complexes displaying light output in two extremesides of the visible spectral window, namely deep-blue [3] and red/near-infrared (NIR) [4], will be presented. The former luminophores tend to be rather challenging due toemission red-shift in the solid state and instability under operative conditions, the latter may serve also as interesting options where NIR luminescence is crucial, such astelecommunications and bioimaging.Since LECs are based on a single active material, the importance of an integrated approach toward the right selection of suitable emitters not only in terms of photophysical properties but also from the point of view of stability and cost will be highlighted [5]. In fact, the active iridium(III) complex, once in the device, is interactingwith added ionic liquids, metal cathodes, electric fields, etc. All these interactions must be taken into account in order to develop lighting devices that can move from research labs to the market.[1] (a) L. S. Brown, Plan B. Mobilizing to save the civilization, W. W. Norton & Company, New York, 2009. (b) Light's Labour's Lost - Policies for Energy-efficient Lighting, tech. rep., International Energy Agency, 2006.[2] (a) https://www.cello-project.eu/ (b) R. D. Costa, E. Orti, H. J. Bolink, F. Monti, G. Accorsi, and N. Armaroli, Angew. Chem., Int. Ed., 2012, 51, 8178-8211.[3] (a) N. M. Shavaleev, F. Monti, R. D. Costa, R. Scopelliti, H. J. Bolink, E. Ortí, G. Accorsi, N. Armaroli, E. Baranoff, M. Grätzel, and M. K. Nazeeruddin, Inorg. Chem., 2012, 51, 2263-2271. (b) N. M. Shavaleev, F. Monti, R. Scopelliti, N. Armaroli, M. Grätzel, and M. K. Nazeeruddin, Organometallics, 2012, 31, 6288-6296. (c) N. M. Shavaleev, F. Monti, R. Scopelliti, A. Baschieri, L. Sambri, N. Armaroli, M. Grätzel, and M. K. Nazeeruddin, Organometallics, 2013, 32, 460-467. (d) F. Monti, F. Kessler, M. Delgado, J. Frey, F. Bazzanini, G. Accorsi, N. Armaroli, H. J. Bolink, E. Ortí, R. Scopelliti, M. K. Nazeeruddin, and E. Baranoff, Inorg. Chem., 2013, 52, 10292-10305.[4] E. C. Constable, M. Neuburger, P. Rösel, G. E. Schneider, J. A.

Four Cu(I) complexes with general formulas [Cu((NN)-N-boolean AND)(2)][BF4] and [((PP)-P-boolean AND) Cu((NN)-N-boolean AND)][BF4] were prepared, where (NN)-N-boolean AND stands for 2-(2-tert-butyl-2H-tetrazol-5-yl)pyridine and (PP)-P-boolean AND is a chelating diphosphine, namely bis-(diphenylphosphino) methane (dppm), bis-(diphenylphosphino) ethane (dppe) or bis[2-(diphenylphosphino) phenyl] ether (POP). In an acetonitrile medium, the Electro-Spray Ionization Mass Spectrometry (ESI-MS) determination provided the preliminary evidence for the occurrence of the dppm-containing complex as a mixture of a cationic mononuclear [Cu((NN)-N-boolean AND)(dppm)](+) species and a bis-cationic dinuclear [Cu-2((NN)-N-boolean AND)(2)(dppm)(2)](2+)-type compound. Definitive evidence of peculiar structural features came from X-ray crystallography, which showed both the dppm-and, unexpectedly, the dppe-based heteroleptic compounds to crystallize as diphosphine-bridged Cu(I) dimers, unlike [Cu((NN)-N-boolean AND) 2](+) and [(POP) Cu( (NN)-N-boolean AND)]+ which are mononuclear species. In solutions of non-coordinating solvents, P-31 NMR studies at variable temperatures and dilution titrations confirmed that the dppm-based complex undergoes a monomer-dimer dynamic equilibrium, while the dppe-containing complex occurs as the bis-cationic dinuclear species, [Cu-2((NN)-N-boolean AND)(2)(dppe)(2)](2+), within a concentration range comprised between 10(-2) and 10(-4) M. Differences among heteroleptic complexes might be related to the smaller natural bite angle displayed by dppm and dppe phosphine ligands (72 and 85, respectively), with respect to that reported for POP (102). The electrochemical features of the new species have been investigated by cyclic voltammetry. Despite the irreversible and complicated redox behaviour, which is typical for copper complexes, the reductions have been attributed to the tetrazole ligand whereas the oxidations are characterized as Cu(I/II) processes with a substantial contribution from the (PP)-P-boolean AND-based ligands in the case of the heteroleptic species. All the four complexes are weakly or not luminescent in CH2Cl2 solution, but heteroleptic complexes are bright green luminophores in a solid matrix, with quantum yields as high as 45% (dppm complex) even at room temperature. This makes them potential candidates as cheap emitting materials for electroluminescent devices.

Two new macrocyclic structures containing 8-hidroxyisoalloxazine and 1,5-dihydroxyanthracene moieties linked by aliphatic chains of different lengths (n = 4 and 6) were designed and synthesized in order to study photoinduced electron transfer (PET) processes from the anthracene unit towards the isoalloxazine singlet excited state induced by structural changes due to different intrachromophoric distances and orientations. The compounds have been fully characterized by NMR spectroscopy and the X-ray solid state structures of both macrocycles have been elucidated. Photophysical measurements, including continuous wavelength photoinduced absorption (cw-PIA), at room temperature and 77 K have been carried out in order to investigate the influence of the close contacts between the aromatic groups (?-? stacking) on the photophysical properties of the macrocycles.

Exciton-polaritons in semiconductors are quasi-particles which have recently shown the capability to undergo phase transition into a coherent hybrid state of light and matter. The observation of such quasi-particles in organic microcavities has attracted increasing attention for their characteristic of reaching condensation at room temperature. In this work, the emission properties of organic polaritons are demonstrated not to depend on the overlap between the absorption and emission states of the molecule and that the emission dynamics are modified in the strong coupling regime, showing a significant enhancement of the photoluminescence intensity as compared to the bare dye. This paves the way to the investigation of molecules with large absorption coefficients but poor emission efficiencies for the realization of polariton condensates and organic electrically injected lasers by exploiting strong exciton-photon coupling regimes.

We have prepared a new borazine derivative that bears mesityl substituents at the boron centers and displays exceptional chemical stability. Detailed crystallographic and solid-state fluorescence characterizations revealed the existence of several polymorphs, each of which showed different emission profiles. In particular, a bathochromic shift is observed when going from the lower- to the higher-density crystal. Computational investigations of the conformational dynamics of borazine 1 in both the gas phase and in the solid state using molecular dynamics (MD) simulations showed that the conformation of the peripheral aryl groups significantly varies when going from an isolated molecule (in which the rings are able to flip over the 90° barrier at RT) to the crystals (in which the rotation is locked by packing effects), thus generating specific nonsymmetric intermolecular interactions in the different polymorphs. To investigate the optoelectronic properties of these materials by fabrication and characterization of light-emitting diodes (LEDs) and light-emitting electrochemical cells (LECs), borazine 1 was incorporated as the active material in the emissive layer. The current and radiance versus voltage characteristics, as well as the electroluminescence spectra reported here for the first time are encouraging prospects for the engineering of future borazine-based devices. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel, promising ligand for luminescent lanthanide complexes tris-((4-(3-methyl-1-phenyl-5-pyrazolonyl)-phenylmethylidene)-2-aminoethyl)amine (trenPMBP) was prepared and used as effective"antenna" for the ligand-sensitized photoluminescence of Tb3+, Dy3+ and Sm3+ ions. All the complexesshow surprisingly intensive photoluminescence in comparison with their simple 4-benzoyl-3-methyl-1-phenyl-5-pyrazolone analogues. One of the reasons of such result can be a relatively high located tripletenergy level of trenPMBP around 22675cm-1, which properly fits with the emissive energy levels ofTb3+ and Dy3+ (20430cm-1 and 20830cm-1, respectively), thus avoiding back-energy transfer from thelanthanide to the ligand.

Innovative Tb3+ antenna complexes employing two different substituted 2-hydroxyphthalamide ligands (HxOH-IAM and bis-HxOH-IAM) acting simultaneously as coordinating sites and light collector units have been synthesized and successively anchored in silica layers by the sol–gel technique. The complexes show remarkable photoluminescence (PL) quantum yields in methanol solution, as high as 0.30 and 0.40 for (HxOH-IAM)4ÃTb3+ and (bis-HxOH-IAM)2ÃTb3+, respectively. The grafting of the Tb3+ complexes in silica single layers accomplished by exploiting the terminal hydroxyl groups of the IAM chains results in highly transparent and homogeneous films displaying bright green emission and PL efficiencies of up to 0.40. The silica layers containing the (bis-HxOH-IAM)2ÃTb3+ show remarkable photostability even under prolonged and continuous irradiation (up to 3.5 h). The nature of the IAM ligands allows the photoexcitation of the complexes at wavelengths even longer than 350 nm, which is a spectral window suitable to develop luminescent lanthanide probes dedicated to bioanalyses and bioimaging applications.

In this paper, we describe the synthesis and the electronic properties of a series of [Cu(NN)2]+ systems. The NN ligands investigated are 2,9-bis[(tert-butyldimethylsilyloxy)methyl]-1,10-phenanthroline (1), 2,9-bis[(triisopropylsilyloxy)methyl]-1,10-phenanthroline (2), 2,9-bis[(tert-butyldiphenylsilylmoxy)ethyl]-1,10-phenanthroline (3), 2,9-bis[2,6-bis(benzyloxy)phenethyl]-1,10-phenanthroline (4) and 2-(1,3-diphenylpropan-2-yl)-9-phenethyl-1,10-phenanthroline (5). The electrochemical properties and the ground state electronic absorption spectra of Cu(1)2-Cu(5)2 are in line with the classical behaviour of such [Cu(NN)2]+ derivatives. Whereas all the compounds exhibit MLCT luminescence centered around 630-650 nm, the emission quantum yields and the lifetimes are dramatically different as a function of stereoelectronic effects and/or the possibility of internal exciplex quenching when oxygen-containing functional groups are attached to the phenanthroline ligands.

Based on 2,2':6',2''-terpyridine ligands (L1), five terpyridine derivatives, namely 4'-carbazol-9-yl-2,2':6',2''-terpyridine (L2), 4'-diphenylamino-2,2':6',2''-terpyridine (L3), 4'-bis(4-tert-butylphenyl)amino-2,2':6',2''-terpyridine (L4), 4'-[naphthalen-1-yl-(phenyl)amino]-2,2':6',2''-terpyridine (L5), 4'-[naphthalen-2-yl(phenyl)amino]-2,2':6',2''-terpyridine (L6) and their corresponding Re(I) complexes ReLn(CO)3Cl (n =1-6) have been synthesized and characterized by elemental analysis and 1H NMR spectroscopy. The X-raycrystal structure of ReL3(CO)3Cl has also been obtained. The luminescence spectra of ReL2(CO)3Cl-ReL5(CO)3Cl, obtained in CH2Cl2 solution at room temperature, show strong d? (Re) -> ?* (diimine) MLCT character(?max ~ 600 nm) and a small red shift relative to ReL1(CO)3Cl. This, confirmed by the study of thetriplet energy levels of the L1-L6 ligands at low temperature (77 K rigid matrix), indicates that the introductionof electron-donating moieties on the terpyridine unit decreases the triplet levels of the ligands,leading to a reduction of the energy gap between d and ?* orbitals. In the solid state, upon MLCT excitation,all the complexes show an even stronger emission and a blue spectral shift (?max ~ 550 nm) comparedto those obtained in solution.

New propylene bridged bis(imidazolium) salts bearing at the wingtip positions a benzyl group functionalisedwith one or two long alkyl chains, as well as the corresponding dinuclear N-heterocyclicdicarbene gold(I) complexes of general formula [Au2(RIme(CH2)3eImR)2](X)2 (X ¼ Br, PF6, BF4) havebeen synthesised and thermally characterised. All the compounds are stable up to 200 C and thebis(imidazolium) salts [H2(RIme(CH2)3eImR)](X)2 (X ¼ Br, PF6) behave as thermotropic liquid crystals inthe temperature range 100e200 C. By contrast, only the gold(I) diNHC complexes with eight aliphaticchains present mesomorphism, whereas those with four chains show numerous crystalline phases withstructural disorder and presumably modified AueAu distances, as indicated by solid state emissionproperties.

The optical, electrochemical and excited state properties of C60 fullerene and its derivatives, combined with their peculiar structural features, have made them ideal modules for the construction of complex architectures which feature light induced processes. Here are described three selected classes of such systems investigated in our group by taking advantage of some intrinsic excited state properties of C60 fullerenes such as fluorescence, triplet lifetimes, or sensitized singlet oxygen luminescence. Fullerene hybrid assemblies with Cu(I), Ru(II), and Re(I) complexes undergo ultrafast photoinduced electron transfer (PET) upon excitation of the metal-to-ligand-charge-transfer (MLCT) excited states of the metal-complexed moiety. In the case of the Cu(I) system, occurrence of PET by fullerene excitation depends on the specific functionalization of the carbon sphere. Fullerodendrimers equipped with oligophenylenevinylene moieties and showing enhanced or reduced PET as a function of dendrimer structure and size are presented along with simpler monochromophoric fullerodendrimers which illustrate the capability of fullerene triplets to probe dendritic shielding effects. The peculiar ground and excited-state properties of rigid and conformationally flexible fullerene-porphyrin systems arranged in a face-to-face fashion are described, both with meso,meso-linked or triply fused porphyrin oligomers. Control of the direction and nature of photoinduced processes is achieved in such systems, which additionally show charge transfer or porphyrin-centered near-infrared luminescence. The whole work is discussed in a historic perspective and further development for photoactive fullerodendrimers and face-to-face arrays, particularly in solar energy conversion devices, is envisaged.

The origin of the optical properties of the firstly reported stable luminescent [Cu(PP)(2)](+) complex [Cu(dppb)(2)](+)[dppb = 1 2 - bis(diphenylphosphino)benzene] is investigated using the exchange-correla non functional PBE0 The choice of the basis set used is discussed and a comparison with the results obtained by other functionals is performed The role played by the bisphosphine ligands within the complex is elucidated by considering the electronic properties of the ligand alone to evidence how both the geometrical changes and the electronic interactions induced by the inclusion of the metal cation affect the electronic behavior of the whole system The NBO analysis shows how the aryl groups of the ligands act as a reservoir of electrons within the complex The electronic excitations of both the complex and of the ligand calculated by including the solvation effects allow to assign the lowest energy absorption broad band recorded in CH(2)Cl(2) solution The peculiar contribution of the phosphorus atoms to the description of the high occupied MOs and the participation of the copper cation to the description of the lowest singlet excited state is pointed out The origin of the observed phosphorescence of the complex is attributed to a triplet state whose SOMO is characterized by the contributions of the valence 4s and of the Rydberg 5s AOs of the metal cation along with the lone pair orbitals of the P atoms (C) 2010 Elsevier B V All rights reserved

Luminescent CdS nanocrystals embedded in a polystyrene matrix were successfully prepared. The in situ growth of CdS QDs was realized by thermal treatment of Cd bis(thiolate)/polymer foil at different times and temperatures (240 degrees C and 300 degrees C) of annealing, in order to evaluate their influence on the quantum dots growth process. As a general trend, the increasing of time and temperature of annealing induces a rise of the CdS nanocrystals size into the polymeric matrix. The size distribution, morphology, and structure of the CdS nanoparticles were analysed with HRTEM and XRD experiments. UV-Vis and PL data are strongly size-dependent and were used to investigate the particles' growth process, too. The CdS nanoparticles behavior in solution indicated a general trend of QDs to aggregation. This predisposition was clearly displayed by DLS measurements.

We present here the synthesis of several new isoalloxazine cyclophanes containing electroactive anthraquinones linked by aliphatic chains of different lengths. Such structural changes provide different interchromophoric orientations leading to the tuning of the rate of the photoinduced electron transfer process from the anthraquinone unit towards the isoalloxazine singlet excited state. Molecular modelling studies were undertaken in order to determine the minimal energy of the proposed structures using Monte Carlo calculations (Amber, Macromodel v.8.1). The compounds have been fully characterised by NMR spectroscopy and the solid state structures of some of the macrocycles have been elucidated. The photophysical studies have been carried out in order to investigate the influence of ?-? stacking on the optical properties of the macrocycles. © 2013 The Royal Society of Chemistry and Owner Societies.

In this work, we explore the effects of the ultrastrong coupling regime between light and molecular exci-tons on the electrical and optical properties of microcavity-OLEDs. We studied two different sampleshaving a coupling value of 31% and 48%. The main effect of the ultrastrong interaction is on the electro-luminescent emission linewidth which was only 28 meV, that is about 12-fold narrower than that of thecorresponding photoluminescence of the uncoupled material and even half the linewidth of photonic(weak-coupled) microcavity working at the same wavelength.

The incorporation of luminescent lanthanide complexes in solid matrices with controlled structural organizationis of widespread interest in materials science and has witnessed important improvements withthe development of low-temperature soft chemistry solution processes, such as sol-gel. In this review,after an introductory part concerning some relevant aspects of the electronic and coordination propertiesof lanthanides, the prominent issues related to the design and synthesis of efficient luminescent antennacomplexes, and their photophysical properties are presented. We describe the basic principles of ligandsdesign to yield systems featuring a coordination site for the metal cation with appended suitable chromophoresas sensitizers (two-component approach). When properly designed, these ligands are capableof forming highly luminescent complexes (overall sensitization yield, se > 0.05 in aqueous medium).

The present invention provides methods for inhibiting or preventing cancer cell growth using silver nanoparticles