A series of novel, highly phosphorescent cyclometalated iridium­(III) complexes of type [(X2C^N)2Ir­(Q2bpy)]+PF6 – (where X2C^N is 2-phenylpyridine or 2-(2,4-difluorophenyl)­pyridine anion and Q2bpy are 4,4′-bifunctionalized 2,2′-bipyridines) is presented. The complexes were fully characterized by means of NMR spectroscopy, high-resolution mass spectrometry (HRMS), cyclic voltammetry, and UV–vis. For several compounds also the crystallographic structures were obtained. The cyclometalates exhibited efficient photoluminescence at 298 K both in solution and in the solid state with good intensity and color purity. The emission wavelength range covered almost the whole visible spectrum and was strongly correlated with the EWG/ERG character of the Q substituent in the ancillary ligand. For further insight into the electronic structure of the complexes, a comprehensive electrochemical support (CV) was introduced, and finally, it was confronted with theoretical background using a density functional theory approach together with time-dependent calculations of the excited states.

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Photonic crystals (PhC) are spatially ordered structures with lattice parameters comparable to the wavelength of propagating light. Their geometrical and refractive index features lead to an energy band structure for photons, which may allow or forbid the propagation of electromagnetic waves in a limited frequency range. These unique properties have attracted much attention for both theoretical and applied research. Devices such as high-reflection omnidirectional mirrors, low-loss waveguides, and high- and low-reflection coatings have been demonstrated, and several application areas have been explored, from optical communications and color displays to energy harvest and sensors. In this latter area, photonic crystal fibers (PCF) have proven to be very suitable for the development of highly performing sensors, but one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) PhCs have been successfully employed, too. The working principle of most PhC sensors is based on the fact that any physical phenomenon which affects the periodicity and the refractive index of the PhC structure induces changes in the intensity and spectral characteristics of the reflected, transmitted or diffracted light; thus, optical measurements allow one to sense, for instance, temperature, pressure, strain, chemical parameters, like pH and ionic strength, and the presence of chemical or biological elements. In the present article, after a brief general introduction, we present a review of the state of the art of PhC sensors, with particular reference to our own results in the field of mechanochromic sensors. We believe that PhC sensors based on changes of structural color and mechanochromic effect are able to provide a promising, technologically simple, low-cost platform for further developing devices and functionalities.

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New quinolines bearing a 2,2Ј-bithiophene motif have been prepared through Ru-and In-catalyzed reactions as well as by Suzuki cross-coupling reactions. The novel quinolines have been characterized by using EI-HRMS and NMR spectroscopy. Additionally, the molecular structures of the novel quinolines were confirmed by X-ray crystallography. The photophysical and electrochemical properties of all quinoline derivatives were investigated by using absorption and luminescence spectroscopy and cyclic voltammetry. The main intense absorption bands associated with the quinoline derivatives were located between 350 and 450 nm. Intense blue-

This paper reports an optical investigation of Eu 3? :PbF 2 nanocrystals distributed into silica glasses fabricated by sol-gel methods. The sample microstructure was investigated using scanning transmission electron microscopy. The b-cubic PbF 2 crystalline phase was identified using X-ray diffraction analysis. The observed emission bands correspond to 5 D 0 ? 7 F J (J = 0-4) transitions of Eu 3? . The spectroscopic parameters for Eu 3? ions were determined based on excitation and emission measurements as well as luminescence decay analysis. Emission originating from 5 D 0 state of Eu 3? ions in sample containing PbF 2 nanocrystals is long-lived in comparison to precursor sol-gel silica glasses.