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The synthesis and characterization of two new complexes, namely Pt(1,3-bis(4-(4-hexyl-2-thienyl)-pyridin-2-yl)-5-mesitylbenzene)Cl and Pt(1,3-bis(4-(4-hexyl-2-thienyl)-pyridin-2-yl)-5-(2-thienyl)benzene)Cl, are reported. Both exhibit luminescence quantum yields approaching unity (Φlum = 0.96–0.99) in the green region of the visible spectrum (534–554 nm) in diluted degassed dichloromethane solution. Similarly to other N^C^N platinum(II) complexes, a broad emission band grows in the deep red region (738–752 nm) upon increasing the concentration, due to the creation of bi-molecular emissive excited states. Interestingly, it appears that the introduction of a 2-thienyl group on the pyridine rings is a route to maintain excellent quantum yields even in concentrated solution. In order to have an insight into the electronic properties of the novel compounds, density functional theory (DFT) and time-dependent (TD)DFT approaches were employed to calculate the molecular geometry, the ground state, the electronic structure and the excited electronic states of the complexes, both as a monomers and dimers in solution.

The second-order nonlinear optical (NLO) properties of the known heteroleptic complex [Cu(1,10-phenanthroline)xantphos][PF6] (complex 1) and the related new complexes [Cu(5-NO2-1,10-phenanthroline)xantphos][PF6] and [Cu(5-NO2-1,10-phenanthroline)(dppe)][PF6] (dppe = 1,2-bis(diphenylphosphino)ethane) (complexes 2 and 3) were investigated in solution by the EFISH (Electric Field-Induced Second Harmonic generation) technique, working at a non-resonant wavelength of 1907 nm. It turned out that they are characterized by large μβ values (957–1100 × 10−48 esu), much higher than that of the Disperse Red One benchmark. Unexpectedly, the homoleptic complex [Cu(2-mesityl-1,10-phenanthroline)2][PF6] (complex 4) shows a similar high second-order NLO response. Quantum chemical calculations based on Density Functional Theory (DFT) methods have been carried out to give insight into the electronic structure of the investigated complexes in relation to NLO properties. This investigation, which represents the first EFISH study on copper(I) complexes, opens a convenient route for the development of low-cost dipolar NLO-active heteroleptic [Cu(P^P)(N^N)][PF6] and homoleptic [Cu(N^N)2][PF6] complexes.

Photochromic compounds are employed in implementing neuron surrogates. They will boost the development of neuromorphic engineering in wetware. In this work, the photochromic behaviours of (E)-3,4,6-trichloro-2-(p-diazenil)-phenol (t-DZH) and its conjugated phenoxide base (t-DZ) have been investigated experimentally in three different media: (1) pure acetonitrile, (2) in water and acetonitrile mixed in a 1/1 volume ratio, and (3) in an aqueous micellar solution of 3-(N,N-Dimethylmyristylammonio)propanesulfonate (SB3-14). The analysis of the spectral and kinetic features of t-DZH and t-DZ has been supported by quantum-mechanical DFT calculations, the maximum entropy method, and the determination of their colourability (C). The versatility of t-DZH and t-DZ makes them promising molecular probes of micro-environments and potential ingredients of photochemical oscillators required for implementing pacemaker neurons capable of communicating through optical signals in wetware.

Computational modelling applied to cultural heritage can assist the characterization of painting materials and help to understand their intrinsic and external degradation processes. The degradation of the widely employed zinc oxide (ZnO)—a white pigment mostly used in oil paints—leads to the formation of metal soaps, complexes of Zn ions and long-chain fatty acids coming from the degradation of the oil binder. Being a serious problem affecting the appearance and the structural integrity of many oil paintings, it is relevant to characterize the structure of these complexes and to understand the reaction pathways associated with this degradation process. Density functional theory (DFT) calculations were performed to investigate the adsorption of the acetate and acetic acid on relatively large ZnO clusters and the formation of Zn–acetate complexes. Carboxylic acids with longer alkyl chains were then investigated as more realistic models of the fatty acids present in the oil medium. In addition, DFT calculations using a periodic ZnO slab were performed in order to compare the obtained results at different levels of theory. Optimization calculations as well as the formation energies of the ZnO@carboxylate coupled systems and the thermodynamics leading to possible degradation products were computed. Our results highlight the potential for DFT calculations to provide a better understanding of oil paint degradation, with the aim of contributing to the development of strengthening and conservation strategies of paintings.

The non-linear optical and antitumoral properties of cis-Ir(N,C-ppy)2(O,O-THC) have previously been established (where ppy and THC are the deprotonated forms of 2-phenylpyridine and tetrahydrocurcumin, respectively). In the present study, this complex is investigated as a green phosphorescent emitter for an OLED fabricated by solution processing. The device efficiency is similar to that of an analogue employing the archetypal complex cis-Ir(N,C-ppy)2(O,O-acac), but shows a higher luminance at low applied voltages (<6 V). In order to explore whether this effect might be observed in the blue region too, a new derivative has been prepared and characterized, namely cis-Ir(N,C-F2ppy)2(O,O-THC) (F2ppyH = 2-(2,4-difluorophenyl)pyridine). It, too, gives an OLED with a particularly high luminance at low voltage, suggesting a beneficial effect of substituting acetylacetonate by tetrahydrocurcuminate.

Titanium dioxide (TiO2) has been used in numerous paintings since its creation in the early 1920s. However, due to this relatively recent adoption by the art world, we have limited knowledge about the nature and risk of degradation in museum environments. This study expands on the existing understanding of TiO2 facilitated degradation of linseed oil, by examining the effect of visible light and crystallographic phase (either anatase or rutile) on the reactivity of TiO2. The present approach is based on a combination of experimental chemical characterization with computational calculation through Density Functional Theory (DFT) modeling of the TiO2-oil system. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FT-IR) enabled the identification of characteristic degradation products during UV and visible light aging of both rutile and anatase based paints in comparison to BaSO4 and linseed oil controls. In addition, cratering and cracking of the paint surface in TiO2 based paints, aged under visible and UV–vis illumination, were observed through Scanning Electron Microscopy (SEM). Finally, Density Functional Theory (DFT) modeling of interactions between anatase TiO2 and oleic acid, a fatty acid component of linseed oil, to form a charge transfer complex explains one possible mechanism for the visible light activity observed in artificial aging. Visible light excitation of this complex sensitizes TiO2 by injecting an electron into the conduction band of TiO2 to generate reactive oxygen species and subsequent degradation of the oil binder by various mechanisms (e.g., formation of an oleic acid cation radical and other oxidation products).

Whereas there is an increasing amount of reports on the second-order nonlinear optical (NLO) and luminescence properties of tetradentate [N2O2] Schiff base–zinc complexes, the study of zinc complexes having two bidentate [NO] Schiff-base ligands is relatively unexplored from an NLO point of view. This work puts in evidence that the known chiral bis2-[(R)-(+)-1-phenylethyliminomethyl]phenolato-N,Ozinc(II) complex is a fascinating multifunctional molecular inorganic–organic hybrid material characterized by interesting second-order NLO and luminescent properties in solution. The emissive properties of the organic 2-(R)-(+)-1-phenylethyliminomethyl]phenol proligand are greatly enhanced upon coordination to the inorganic Zn(II) center.

The synthesis and characterization of two new complexes, namely Pt(1,3-bis(4-(4-hexyl-2-thienyl)-pyridin-2-yl)-5-mesitylbenzene)Cl and Pt(1,3-bis(4-(4-hexyl-2-thienyl)-pyridin-2-yl)-5-(2-thienyl)benzene)Cl, are reported. Both exhibit luminescence quantum yields approaching unity (Φlum = 0.96–0.99) in the green region of the visible spectrum (534–554 nm) in diluted degassed dichloromethane solution. Similarly to other N^C^N platinum(II) complexes, a broad emission band grows in the deep red region (738–752 nm) upon increasing the concentration, due to the creation of bi-molecular emissive excited states. Interestingly, it appears that the introduction of a 2-thienyl group on the pyridine rings is a route to maintain excellent quantum yields even in concentrated solution. In order to have an insight into the electronic properties of the novel compounds, density functional theory (DFT) and time-dependent (TD)DFT approaches were employed to calculate the molecular geometry, the ground state, the electronic structure and the excited electronic states of the complexes, both as a monomers and dimers in solution.

The non-linear optical and antitumoral properties of cis-Ir(N,C-ppy)[sub.2](O,O-THC) have previously been established (where ppy and THC are the deprotonated forms of 2-phenylpyridine and tetrahydrocurcumin, respectively). In the present study, this complex is investigated as a green phosphorescent emitter for an OLED fabricated by solution processing. The device efficiency is similar to that of an analogue employing the archetypal complex cis-Ir(N,C-ppy)[sub.2](O,O-acac), but shows a higher luminance at low applied voltages (<6 V). In order to explore whether this effect might be observed in the blue region too, a new derivative has been prepared and characterized, namely cis-Ir(N,C-F[sub.2]ppy)[sub.2](O,O-THC) (F[sub.2]ppyH = 2-(2,4-difluorophenyl)pyridine). It, too, gives an OLED with a particularly high luminance at low voltage, suggesting a beneficial effect of substituting acetylacetonate by tetrahydrocurcuminate.

The luminescence and second order non linear optical (NLO) response of [Ir(ttpy) 2 (5-R-1,10-phen)][PF 6 ] (ttpy = cyclometallated 3′-(2-pyridil)-2,2′:5′,2″-terthiophene, phen = phenanthroline; R = Me, NO 2 ) and [Ir(pq) 2 (5-R-1,10-phen)][PF 6 ] (pq = cyclometallated 2-phenylquinoline) have been investigated experimentally in CH 2 Cl 2 solution and compared with that of [Ir(ppy) 2 (5-R-1,10-phen)][PF 6 ] (ppy = cyclometallated 2-phenylpyridine), characterized by one of the highest second order NLO response ever reported for a metal complex. Substitution of ppy with the more π-delocalized pq does not affect significantly the luminescence and NLO properties. A slightly lower NLO response and a much poorer luminescence is observed for the related complexes with ttpy. In these complexes, DFT/TDDFT calculations show that the presence of ttpy induces a significant downshift of the HOMO energy, compared to ppy and pq. The NLO response is dominated by intense MLCT excited states, which are also assigned as originating the emission.