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Theoretical calculations are proving as an essential tool to understand luminescence processes even for systems including lanthanide (Ln3+) ions. As such, the aim of this study is that of presenting a general and comprehensive theoretical protocol based on DFT calculations to rationalize and possibly drive the design of new luminescent Ln3+ complexes through the ab initio determination of the electronic properties of a ligand and two Eu3+ complexes. Different theoretical methodologies have been combined to look into the excited state energies, the luminescence quantum yield, and the energy transfer processes. The protocol has been validated for a β-diketone ligand and two Eu3+ complexes, which contain, in addition to the main ligand, ethanol or triphenylphosphine oxide. Moreover, by starting from the geometry optimization up to the estimation of the ligands’ singlet and triplet lowest energy states, theoretical results quantitatively agree with luminescence experimental parameters, providing at the same time insights into the different energy transfer processes. The different quantum yields of the two complexes have been correctly reproduced.

The relative stability oftrans-[(η5-C5H5)Fe(η1-CO)(μ-CO)]2(trans-I) andcis-Itautomers in a vacuum and in solvents with different dielectric constants (ε) has been investigated by exploiting density functional theory (DFT). Theoretical results indicate that, in agreement with experimental evidence,trans-Iis more stable thancis-Iin a vacuum (∼1.5 kcal mol−1;ε= 1), while the opposite is true in media withε> 7. Differently from solution, DFT outcomes pertaining to the vapor-phasecis-I⇆trans-Iequilibrium at T = 368 K, the temperature at which the Fe L2,3-edges and the C and O K-edge X-ray absorption spectroscopy (XAS) data ofIhave been recorded, ultimately indicate thetrans-Ipredominance (∼93%). Compositions, oscillator strengths (f) and excitation energy (EE) values ofcis-Itransitions substantially mirror those oftrans-I; nevertheless, the weightedcis-If(EE) distributions negligibly contribute to the diverse simulated XA spectra ofI.

The unoccupied electronic structures of three closed-shell, highly popular organoiron complexes ([Fe(CO)5], [(η5-C5H5)Fe(CO)(μ-CO)]2, and [(η5-C5H5)2Fe]; 0, I, and II, respectively) have been investigated both experimentally and theoretically by combining original gas-phase X-ray absorption spectroscopy (XAS) outcomes recorded at the C and O K-edge with results of scalar relativistic time-dependent density functional calculations carried out within the zeroth order regular approximation. Experimental evidence herein discussed complement the Fe L2,3-edges XAS ones we recently recorded, modeled, and assigned for the same complexes (Carlotto et al. Inorg. Chem. 2019, 58, 5844). The first-principle simulation of the C and O K-edge features allowed us to univocally identify the electronic states associated to the ligand-to-metal charge transfer (LMCT) transitions both in I and in II. At variance to that, LMCT transitions with sizable oscillator strengths do not play any role in determining neither the C nor the O K-edge spectral pattern of 0. The higher IC-acceptor capability of the CO ligand, regardless of its terminal or bridging coordination, with respect to [(η5-C5H5)]- is herein ultimately confirmed.

For a series of organonitrile [RCN (R = Me, CF3, Ph, CH3Ph, CF3Ph)] ligands, the nature of the N-Pt bond in the related cis-/trans-(RCN)2PtCl2 complexes has been computationally investigated by Density Functional Theory. A fragment based bond analysis has been performed in the canonical Kohn-Sham molecular orbitals framework, and it has been ultimately assessed that this bond is characterized both by N→Pt σ and by N←Pt π contributions. Voronoi Deformation Density charges further confirms the occurrence of N←Pt π interactions. Moreover, the Energy Decomposition Analysis-Natural Orbital for Chemical Valence (EDA-NOCV) method shows that the strength of the N←Pt π interaction is not negligible by contributing to about 30-40% of the total orbital interaction. Finally, the well-known νCN blue-shift occurring upon coordination to PtII, has been thoroughly investigated by exploiting the EDA-NOCV and by evaluating νCN and force constants. The origin of the νCN blue-shift in these systems has been discussed on the basis of the CN bond polarization. N←Pt π backbonding causes only a systematic decrease of the observed νCN blue-shift when compared to the one calculated for RCN-X (X = H+, alkaline, Lewis acids) herein reported (X = purely σ acceptors).

The occupied and unoccupied electronic structures of three highly popular, closed shell organoiron complexes ([Fe(CO)(5)], [(eta(5)-C5H5 )Fe(CO)(mu-CO)](2), and [(eta(5)-C5H5)(2)Fe]) have been theoretically investigated by taking advantage of density functional theory (DFT) calculations coupled to the isolobal analogy (Elian et al. Inorg. Chem. 1976, 15, 1148). The adopted approach allowed us to look into the relative role played by the ligand -> Fe donation and the Fe -> ligand back-donation in title molecules, as well as to investigate how CO- (terminal or bridging) and [(eta(5)-C5H5)](-)-based pi* orbitals compete when these two ligands are simultaneously present as in [(eta(5)-C5H5)Fe(CO)(mu-CO)](2). Insights into the nature and the strength of the bonding between Fe and the C donor atoms have been gained by exploiting the Nalewajski-Mrozek bond multiplicity index (Nalewajski et al. Int. J. Quantum Chem. 1994, 51, 187), which have been found especially sensitive even to tiny bond distance variations. The bonding picture emerging from ground state DFT results proved fruitful to guide the assignment of original, high-resolution, gas-phase L-2,L-3-edges X-ray absorption spectra of the title molecules, which have been modeled by the two-component relativistic time-dependent DFT including spin orbit coupling and correlation effects and taking advantage of the full use of symmetry. Assignments alternative to those reported in the literature for both [Fe(CO)(5)] and [(eta(5)-C5H5)(2)Fe] are herein proposed. Despite the high popularity of the investigated molecules, the complementary use of symmetry, orbital, and spectroscopy allowed us to further look into the metal-ligand symmetry-restricted-covalency and the differential-orbital covalency, which characterize them.

The unoccupied electronic structures of three closed-shell, highly popular organoiron complexes ([Fe(CO)(5)], [(eta(5)-C5H5)Fe(CO)(mu-CO)](2), and [(eta(5)-C5H5)(2)Fe]; 0, I, and II, respectively) have been investigated both experimentally and theoretically by combining original gas-phase X-ray absorption spectroscopy (XAS) outcomes recorded at the C and O K-edge with results of scalar relativistic time-dependent density functional calculations carried out within the zeroth order regular approximation. Experimental evidence herein discussed complement the Fe L-2,L-3-edges XAS ones we recently recorded, modeled, and assigned for the same complexes (Carlotto et al. Inorg. Chem. 2019, 58, 5844). The first-principle simulation of the C and O K-edge features allowed us to univocally identify the electronic states associated to the ligand-to-metal charge transfer (LMCT) transitions both in I and in II. At variance to that, LMCT transitions with sizable oscillator strengths do not play any role in determining neither the C nor the O K-edge spectral pattern of 0. The higher pi-acceptor capability of the CO ligand, regardless of its terminal or bridging coordination, with respect to [(eta(5)-C5H5)](-) is herein ultimately confirmed.

Surface modification with functional films is a popular way to improve the properties of inorganic particles for a number of applications. A well-known case is that of dye-sensitized cells, where absorption of the polar spectrum in the visible and near-infrared region of metal oxides such as TiO2 or ZnO is enhanced by films of metal complexes with suitable HOMO-LUMO gaps. It is generally assumed that in these hererostructures the supporting metal oxide is chemically innocent, and that molecules are adsorbed - chemically or physically - unchanged. In contrast to this picture, we show that, starting from room temperature, TiO2 actively interacts with adsorbed porphyrins, exchanging atoms, and giving rise to self-hydrogenations, selfmetalations, and dehydrogenations reactions, which ultimately bring to the synthesis of films of exceptionally high thermal stability (up to to 450 degrees C), potentially useful for sensors and photocatalysis applications in harsh environments. Furthermore, our findings indicate that metal exchange with the very reactive Ti atoms must be taken into account when designing porphyrinsensitized solar cells, because the critical temperature for the onset of self-metalation is very close to the normal operating temperature of photovoltaic devices.

The main object of this study is the treatment of polymeric (PVC, PC) surfaces with the aim of inducing enhanced superhydrophilic characteristics together with nanohardness features; this would allow polymeric surfaces to have longer durability and prevent the accumulation of dirt on the surface which could disable the proper use of these polymeric surfaces. Indeed plastic surfaces are difficult substrates to be covered effectively and functionalized, mainly due to their high sensitivity to heat treatments and irradiation in the UV-Vis range together with their inert behavior. Their functionalization is achieved through the deposition of ceramic coatings such as titania (TiO2), on the polymeric surfaces via PECVD (Plasma Enhanced Chemical Vapor Deposition) at low temperatures. Characterizations are carried out by contact angle analysis for the superhydrophilic characteristics, and by nanoindentation analysis for the tribological features. A cold PECVD discontinuous method allowed us to improve nanohardness, reaching a value of 1.39 GPa which is nearly ten times higher than that of the uncoated polymeric substrate, and seems a promising solution for improving uniformity of the coatings. Superhydrophilic behavior of the activated TiO2 surfaces showed contact angle values lower than 10 degrees.

The main object of this study is the treatment of polymeric (PVC, PC) surfaces with the aim of inducing enhanced superhydrophilic characteristics together with nanohardness features; this would allow polymeric surfaces to have longer durability and prevent the accumulation of dirt on the surface which could disable the proper use of these polymeric surfaces. Indeed plastic surfaces are difficult substrates to be covered effectively and functionalized, mainly due to their high sensitivity to heat treatments and irradiation in the UV-Vis range together with their inert behavior. Their functionalization is achieved through the deposition of ceramic coatings such as titania (TiO(2)), on the polymeric surfaces via PECVD (Plasma Enhanced Chemical Vapor Deposition) at low temperatures. Characterizations are carried out by contact angle analysis for the superhydrophilic characteristics, and by nanoindentation analysis for the tribological features. A cold PECVD discontinuous method allowed us to improve nanohardness, reaching a value of 1.39 GPa which is nearly ten times higher than that of the uncoated polymeric substrate, and seems a promising solution for improving uniformity of the coatings. Superhydrophilic behavior of the activated TiO(2) surfaces showed contact angle values lower than 10 degrees.

Zirconium dioxide is one of the most studied ceramic materials under various forms (film, powder, bulk, etc.). Pure ZrO2 is monoclinic at room temperature and it undergoes phase transitions to the tetragonal and cubic structures above 1170 and 2370 °C, respectively. The introduction of MgO, CaO, Sc2O3, Y2O3 and other aliovalent oxides1 in the ZrO2 structure allows the ZrO2 stabilization in the cubic fluorite structure from room temperature to its melting point (2680 °C), thus enabling the production of materials for high temperature applications.2,3 At the same time, the doping of ZrO2 increases oxygen ion vacancies with a significant rise of the ZrO2 ionic conductivity. In fact, stabilized ZrO2 is used in oxygen sensors and in Solid Oxide Fuel Cells (SOFC) as electrolyte and anode support. Herein we report the results of two processes to obtain thin film of nanostructured stabilized ZrO2: the former corresponds to a MOCVD deposition of ZrO2 stabilized with aliovalent metal oxides such as CaO, MgO, Y2O3, Sc2O3, and to be used as SOFC electrolyte; the latter consists of an Aerosol-CVD process to produce porous films of stabilized ZrO2 and Ni/c-ZrO2 for SOFC anode applications.

In the field of stone conservation, consolidation is of paramount relevance and the most critical tasks required are durability and compatibility of the products to be applied with the original substrates. Due to the lack of conservation efficiency of a great variety of commercial polymers employed as stone preservatives, a novel approach for limestone consolidation has been pursued with the aim to identify suitable products for a compatible and durable treatment. Linear and branched calcium metallorganic compounds have been designed, synthesized and their potential as stone consolidants evaluated. They have been applied either on glassy substrate and on deteriorated marble specimens to study respectively the kinetic pathways leading to calcium carbonate and the induced variation of marble cohesion. Preliminary tests have been performed on calcium alkoxides and other inorganic products, i.e. ethyl silicate (TEOS), solution of Ba(OH)2, (NH4)2CO3 and alcoholic suspension of Ca(OH)2, to compare the consolidant efficiency. Physico-chemical measurements (?-FT-IR. FEG-ESEM-EDS, XRD) have been used to study the mechanism of CaCO3 formation, while stone cohesion was evaluated by ultrasonic velocity tests. The strengthening effects of Ca(OCH3)2 turned out to be comparable to traditional inorganic consolidants. Furthermore, calcium alkoxides are effective even in very low concentration as the impregnation occurs without pore saturation, thus ensuring the vapour permeability of the treated stone without the detrimental effects of coating cracking , as observed when TEOS is employed, or pore sealing produced by several organic polymers.

Cobalt aluminate (CoAl2O4) for its thermal, chemical and photochemical stability as well as for its optical properties, is widely used as pigment (the well known Thenard's Blue), coating, catalyst and in optical devices as color filter and pigment layer on luminescent materials.