Mono-molecular isomerization processes of aluminium tris (8-hydroxy-quinolinate) (Alq3): a DFT study of gas-phase reaction paths

Density Functional Theory has been applied to investigate isomerization processes of aluminum tris(8-hydroxyquinolinate) (Alq3). Both mer–fac isomerization and mer-Alq3 chirality inversion have been reported. This represents an attempt to describe phenomena which could take place during Alq3 amorphous-films deposition or during solid-state changes of phase. Furthermore, it represents the opportunity to apply modern theoretical methodologies to shed light on the general problem of isomerizations in tris–chelate complexes which were widely studied experimentally and by approximate theoretical methods in the seventies and in part of the eighties

New Investigations of Geometric, Electronic, and Spectroscopic Properties of Tetrapyrrolic Macrocycles by a TD-DFT Approach. Carbon, Nitrogen, and Chalcogen (O, S, Se) Peripheral Substitution Effects on Ni(II) Porphyrazinato Complexes

The electronic structure of five complexes [M(oXHpz)] [M = Ni2+; oXHpz2- = 2,3,7,8,12,13,17,18-octakis-substituted (X = CH2, NH, O, S, Se)-5,10,15,20-tetraazaporphyrinate dianion] has been investigated using a d. functional approach. All the geometries have been obtained minimizing the total intramol. energy using a nonlocal hybrid functional (B3LYP) at the 6-31g* level. The electronic configuration of Ni2+ is (dx2-y2)0(dxy)2(dxz,dyz)4(dz2)2. Optimized geometries exhibit a planar conformation and are all above the threshold for ruffling, which is described by a Ni-Np bond distance of 1.85-1.87 Å for sterically unhindered porphyrazines. Indeed, the smallest bond distance is 1.880 Å for Ni(oOHpz). Peripheral substituents yield modifications to the "core" of the macrocycle and to the energy levels, changing σ and π interactions. Furthermore, within a time-dependent d. functional theory approach, excited states of Ni(oXHpz) [X = CH2, NH, O, S, Se,] complexes have been studied and compared with available exptl. UV-vis spectra. [on SciFinder(R)

Relativistic Effects on Bonding in CuIn, AgIn, AuIn

A theoretical investigation, based on density functional theory and on a relativistic first-order perturbation method, has been carried out on the intermetallic diatomic molecules CuIn, AgIn, AuIn. The electronic structure, studied at nonrelativistic level, indicates the presence of a single bond mainly brought about by the metal (n+1)s-In 5pσ interaction occurring in the sigma HOMO orbital. The influence of the relativistic effects seems to be very remarkable for AuIn, although not negligible for AgIn and accounts for the experimental dissociation-energy trend along the triad

Synthesis and physico-chemical properties of the bis(2,3,7,8,12,13,17,18-octakis-(octhylthio)-5,10,15,20-tetraazaporphyrinato)lutetium(III) complex

The synthesis and the physico-chemical properties of the bis(2,3,7,8,12,13,17,18-octakis-(octhylthio)-5,10,15,20-tetraazaporphyrinato)lutetium(III) double-decker complex, Lu(OOTTAP)2, are described, ESR, 1H and 13C NMR, UV-visible and NIR studies show that radical nature of this compound and suggest that the unpaired electron cannot be assigned to a specific tetra-azaporphyrinic ring on the time scales available. Some relevant UV-visible spectroscopic and redox features of Lu(OOTTAP)2 resemble closely those of diphthalocyanine complexes, while the intensity and vibrational structure of the NIR spectra are rather reminiscent of those of bis-porphyrin systems