: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

The potential of palladacycles: more than just precatalysts

Light-Emitting Self-Assembled Materials Based on d(8) and d(10) Transition Metal Complexes.

Fluorescent detection of zinc in biological systems: recent development on the design of chemosensors and biosensors

Physical vapor deposition under conditions of obliquely incident flux and limited adatom diffusion results in a film with a columnar microstructure. These columns will be oriented toward the vapor source and substrate rotation can be used to sculpt the columns into various morphologies. This is the basis for glancing angle deposition (GLAD), a technique for fabricating porous thin films with engineered structures. The origin of the columnar structure characteristic of GLAD films is discussed in terms of nucleation processes and structure zone models. As deposition continues, the columnar structures are influenced by atomic-scale ballistic shadowing and surface diffusion. Competitive growth is observed where the tallest columns grow at the expense of smaller features. The column shape evolves during growth, and power-law scaling behavior is observed as shown in both experimental results and theoretical simulations. Due to the porous nature of the films and the increased surface area, a variety of chemical applications and sensor device architectures are possible. Because the GLAD process provides precise nanoscale control over the film structure, characteristics such as the mechanical, magnetic, and optical properties of the deposited film may be engineered for various applications. Depositing onto prepatterned substrates forces the columns to adopt a planar ordering, an important requirement for photonic crystal applications.

Glancing angle deposition: Fabrication, properties, and applications of micro- and nanostructured thin films

Azobenzenes and heteroaromatic nitrogen cyclopalladated complexes for advanced applications

Cyclometallated chloridoplatinum complexes containing neutral monodentate ligands such as 2-phenylpyridine (1a), 2-(2′-thienyl)pyridine (1c) or 4-methoxypyridine (1d), as well as the cyclometallated benzo[h]quinoline chlorido complex with 4-methoxypyridine (2d), can be synthesised in a few minutes by irradiating the reaction mixture with microwaves. The single-crystal X-ray molecular structures of the solvato complexes 1·dmso and 2·dmso as well as 1c, 1d and 2d are reported. The availability of this class of complexes in a few minutes offers the possibility of a combinatorial approach for the preparation of libraries of homologous compounds of potential interest for applicative purposes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Efficient, Ultrafast, Microwave-Assisted Syntheses of Cycloplatinated Complexes

Synthesis and photophysical characterisation of soluble photoluminescent metal complexes with substituted 8-hydroxyquinolines

A series of tetradentate dimeric salicylaldimine ligands (H2LnRm) with terminal chains of variable length (Rm) and a central flexible (CH2)n spacer (Ln = 10 and 12) was synthesized. For all ligands, according to their rod-like molecular shape, mesomorphism characteristic of calamitic systems (nematic and smectic C phases) is observed. The reaction with ZnII acetate dihydrate afforded a series of ZnLnRm derivatives (1–6) that show mesomorphic behaviour only in the presence of the longest terminal tails (R12). Interestingly, the flexibility of the very long spacer in the central core and the presence of the tetrahedral ZnII centre introduce nonlinearity in the central part of the molecule, responsible for the appearance of an intercalated smectic C mesophase. Moreover, the coordination of the ZnII ion to the salen-like framework induces, in all the corresponding complexes, interesting blue-light-emitting properties at room temperature in dichloromethane solution (EQY in the 19–22 % range at about 450 nm), as well as in the solid (EQY: 9 % at about 450 nm) or, when present, in the mesophase (EQY 8 % at 440 nm).(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Coordination Induction of Nonlinear Molecular Shape in Mesomorphic and Luminescent ZnII Complexes Based on Salen-Like Frameworks

The series of dinuclear 4,4′-bis(hexyloxy)azobenzene, [H(Azo-6)], cyclopalladated complexes of general formula [Azo-6)Pd(µ-X)]2, (X = Cl, Br, I, N3, SCN, OAc) and [Azo-6)2Pd2(µ-Ox)] (Ox = oxalate) have been synthesized and investigated for mesomorphism and spectroscopic properties. Single-crystal X-ray analysis of the dinuclear bromo- and iodo-bridged complexes has been performed. The structural data, compared with those of the known homologous chloro compound, show that all the [Azo-6)Pd(µ-X)]2)] (X = Cl, Br, I) molecules crystallize in the monoclinic space group P21/c and are isomorphous. They are arranged in slipped pairs with intermolecular non-bonding Pd–Pd contacts ranging from 3.668(1) A(X = Cl) to 3.758(3) A(X = I). The different nature of the bridging group allows variation of the distance between the palladium atoms and the bond environment experienced by the metal centers. Thus, this comparative study reveals that the effectiveness of the bridging group in promoting thermotropic mesophases is greater for chloride, bromide, azide or oxalate than for iodide, thiocyanate or acetate. The greatest range of liquid-crystal behavior was displayed by [Azo−6)2Pd2(µ−Ox)]. Remarkably, this compound is the first example of a metallomesogen containing the bridging oxalate group.



The bimetallic complexes exhibit different absorption spectra (i.e. colors) depending, in general terms, on the nature of the bridge connecting the two cyclometalated [H(Azo-6)] moieties, which can be varied so as to tune the optical properties. Blocking the azo group in the trans position results in several cases in weakly luminescent complexes, with luminescence efficiencies ϕ ≈10−4 and luminescence lifetimes of the order of nanoseconds.



Using the data obtained from the 4,4′-bis(hexyloxy)azoxybenzene [H(Azoxy-6)] derivative, [Azoxy-6)Pd(µ -Cl)]2, from the mononuclear acetylacetonate (acac) complexes [(Azo-6)Pd(acac)] and [(Azoxy-6)Pd(acac)], and from the uncomplexed [H(Azo-6)] and [H(Azoxy-6)] ligands, the nature of the excited states relevant to the photophysical behavior are discussed. Copyright © 1999 John Wiley & Sons, Ltd.

Iolinda Aiello

Papers

Azobenzenes and heteroaromatic nitrogen cyclopalladated complexes for advanced applications

Efficient, Ultrafast, Microwave-Assisted Syntheses of Cycloplatinated Complexes

Synthesis and photophysical characterisation of soluble photoluminescent metal complexes with substituted 8-hydroxyquinolines

Coordination Induction of Nonlinear Molecular Shape in Mesomorphic and Luminescent ZnII Complexes Based on Salen-Like Frameworks

Dinuclear cyclopalladated azobenzene complexes : a comparative study on model compounds for organometallic liquid-crystalline materials