Electronic circular dichroism and circularly polarized luminescence acid/base switching activity has been demonstrated in helicene-bipyridine proligand 1 a and in its "rollover" cycloplatinated derivative 2 a. Whereas proligand 1 a displays a strong bathochromic shift (>160 nm) of the nonpolarized and circularly polarized luminescence upon protonation, complex 2 a displays slightly stronger emi...

Phenyleneethynylene-based conjugated copolymers using benzo[1,2-d:4,5-d']bis[1,3]dioxole (BDO) in the repeating unit are reported. The electronic structure of the BDO unit imparts a localized HOMO topology while the LUMO is delocalized over the polymer backbone, so that the lowest optical absorption band of the polymer has considerable intramolecular charge transfer character. This contrasts wi...

C59-X (X= C, N, P, As and Sb) was studied by Density Functional Theory DFT at the B3LYP/3-21G** level. Group V elements have been selected to be substituted in the fullerene-C60 cage in order to show the effect of such substations upon structural and electronic properties of the studied molecules. It is found that elements of Group V doped C60 have an electronic structure similar to those of n-...

The current-voltage and the conductance-voltage characteristics are analyzed for a particular type of molecular wire embedded between two electrodes. The wire is characterized by internal molecular units where the lowest occupied molecular orbital (LUMO) levels are positioned much above the Fermi energy of the electrodes, as well as above the LUMO levels of the terminal wire units. The latter a...

The synthesis and characterization of 1, 3-bis [(furan-2-yl) methylene] urea (BFMU) and 1, 3-bis [furan-2-yl) methylene] thiourea (BFMT) have been reported by our research team. The effects of solvents polarity on their electronic transition energies (HOMO-LUMO) and associated qualitative structure activity relationship parameters (i.e. log P, ionization energies and global hardness) were inves...

In this communication we provide the first UHV-STM images and STM-based current-voltage (I-V) and orbital mediated tunneling spectroscopy (OMTS) data on a self-assembled porphyrin nanostructure at the single structure level. We will show that transverse conductivity over distances less than 10 nm can occur by barrier type tunneling but that long distance conduction solely occurs through the LUM...

We study Ge2O2 and Ge2O2 2 with density functional theory ~DFT! and photoelectron spectroscopy ~PES!. We find that Ge2O2 is a rhombus ~D2h), closed-shell molecule with a large HOMO-LUMO gap. The PES spectrum of Ge2O2 2 is obtained at four detachment photon energies: 1064, 532, 355, and 266 nm. Vibrational structure is resolved at the lowest photon energy with a single progression and a frequenc...

A dodecazinc silicotungstate K(20)Na(2)[Zn(6)(OH)(7)(H(2)O)(Si(2)W(18)O(66))](2)·34H(2)O (1) has been synthesized and characterized by X-ray crystallography, elemental analysis, infrared, UV-vis spectroscopy, cyclic voltammetry, acid-base titration, and DFT calculations. The twelve zinc atoms between the two [Si(2)W(18)O(66)](16-) frameworks make this complex more stable hydrolytically than the...

The efficiency of dye-sensitized solar cells (DSCs) depends critically on the electronic structure of the interfaces in the active region. We employ recently developed dispersion-inclusive density functional theory (DFT) and GW methods to study the electronic structure of TiO2 clusters sensitized with catechol molecules. We show that the energy level alignment at the dye-TiO2 interface is the r...

A detailed study of energy differences between the highest occupied and lowest unoccupied molecular orbitals (HOMO-LUMO gaps) in protein systems and water clusters is presented. Recent work questioning the applicability of Kohn-Sham density-functional theory to proteins and large water clusters (Rudberg 2012 J. Phys.: Condens. Matter 24 072202) has demonstrated vanishing HOMO-LUMO gaps for thes...