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The nitrogen isotropic hyperfine coupling constant (hcc) and the g tensor of a phototypical spin probe (dl-tert-butyl nitroxide, DTBN) in aqueous solution was investigated by means of an integrated computational approach including Car-Parinello molecular dynamics and quantum mechanical calculations involving a discrete-continuum embedding. The quantitative agreement between computed and experimental parameters fully validates the integrated approach.

The electronic, structural and spectroscopic properties of the [Ru(4,4'-COOH-2,2'-bpy)(sub 2)(NCS)(sub 2)] complex (N3) in vacuo and in ethanol and water solvents are investigated by means of combined Time dependent density functional theory (DFT/TD-DFT) calculations. DFT/TD-DFT calculations are capable of accurately describing the spectral features and solvatochromism of the N3 sensitizer.

A first-principles study of the active site with regard to glutahtione transferase is presented.

The second-order nonlinear optical (NLO) properties of [Ln[(hfac).sub.3](diglyme)] (hfac = hexafluoroacetylacetonate, diglyme = bis(2-methoxyethyl)ether, Ln = La, Ce, Pr, Sm, Eu, Gd, Er, Lu) complexes are examined for providing evidence for the relevant role of f electrons in tuning the second-order NLO response dominated by the octupolar contribution. The lanthanide NLO chromophores have allowed a clean valuation of the affect of f electrons on the quadratic hyperpolarizability and on its dipolar and octupolar contributions.

Novel unsymmetrical organic sensitizers comprising donor, electron-conducting, and anchoring groups are engineered at a molecular level and are prepared for sensitization of mesoscopic titanium dioxide injection solar cells. The photovoltaic performance of D5, D7, D9 and D11 sensitizers in liquid- and solid-state-based electrolytes is examined.

The article discusses the importance of the protonation of the sensitizer on the excited states of the Ru(II)-sensitized Ti[O.sub.2] nanoparticles. The protonation is found to highly affect the Ti[O.sub.2] positioning in these particles.

The synthesis, electronic and photovoltaic properties of the squaraine sensitizer are described. It is shown that creating directionality and inhibiting self-quenching of the excited state of the sensitizer is the key for unprecedented efficiency of squaraines.

A detailed characterization of the electronic structure and absorption spectrum of the prototypical [Fe(CN)(sub 6)](super 4-)/TiO2 system is provided based on density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. It is shown that a direct charge injection process from an occupied dye molecular state to a nanoparticle excited state localized on few Ti atoms takes place in the system.

We present a first-principle computational modeling investigation, based on density functional theory (DFT) and time-dependent DFT, on the structural, electronic, optical, and charge generation properties of the semiconductor/dye/catalyst heterointerfaces in a prototypical dye-sensitized photoanode for water oxidation. The investigated architecture comprises a Ru(ll) dye-sensitized TiO2 substrate tethered to an IrO2 nanoparticle catalyst. Our realistic modeling strategy and quantitative analysis of the relevant interfacial hole/electron transfer reactions indicates the slow hole injection into IrO2 and the fast dye excited-state quenching to IrO2 as the primary sources of the relatively poor cell efficiency experimentally observed. On the basis of this atomistic and electronic structure information, we propose and computationally test, against a prototype dye, a new class of Ru(II) sensitizers, which show potentially improved photoelectrochemical performances. This study constitutes a first step toward the computer-assisted design of new and more efficient materials for solar fuels production through dye-sensitized photoelectrochemical cells. [ABSTRACT FROM AUTHOR]

The article cites a study related to the photophysical properties of [Ru(phen)2(dppz)]2+ intercalated into DNA. The unique photophysical properties of the DNA-intercalating [Ru(phen)2(dppz)]2+ complex, 1, have attracted considerable interest over the last 15 years, due to the so-called "light-switch" effect. This complex does not luminescence in water, but the emission is switched on by interaction with DNA. Moreover, the absorption spectrum of the free complex in solution shows well characterized metal-to-ligand charge transfer bands, which are perturbed upon binding to DNA. Therefore, complex 1 represents a sensitive spectroscopic probe for DNA.

The article presents information on the time-dependent DFT study of [Fe(CN)6]4 sensitization of TiO2 nanoparticles. A key process in the operation of dye-sensitized photovoltaic solar cell devices is the charge injection from the dye molecule at the surface of the semiconductor nanoparticle to the conduction band states within the nanoparticle itself. On the basis of DFT and TDDFT calculations we have provided a detailed characterization of the electronic structure and absorption spectrum of the prototypical [Fe(CN)6]4ff 102 system.

Novel organic sensitizers comprising donor, electron-conducting, and anchoring groups were engineered at molecular level and synthesized. The functionalized unsymmetrical organic sensitizers 3-{5-[N,N-bis(9,9-dimethylfluorene-2-yl)phenyl]-thiophene-2-yl}-2-cyano-acrylic acid (JK-1) and 3-{5′-[N,N-bis-(9,9-dimethylfluorene-2-yl)phenyl]-2,2′-bisthiophene-5-yl}-2-cyano-acrylic acid (JK-2), upon anchoring onto TiO2 film, exhibit unprecedented incident photon to current conversion efficiency of 91%. The photovoltaic data using an electrolyte having composition of 0.6 M M-methyl-N-butyl imidiazolium iodide, 0.04 M iodine, 0.025 M Lil, 0.05 M guanidinium thiocyanate, and 0.28 M tert-butylpyridine in a 15/85 (v/v) mixture of valeronitrile and acetonitrile revealed a short circuit photocurrent density of 14.0 ± 0.2 mA/cm², an open circuit voltage of 753 ± 10 mV, and a fill factor of 0.76 ± 0.02, corresponding to an overall conversion efficiency of 8.01% under standard AM 1.5 sunlight. DFT/TDDFT calculations have been performed on the two organic sensitizers to gain insight into their structural, electronic, and optical properties. Our results show that the cyanoacrylic acid groups are essentially coplanar with respect to the thiophene units, reflecting the strong conjugation across the thiophene-cyanoacrylic groups. Molecular orbitals analysis confirmed the experimental assignment of redox potentials, while TDDFT calculations allowed assignment of the visible absorption bands. [ABSTRACT FROM AUTHOR]

The article presents the study regarding the function of squaraine sensitizer. The synthesis, electronic and photovoltaic properties of the squaraine sensitizer had been determined using synthetic strategy which yielded with very high incident monochromatic photon-to-current conversion. Making directionality and inhibiting self-quenching of the sensitizer are the key for unprecedented efficiency of squaraines.

Combined Car-Parrinello and time-dependent DFT calculations performed on [Ru(phen)2dppz]2+ intercalated into an adenine-thymine tetramer reveal a remarkable influence of the base pairs in determining the electronic structure and the character of the excited states involved in the absorption and emission processes.

We report a combined experimental and computational study of polynuclear [Ru(n)(TPPZ)(n)(+1)](2)(n)(+) complexes, of interest in the field of photoactive polymers. The complexes with n = 1, 2, 3 and n > 5 have been synthesized and spectroscopically characterized. A red-shift of the visible band maximum from 2.59 to 2.03 eV is observed going from the monomer to the longer oligomeric species (n > 5). To characterize the geometries, electronic structure, and excited states of these complexes, density functional theory (DFT) and time-dependent DFT calculations on the [Ru(n)(TPPZ)(n)(+1)](2)(n)(+) series with n = 1-4 in solution have been performed. The agreement between experimental and calculated spectra is good, both in terms of absorption maximum energies and relative intensities for different values of n. For all the investigated complexes, we assign the main band in the visible region as a metal-to-metal plus ligand charge transfer (MMLCT) transition. The resulting excited states are delocalized throughout the entire complexes, as they originate from a superposition of pi(TPPZ)-t(2g)(Ru) states. The low-energy shoulder of the main visible absorption band, present in the experimental spectra for n > 1, is proposed to arise from spin-forbidden singlet-triplet transitions of similar MMLCT character, consistent with the observed enhancement of this feature in the spectra of the corresponding Os oligomers.