9,11-DIcis-12-FLUORORHODOPSIN. CHROMOPHORE PROPERTIES FROM 19F-NMR STUDIES

From a 19F-NMR study of 9,11-dicis-12-fluororhodopsin and its photobleached product, we concluded that the initially formed chromophore retained its configuration and the photoproduct corresponded to the two-bond isomerized all-trans. Upon standing, it slowly isomerized to the 9-cis isomer. The method represents a direct, non-destructive procedure for determining configuration purity of the pigment formed. Its unique fluorine opsin shift value is consistent with the expected different orientation of the fluoro-substituent in a dicis pigment.     

Ruthenium(II) Photosensitizers of Tridentate Click‐Derived Cyclometalating Ligands: A Joint Experimental and Computational Study

A systematic series of heteroleptic bis(tridentate)ruthenium(II) complexes of click‐derived 1,3‐bis(1,2,3‐triazol‐4‐yl)benzene N^C^N‐coordinating ligands was synthesized, analyzed by single crystal X‐ray diffraction, investigated photophysically and electrochemically, and studied by computational methods. The presented comprehensive characterization allows a more detailed understanding of the radiationless deactivation mechanisms. Furthermore, we provide a fully optimized synthesis and systematic variations towards redox‐matched, broadly and intensely absorbing, cyclometalated ruthenium(II) complexes. Most of them show a weak room‐temperature emission and a prolonged excited‐state lifetime. They display a broad absorption up to 700 nm and high molar extinction coefficients up to 20 000 M ^?1 cm^?1 of the metal‐to‐ligand charge transfer bands, resulting in a black color. Thus, the complexes reveal great potential for dye‐sensitized solar‐cell applications.     

Understanding phenol adsorption mechanisms on activated carbons

The interactions between phenol molecules and activated carbons were investigated in order to understand the adsorption mechanism of this aromatic compound. A series of activated carbons with varied chemical composition but similar porous features were synthesized and submitted to phenol exposure from aqueous phase, followed by thermogravimetric analysis and identification of the desorbed species by temperature programmed desorption coupled with mass spectrometry. Based on these experiments, both physi- and chemisorption sites for phenol were identified on the activated carbons. Our results demonstrate that physisorption of phenol depends strictly on the porosity of the activated carbons, whereas chemisorption depends on the availability of the basal planes in the activated carbons. Thus, oxidation of the carbon can suppress the fraction of chemisorbed phenol since the surface functionalities incorporate to the edges of the basal planes; notwithstanding, hydrophilic carbons may present a small but not negligible contribution of chemisorbed phenol depending on the extent of the functionalization. Moreover, these adsorption sites (chemi-) are recovered by simply removal of the surface functionalities after thermal annealing.     

Effective temperature in driven vortex lattices with random pinning

We study numerically correlation and response functions in nonequilibrium driven vortex lattices with random pinning. From a generalized fluctuation-dissipation relation, we calculate an effective transverse temperature in the fluid moving phase. We find that the effective temperature decreases with increasing driving force and becomes equal to the equilibrium melting temperature when the dynamic transverse freezing occurs. We also discuss how the effective temperature can be measured experimentally from a generalized Kubo formula.     

Molecular multivalent electrolytes: microstructure and screening lengths

We study small rod-like molecular electrolytes solutions with their corresponding atomic counterions. The asymptotic length scales (decay length and wavelength) of the structural correlations are analyzed using the formalism of the dressed interaction site theory (DIST). The correlation functions are determined using the reference interaction site model equation complemented with a mixed approach in which the hypernetted-chain closure is used for the repulsive interactions, and the mean spherical approximation is used for the attractive interactions. The results from this scheme are in good agreement with the Monte Carlo computer simulations reported here. The asymptotic properties of the correlation functions of this molecular system are compared against those corresponding to two related simple (atomic) electrolyte models. The main conclusion is that the molecular structure of the ions lowers by two orders of magnitude the concentration at which the transition from monotonic to oscillatory decay occurs.     

Domain growth in ternary fluids: A level set approach

We analyze phase separation in ternary systems in the asymptotic hydrodynamic regime when the volume fractions and concentrations are constant. The multiphase Navier-Stokes equations are solved using a level set method. A new projection method was developed to treat multiple junctions for systems with more than two phases. It is found that surface tension ratios can alter the growth mechanism of a minority phase in the presence of two majority phases. When the minority phase wets the interface of the majority phases the domain growth rate of all three phases is initially similar to that of a symmetric binary fluid but slows down at later times.     

Stark control of a chiral fluoroethylene derivative

Hydrogen dissociation is an unwanted competing pathway if a torsional motion around the C═C double bond in a chiral fluoroethylene derivative, namely (4-methylcyclohexylidene) fluoromethane (4MCF), is to be achieved. We show that the excited state H-dissociation can be drastically diminished on time scales long enough to initiate a torsion around the C═C double bond using the nonresonant dynamic Stark effect. Potential energy curves, dipoles, and polarizabilities for the regarded one-dimensional reaction coordinate are calculated within the CASSCF method. The influence of the excitation and the laser control field is then simulated using wave packet dynamics.