Scientific Program

Conference Series Ltd invites all the participants across the globe to attend 4th International Conference on Physical and Theoretical Chemistry Dublin, Ireland.

Day 1 :

Conference Series Physical Chemistry 2017 International Conference Keynote Speaker Stefan Haacke photo
Biography:

Stefan Haacke is professor in Physics at Strasbourg University and Director of the Institute of Physics and Chemistry of Materials Strasbourg. His research on ultrafast spectroscopy of biologic molecules and organic nanostructures has been published in 114 papers, and a multi-author book co-edited w. Irene Burghardt (Frankfurt). Present international collaborations involve partners at the National Seoul University, Sogang University Seoul, Nagoya Institute of Technology, Bowling Green University Ohio, University of Siena and the University of Frankfurt. He is coordinator of the French-German project Femto-ASR, on the ultrafast photochemistry of Anabaena Sensory Rhodpsin and its mutants, and partner in the projects FemtoDNA, 2D femtosecond UV spectroscopy applied to labeled DNA double strands, and PhotIron. Most notable is his membership in the advisory board of the Int. Conf. on Photochemistry (ICP) that will be held in Strasbourg in July 2017.

Abstract:

Over last decades, transition metal complexes (Pt, Ir and Ru) have received great attention due to their long-lived electronic excited states, for applications such as OLEDs and dye-sensitized solar cells (DSSCs). However, the replacement of these expensive, scarce and toxic metals by earth-abundant metals such as Fe or Cu is still extremely challenging due to very short excited state lifetimes of the metal-to-ligand charge transfer states (MLCT), limited, in the case of Fe, by spin cross-over into metal-centered high spin states as observed in Fe-pyridine complexes[1].

A possible way to stabilize the lowest energy triplet 3MLCT energetically and thus temporally is to increase the ligand field strength by chemical design. Recently, the use of N-heterocyclic carbenes (NHC) ligands was reported to lead to a prolonged 3MLCT lifetime (9 ps)[2], which we were able to extend up to 16.5 ps due to carboxylation of the ligands[3] (fig. A). Very recently, the Wärnmark group working on the same carboxylated complex, reported efficient electron injection into TiO2 by using THz spectroscopy, but also deleterious charge recombination.[4]

We have designed new complexes where iron was coordinated by benzimidazolylidene-based (Biz) which affords a new record 3MLCT lifetime of 26 ps in MeCN.[5] Streak camera fluorescence experiments on complexes grafted on TiO2 and Al2O3 substrates indicate electron injection through shorter 3MLCT state lifetime on TiO2 than on high-band gap Al2O3 (fig. B), but also surprisingly long 3MLCT state lifetime components induced only through binding on the semiconductor surfaces. A detailed modeling of the effect of surface attachment on the excited state ordering is in progress.

Research is funded by the ANR projet PhotIron.

(A) Kinetic traces of excited state absorption (ΔA>0, red) and ground state bleach (ΔA<0, blue) GSB of Iron complexes. 3MLCT lifetimes are 16.5 ps (Fe(CarbenCOOH)2) and 26ps (Fe(BizCOOH)2) in MeCN. (B) Kinetic traces of 3MLCT of Iron complexes grafted on TiO2 and Al2O3.

Conference Series Physical Chemistry 2017 International Conference Keynote Speaker Junrong Zheng photo
Biography:

Prof. Junrong Zheng completed his PhD and postdoctoral studies from Stanford University. He is professor of chemistry at Peking University, and a co-founder of Uptek Solutions, a Long-Island-based laser company. He is a recipient of numerous prestigious awards including the Sloan Fellowship and the Packard Fellowship.

Abstract:

Electron/hole transformations on interfaces determine fundamental properties of opto-electro-chemical devices, but remain a grand challenge to experimentally investigate and theoretically describe. Herein combining ultrafast VIS/NIR/MIR frequency-mixed microspectroscopy and state-of-the-art two-dimensional atomic device fabrications, we are able to directly monitor the phase transitions of charged quasiparticles in real time on the ultimate interfaces – between two atomic layers. On type II semiconductor/semiconductor interfaces between two transition metal dichalcogenide (TMDC) monolayers, interfacial charge transfers occur within 50fs and interlayer hot excitons (unbound interlayer e/h pairs) are the necessary intermediate of the process for both energy and momentum conservations. On semiconductor/conductor (graphene) interfaces, interlayer charge transfers result in an unexpected transformation of conducting free carriers into insulating interlayer excitons between the conducting graphene and the semiconducting TMDC. The formation of interlayer excitons significantly improves the charge separation efficiency between the two atomic layers for more than twenty times.

FIG. 1. Interlayer charge transfers between MoSe2/WS2 atomic layers.  The interlayer charge transfers (<50fs) result in the formation of interlayer hot excitons, much faster than the formation of intralayer excitons (~600fs).

Conference Series Physical Chemistry 2017 International Conference Keynote Speaker Elena G. Kovaleva photo
Biography:

Elena G. Kovaleva has her expertise in electrosurface and electrocapillary  phenomena in inorganic nanoporous and nanosized systems, organo-inorganic hybride materials, ion-exchange resins by EPR of pH-sensitive nitroxides as spin probes and labels as well as other paramagnetic particles as Сu2+, Co3+, Mn2+, Cr3+. Recently she developed the technique for determination of local acidity and near-surface (Stern) potential in porous and nanostructured  hydrated materials. She is currently working on the problem of the effect of electrostatic properties of a charged surface on catalytic activity heterogeneous catalysts carrying industrial enzymes.

Abstract:

Statement of the Problem: Many solid-phase materials , for instance, porous and nanostructural objects as well as the systems of specific functionality are widely used in aqueous solutions as promising heterogeneous catalysts of various reactions, can serve as suitable carriers for catalytically active organic and bioorganic groups and enzymes, and also be adsorbents of large and small molecules. The properties of solid-phase materials are affected therefore both the chemical nature of the solution and some specific conditions arising in the phase and on the surface of these materials.  Surface electrical potential (SEP) is among the most important surface characteristics of these materials. At present, there is no method for measuring SEP of hydrated porous and nanostructured materials. The purpose of this study is to develop the method for measuring SEP of different solid phase hydrated materials by EPR of pH sensitive nitroxides (NR) as spin probes and labels. Methodology & Theoretical Orientation: A variety of nitroxides with the range of pH-sensitivity from 2 to 8.5 pH were incorporated into nanoporous and nanostructured inorganic oxides as powders and membranes and a diversity of organo-inorganic hybride materials both by adsorption from aqueous solution and through covalent binding technique. pH-dependent parameters of EPR spectra were measured through monitoring pH in a bulk solution and inside materials. Findings: The negative and positive values of Stern potential  for the positively and negatively charged surfaces were measured from the characteristic shifts of the EPR titration curves for the “slow-motional” NR located in the  material near-surface about those for a bulk solution. Stern layer thickness for mesoporous silicas  was determined from the near-surface electrical potential profile using a model of  practically cylindrical nanosized hydrated channels of the mesoporous silicas with channel diameters ranging from 2.3 to 8.1 nm. Conclusion & Significance: An unique technique for measuring the near-surface (Stern) potential as well as Stern layer thickness and surface charge  based on EPR of pH-sensitive nitroxides as spin probes and labels,  have been developed for a wide range of hydrated porous and nanostructured materials with a great potential for adsorption processes and heterogeneous catalysis.