TY  - JOUR
A1  - Kroener, Dominik
A1  - Schimka, Selina
A1  - Klamroth, Tillmann
T1  - Laser control for coupled torsions in chiroptical switches: a combined quantum and classical dynamics approach
JF  - The journal of physical chemistry : C, Nanomaterials and interfaces
N2  - We present a novel laser pulse control for the chiroptical switch 1-(2-cis-fluoroethenyl)-2-fluoro-3,5-dibromobenzene mounted on adamantane, where the latter imitates a linker group or part of a solid surface. This molecular device offers three switching states: a true achiral "off"-state and two chiral "on"-states of opposite handedness. Due to the alignment of its chiral axis along the surface normal several defined orientations of the switch have to be considered for an efficient stereocontrol strategy. In addition to these different initial conditions, coupled torsional degrees of freedom around the chiral axis make the quest for highly stereoselective laser pulses a challenge. The necessary flexibility in pulse accomplished by employing the iterative stochastic pulse optimization method we presented recently. Still, the complexity of the system dictates a combined treatment by fast molecular dynamics and computationally intensive quantum dynamics. Although quantum effects are found to be of importance, the pulses optimized within the classical treatment allow us to turn on the chirality of the switch, achieving high enantioselectivity in the quantum treatment for all orientations at the same time.
Y1  - 2014
U6  - https://doi.org/10.1021/jp410342a
SN  - 1932-7447
VL  - 118
IS  - 2
SP  - 1322
EP  - 1331
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Utecht, Manuel Martin
A1  - Pan, Tianluo
A1  - Klamroth, Tillmann
A1  - Palmer, Richard E.
T1  - Quantum chemical cluster models for chemi- and physisorption of chlorobenzene on Si(111)-7x7
JF  - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory
N2  - Motivated by recent atomic manipulation experiments, we report quantum chemical calculations for chemi- and physisorption minima of chlorobenzene on the Si(111)-7x7 surface. A density functional theory cluster approach is applied, using the B3LYP hybrid functional alongside Grimme's empirical dispersion corrections (D3). We were able to identify chemisorption sites of binding energies of 1.6 eV and physisorption energies of 0.6 eV, both in encouraging agreement with the trend of experimental data. The cluster approach opens up the possibility of a first-principles based dynamical description of STM manipulation experiments on this system, the interpretation of which involves both the chemi- and physisorbed states. However, we found that special care has to be taken regarding the choice of clusters, basis sets, and the evaluation of the dispersion corrections.
Y1  - 2014
U6  - https://doi.org/10.1021/jp504208d
SN  - 1089-5639
VL  - 118
IS  - 33
SP  - 6699
EP  - 6704
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Winter, Alette
A1  - Thiel, Kerstin
A1  - Zabel, Andre
A1  - Klamroth, Tillmann
A1  - Poeppl, Andreas
A1  - Kelling, Alexandra
A1  - Schilde, Uwe
A1  - Taubert, Andreas
A1  - Strauch, Peter
T1  - Tetrahalidocuprates(II) - structure and EPR spectroscopy. Part 2: tetrachloridocuprates(II)
JF  - New journal of chemistry
N2  - We present and discuss the results of crystallographic and electron paramagnetic resonance (EPR) spectroscopic analyses of five tetrachloridocuprate(II) complexes to supply a useful tool for the structural characterisation of the [CuCl4](2-) moiety in the liquid state, for example in ionic liquids, or in solution. Bis(benzyltriethylammonium)-, bis(trimethylphenylammonium)-, bis(ethyltriphenylphosphonium)-, bis(benzyltriphenylphosphonium)-, and bis(tetraphenylarsonium) tetrachloridocuprate(II) were synthesised and characterised by elemental, IR, EPR and X-ray analyses. The results of the crystallographic analyses show distorted tetrahedral coordination geometry of all [CuCl4](2-) anions in the five complexes and prove that all investigated complexes are stabilised by hydrogen bonds of different intensities. Despite the use of sterically demanding ammonium, phosphonium and arsonium cations to obtain the separation of the paramagnetic Cu(II) centres for EPR spectroscopy no hyperfine structure was observed in the EPR spectra but the principal values of the electron Zeeman tensor, g(parallel to) and g(perpendicular to), could be determined. With these EPR data and the crystallographic parameters we were able to carry out a correlation study to anticipate the structural situation of tetrachloridocuprates in different physical states. This correlation is in good agreement with DFT calculations.
Y1  - 2014
U6  - https://doi.org/10.1039/c3nj01039b
SN  - 1144-0546
SN  - 1369-9261
VL  - 38
IS  - 3
SP  - 1019
EP  - 1030
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -