TY - JOUR A1 - Kogikoski Junior, Sergio A1 - Tapio, Kosti A1 - Edler von Zander, Robert A1 - Saalfrank, Peter A1 - Bald, Ilko T1 - Raman enhancement of nanoparticle dimers self-assembled using DNA origami nanotriangles JF - Molecules : a journal of synthetic chemistry and natural product chemistry / Molecular Diversity Preservation International N2 - Surface-enhanced Raman scattering is a powerful approach to detect molecules at very low concentrations, even up to the single-molecule level. One important aspect of the materials used in such a technique is how much the signal is intensified, quantified by the enhancement factor (EF). Herein we obtained the EFs for gold nanoparticle dimers of 60 and 80 nm diameter, respectively, self-assembled using DNA origami nanotriangles. Cy5 and TAMRA were used as surface-enhanced Raman scattering (SERS) probes, which enable the observation of individual nanoparticles and dimers. EF distributions are determined at four distinct wavelengths based on the measurements of around 1000 individual dimer structures. The obtained results show that the EFs for the dimeric assemblies follow a log-normal distribution and are in the range of 10(6) at 633 nm and that the contribution of the molecular resonance effect to the EF is around 2, also showing that the plasmonic resonance is the main source of the observed signal. To support our studies, FDTD simulations of the nanoparticle's electromagnetic field enhancement has been carried out, as well as calculations of the resonance Raman spectra of the dyes using DFT. We observe a very close agreement between the experimental EF distribution and the simulated values. KW - surface-enhanced Raman scattering KW - DNA origami KW - resonance Raman KW - scattering KW - nanoparticle dimers Y1 - 2021 U6 - https://doi.org/10.3390/molecules26061684 SN - 1420-3049 VL - 26 IS - 6 PB - MDPI CY - Basel ER - TY - JOUR A1 - Penschke, Christopher A1 - Edler von Zander, Robert A1 - Beqiraj, Alkit A1 - Zehle, Anna A1 - Jahn, Nicolas A1 - Neumann, Rainer A1 - Saalfrank, Peter T1 - Water on porous, nitrogen-containing layered carbon materials BT - the performance of computational model chemistries JF - Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies / RSC, Royal Society of Chemistry N2 - Porous, layered materials containing sp(2)-hybridized carbon and nitrogen atoms, offer through their tunable properties, a versatile route towards tailormade catalysts for electrochemistry and photochemistry. A key molecule interacting with these quasi two-dimensional materials (2DM) is water, and a photo(electro)chemical key reaction catalyzed by them, is water splitting into H-2 and O-2, with the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) as half reactions. The complexity of some C/N-based 2DM in contact with water raises special needs for their theoretical modelling, which in turn is needed for rational design of C/N-based catalysts. In this work, three classes of C/N-containing porous 2DM with varying pore sizes and C/N ratios, namely graphitic carbon nitride (g-C3N4), C2N, and poly(heptazine imides) (PHI), are studied with various computational methods. We elucidate the performance of different models and model chemistries (the combination of electronic structure method and basis set) for water and water fragment adsorption in the low-coverage regime. Further, properties related to the photo(electro)chemical activity like electrochemical overpotentials, band gaps, and optical excitation energies are in our focus. Specifically, periodic models will be tested vs. cluster models, and density functional theory (DFT) vs. wavefunction theory (WFT). This work serves as a basis for a systematic study of trends for the photo(electro)chemical activity of C/N-containing layered materials as a function of water content, pore size and density. Y1 - 2022 U6 - https://doi.org/10.1039/d2cp00657j SN - 1463-9076 SN - 1463-9084 VL - 24 IS - 24 SP - 14709 EP - 14726 PB - Royal Society of Chemistry CY - Cambridge ER -