Category Archives

23 Articles

Selective Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Diformylfuran by Visible Light‐Driven Photocatalysis over In Situ Substrate‐Sensitized Titania

Our work done in collaboration with the group of Prof. JC Colmenares is out. Check how we used H-terminated clusters to get insights into chemical transformations of HMF at the TiO2(atanase) surface. Our approach involve state-of-the-art DLNO-CCSD(T) energy calculations and numerical partial Hessian evaluation for reliable IR and Raman spectra prediction.

“Selective Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Diformylfuran by Visible Light‐Driven Photocatalysis over In Situ Substrate‐Sensitized Titania”

A. Khan, M. Goepel, A. Kubas, D. Łomot, W. Lisowski, D. Lisovytsky, A. Nowicka, J.C. Colmenares, R. Glaser
ChemSusChem, 2021, https://doi.org/10.1002/cssc.202002687

New work on flow hydrogenation is online!

Boosting the Performance of Nano-Ni Catalysts by Palladium Doping in Flow Hydrogenation of Sulcatone

Catalysts 2020, 10(11), 1267

The effect of Pd doping on nano-Ni catalyst hydrogenation aptitude in sulcatone (6-methyl-5-hepten-2-one) hydrogenation was investigated. Obtained results demonstrated that the addition of non-catalytic amounts of Pd to the surface of parent Ni catalyst improves the activity to the extent that it surpassed the activity of 2.16 wt% Pd catalyst (model catalyst) at optimal reaction conditions in the flow hydrogenation of an unsaturated ketone. Pd doping improves hydrogen activation on the catalyst, which was found to be a rate-limiting step using kinetic isotopic measurements and theoretical calculations.

CoopCat group seminar: Michał Tomza

mtomza_icfo

It is my pleasure to invite you to an online seminar of the Cooperative Catalysis Group. Tomorrow, on Friday, our guest will be the recipient of this year’s NCN scientific prize dr hab. Michał Tomza from the Faculty of Physics of the University of Warsaw.

Below please find the Zoom link and talk details.

Time: Oct 30, 2020 11:00 AM Warsaw
https://zoom.us/j/96570388483?pwd=c1BTV3pZcktTU0tUbmtEdFB0ejJUUT09
Meeting ID: 965 7038 8483
Passcode: 336789


Talk title: “Accurate ab initio quantum-chemical calculations for ultracold scattering experiments”

Abstract:
Hybrid systems of laser-cooled trapped ions and ultracold atoms combined in a single experimental setup have recently emerged as a new platform for fundamental research in quantum physics and chemistry [1]. Reaching the ultracold s-wave quantum regime has been one of the most critical challenges in this field for a long time. Unfortunately, the lowest attainable temperatures in experiments using the Paul ion trap are limited by the possible rf-field-induced heating related to the micromotion [2]. Recently, buffer gas cooling of a single ion in a Paul trap to the quantum regime of ion-atom collisions was realized, and a deviation from classical Langevin theory was observed by studying the spin-exchange dynamics, indicating quantum effects in the ion-atom collisions [3]. In my seminar, I will present how quantum chemical calculations of electronic structure and scattering dynamics can guide and explain quantum physics and chemistry experiments. In particular, I will describe how, in collaboration with experimental groups from Amsterdam [3], Stuttgart [4], and Freiburg, we have overcome the micromotion limitation. I will also discuss incoming applications, including first observation and application of magnetic Feshbach resonances, to control ultracold ion-atom collisions.

[1] Tomza et al, Rev. Mod. Phys. 91, 035001 (2019)
[2] Cetina et al., Phys. Rev. Lett. 109, 253201 (2012)
[3] Feldker et al, Nature Phys. 16, 413 (2020)
[4] Schmid et al, Phys. Rev. Lett. 120, 153401 (2018)

Group seminars

Each Friday CoopCat group holds on-line seminars during the coronavirus outbreak. Please let mail akubas@ichf.edu.pl if you would like to join us!

Upcoming seminar: Friday, 23.10.2020, 10 am
dr Dariusz Piekarski
“Insight into the Folding and Cooperative Multi‐Recognition Mechanism in Supramolecular Anion‐Binding Catalysis”

Recent seminar: Friday, 16.10.2020, 10 am
dr Michał Kochman

“Modeling solvent effects in the photophysics of organic molecules”

CoopCat group has new members!

Dr Michał Kochman and dr Dariusz Piekarski received PD2PI grants to carry out research in CoopCat group. Michał will look on trans-cis photoisomerization of retinoids using quantum chemical methods. Darek will focus on machine learning design of anion binding catalysts.

James Pogrebetsky started PhD project with us. He will work together with Aleksandra to develop new embedding scheme to represent metallic surfaces.

UV-VIS of [2Fe-2S] cluster computed with CI approach for the first time

Adam’s work on [2Fe-2S] cluster is out:

Characterization of charge transfer excited states in [2Fe–2S] iron–sulfur clusters using conventional configuration interaction techniques

The experimental UV–Vis spectra of the biologically relevant [2Fe–2S] iron–sulfur clusters feature typically three bands in the 300–800 nm range. Based on ground-state orbitals and using the one electron transition picture, these bands are said to be of charge transfer character. The key complication in the electronic structure calculations of these compounds are the antiferromagnetic coupling of the iron centers and high covalency of Fe–S bonds. Thus, the examples of the direct computations of electronically excited states of these systems are rare. Whereas low lying electronic excited states were subject of recent studies, higher energy states computed with many-body theories were never reported. In this work we present, for the first time, calculations of the electronic spectra of [Fe2S2](SMe)2−4 biomimetic compound. We demonstrate that spin-averaged restricted open-shell Hartree–Fock orbitals are superior to high-spin orbitals and are convenient reference for subsequent configuration interaction calculations. Moreover, the use of conventional configuration interaction methods enabled us to study the nature of the excited states in details with the difference density maps. By systematic extension of the donor orbital space we show that key excitations in the 300–800 nm range are of Fe 3d ← (μ-S) character.

More on GO-porphyrin is out

Check our latest paper on GO-porphyrins interface. Our contribution includes structure and spectra simulations, explanation of exp-observed peaks as well as charge-transfer study in the nanohybrid using high-level multireference methods (CASSCF/DLPNO-NEVPT2).

Interaction of Light with Non-Covalent Zinc Porphyrin-Graphene Oxide Nanohybrid

The present study explores the influence of graphene oxide (GO) on deactivation pathways of the excited states of zinc 5,10,15,20-tetrakis(4-(hydroxyphenyl) porphyrin (ZnTPPH). The interaction of light with free ZnTPPH molecules and with ZnTPPH molecules adsorbed on graphene oxide sheets was probed via UV-Vis spectroscopy, fluorescence spectroscopy, femtosecond pump–probe spectroscopy and nanosecond flash photolysis. Formation of the ground-state ZnTPPH-GO complex in solution was monitored by the red-shift of the porphyrin Soret absorption band. It was found that Stern−Volmer fluorescence quenching can be described in terms of two different quenching regimes depending on the GO concentration. In addition, our comprehensive analysis of the steady-state and time-resolved emission experiments led to the conclusion that the observed quenching was entirely attributable to a static mechanism. Laser flash photolysis showed that the triplet lifetime of the ZnTPPH was increased in the presence of GO from 174 µs to 292 µs, which is related to the decrease of the rate constant of a radiationless decay mechanism involving rotation of the peripheral hydroxyphenyl rings of the porphyrin. Femtosecond transient absorption spectroscopy demonstrated the presence of a fast photoinduced electron transfer from the singlet excited state of ZnTPPH to the GO sheets, as indicated by the formation of a porphyrin radical cation. Quantum chemical calculations were used to gain deeper insights into the nature of the electronically excited states in the ZnTPPH-GO complex.

New paper published

Magda’s work in collaboration with Emil and Ania from R. Nowakowski group has been published!

Effect of unimodality and bimodality of Pd nanoparticles on the catalytic activity of Pd/SiO2 in the removal of diclofenac from water

In this work, we investigated the catalytic performance of uni- and bimodal Pd/SiO2 catalysts in the aqueous phase hydrodechlorination (HDC) of diclofenac – a very popular nonsteroidal anti-inflammatory drug. Unimodality and bimodality was confirmed by temperature-programmed hydride decomposition (TPHD) and TEM. The highest activity and 100% efficiency in batch and flow mode were observed for bimodal Pd NPs. This outstanding efficiency could be attributed to the close coexistence of small and large metal nanoparticles with different affinity to hydrogen and chloroorganic compound. The obtained results encourage discussion on the necessity to strive for perfect unimodal catalysts for the HDC processes.