Doctoral Researchers

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Topic: Synthese und Eigenschaften von Stimuli-responsiven formanisotropen Kolloiden

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Ruiz Agudo Group

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Topic: Transition Metal Complexes with Rigid Cyclometalating N^N^C Chelate Ligands with a Quinoline-Pyridine-Naphthaline Skeleton 

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Philipp studied Chemistry at the University of Konstanz from 2013-2019. For his master thesis he joined the Gaich group working in the field of diterpene synthesis. In August 2019 he continued his work as a PhD student.

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Project title:

Binary Prussian Blue Analogue Mesocrystals

Project description:

My research focus is the preparation of binary Prussian Blue Analogue (PBA) mesocrystals, and the investigation of their formation mechanism and electrocatalytic performance.

PBAs are transition metal cyanide complexes that belong to the metal organic frameworks. A large variety of different transition metal ions with different oxidation states can be introduced and combined which allows for vast PBA compositions. The bridging of the transition metal centers via conductive cyanide ligands enables charge transfer within the framework. These properties make PBAs promising materials for electrochemistry and -catalysis.

In recent years, the controlled synthesis of PBA nanostructures has emerged which further enhances the unique properties due to the size-dependent properties of nanomaterials. The assembly of anisotropic PBA nanocrystals into crystallographically aligned superstructures, so-called mesocrystals, might enable the exploitation of the nanocrystals’ properties on macroscopic scale.

With this research project we intend to prepare novel functional materials for application in electrocatalysis, e.g., as catalysts for the hydrogen (HER) or oxygen evolution reaction (OER), which are crucial reactions for the future prospect of fuel cell-based energy supply. The preparation of binary PBA mesocrystals could allow the catalysis of two different reactions simultaneously with only one catalyst material.

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Topic: Bismuth Complexes as Luminescent Emitters

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Lena started studying Life Science at the University of Konstanz in 2015 and joined the Gaich group in july 2020. In july 2021 Lena started her PhD and is currently working on the synthesis of lathyrane diterpenoids

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Physical Chemistry

Towards sustainable cements: Understanding the crystallization of cementitious hydrates in LC3 blends as eco-friendly binder

Limestone calcined clay cements (LC³) are a very special and promising type of new cements. They take advantage of synergistic effects in the interaction of calcined clay and limestone as supplementary cementitious materials. With these cements it is already possible to reduce the clinker content to less than 50% and thus save more than 30% in CO₂ emissions. Additionally, LC³ blends are roughly 15-25% cheaper in production than ordinary Portland Cement (OPC). However, one of the few disadvantages still lies in the rheology of calcined clay-containing materials. Once water has been added, they are not as easy to handle as traditional Portland cement, making them somewhat more difficult to work with on the construction site. 

This is where the research of Yannick Emminger comes in and tries to find a way to firstly investigate and secondly influence the crystallisation of the different hydrates in LC³, making it more applicable for construction. Hereby, the hydrates (C-S-H, C-A-S-H, ettringite, calcium carboaluminates, AFm and AFt phases,...) are synthesised via a precipitation reaction from an aqueous solute phase and subsequently analysed. The aim is to monitor the nucleation and control it through additive assistance. For that, analytical methods like FTIR, SEM, EDX, TEM, SAED, TGA, ITC, XRD, DLS, AUC, 1H-/ 13C-/ 27Al-/ 29Si-NMR, and more, are used.

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The design and synthesis of low-dimensional nanomaterials and hydroxides with intercalated anions

Qiqi's research mainly focuses on the design and synthesis of low-dimensional nanomaterials and hydroxides with intercalated anions. On the one hand, the performance of a material is strongly related to its size and dimensions. However, the complexity of the synthesis system caused by the multitude of hydroxide species and the lack of suitable research methods not only results in the current preparation of target hydroxides primarily relying on empirical "trial and error" methods, but also causes some technical deficiencies in existing preparation methods, such as high cost, cumbersome operation, and the use of toxic organic solvents in the synthesis process. In response to this problem, Qiqi plans to use a combination of “theoretical simulation, empirical knowledge analysis, and experimental verification” to explore how to establish a model that can guide the preparation of materials with specific dimensions/sizes. On the other hand, the intercalation of guest anions can affect the final size, composition, morphology, and performance of hydroxides. However, the ultra-small size of intercalated anions and the instantaneous nature of intercalation/deintercalation makes the feasible methods for studying the intercalation mechanism relatively scarce, leading to a bottleneck problem of the inability to deeply understand the mechanism of the effect of reaction parameters on the intercalation process of anions at the molecular/atomic level. To address this issue, Qiqi plans to explore and study the causal quantitative relationship between external reaction parameters (such as temperature, concentration, reaction pH, etc.) and the intercalation mechanism of anions with the help of NH₃ diffusion-induced hydroxide precipitation and in situ pH monitoring.

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Alexander is a chemist and especially interested in material sciences. He researches the influence different hydrophilic functionalities of telechelics (short polymers with 2 terminal functional groups) on the formation, stability and structure of nanoparticles formed thereof, which are created and analyzed in the working group of Prof. Dr. Stefan Mecking. To investigate these processes and properties he performs multi-scale simulations of such nanoparticles.

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Quantitative analysis of nanoparticle interactions and their distributions

The aim of the research is to develop a new methodology to determine size- and shape-dependent distributions of interaction constants, stoichiometry, and cooperativity of the aggregation process, even of polydisperse isotropic and anisotropic nanoparticles using combined sedimentation- and diffusion coefficient distributions from Analytical UltraCentrifugation (AUC).

Regarding anisotropic nanoparticles, face dependent interactions play a fundamental role, and this shall be investigated as well.

Once interactions between similar monodisperse, isotropic nanoparticles have been investigated, more complex systems, made up of polydisperse, isotropic nanoparticles shall be considered.

Despite the large volume of information on nanoparticles, regarding the systems per se, but also their applications in different fields, the determination of the strength of interaction and with it the thermodynamic driving force, as well as the stoichiometry of particle interactions and the cooperativity remains elusive. This is why this investigation is deemed necessary.

AUC is used to compare and implement the result normally obtained with Dynamic Light Scattering (DLS) and Isothermal Titration Calorimetry (ITC): the problem with the DLS, even though it has since been established as a solid analysis to evaluate the size of nanoparticles, is that it overestimates the larger sizes in the sample due to the ratio of scattering intensity to particle radius to the power of 6; on the other hand, ITC only gives average interactions values, and requires a substantial amount of sample.

Considering nanoparticles with broader size and/or shape distribution, a distribution in the interaction constant and stoichiometries is to be expected: AUC permits to physically separate nanoparticles of different size and shape and detects every particle. Thus, AUC is able to determine distributions rather than average values.

Still, the AUC analysis needs to be validated: for this, Field Flow Fractionation (FFF), separating the particles and determining their diffusion coefficient- and particle size distributions, and Transmission Electron Microscopy (TEM), for size and shape analysis, will come in hand to complement the results obtained from AUC.

Planned systems to be investigated are polystyrene and gold spherical nanoparticles, gold nanorods and cubic/cuboids nanoparticles based on oxides of manganese and iron.

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Project Title

Synthesis and Characterization of Multielemental Colloidal Nanocrystals

Research Interests

Plasmonic hybrid metal-semiconductor nanocrystals (NCs) have emerged as promising candidates to address energy and environmental challenges through solar-powered heterogeneous catalysis. By combining both plasmonic metal and quantum sized semiconductor (SC) materials, these nanocrystal heterostructures exhibit unique and enhanced synergistic properties which can be precisely tuned for the desired photocatalytic application via their composition, size, and shape.

However, the synthesis of metal-SC NCs prepared in an either aqueous or organic medium by colloidal chemistry methods using heterogeneous seeded nucleation and growth is still challenging. They either suffer from poor crystallinity of the SC shell when synthesized in water or are severely limited in the size of the metal NC core due to the lack of accessible surface ligands to stabilize large metal structures in organic solvents.

In the current project, we aim to bridge this gap by developing an advanced route for the synthesis of colloidal hybrid metal-SC NCs with tunable dimensions, morphologies, compositions and atomic distributions. The core of the proposed strategy consists of the use of a custom-designed polymer that enables the transfer of noble-metal nanoparticles of different dimensions and shapes from water to organic, apolar solvents. After stabilization in organic solvents, crystalline metal chalcogenides but also oxides, phosphides or nitrides can be successfully grown on the noble metal NCs.

The proposed strategy will open new pathways to exploit the full potential of previously inaccessible noble metal and semiconductor heterostructures by precisely fine-tuning dimension, morphology, and composition for potential photocatalytic applications.

Education

08/2022 – Present

University of Konstanz: Doctoral Candidate

Department of Chemistry

Topic: "Synthesis and Characterization of Multielemental Colloidal Nanocrystals"

Working Group: Prof. Dr. Helmut Cölfen in cooperation with Dr. Guillermo González-Rubio

(Physical Chemistry)

12/2022 Symposium NanoBW 2022

04/2019 – 06/2022

University of Konstanz: Master Studies in Nanoscience

Study Focus:

• Current Issues and Methods in Nanoscience
• Nano/Material Analytics
• Semiconductor Technology and Physics of Solar Cells (inorganic/hybrid/organic)
• Surface Science and Heterogeneous Catalysis

Thesis: "Preparation and Optical Gain Measurements of Homogeneous Nanocrystal Films for Lasing Applications"

Working Group: Prof. Dr. Klaus Boldt in cooperation with Prof. Dr. Helmut Cölfen

(Physical Chemistry)

01/2022 – 06/2022 Industrial Internship

Innovative Sensor Technology iST AG, Ebnat-Kappel, Sankt Gallen, Schweiz

Research and Development of Conductivity Sensors and Microheaters manufactured by Thick Film Technology

10/2015 – 03/2019

University of Konstanz: Bachelor Studies in Nanoscience

Thesis: "Two-dimensional Hybrid Perovskite Phases with a Photoswitchable Additive"

Working Group: Prof. Dr. Sebastian Polarz

(Material Science)

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Equipment Supervisor for Cary 60 UV/Vis in PAC

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Topic: Bismuth Complexes as Luminescent Emitters

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Topic: Redox Active Ruthenium Metallamacrocycles with Hydrogen Bonding

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Raman detection in Field-Flow-Fractionation

Asymmetric flow Field-Flow-Fractionation is a chromatographic technique that separates analyte particles, such as proteins, polymers, or inorganic nanoparticles, based on their size.
Commonly, light scattering, refractive index detection, and UVVis Absorption is used to detect the fractionated sample.

An on-line flow raman detection device is developed to extend this detection chain.

The raman effect is a scattering effect that induces a wavelength shift in the scattered light based on the bond structure of the sample.
Thus, information about the molecular structure of the sample can be obtained in a non-invasive way without the use of labels.

In the on-line flow raman detection device, these raman signals can be detected along the other detection signals from the detection chain.
This can be used to gain further insight into complex mixtures of different analytes using global analysis and reveal properties not otherwise accessible.

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molecular adsorption on inorganic surfaces; ATR-FTIR

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Lukas studied Chemistry at the University of Konstanz from 2011 to 2017. In 2017 he joined the group of Rainer F. Winter (Uni Konstanz) for his master thesis with the title "Synthesis, electrochemical and spectral studies of ethynylferrocene modified triazatruxenes". In August 2019 he joined the Gaich/Huhn group for his PhD and is currently working on the synthesis of photochromic diarylethene switches.

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Chemistry for cultural heritage preservation of porous stone materials

Andra-Lisa Hoyt's research focuses on the intersection of materials science with conservation and restoration of cultural heritage objects, specifically stone objects, which are subject to natural and human-accelerated degradation, e.g. through climate change. Her work involves the development and testing of treatment options for porous materials, which are particularly vulnerable to the ingress of pollutants. Her doctoral thesis includes the prediction of infiltration behavior of restoration-relevant material/liquid systems using a micro-model, characterization and testing of alternative restoration materials for porous carbonate stones, and the study of liquid mineral precursors as a binder for loose grains. The results of her research have the potential to shorten the time frame for object characterization and compatible treatment, as well as the development of new restoration materials.

In 2018 she was awarded a personal doctoral scholarship by the German Federal Environmental Foundation and now continues her research on a University scholarship. She has presented her work at multiple international conferences such as the American Chemical Society Meeting, assemblies of the young chemists’ society of Germany, and crystallization conferences (CRYSPOM).

Keywords: infiltration, porous materials, micromodels, liquid mineral precursors, stone treatment, material characterization

Education: 

01/2018 - Present
University of Konstanz: DBU-Fellow and Doctoral Candidate with Prof. Dr. Cölfen, Department of Chemistry  07/2017 - 09/2017
BASF, Ludwigshafen: Internship in Research and Development  06/2014 - 04/2017
University of Konstanz: Master studies and Thesis with Prof. Dr. Cölfen, Department of Chemistry
"Calcium Carbonate Precursor Formulations for Consolidation and Restoration of Carbonate-based Artifacts" 09/2013 - 05/2014
University of Massachusetts Amherst: Graduate Studies Abroad in the Chemistry Department and Research Internship in the Polymer Science & Engineering Department with Prof. Dr. Briseno 10/2010 - 08/2013
University of Konstanz: Bachelor studies and Thesis with Prof. Dr. Winter, Department of Chemistry
"Divinylphenylenverbrückte heterobimetallische Ru/Os-Komplexe: Synthese neuer Verbindungen und Studium der elektronischen Struktur"

Research Interests: 

"Preservation of carbonate-based natural materials based on a better understanding of crystallization processes in pores"
Liquid Precursors, Calcium Carbonate, Stone Conservation

Responsibilities

Wenbo started his studies of Chemistry in 2013 at Zhejiang University. Later he switched to Pharmacy because he cared about human health. After suffering from biology courses for three years, he joined the Gaich group for his Master thesis. In October 2019 he started his PhD and is currently struggling with his total synthesis of meroterpenoids.

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Yulia studied Chemistry at Saint Petersburg State University from 2015 to 2021. She completed her master thesis "Synthesis and reactions of 5-(3-aryl-2H-azirin-2-yl)-1,2,3-triazoles" under the supervision of Prof. Dr. Alexander F. Khlebnikov. In October 2021 she joined the Gaich group and is currently working on the synthesis of terpenoid natural products.

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Topic: Conductance of different Complexes with Metal-to-Metal Multiple Bonds

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time-resolved quantum cascade laser (QCL) IR-spectroscopy
single wavelength and dual-comb spectrocopy
protein folding dynamics

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Bastian started studying Life Science at the University of Konstanz in 2015. He joined the Gaich group in june 2020 for his master thesis and continued his work on novel silicon chemistry and the total synthesis of diterpenes as a PhD student in june 2021.

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Topic: Electrochromic (metal-)organic Redox Systems with cationic and paramagnetic ligand platforms

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Topic: conductance of extended π-Systems

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Kevin tackles protien folding problems and strifes to find structure-function-relationships of ubiquitin and ubiquitin chains. Roughly 5% of the human genome encode for Ub-ligases and ubiquitin plays a fundamental role in many cellular processes like protein degradation, DNA, and membrane regulation. Yet, how different Ub-chains affect different cellular mechanisms remains poorly understood. His research aims to shed some light on these processes.

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Philipp studied Chemistry at the University of Konstanz from 2016-2021. In October 2021 he joined the Gaich group for his PhD thesis (Fast Track program) working on the total synthesis of taxanoid diterpenes.
 

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My research concentrates on the understanding of homogeneous crystallisation processes of calcium silicate hydrates (C-S-H), which is the most important compound in modern cement. The main focus lies here in the pre-nucleation and early post-nucleation regime. Further, the influence of zinc on the nucleation of C-S-H is investigated, since it’s one of the most common impurities in cement. Another topic is the influence of dehydration processes (e. g. due to cosmotropic/chaotropic effects) on pre-nucleation species of C-S-H and the altering on its nucleation pathway. In general, all C-S-H is synthesised with simple silicon and calcium precursors via automated titration set-ups.

The crystallisation process is in-situ monitored with different electrodes and the obtained solid & pre-nucleation species are respectively analysed with the following methods: FT-IR, PXRD, TGA, SEM/EDX & (HR)TEM/EDX/ED, AUC, ToF-MS.

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time-resolved IR-spectroscopy; quantum cascade lasers;

lipid-induced dynamics of membrane proteins

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Research Projects

• Tailored Colloids as Model Systems
• Plasmonic Colloids
• Nanoparticle Arrays
  

Education

11/2016 – Present
University of Konstanz: Ph.D. student in the group of Prof. Dr. Alexander Wittemann, Department of Chemistry, Colloid Chemistry, “Bildung und Untersuchung organisierter Strukturen aus Nanopartikeln und Nanopartikelmischungen”

10/2013 – 07/2016
University of Halle (Saale): Master of Science, Department of Physical Chemistry, thesis in the group of Prof. Dr. Kirsten Bacia, "Phase behavior in a ternary lipid mixture studied by fluorescence correlation spectroscopy"

10/2010 – 08/2013
University of Halle (Saale): Bachelor of Science, Department of Inorganic Chemistry

Responsibilities

Polina received her B.S. and M.S. in chemistry from  St Petersburg University and then joined Prof. Dr. Peter group. In her PhD project she enjoys bridging the information between atomistic and coarse grained scales in the protein simulations with the focus on ligand binding. 

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Topic: Excited states and dynamics of current-driven molecular spin systems (SFB 1432)

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Block copolymers for the dissolution of atherosclerotic plaques

In my PhD project I am synthesizing copolymeric nanoparticles. These are composed of bio-inspired poly(2-oxazolines). Various analytical methods and techniques are used to characterize the functional polymers. Their chemical composition is determined using gel permeation chromatography (GPC), infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy. Applying dynamic light scattering (DLS), analytical ultracentrifugation (AUC) and particle tracking microscopy (PTM), their sizes are investigated on the nanometer scale. By means of “click reactions”, the polymer backbones are equipped with diverse functional groups to dissolve pathological, cholesterol and mineral calcium phosphate deposits. Potentiometric titrations, UV/VIS and inductively coupled plasma optical emission spectrometry (ICP-OES) are employed to evaluate the maximum dissolution capacity in vitro. Thus, this nanomedicine approach aims to prevent the formation/development of atherosclerotic plaques in blood vessel walls. Furthermore, multiple cytotoxicity studies on different cell lines will be used to evaluate the biocompatibility of the functional nanoparticles. The polymers will be tested in vivo in cooperation with the Albert-Ludwigs-University Freiburg. The aim is to investigate whether the fluorescence-labeled polymers are excreted by the test animals.