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Gdańsk University of Technology

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Publications from the year 2024

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  • Comparison of 3D Point Cloud Completion Networks for High Altitude Lidar Scans of Buildings
    • Marek Kulawiak
    2024 PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING

    High altitude lidar scans allow for rapid acquisition of big spatial data representing entire city blocks. Unfortunately, the raw point clouds acquired by this method are largely incomplete due to object occlusions and restrictions in scanning angles and sensor resolution, which can negatively affect the obtained results. In recent years, many new solutions for 3D point cloud completion have been created and tested on various objects; however, the application of these methods to high-altitude lidar point clouds of buildings has not been properly investigated yet. In the above context, this paper presents the results of applying several state-of-the-art point cloud completion networks to various building exteriors acquired by simulated airborne laser scanning. Moreover, the output point clouds generated from partial data are compared with complete ground-truth point clouds. The performed tests show that the SeedFormer network trained on the ShapeNet-55 data set provides promising shape completion results.

  • Comparison of Deep Learning Approaches in Classification of Glacial Landforms
    • Paweł Nadachowski
    • Zbigniew Łubniewski
    • Karolina Trzcińska
    • Jarosław Tęgowski
    2024 International Journal of Electronics and Telecommunications

    Glacial landforms, created by the continuous movements of glaciers over millennia, are crucial topics in geomorphological research. Their systematic analysis affords invaluable insights into past climatic oscillations and augments understanding of long-term climate change dynamics. The classification of these types of terrain traditionally depends on labor-intensive manual or semi-automated methods. However, the emergence of automated techniques driven by deep learning and neural networks holds promise for enhancing efficiency of terrain classification workflows. This study evaluated the effectiveness of Convolutional Neural Network (CNN) architectures, particularly Residual Neural Network (ResNet) and VGG in comparison with Vision Transformer (ViT) architecture in the glacial landform classification task. By using preprocessed input data from Digital Elevation Model (DEM) which covers regions such as the Lubawa Upland and Gardno-Leba Plain in Poland, as well as the Elise Glacier in Svalbard, Norway, comprehensive assessments of those methods were conducted. The final results highlight the unique ability of deep learning methods to accurately classify glacial landforms. Classification process presented in this study can be the efficient, repeatable and fast solution for automatic terrain classification.

  • Comparison of Deep Neural Network Learning Algorithms for Mars Terrain Image Segmentation
    • Wojciech Wicki
    • Wiktor Burblis
    • Miłosz Tkaczeń
    • Jerzy Demkowicz
    2024 Full text

    This paper is dedicated to the topic of terrain recognition on Mars using advanced techniques based on the convolutional neural networks (CNN). The work on the project was conducted based on the set of 18K images collected by the Curiosity, Opportunity and Spirit rovers. The data were later processed by the model operating in a Python environment, utilizing Keras and Tensorflow repositories. The model benefits from the pretrained backbones trained for analysis of the RGB images. The project achieves an accuracy of 83.5% when extending the scope of classification to unknown objects and 94.2% when omitting unknown results. The results were compared with related projects of Zooniverse and NASA's Jet Propulsion Laboratory scientific group. From amongst the evaluated configurations, the best results and resource utilization were achieved by applying the UNet architecture with resnext_50 backbone and Adam optimizer.

  • Comparison of Doppler Effect Estimation Methods for MFSK Transmission in Multipath Hydroacoustic Channel
    • Agnieszka Czapiewska
    • Andrzej Łuksza
    • Ryszard Studański
    • Łukasz Wojewódka
    • Andrzej Żak
    2024 Full text IEEE Access

    Underwater wireless communication remains a challenging topic, particularly for applications such as wreck penetration where multipath and Doppler effects are very intense. These effects are becoming even more difficult to mitigate for fast data transmission systems that utilize wideband signals. Due to the low propagation speed of acoustic wave in the water, there is a significant difference between the Doppler shift for lower and upper frequencies of the utilized spectrum. To address these challenges, this paper describes various methods for determining the Doppler frequency shift for MFSK signals, including cross-correlation, double FFT, pilots, and additional Up-Down chirp signals. The reception quality of the transmitted data in a real environment was used as an evaluation criterion for each method. The tests were carried out in motion within the towing tank for different movement speeds of the transmitter relative to the receiver. The tank’s limited dimensions created conditions for multipath signal propagation. Under very difficult multipath signal propagation conditions, the pilots method was found to be the most effective. It gave over two times lower BER than the well-known Up-Down chirp method.

  • Comparison of experimental results with simulation studies of "digital" hydrostatic transmission
    • Zubair Ahmed Jan
    • Krzysztof Kędzia
    • Paweł Śliwiński
    2024

    The publication presents the results of experimental research on a "digital" hydrostatic transmission conducted at INOE 2000 IHP within the framework of the grant "Method of effective use of the digital hydraulics concept in multi-source hydrostatic drive systems". The primary goal of the research is to compare the effectiveness (efficiency) of using different methods of controlling the pump capacity and the hydraulic motor capacity in multi-source, hydrostatic drive systems and to compare the experimental results with simulation studies obtained in the MATLAB Simulink program.

  • Comparison of heat transfer from single- and double-sided heated horizontal plate under free convection in air with constant heat flux condition
    • Michał Ryms
    • Krzysztof Tesch
    • Witold Lewandowski
    2024 Full text INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER

    This paper presents the results of an experimental and numerical study of convective heat transfer from a newly designed double-sided heated horizontal plate in air. To ensure equal heat transfer from both surfaces, the plate was equipped with two independently supplied electric heaters and resistance thermometers on each side. Minimizing the plate's thickness reduced lateral heat loss and improved measurement accuracy. The study used the balance method for convective heat transfer analysis, and results were validated through standard numerical calculations for q = const. Additionally, results were compared with experimental literature for intermediate cases, such as a cuboid, where convection occurs from both horizontal and vertical sides. Experimental results for the plate showed a 15.5–18.0% difference from numerical ones and a 24.7–29.3% difference from average extreme cases. These findings, presented as the Nusselt-Rayleigh relationship, were positively verified by numerical calculations, confirming their reliability. This advancement enables separate studies of free convection from the upper and lower parts of horizontal plates.

  • Comparison of methods for diagnosing marine IC engines based on working medium parameters including exhaust gas specific enthalpy
    • Patrycja Puzdrowska
    2024 Full text Combustion Engines

    Article points out methods currently used to diagnose marine engines in operation. The development of tools and programs for implementing these methods was pointed out. The problem of unsatisfactory measurement susceptibility of marine engines was highlighted. Three methods of parametric diagnosis are presented: measurement of in-cylinder parameters and in exhaust gas duct, numerical simulation due to computer software and calculations based on Wibe function. Unfitness states that were analyzed during tests are presented: reduced injection pressure, obstructed intake air duct and reduced compression ratio. The specific enthalpy of the exhaust gas within one engine cycle was determined as a new diagnostic parameter. As a supplement, thermograms of the engine in various states of inoperability were presented. The obtained results were compared and a series of conclusions derived from them were presented. It was evaluated that numerical simulation is an excellent tool for planning experimental studies. Tests on the engine in operation were found to be the most diagnostically reliable.

  • Comparison of Tire Rolling Resistance Measuring Methods for Different Surfaces
    • Jerzy Ejsmont
    • Grzegorz Ronowski
    • Lisa Ydrefors
    • Wojciech Owczarzak
    • Sławomir Sommer
    • Beata Świeczko-Żurek
    2024 Full text INTERNATIONAL JOURNAL OF AUTOMOTIVE TECHNOLOGY

    The rolling resistance of car tires is one of the most important parameters characterizing tires today. This resistance has a very significant contribution to the energy consumption of wheeled vehicles. The climate crisis has forced tire and car manufacturers to place great emphasis on the environmental impact of their products. Paradoxically, the development of electric vehicles has led to an even greater importance of rolling resistance, because in electric vehicles, a large part of the influence of grade resistance and inertial resistance has been eliminated due to re-generative braking, which resulted in rolling resistance and air resistance remain as the most important factors. What is more, electric and hybrid vehicles are usually heavier, so the rolling resistance is increased accordingly. To optimize tires for rolling resistance, representative test methods must exist. Unfortunately, the current standards for measuring rolling resistance assume that tests are carried out in conditions that are far from real road conditions. This article compares the results of rolling resistance tests conducted in road conditions with the results of laboratory tests conducted on roadwheel facilities. The overview of results shows that the results of tests conducted in accordance with ISO and SAE standards on steel drums are very poorly correlated with more objective results of road tests. Significant differences occur both in the Coefficients of Rolling Resistance (CRR) and in the tire ranking. Only covering the drums with replicas of road surfaces leads to a significant improvement in the results obtained. For investigations of rolling resistance in non-steady-state conditions, the flat track testing machine (TTF), equipped with asphalt cassettes, is shown to provide measurement data in agreement with the road test data.

  • Completely entangled subspaces of entanglement depth k
    • Maciej Demianowicz
    • Kajetan Vogtt
    • Remigiusz Augusiak
    2024 Full text PHYSICAL REVIEW A

    We introduce a class of entangled subspaces: completely entangled subspaces of entanglement depth k (k-CESs). These are subspaces of multipartite Hilbert spaces containing only pure states with an entanglement depth of at least k. We present an efficient construction of k-CESs of any achievable dimensionality in any multipartite scenario. Further, we discuss the relation between these subspaces and unextendible product bases (UPBs). In particular, we establish that there is a nontrivial bound on the cardinality of a UPB whose orthocomplement is a k-CES. Further, we discuss the existence of such UPBs for qubit systems.

  • Composite 2D Material-Based Pervaporation Membranes for Liquid Separation: A Review
    • Roberto Castro Munoz
    2024 Full text MOLECULES

    Today, chemistry and nanotechnology cover molecular separations in liquid and gas states by aiding in the design of new nano-sized materials. In this regard, the synthesis and application of two-dimensional (2D) nanomaterials are current fields of research in which structurally defined 2D materials are being used in membrane separation either in self-standing membranes or composites with polymer phases. For instance, pervaporation (PV), as a highly selective technology for liquid separation, benefits from using 2D materials to selectively transport water or other solvent molecules. Therefore, this review paper offers an interesting update in revising the ongoing progress of PV membranes using 2D materials in several applications, including solvent purification (the removal of water from organic systems), organics removal (the removal of organic molecules diluted in water systems), and desalination (selective water transport from seawater). In general, recent reports from the past 3 years have been discussed and analyzed. Attention has been devoted to the proposed strategies and fabrication of membranes for the inclusion of 2D materials into polymer phases. Finally, the future trends and current research gaps are declared for the scientists in the field.

  • Comprehensive Analysis and Environmental Risk Assessment of Benzotriazoles in Airport Stormwater: A HS-SPME-GC × GC-TOF-MS-Based Procedure as a Tool for Sustainable Airport Runoff Water Management
    • Anna Maria Sulej-Suchomska
    • Kozioł Krystyna
    • Żaneta Polkowska
    2024 Sustainability

    Despite the numerous benefits of intensive air transport development, many activities associated with the operation of airports contribute to environmental pollution. The purpose of this research was the development, optimization, and validation of a headspace–solid-phase microextraction–comprehensive two-dimensional gas chromatography–time of flight–mass spectrometry (HS-SPME-GC × GC-TOF-MS)-based procedure for determining anti-corrosive compounds in airport stormwater. Optimized HS-SPME conditions include: 45 min extraction time, 100 ◦C temperature, 1.0 g salt addition, and 10 min desorption time at 270 ◦C. The developed procedure is sensitive, selective, accurate (recoveries ≥ 80.0%), and precise (the coefficient of variation (CV) ≤ 14.9%), making it a highly suitable tool for extensive airport stormwater quality monitoring. The validated analytical protocol was successfully used to detect pollutants, including 1H-BT, 4-MeBT, 5-MeBT, and 5,6-diMe-1H-BT, in stormwater from various European airports with different flight capacities. Throughout the sampling period at the investigated airports, 1H-benzotriazole was found in the highest concentrations, ranging from below the MQL to 467 mg/L. An ecotoxicological risk assessment revealed that 69% of the sites exhibited high risk levels (Risk Quotient ≥ 1). The developed procedure and carried out environmental risk assessments of benzotriazoles in airport stormwater enable an evidence-based approach to sustainable airport stormwater management.

  • Comprehensive evaluation of physical properties and carbon dioxide capacities of new 2-(butylamino)ethanol-based deep eutectic solvents
    • Bartosz Nowosielski
    • Marzena Jamrógiewicz
    • Iwona Cichowska-Kopczyńska
    • Dorota Warmińska
    2024 PURE AND APPLIED CHEMISTRY

    The aim of this research was to assess the impact of the components of alkanolamine deep eutectic solvents (DESs) on the physical properties of those DESs and their carbon dioxide capacity. To achieve this goal, novel deep eutectic solvents were synthesized by using 2-(butylamino)ethanol (BAE) as the hydrogen bond donor (HBD), along with tetrabutylammonium bromide TBAB), tetrabutylammonium chloride (TBAC), or tetraethy- lammonium chloride (TEAC) as the hydrogen bond acceptors (HBA) at various molar ratios (1:6, 1:8, and 1:10). To confirm the presence of hydrogen bond interactions between the components Fourier Transform Infrared Spectroscopy measurements were conducted. Furthermore, thermal properties, including melting points and thermal stability, of these deep eutectic solvents as well as key physical properties, such as density, viscosity, refractive index, and sound velocity, within the temperature range of 293.15–333.15 K and at a pressure of 0.1 MPa were examined. The effect of the molar ratio of HBA to HBD, the type of anion, and the length of the alkyl chain were studied and analysed in regard to physicochemical properties. In this work, the solubility of carbon dioxide in DESs derived from 2-(butylamino)ethanol, 3-aminopropan-1-ol (AP), and 2-(methylamino)ethanol (MAE) was measured. The highest CO 2 capacity was found for TEAC:MAE 1:10 DES characterized by the shortest alkyl chain length in both HBA and HBD molecules, the highest amine content, and the lowest viscosity. Additionally, the effect of water addition on carbon dioxide solubility was explored. The results showed that the influence of water on CO 2 solubility varies with the type of DES. In general, this work highlighted that DESs can serve as effective media for carbon dioxide capture, and their performance can be tailored by changing the type of hydrogen bond acceptor or donor, their molar ratio and by the addition of water.

  • Comprehensive exploration of technological tensioning effects in welded thin plate girders: an in-depth investigation
    • Hassanein I. Khalaf
    • D. Chodorowska
    • Raheem Al-Sabur
    • Andrzej Kubit
    • Wojciech Macek
    2024 Journal of the Brazilian Society of Mechanical Sciences and Engineering

    Thin-walled plate girders are widely used in structures and construction due to their effectiveness in transferring loads. The permanent deformations of the girder lead to a lack of stability, which necessarily leads to its replacement. Replacing permanently deformed thin-walled load-bearing structures requires large financial outlays. Technological prestressing is one of the most effective methods for studying and treating permanent deflections in girder elements. This study looks at the defection of welded thin-plate S235JR steel girders, examining how technological tensioning effects interact with different loading conditions. Four girders, A2 (welded in bottom caps), A3 (welded in two side caps), and A4 (welded in two side caps and bottom caps), as well as the prestressed B2 girder, which has two welded side caps, were subjected to a bend test. The girders were subjected to a load P (20, 40, 60, 80 and 95) kN. All points were examined during the 95 min of cooling time. For technological compression, the results showed that there is a convergence between the analytical solution and the experimental results, as the most significant deviation achieved in the analysis was 5.21 mm compared to 6 mm experimentally. When the girder is loaded with the force P = 50 N, the maximum deflection achieved at girder A4 is 4 mm, compared with 1mm at girder A2. In prestressed girder B, the deflections that were reached were 2.50 mm, 3.50 mm, and 3.52 mm in the analytical, experimental, and FE numerical models, respectively. The tensions that were reached were 36.96 MPa, 44.28 MPa, and 27.93 MPa.

  • COMPREHENSIVE MONITORING OF CHANGES IN THE GEOMETRIC STRUCTURE OF A HISTORIC BUILDING THE "SALA BHP" IN GDAŃSK
    • Jacek Sztubecki
    • Maciej Niedostatkiewicz
    • Maria Mrówczyńska
    • Tomasz Majewski
    2024 Full text Civil and Environmental Engineering Reports

    The article presents selected results of the analysis of the comprehensive monitoring of the historical building of the “Sala BHP” in Gdansk. The necessity of monitoring was caused by scratches on its structural and finishing elements that occurred in the previous period. A preliminarily assumed factor that could cause the expansion of existing damages and the possible formation of new ones was the planned implementation of an investment consisting of the erection of multi-storey buildings on adjacent plots. As part of the preventive work, a comprehensive monitoring of the facility was proposed, consisting of geodetic determination of vertical and horizontal displacements of measurement points, measurement of changes in the width of existing cracks, and control of the height of the water table in piezometers located in the area adjacent to the „Sala BHP” building. As part of the technical condition inspection, the collected data was analyzed, and the measurement data was compared. In the course of the studies, no strong correlations between displacements and individual factors were observed, and thus the preliminary thesis on the direct impact of the investment carried out on the neighboring „Sala BHP” building on the formation of scratches was not confirmed. To confirm the conclusion that the current technical condition of the structure is a consequence of the typical operation of a building with a flexible structure, and most importantly, the occurring defects and damages do not threaten the safety of its structure and use, an additional analysis of the uniformity of the obtained displacements occurrence was carried out, using the transformation method for the purpose. The method shows the non-uniformity of the occurrence of the displacements of the control point network. The results of the analysis confirmed the previously formulated conclusions.

  • Computational analysis of power-law fluids for convective heat transfer in permeable enclosures using Darcy effects
    • Maryam Rehman
    • Muhammad Bilal Hafeez
    • Marek Krawczuk
    2024 Full text JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY

    Natural convection is a complex environmental phenomenon that typically occurs in engineering settings in porous structures. Shear thinning or shear thickening fuids are characteristics of power-law fuids, which are non-Newtonian in nature and fnd wide-ranging uses in various industrial processes. Non-Newtonian fuid fow in porous media is a difcult problem with important consequences for energy systems and heat transfer. In this paper, convective heat transmission in permeable enclosures will be thoroughly examined. The main goal is to comprehend the intricate interaction between the buoyancyinduced convection intensity, the porosity of the casing, and the fuid’s power-law rheology as indicated by the Rayleigh number. The objective is to comprehend the underlying mechanisms and identify the ideal conditions for improving heat transfer processes.The problem’s governing equations for a scientifc investigation are predicated on the concepts of heat transport and fuid dynamics. The fuid fow and thermal behavior are represented using the energy equation, the Boussinesq approximation, and the Navier–Stokes equations. The continuity equation in a porous media represents the conservation of mass. Finite Element Analysis is the numerical method that is suggested for this challenging topic since it enables a comprehensive examination of the situation. The results of the investigation support several important conclusions. The power-law index directly impacts heat transmission patterns. A higher Rayleigh number indicates increased buoyancyinduced convection, which increases the heat transfer rates inside the shell. The porosity of the medium signifcantly afects temperature gradients and fow distribution, and it is most noticeable when permeability is present. The fndings show how, in the context of porous media, these parameters have complicated relationships with one another

  • Computational analysis of substituent effects on proton affinity and gas-phase basicity of TEMPO derivatives and their hydrogen bonding interactions with water molecules
    • Abolfazl Shiroudi
    • Maciej Śmiechowski
    • Jacek Czub
    • Mohamed A. Abdel-Rahman
    2024 Full text Scientific Reports

    The study investigates the molecular structure of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and its derivatives in the gas phase using B3LYP and M06-2X functional methods. Intermolecular interactions are analyzed using natural bond orbital (NBO) and atoms in molecules (AIM) techniques. NO2-substituted TEMPO displays high reactivity, less stability, and softer properties. The study reveals that the stability of TEMPO derivatives is mainly influenced by LP(e) → σ∗ electronic delocalization effects, with the highest stabilization observed on the oxygen atom of the nitroxide moiety. This work also considers electron density, atomic charges, and energetic and thermodynamic properties of the studied NO radicals, and their relative stability. The proton affinity and gas-phase basicity of the studied compounds were computed at T = 298 K for O-protonation and N-protonation, respectively. The studied DFT method calculations show that O-protonation is more stable than N-protonation, with an energy difference of 16.64–20.77 kcal/mol (22.80–25.68 kcal/mol) at the B3LYP (M06-2X) method. The AIM analysis reveals that the N–O…H interaction in H2O complexes has the most favorable hydrogen bond energy computed at bond critical points (3, − 1), and the planar configurations of TEMPO derivatives exhibit the highest EHB values. This indicates stronger hydrogen bonding interactions between the N–O group and water molecules.

  • Computational Approach towards Repetitive Design Tasks: The Case Study of Parking Lot Automated Design
    • Jan Cudzik
    • Michał Nessel
    2024 Full text Sustainability

    The study aims to develop and assess an algorithm for efficiently generating parking spot layouts within predefined area outlines. The algorithm is an attempt to streamline the decisionmaking process by producing different design variants and optimizing the utilization of available space. The algorithm’s primary objective is to streamline decision-making by generating diverse design variants while optimizing the use of available space, with a distinct focus on mitigating environmental impact and fostering ecological well-being. Researchers conduct thorough tests on the algorithm across various outlines, resulting in multiple layout options for each scenario. They analyzed five representative parking locations and compare the algorithm’s results with the existing parking spot layouts. Throughout the evaluation process, they consider quantitative and qualitative data, considering the complexities of communication solutions within each context. The study findings indicate that the algorithm demonstrates comparable or superior performance to existing solutions. Overall, the study highlights the promising potential of algorithmic design approaches in the context of parking lot automated design. Achieving a balance between innovative designs and user-friendly layouts is crucial, and this is achievable by conducting comprehensive analyses that consider various factors. The consistent findings underscore the algorithm’s potential to significantly contribute to sustainable design practices in parking lot layouts, highlighting decreased environmental strain, efficient land use, and creating urban spaces that prioritize ecological benefits. Furthermore, seamlessly integrating algorithmic solutions with existing communication systems is paramount to ensure practical applicability in real-world scenarios. This integration will enable more effective and practical implementation of the algorithm’s outputs in actual parking lot design projects.

  • Computational Bar Size Optimization of Single Layer Dome Structures Considering Axial Stress and Shape Disturbance
    • Ahmed Manguri
    • Najmadeen Saeed
    • Farzin Kazemi
    • Neda Asgarkhani
    • Marcin Szczepański
    • Robert Jankowski
    2024

    A computational method is proposed in this paper to minimize the material usage in the construction of modern spatial frame structures by prestressing a minimal number of members. The computational optimization is conducted in two steps. Firstly, a numerical model of a single-layer dome structure is used to minimize the cross-sectional area through several iterations. Different assumed ratios (r) ranging from 0.95 to 0.75 are multiplied by the designed cross-sectional area, and the optimal actual ratio (R) is determined through multiple steps using MATLAB. The selection of the optimum ratio is based on ensuring structural stability and considering various constraints. Secondly, a computational optimization is performed using the fmincon function in MATLAB, which employs an interior-point optimization algorithm to search for the minimum summation of the function. The algorithm is designed to exclude actuators with negligible actuation, thereby minimizing the number of actuators. Constraints are set on the stress of all members and the nodal displacements to maintain the desirable shape of the optimized structure. The obtained results demonstrate that the cross-sectional area of the numerical dome structure can be reduced by up to 18% by prestressing only nine members. The validity of the results is confirmed by comparing them with those obtained from MATLAB and SAP2000 software.

  • Computational modelling of historic masonry railroad arch bridges
    • Bartosz Sobczyk
    • Łukasz Pyrzowski
    • Mikołaj Miśkiewicz
    2024 COMPUTERS & STRUCTURES

    The problems encountered during the analyzes of structural response of historic masonry railroad arch bridges are described in this paper. The attention is mainly focused on the stiffness of the masonry arches, their strengths and appropriate estimation of railroad load intensity. Issues related to computational modelling of two, existing, almost 130 years old masonry arch railroad bridges are presented in this context. The main properties and results of detailed inspection of the structures are shown. Computational models that were created in the finite element method environment in order to efficiently describe the responses of the bridges under typical loading conditions and estimate their load carrying abilities are presented. The outcomes of several nonlinear static analyses that were conducted for this purpose are discussed. What is more the results of finite element analyses are reviewed against the inspected bridge condition and final conclusions are formulated on that basis. All the analyses allowed to find the possible causes of the deterioration of the bridges condition.

  • Computational Study of Molecular Interactions in ZnCl2(urea)2 Crystals as Precursors for Deep Eutectic Solvents
    • Adrian Malinowski
    • Maciej Śmiechowski
    2024 Crystals

    Deep eutectic solvents (DESs) are now enjoying an increased scientific interest due to their interesting properties and growing range of possible applications. Computational methods are at the forefront of deciphering their structure and dynamics. Type IV DESs, composed of metal chloride and a hydrogen bond donor, are among the less studied systems when it comes to their understanding at a molecular level. An important example of such systems is the zinc chloride–urea DES, already used in chemical synthesis, among others. In this paper, the ZnCl2(urea)2 crystal is studied from the point of view of its structure, infrared spectrum, and intermolecular interactions using periodic density functional theory and non-covalent interactions analysis. The two main structural motifs found in the crystal are a strongly hydrogen-bonded urea dimer assisted by chloride anions and a tetrahedral Zn(II) coordination complex. The crystal is composed of two interlocking parallel planes connected via the zinc cations. The infrared spectrum and bond lengths suggest a partially covalent character of the Zn–Cl bonds. The present analysis has far-reaching implications for the liquid ZnCl2–urea DES, explaining its fluidity, expected microstructure, and low conductivity, among others.