1
|
Akshat R, Bharti A, Padmanabhan P. Atomistic molecular dynamics simulation and COSMO-SAC approach for enhanced 1,3-propanediol extraction with imidazolium-based ionic liquids. J Mol Model 2024; 30:164. [PMID: 38733431 DOI: 10.1007/s00894-024-05964-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 05/03/2024] [Indexed: 05/13/2024]
Abstract
CONTEXT 1,3-Propanediol (1,3-PDO) is a key chemical in various industries, including pharmaceuticals and material sciences, and is projected to see significant market growth. However, the current challenges in its downstream processing, particularly in terms of cost and efficiency, highlight the need for innovative solutions. Our study delves into using ionic liquids (ILs) as a potential alternative, aiming to address these critical separation challenges more sustainably and efficiently. In this study, we utilized molecular dynamics (MD) simulations and the COSMO-SAC to examine 1,3-propanediol (1,3-PDO) extraction using four imidazolium-based ionic liquids with 1-butyl-3-methylimidazolium [Bmim] cation and with different anions bis(pentafluoroethanesulfonyl)imide [NPF2]-, bis(trifluoromethylsulfonyl)imide [NTF2]-, thiocyanate [SCN]-, and trifluoromethanesulfonate [TFO]-. Molecular dynamics simulations, incorporating analysis of radial distribution functions (RDF) and spatial distribution functions (SDF), revealed that [Bmim][SCN] and [Bmim][TFO] exhibit enhanced interactions with 1,3-PDO. Notably, [Bmim][SCN] formed the most hydrogen bonds, averaging 1.639 per molecule, due to its coordinating [SCN]- anion. This was in contrast to the fewer hydrogen bonds formed by non-coordinating anions in [Bmim][NPF2] and [Bmim][NTF2]. In ternary systems, [Bmim][SCN] and [Bmim][TFO] demonstrated superior selectivity for 1,3-PDO extraction compared to the other ionic liquids, with selectivity values around 29. These findings, supported by COSMO-SAC predictive modeling, highlight the potential of [Bmim][SCN] as a promising candidate for 1,3-PDO extraction, emphasizing the importance of anion selection in optimizing ionic liquid properties for this application. METHODS In our study, we employed MD simulations, incorporating the OPLS-AA force field, and COSMO-SAC to investigate the extraction of 1,3-PDO using imidazolium-based ionic liquids: [Bmim][NTF2], [Bmim][NPF2], [Bmim][SCN], and [Bmim][TFO]. The MD simulations were conducted using LAMMPS software, focusing on elucidating the RDF, SDF, and hydrogen bonding. Analysis of the distribution coefficient (β) and selectivity (S) for the ternary mixture was also conducted. These aspects of the simulation were analyzed using TRAVIS and VMD software. Additionally, the COSMO-SAC model was employed to determine the activity coefficients of 1,3-PDO in the ionic liquids, with molecular optimization conducted using Gaussian16 and sigma profile calculations performed using COSMO-SAC.
Collapse
Affiliation(s)
- Raj Akshat
- Department of Bioengineering and Biotechnology, Birla Institute of Technology Mesra, Ranchi, Jharkhand, 835215, India
| | - Anand Bharti
- Department of Chemical Engineering, Birla Institute of Technology, Ranchi, Jharkhand, 835215, India.
| | - Padmini Padmanabhan
- Department of Bioengineering and Biotechnology, Birla Institute of Technology Mesra, Ranchi, Jharkhand, 835215, India.
| |
Collapse
|
2
|
Yuan Q, Feng W, Cheng L. Theoretical study of the saturation and nature of the hydrogen bonds to gold. J Chem Phys 2023; 159:174304. [PMID: 37916593 DOI: 10.1063/5.0171292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 10/16/2023] [Indexed: 11/03/2023] Open
Abstract
Traditional hydrogen bonds are well-known to exhibit directionality and saturation. By contrast, gold involved hydrogen bonds (GHBs) have been extensively studied but remain lack of in-depth understanding towards the intrinsic nature and saturation property. This work exemplifies three series of complexes: [L-Au-L]-⋯(HF)n (L = H, CH3, (CH3)3; n = 1-8) containing GHBs to dig into the intrinsic nature with the aid of multiple theoretical analysis methods, finding that the formation of GHB is highly subject to orbital interactions along with steric hindrance. Moreover, the saturation level of GHBs largely depends on the ligand attached to the gold center, since different ligands typically possess varying electron-giving ability and steric volume. This work confirms the coexistence of as many as 6 GHBs for one Au atom and thoroughly studies the saturation level of GHBs, which will provide new insights into GHBs and facilitate future synthesis of more complicated gold complexes.
Collapse
Affiliation(s)
- Qinqin Yuan
- Department of Chemistry, Anhui University, Hefei 230601, China
| | - Wanwan Feng
- Department of Chemistry, Anhui University, Hefei 230601, China
| | - Longjiu Cheng
- Department of Chemistry, Anhui University, Hefei 230601, China
- Key Laboratory of Functional Inorganic Materials of Anhui Province, Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials, Key Laboratory of Structure and Functional Regulation of Hybrid Materials (Anhui University), Ministry of Education, Hefei 230601, China
| |
Collapse
|
3
|
Pandey PK, Chandra A. Mechanism, Kinetics, and Potential of Mean Force of Evaporation of Water from Aqueous Sodium Chloride Solutions of Varying Concentrations. J Phys Chem B 2023; 127:4602-4612. [PMID: 37163726 DOI: 10.1021/acs.jpcb.2c09004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The mechanism, kinetics, and potential of mean force of evaporation of water from aqueous NaCl solutions are investigated through both unbiased molecular dynamics simulations and also biased simulations using the umbrella sampling method. The results are obtained for aqueous solutions of three different NaCl concentrations ranging from 0.6 to 6.0 m and also for pure water. The rate of evaporation is found to decrease in the presence of ions. It is found that the process of evaporation of a surface water molecule from ionic solutions can be triggered through its collision with another water or chloride ion. Such collisions provide the additional kinetic energy that is required for evaporation. However, when the collision takes place with a Cl- ion, the evaporation of the escaping water also involves a collision with water in the vicinity of the ion at the same time along with the ion-water collision. These two collisions together provide the required kinetic energy for escape of the evaporating water molecule. Thus, the mechanism of evaporation process of ionic solutions can be more complex than that of pure water. The potential of mean force (PMF) of evaporation is found to be positive and it increases with increasing ion concentration. Also, no barrier in the PMF is found to be present for the condensation of water from vapor phase to the surfaces of the solutions. A detailed analysis of the unsuccessful evaporation attempts by surface water molecules is also made in the current study.
Collapse
Affiliation(s)
- Prashant Kumar Pandey
- Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh, India 208016
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh, India 208016
| |
Collapse
|
4
|
Heindel JP, Hao H, LaCour RA, Head-Gordon T. Spontaneous Formation of Hydrogen Peroxide in Water Microdroplets. J Phys Chem Lett 2022; 13:10035-10041. [PMID: 36264238 DOI: 10.1021/acs.jpclett.2c01721] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
There is accumulating evidence that many chemical reactions are accelerated by several orders of magnitude in micrometer-sized aqueous or organic liquid droplets compared to their corresponding bulk liquid phase. However, the molecular origin of the enhanced rates remains unclear as in the case of spontaneous appearance of 1 μM hydrogen peroxide in water microdroplets. In this Letter, we consider the range of ionization energies and whether interfacial electric fields of a microdroplet can feasibly overcome the high energy step from hydroxide ions (OH-) to hydroxyl radicals (OH•) in a primary H2O2 mechanism. We find that the vertical ionization energies (VIEs) of partially solvated OH- ions are greatly lowered relative to the average VIE in the bulk liquid, unlike the case of the Cl- anion which shows no reduction in the VIEs regardless of solvation environment. Overall reduced hydrogen-bonding and undercoordination of OH- are structural features that are more readily present at the air-water interface, where the energy scale for ionization can be matched by statistically probable electric field values.
Collapse
Affiliation(s)
- Joseph P Heindel
- Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Hongxia Hao
- Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California94720, United States
| | - R Allen LaCour
- Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Teresa Head-Gordon
- Kenneth S. Pitzer Theory Center and Department of Chemistry, University of California, Berkeley, California94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
- Departments of Bioengineering and Chemical and Biomolecular EngineeringUniversity of California, Berkeley, California94720, United States
| |
Collapse
|
5
|
Pethes I. Towards the correct microscopic structure of aqueous CsCl solutions with a comparison of classical interatomic potential models. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
6
|
MD studies of methanol confined in the metal-organic framework MOF MIL-88B-Cl. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
7
|
Lin J, Oliver AG, Serianni AS. D-Mannosamine hydrochloride (2-amino-2-deoxy- D-mannose hydrochloride): ionic hydrogen bonding in saccharides involving chloride and aminium ions. Acta Crystallogr C Struct Chem 2022; 78:223-230. [DOI: 10.1107/s2053229622002121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 02/23/2022] [Indexed: 11/10/2022] Open
Abstract
D-Mannosamine hydrochloride (2-amino-2-deoxy-D-mannose hydrochloride), C6H14NO5
+·Cl−, (I), crystallized from a methanol/ethyl acetate/n-hexane solvent mixture at room temperature in a 4
C
1 chair conformation that is slightly distorted towards the C3,O5
B form. A comparison of the structural parameters of (I) with the corresponding parameters in α-D-glucosamine hydrochloride, (II), and β-D-galactosamine hydrochloride, (III)/(III′), was undertaken to evaluate the effects of ionic hydrogen bonding on structural properties. Three types of ionic hydrogen bonds are present in the crystals of (I)–(III)/(III′), i.e. N+—H...O, N+—H...Cl−, and O—H...Cl−. The exocyclic structural parameters in (I), (II), and (III)/(III′) appear to be most influenced by this bonding, especially the exocyclic hydroxy groups, which adopt eclipsed conformations enabled by ionic hydrogen bonding to the chloride anion. Anomeric disorder was observed in crystals of (I), with an α:β ratio of 37:63. However, anomeric configuration appears to exert minimal structural effects; that is, bond lengths, bond angles, and torsion angles are essentially identical in both anomers. The observed disorder at the anomeric C atom of (I) appears to be caused by the presence of the chloride anion and atom O3 or O4 in proximal voids, which provide opportunities for hydrogen bonding to atom O1 in both axial and equatorial orientations.
Collapse
|
8
|
Li W, Lei X, Feng H, Li B, Kong J, Xing M. Layer-by-Layer Cell Encapsulation for Drug Delivery: The History, Technique Basis, and Applications. Pharmaceutics 2022; 14:pharmaceutics14020297. [PMID: 35214030 PMCID: PMC8874529 DOI: 10.3390/pharmaceutics14020297] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/28/2021] [Accepted: 01/24/2022] [Indexed: 12/17/2022] Open
Abstract
The encapsulation of cells with various polyelectrolytes through layer-by-layer (LbL) has become a popular strategy in cellular function engineering. The technique sprang up in 1990s and obtained tremendous advances in multi-functionalized encapsulation of cells in recent years. This review comprehensively summarized the basis and applications in drug delivery by means of LbL cell encapsulation. To begin with, the concept and brief history of LbL and LbL cell encapsulation were introduced. Next, diverse types of materials, including naturally extracted and chemically synthesized, were exhibited, followed by a complicated basis of LbL assembly, such as interactions within multilayers, charge distribution, and films morphology. Furthermore, the review focused on the protective effects against adverse factors, and bioactive payloads incorporation could be realized via LbL cell encapsulation. Additionally, the payload delivery from cell encapsulation system could be adjusted by environment, redox, biological processes, and functional linkers to release payloads in controlled manners. In short, drug delivery via LbL cell encapsulation, which takes advantage of both cell grafts and drug activities, will be of great importance in basic research of cell science and biotherapy for various diseases.
Collapse
Affiliation(s)
- Wenyan Li
- Department of Neurosurgery, First Affiliated Hospital, Army Medical University, 30 Gaotanyan Street, Chongqing 400038, China; (W.L.); (X.L.); (H.F.)
| | - Xuejiao Lei
- Department of Neurosurgery, First Affiliated Hospital, Army Medical University, 30 Gaotanyan Street, Chongqing 400038, China; (W.L.); (X.L.); (H.F.)
| | - Hua Feng
- Department of Neurosurgery, First Affiliated Hospital, Army Medical University, 30 Gaotanyan Street, Chongqing 400038, China; (W.L.); (X.L.); (H.F.)
| | - Bingyun Li
- Department of Orthopaedics, School of Medicine, West Virginia University, Morgantown, WV 26506, USA;
| | - Jiming Kong
- Department of Human Anatomy and Cell Science, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB R3E 0J9, Canada
- Correspondence: (J.K.); (M.X.)
| | - Malcolm Xing
- Department of Mechanical Engineering, University of Manitoba, 75 Chancellors Circle, Winnipeg, MB R3T 5V6, Canada
- Correspondence: (J.K.); (M.X.)
| |
Collapse
|
9
|
Insights on choline chloride-based deep eutectic solvent (reline) + primary alcohol mixtures: a molecular dynamics simulation study. J Mol Model 2022; 28:30. [PMID: 34993665 DOI: 10.1007/s00894-021-05017-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 12/23/2021] [Indexed: 10/19/2022]
Abstract
Deep eutectic solvents (DESs) emerged as green solvents for new generation technologies owing to their high chemical and thermal stability. Addition of restricted amount of organic solvents into the DESs plays a significant role in the improvement of thermodynamic and the transport properties to work as a potential solvent in process industries. In this paper, molecular dynamics (MD) simulations were performed to understand the thermophysical and transport properties of choline chloride-based DES (reline) and primary alcohol (methanol and ethanol) mixture in relation to microscopic structure. Density, radial distribution function, coordination number, average number of H-bond, diffusion coefficient and spatial distribution function was calculated in order to understand the structure and involvement of H-bond network at an atomic level. H-bond and spatial distribution function analyses revealed that the chloride ion prefers to be spatially distributed around hydroxyl group of alcohol and found to be more pronounced upon increase in alcohol concentration. As a consequence, it was observed that the H-bonds between Cl- and urea decreases overall with the loading of alcohol and effect is more pronounced beyond a concentration of 0.4. Self-diffusion values for choline, Cl- and urea were found to be increased significantly upon increase in concentration of alcohol from 0.6 to 0.8. Overall, our simulation points to the interplay and interactions between the chloride ions and the solvents in determining the structural and transport properties of choline chloride-based DES.
Collapse
|
10
|
Sarkar S, Maity A, Chakrabarti R. In Silico Elucidation of Molecular Picture of Water-Choline Chloride Mixture. J Phys Chem B 2021; 125:13212-13228. [PMID: 34812630 DOI: 10.1021/acs.jpcb.1c06636] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Choline chloride (ChCl) is a component of several deep eutectic solvents (DESs) having numerous applications. Recent studies have reported manifold promising use of aqueous choline chloride solution as an alternative to DES, where water plays the role of the hydrogen-bond donor. The characteristic physical properties of the DESs and aqueous DES originate from the "inter-" and intraspecies hydrogen-bond network formed by the constituents. However, a detailed molecular-level picture of choline chloride and water mixture is largely lacking in the literature. This motivates us to carry out extensive all-atom molecular dynamics simulations of the ChCl-water mixture of varying compositions. Our analyses clearly show an overall increase in the interspecies association with an increase in ChCl concentration. At higher concentrations, the trimethylammonium groups of choline are stabilized by a nonpolar interaction, whereas the hydroxyl groups preferentially interact with water. Chloride ions are found to be involved in two types of interactions: one where chloride ions intercalate two or more choline cations, and the other one where they are surrounded by five to six water molecules forming solvated chloride ions. However, the relative fractions of these two types of associations depend on the concentration of ChCl in the mixture. Another important structural aspect is the disruption of the hydrogen-bonded water network due to the presence of both choline cations and chloride ions. However, chloride ions participate to partially restore the tetrahedral arrangement of partners around water molecules.
Collapse
Affiliation(s)
- Soham Sarkar
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
| | - Atanu Maity
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
| | - Rajarshi Chakrabarti
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
| |
Collapse
|
11
|
Aldakkan BS, Hammami MA, Qi G, Kanj MY, Giannelis EP. Stimuli-Responsive, Hydrolyzable Poly(Vinyl Laurate- co-vinyl Acetate) Nanoparticle Platform for In Situ Release of Surfactants. ACS APPLIED MATERIALS & INTERFACES 2021; 13:25553-25562. [PMID: 34006101 DOI: 10.1021/acsami.1c04977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A stimuli-responsive, sub-100 nm nanoparticle (NP) platform with a hydrolyzable ester side chain for in situ generation of surfactants is demonstrated. The NPs were synthesized via copolymerization of vinyl-laurate and vinyl-acetate [p-(VL-co-VA), 3:1 molar ratio] and stabilized with a protective poly(ethylene-glycol) shell. The NPs are ∼55 nm in diameter with a zeta potential of -54 mV. Hydrolysis kinetics in an accelerated, base-catalyzed reaction show release of about 11 and 30% of the available surfactant at 25 and 80 °C, respectively. The corresponding values in seawater are 22 and 76%. The efficiency of the released surfactant in reducing the interfacial tension, altering wettability, and stabilizing oil-water emulsion was investigated through contact angle measurements and laser confocal scanning microscopy and benchmarked to sodium laurate, a commercially available surfactant. All these measurements demonstrate both the efficacy of the NP system for surfactant delivery and the ability of the released surfactant to alter wettability and stabilize an oil-water emulsion.
Collapse
Affiliation(s)
- Bashayer S Aldakkan
- Department of Materials Science and Engineering, Cornell University, Ithaca 14850, New York, United States
| | - Mohamed A Hammami
- Department of Materials Science and Engineering, Cornell University, Ithaca 14850, New York, United States
| | - Genggeng Qi
- Department of Materials Science and Engineering, Cornell University, Ithaca 14850, New York, United States
| | - Mazen Y Kanj
- College of Petroleum Engineering & Geosciences, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia
| | - Emmanuel P Giannelis
- Department of Materials Science and Engineering, Cornell University, Ithaca 14850, New York, United States
| |
Collapse
|
12
|
Grabowska J, Kuffel A, Zielkiewicz J. Revealing the Frank-Evans "Iceberg" Structures within the Solvation Layer around Hydrophobic Solutes. J Phys Chem B 2021; 125:1611-1617. [PMID: 33539702 PMCID: PMC7898264 DOI: 10.1021/acs.jpcb.0c09489] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Using computer simulations, the structural properties of solvation water of three model hydrophobic molecules, methane and two fullerenes (C60 and C80), were studied. Systems were simulated at temperatures in the range of 250-298 K. By analyzing both the local ordering of the molecules of water in the solvation layers and the structure of hydrogen bond network, it is shown that in the solvation layer of hydrophobic molecules, ordered aggregates consisting of water molecules are formed. Even though it is difficult to define the exact structure of these aggregates, their existence alone is clearly noticeable. Moreover, these aggregates become more pronounced with the decrease of temperature. The existence of the ordered aggregates around the hydrophobic solutes complies with the concept of "icebergs" proposed by Frank and Evans.
Collapse
Affiliation(s)
- Joanna Grabowska
- Faculty of Chemistry, Department of Physical Chemistry, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
| | - Anna Kuffel
- Faculty of Chemistry, Department of Physical Chemistry, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
| | - Jan Zielkiewicz
- Faculty of Chemistry, Department of Physical Chemistry, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
| |
Collapse
|
13
|
Agieienko V, Buchner R. Dielectric relaxation of deep eutectic solvent + water mixtures: structural implications and application to microwave heating. Phys Chem Chem Phys 2020; 22:20466-20476. [DOI: 10.1039/d0cp03334k] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
All dipolar species at their full individual strengths but synchronized in motion: structural implications of cooperative dynamics in glyceline/water and reline/water mixtures.
Collapse
Affiliation(s)
- Vira Agieienko
- Department of Physical Chemistry
- A. M. Butlerov Chemical Institute
- Kazan (Volga Region) Federal University
- 420008 Kazan
- Russian Federation
| | - Richard Buchner
- Institut für Physikalische und Theoretische Chemie
- Universität Regensburg
- D-93040 Regensburg
- Germany
| |
Collapse
|